Human eye response

I find it very interesting that it's completely impossible for us as a species, to see true dynamic range. We don't actually see the world the way it really is - our eyes compress luminosity so that everything in the upper regions all looks the same:

The human eye compresses luminosity. In other words, we are unable to see true dynamic range. It is a physical impossibility. Digital cameras can however see the true dynamic range. Even so, just because they can, does not mean they render images the way we see them. We need to use grads to do that.

The human eye compresses luminosity. In other words, we are unable to see true dynamic range. It is a physical impossibility. Digital cameras can however see the true dynamic range. Even so, just because they can, does not mean they render images the way we see them. We need to use grads to do that.

We are in fact, all blind to true luminosity in the real world. Whereas digital cameras aren't: they are able to see that the sky is 4 stops brighter than the ground. But just because they can see it - it doesn’t mean digital cameras are giving us what we want. It just means that digital cameras don’t see the way we see. And that’s the important bit.

We tend to view everything we look at, as a mid-exposure. When I look at the sky, in my mind I see a mid-exposure of it. And when I look at the ground, I see a mid-exposure of it also. As my eye scans around, I build up an internal representation of the world - a collage or collection of mid-exposures.

This is why I don't agree with the concept that 'if a scene can fit inside the entire histogram, then we don't need grads'. This belief, lacks understanding of what it is we are trying to do with grads in the first place and also what a histogram represents.

Image shot without a grad. Sky is overexposed while ground is underexposed. Although it is contained within the histogram, and is a true representation of what is there, it does not match how the eye perceives the scene  (the human eye compresses dynamic range whereas digital cameras do not),

Image shot without a grad. Sky is overexposed while ground is underexposed. Although it is contained within the histogram, and is a true representation of what is there, it does not match how the eye perceives the scene (the human eye compresses dynamic range whereas digital cameras do not),

With a grad in place, the dynamic range of the scene is reduced - but not only that - the ground values move towards the mid-tone area (right) of the histogram, while the sky tones move towards the left (mid-tone) area of the histogram. Giving an image that is closer to how our eye sees.

With a grad in place, the dynamic range of the scene is reduced - but not only that - the ground values move towards the mid-tone area (right) of the histogram, while the sky tones move towards the left (mid-tone) area of the histogram. Giving an image that is closer to how our eye sees.

In the images above, the left-hand one is an example of what happens when I don't use grads. The image may well 'fit into the histogram', but the ground is underexposed and the sky is overexposed:

The left-hand side of the histogram represents dark tones while the right-hand side represents bright tones. I now have a muddy underexposed ground (left-hand side of the histogram) and overexposed sky (right-hand side of the histogram).

So everything fits, but the image sucks.

And the thing about histograms is: Just because you have the space - it doesn't mean you have to fill it. 

The problem is, my eye doesn't see the ground as a dark area, nor the sky as a bright area. My eye tends to perceive them both as similar to each other and as a mid-tone. So if I wanted my histogram to represent what I saw, I would expect to see a 'single humper' histogram like this one:

One where the ground is a mid-tone and the sky is a mid-tone too. In effect, the ground and sky would share the same area of the histogram. 

And that's where grads come in, because they do this for us. They not only push the sky from the right side of the histogram to the middle tone, they also move the ground from the left side of the histogram towards the middle tone. Yep, grads not only darken the sky - they also brighten the ground because they reduce the dynamic range or width of the histogram. Since your camera is always aiming for an 18% mid-tone, everything moves towards the middle: sky goes left and ground goes right.

Again: just because you have the space - it doesn't mean you have to fill it :-)

If you do choose to use grads, there are a couple of benefits to using them:

1) You will have more space in the left-hand side for more shadow tonal information. When you don't use grads and squeeze everything into the histogram you push the ground to the left - and underexpose it. And when underexposing - you tend to compress (or quantise) different lower tones into fewer tones. Twenty discreet tones are summed into one or two tones. However, If you use grads, you open up the shadows by moving the ground towards the middle area of the histogram and this compression becomes less of an issue.

2) Conversely, the same is true for the sky. You have more space on the right for more tonal gradations and you record more tonal graduations. If you didn't use grads - many of the brighter tones are squeezed together or quantised - several tones become one in an attempt to fit it all into the dynamic range of the camera.

3) If you use grads the RAW image doesn't suck so much to look at.

Point 3 is perhaps the most important one for me. If we put all the science to one side, I'd much rather come home with something that already looks inspiring to work with.  A more balanced exposure through the use of grads will do that for me.  I wish to be engaged when I review the RAW files,   I don't wish to have to think about jumping through some additional hoops before I can figure out if there is anything of value there. If I don't use grads, I may let a few images fall between the cracks if I have to do additional processing before I can visualise if the image holds promise.

So for me, coming home with a more pleasing balanced image that requires less work to see if there is potential, is the most important aspect for using grads.

But that's just me. Which of the two images above would you choose to come home with?

Grad Filters - soft graduations or hard graduations?

Lee filters introduce two new graduations of ND filter

In April,  Lee-Filters announced two new graduation sets to their ND product range. Up until now, you had the choice of either soft-graduation or hard-graduation ND filters. Now you have two further choices - very-hard-graduation and also medium-graduation filters.

Lee filters have just introduced a new 'very-hard' and also a new 'medium' graduation filter set to their existing line of soft and hard ND-grad sets.

Lee filters have just introduced a new 'very-hard' and also a new 'medium' graduation filter set to their existing line of soft and hard ND-grad sets.

I currently own the 1, 2 & 3 stop versions of both soft and hard-grad filters. They are useful in many different ways. But with the news of the newer graduation types, I think my filter set is going to change.

Soft or Hard, which should you choose?

Each year when I send out my trip notes for the workshops I'm running, I ask everyone to buy the hard-graduation filters. Despite some participants reluctance to get the hard-grads because they think the graduation may be too obvious (it's not) in the picture, I find the existing Lee hard-grads just about right for most applications.

The reason is that Hard grads are actually quite diffused once they are put up so close to the front of the lens. They give enough bite to change the picture, and do so without being too obvious where their placement is. They are perfect for when you just want to grad the sky only.

Soft grads on the other hand are too soft for just grading the sky - their bite doesn't cut in as much as I'd like. But I do find that Soft-grads have other uses: they are ideal for instances when there is a gradual change from the bottom of the frame to the top. Instances like lakes where the water is extremely dark at the bottom of the frame and it gets brighter towards the horizon. Using soft grads across the middle of the water help control that.

So in general: hard grads are for controlling the sky when there is a sudden shift between ground and sky. Soft grads are useful for scenes where the entire scene changes gradually as you move up the frame.

Grad Placement may not be so critical, and here's why

It really depends on the focal length. Smaller focal-lengths provide a sharper rendering of the graduation whereas larger focal-lengths diffuse the graduation, making hard-grads softer.

If you zoom out - the graduation becomes more defined. And as you zoom in, the graduation becomes more diffused. With a hard-grad it means it's a hard-grad at 24mm but it starts to act more like a soft-grad when used at 75mm. Soft grads are soft at 24m but they become far too soft once you get up to and beyond 75mm.

I illustrate this below. Using the same hard-grad, I zoom in from 24mm to 150mm. As I do so, the graduation becomes softer. I am essentially zooming into the graduation:

Using the same hard-grad, as I go up the focal lengths from 24mm to 150mm, the graduation becomes more diffused. My hard-grad essentially becomes a soft-grad at 150mm.

Using the same hard-grad, as I go up the focal lengths from 24mm to 150mm, the graduation becomes more diffused. My hard-grad essentially becomes a soft-grad at 150mm.

I have a medium-format rangefinder system. I can't see through the lens, but I've never had a problem with placing the hard-grads, and it's all because of a combination of them being so diffused so close to the lens, and the higher focal lengths. My wide angle is a 50mm for example.

Which Graduations should I choose, and why?

Your choice of camera format will also determine how your grads will behave.  Smaller-formats user smaller focal lengths, while larger formats use larger focal lengths for the same angle of view. For example, a 24mm lens in 35mm format has the same angle of view as a 50mm does in medium-format. But the same grad used on a 24mm will be more defined than if it were used on a 50mm, even though both lenses give the same angle of view.

In the graph below, I show the equivalent focal lengths for the 'same angle of view' as you go up the formats from MFT (Micro-Four-Thirds) to Large format. You can see that the focal lengths get longer and longer. This means that your soft-grad filter will become softer and softer as you move up the formats.

As you go up the formats, the focal lengths get longer for the same angle of view. This also means that any hard-grads you buy become softer as you move up for camera formats. Or harder as you go down the formats.

As you go up the formats, the focal lengths get longer for the same angle of view. This also means that any hard-grads you buy become softer as you move up for camera formats. Or harder as you go down the formats.

So it's not just a simple case of choosing soft grads over hard ones, because you think they will be less noticeable in the final image. You also have to take into account the focal lengths you're using.

In my own case, I use Medium Format cameras, and I mostly use hard-grads because they give me the right amount of graduation across the frame for the focal lengths I mostly use (50 and 80). When I use the hard-grads with the 50mm, the placement isn't so critical as there's a degree of diffusion there already, but the filter still bites into the image enough to make hard-grads a viable choice. When I use soft-grads though, they tend to be too diffused for the focal lengths I use. 

Which of the new range will I be tempted to get?

Since I'm a medium format shooter, I'm tempted to replace most of my soft-grads with the new medium grads. The medium-grads will give me what I am looking for (but not getting) from my soft-grads.

I will remain using the standard hard-grads, as they are perfect for my wide and standard lenses, but I am interested in buying some very-hard-grads for use with my telephoto lenses. As explained, when you get up to such high focal-lengths, hard-grads become less and less effective.

Using different types of graduation is a key component to good exposures. I've found for many years that I could do with some graduation filters that are somewhere between the old hard-grad and soft-grad sets, and there is also cause to have very-hard grads for use when using higher focal lengths. So for me, I will be buying some of the medium-grads and very-hard grads to compliment my ever-growing set of ND filters.

Lee Seven5 Filter System Review

For a very long time, I've used Lee 100mm neutral density filters in my landscape photography. Neutral Density filters are, I feel, a vital piece of kit that all landscape photographers should own. The Lee system is in my experience the best you can get. I feel I can say this with some authority as I've had the privilege of working with all the filter manufacturers products over the past six years I've been running workshops.

Most pro-end filters are perfectly fine in terms of optics and colour rendition, but I've found many manufacturers products fall short in terms of filter holder design (i.e lack-of) or in being used in a compounded fashion - stack more than one filter together and an evident magenta colour cast will surface. It's always there, but it varies from manufacturer to manufacturer. I have however, found the Lee filter system to be the least prone to colour casts, provided that the filters haven't aged. It's unfortunately the case that all filters tend to lose the colour accuracy over time as the dyes begin to fade. All Lee filters are date stamped and they recommend you replace them every three years or so (this is usually a non-issue for me, as I tend to use them so much, that I wear our my gear a lot earlier than that).

ND (Neutral Density) filters are essential in controlling the dynamic range and exposure between ground and sky - not just with film, but also with digital capture. If you're uncertain about their benefit, then I can't state how important they are. Even the 1 stop Hard-grad is vital. But you do need to buy a good quality set. Don't cut corners by going cheap - you'll regret it.

Anyway, this posting is about the miniature filter system by Lee. It's called the Seven5 filter system. It's been designed for compact systems and the filters are therefore considerably smaller than it's big-brother 100mm filters.

I've been meaning to write a review of the Lee Seven5 filter system for some time now. This review is primarily aimed at those who are thinking of using this system with a small format camera system such as a Micro-Four-Thirds format up to 35mm rangefinder.

I bought my set of Seven5 filters because I was looking for a compact filter system that would work with a little Lumix GX1 Micro-Four-Thirds system I bought for illustrative and teaching purposes on my workshops. I'm not a digital shooter, preferring to work with film for all of the work you see on this website. So I wanted a small camera format that was very compact. The Lumix GX1 along with a Panasonic 12-35 lens is what I chose, and the Seven5 filter system fitted the bill in terms of compactness.

The good

It's really compact. I like the filter holder and the adaptor rings. The filter holder is especially simple and it comes with the polariser attachment already built in.

Which brings me on to the polariser. What I've always liked about the Lee system is that the polariser fits on to the front of the holder.Which makes it much easier to rotate while keep the grads where they are. The only downside in this approach is that the polariser needs to be a lot larger to avoid vignetting (which is a costly exercise as the filter for the normal system is 105mm).

The Seven5 polariser is easy to fit onto the holder in one short rotation. The 100mm filter system on the other hand requires you to thread the filter on and off. I've never liked this - so much so - that I bought two filter holders - one for general grad use, while the other has the polariser permanently attached. It's much easier to swap filter holders than it is to thread and unthread a filter from one holder. With the Seven5 system this problem has been removed all together - it's a simple snap and rotate to lock it on and remove it quickly too. Very nice.

The bad

Whoever designed these filters for use of smaller systems assumed that the diameter of the lenses would be smaller than those of 35mm lenses, which in most cases isn't true. I've used these filters on a Micro-Four-Thirds system for a while now, and they don't cover the entire area of the lens when you wish to place the grad around 3/4 of the way up the frame - particularly when composing in portrait orientation. It's not uncommon to find the filter is not long enough with the bottom edge protruding into the lower region of the image. I think this was a design constraint to keep the whole system compact, but it does impact their use.

The other thing that I find confusing is the degree of 'suddenness' of the graduation in each of the hard-grad filters. They're too sudden for systems such as Micro-Four-Thirds or even 35mm cameras.

I have some thoughts on why extremely sudden grads don't work with small-format systems.

Hard-Grad's tend to be more obvious on wide angle lenses than telephotos because when a shorter focal-length is used, we're really zooming-out of the image and are therefore zooming out of the graduation. If we go the other way and go up the focal-lengths, then we're really zooming into the graduation - so the graduation becomes more and more diffused as we zoom up. So using sudden graduations like the ones that Lee produce for the Seven5 system on systems such as Micro-Four-Thirds where the focal lengths are smaller - (for example - an equivalent angle of view to 50mm on MFT is 25mm), it becomes apparent that the graduations are going to be more evident.

I should at this point make it clear that I use hard-grads most of the time. They are used far more often than soft grads - which are really for use in controlling more gradual tonal changes across the entire frame rather than for controlling the contrast between sky and ground. So it's not that hard-grads are too sudden in per se - they're not - they usually work very well for most of the situations I encounter in my landscape work. I do get emails asking about the correct placement, but these questions usually hint at the wrong strength of filter being used - if you can see the graduation - it's probably because you're using too strong a filter.  Hard grads aren't too sensitive to correct placement provided the strength is about right.

One last thing, I wish someone would produce a nice little filter bag for the Seven-5 system. I don't see the point in owning small filters, only to store them in a large bag. It kind of defeats the purpose of going compact.

In Summary

So my two main issues with this filter system are this:  Using it with small format systems, the filters are often too short (have less travel than I need for grad placement) and the hard-graduations themselves are too obvious / sudden.

If you already own the Lee 100mm filter system, it would recommend buying these for one reason - if you feel going compact is of the utmost importance for you. I can fully appreciate that a compact filter system for Leica Rangefinder users and smaller formats is very attractive. It certainly was for me when I chose to buy these.

Although the 100mm filters are considerably larger and bulkier, the graduations and filter-travel are just about right for using on any system from Micro-Four-Thirds upwards, so again, i'd only opt for the Seven5 system if compactness is the driving force behind your need to buy them.

Despite these points, I'm still happy I bought mine and I've learned to live with the limitations of the filter system because for me, it's the compactness of the design that was the essential aspect of buying them in the first place.

Probably the best filter bag in the world

Last year, I wrote a review about the Kinesis filter bag.

Before I continue, I would like to make it very clear that I love this bag very much and it has become my favourite filter bag of all time. I can't recommend this bag highly enough.

Just shortly after publishing my review, I was alerted that there is a problem with the bag ‘outgassing’. The concern seemed to be about the material within the bag releasing a gas that seems to leave a residue on the filters.

kinesis Large Grad Pouch, goes around your tripod collar, for easy access to the 'indexed' card system of filters inside.

At the time, I did some testing of my bag and found that this did seem to be the case. I was very disappointed because I love the design of the bag and it is extremely functional. But I decided to change to the Lowe Pro filter bag.

To try to cut what is already a long story short, I found the Lowe Pro bag had the same problems. In fact, I would say that probably any newly manufactured filter bag would probably releases gas or chemicals, simply because it is new.

With both filter bags, I found that after a few months, the issue was no longer there. I can only surmise that this is something to do with newly manufactured materials, and in no way does it affect the life of your filters.

I've been using the Kinesis now for the past 9 months or so and have really grown to love it. It is my favourite filter bag of all time, mainly because of how functional it is: It has a lovely little strap that allows me to hang it around my tripod collar where I have instant access to all my filters like a little indexing system. I can heep my head at camera level and if I need to change filters, there's no moving over to the bag to find them and there's no wondering where to put the filter bag either. It works 'with me'.

Also, because the filters are stored sideways and are all accessible like a filing system, I can easily drop a filter back in its slot, and pull another out.

I keep all my filters in this bag now, and I have them ordered in the following way, so I know where everything is, without any fidgeting whilst on location:

1 stop ND 2 stop ND 3 stop ND 3 stop ND (yes, I have two, as sometimes I use 6 stops ND) 1 stop soft grad 2 stop soft grad 3 stop soft grad 1 stop hard grad 2 stop hard grad 3 stop hard grad

As many of you may know, I really believe in 'process'. I keep everything in the same place all the time, because it cuts down on any delay in working in the field. When everything is in the same place, your hand just reaches for the right object based on muscle memory.

This ‘order’ works for me very well, and the bag also has enough space to leave some lens cleaning cloths inside it, or even store the entire lee filter holder (With filters already mounted) when I need to take the holder off the camera.

In short, the bag has become a spare pair of hands for me now, and I will often put in the dark slide for my Hasselblad camera, or anything that needs to be taken off the camera for a few moments. I've never known where to put things when I need to take them off the camera for a few moments, and often lie filters on rocks or on the top of my camera bag. That little strap around the filter bag keeps the filters where they need to be - within easy reach.

I should warn you that this bag is a bit bigger than most filter bags, but it's ergonomics makes me want to take it with me at all times.

If you would like to read the original review about the Kinesis filter bag, then it is here.

Kinesis Large Grad Filter Pouch

If you've got a lot of ND and ND grad filters like I have, then you're probably making do with the (cloth) Lee Filter case. I have the excellent leather access case - see below -  (but it's rather heavy out in the field and it only stores six filters). It is a great filter case, sturdy, and has amazingly quick access to my filters. I've had no complaints using it, except perhaps the weight of it, and the fact that I could do with a few more slots for a couple of more filters.

I personally detest the cloth case made by Lee. The zip makes getting access to the filters cumbersome, and once i've got the case open (like a book - using both hands), I have to go through each page in the holder to guess which filter is in each cloth cover. If I'm using the ND filters - which are square, they are buried deep within one of the cloth pages, and it can take a while to fish them out.

I hate faffing (a UK term for fidgeting).

Anything that causes me any delay in making the images I'm seeing open up in front of me - must go. I've discarded a lot of equipment over the years because it's either too cumbersome, or simply it gets in the way. You'd be surprised how much stuff isn't made to do the job it's advertised to do. Well, the Lee case isn't quite in that territory - it works, but it's a little fidgety for me.

Each month on my workshops, I get folks coming along with the latest and greatest cameras, tripods and bags. The past few months I've started to see the Kinesis Large Grad Filter Pouch on my trips and I've just placed an order for one today (Kinesis have a problem with their web site which means you have to email them to buy anything from them if you are not in the US - get this sorted out Kinesis! You'll be losing a lot of trade from this!).

The pouch as you can see is like a mini filing cabinet. I like how the filters are stored sideways, and there are some nice velcro labels attached to each section so you can find the right filter quickly. Access is a breeze. No horrible zip to undo, no filters falling out all over the place either. The filters are tightly packed together, and there's ample room in there for quite a number of them too.

I can't stress how important 'process' is to my photography. I have all my gear organised. I put things away in the places they were before I used them, because it means I don't have to spend time hunting (faffing). Likewise, I dumped the Lee cloth case because it's just a pain to use. I never zip it up because it takes a lot of time to unzip it round three edges of the case. The Kinesis has been designed with thought and care. It doesn't just store your filters - it has been put together to give you quick and easy (read organised) access.

Highly recommended.

HiTec 10 stop ND filter

I had a Lee Big-Stopper filter, which I don't use much, as my film cameras go into seriously long exposures due to reciprocity effect, but I do use the 10 stop now and then. Well, I used to, because mine shattered to pieces. I love the Lee filter system. It's extremely high quality, but I've always gotten along fine with the resin filters they do, so I don't own any glass ones now (broke them all), whereas my resin 3 stop is still going strong after many years of service.

I just learned today that HiTec do a 10 stop filter made of resin, that you can buy (in two variants - one for the HiTec holder and the other for use with a Lee filter holder). I've just ordered one and hope it will have many years of service (for the rare times I intend to use it).  The good news is that it's also cheaper than the Lee Big-Stopper too, and it's widely available. I was able to place an order on Teamwork Photo's website today for two of them and they're dispatching tomorrow!

If your Lee Big Stopper is still in one piece, may I suggest you get some hard case for it, to protect it. Mine broke simply because it was in the pouch that Lee provided it in, tucked inside my camera bag. I've heard similar stories from others too.

Good luck!

ND Grads and Rangefinders

In 2008 I wrote an article on this blog regarding how to place ND grads on a rangefinder camera. I've since then had the occasional email from someone about how to correctly place them and I'd like to add some additional things to my original posting about this issue. I'd firstly like to start by saying that I like mistakes in my photography. I like the surprise element so I'm not too bothered whether the grad placement is exact. If I like the results, and they're pleasing to me, then that's all that I'm bothered about.

Here are a few examples of images where I really got the grad placement really wrong, and yet the images (in my opinion - which is really all that matters) are a success because of the wrong placement:

I was aware when shooting the Calanish standing stones, that placing the grad half way across them would cause the top parts of the stones to be black and the bottom parts to be correctly exposed. I wanted to make sure the sky was the same luminance as the ground so I placed the grad right above them and hoped for the best. The final image you see here has an almost halo like effect in the sky - this has been caused by the natural light fall-off that the lens exhibits being compounded by the grad. Yes, my Mamiya 7 lenses exhibit light fall-off. It is quite pronounced in the wide angles and I love the effect very much. I really like this image and felt it worked very well because the top 1/3rd of the sky is similar in tone to the lower tones of the grass.

I think one of the biggest mistakes folks make when using grads is to assume they should always go over the horizon. They don't always have to be.

And with this image taken on the Isle of Eigg, I can't quite remember my justification for keeping the grad so high - perhaps I just forgot to adjust it when I'd changed composition (this is a common mistake for a lot of photographers - rangefinder or not). Anyway, I love the effect that the grad caused and I feel it's added a lot of mood to the shot. Now imagine if I'd placed the grad correctly - would the image be as dramatic? I don't think so.

But what if the grad is just slightly too high, just not quite right? Well, in the next image, I managed to place it in the wrong place:

I think my reasons for leaving the grad a little high above the horizon was that I was worried that I'd perhaps compress the tones in the Isle of Rum on the horizon - and therefore  under-expose the island. So I opted for moving the grad slightly higher, but managed to move it just a bit too high. Does it kill the image? Well, it's a personal taste question, but for me, I prefer when grads are just slightly above the horizon, as I kind of expect horizons to be bright. It gives a sense of presence to an image, so in that way, I don't think the bright horizon is too much of an issue. But now that I've pointed out to you that the grad is in the wrong place - you'll probably feel the image has an issue. If that's true - it's your problem and not mine. I feel that I'm able to take a step further away from the image and just see it in its entirety. And when I look at it, like someone would who is viewing it for the first time - I don't notice the grad placement - there's simply far too much else of interest going on for me. So I think the lesson with this is to be able to not focus on something too much. Once you notice a problem, you tend to stare at it..... once you point out a problem, everyone notices it. But if you hadn't pointed it out, most folks I reckon, wouldn't see it. What others see and what you see are two very different things.

But I'm sure there are images where the grad placement is critical. I certainly get emails from folks who tell me the grad placement was very noticeable, and for that, I'd like to suggest that the reason it is so noticeable, is because they've used too strong a grad in the first place. The tell tale signs for too strong a grad are usually overly bright grounds and dark skies. Sure, it looks dramatic, but it also suffers from being extremely sensitive to where the grad is placed. So maybe this is a lesson in easing off the strength of grad you use, and learning to tell which lighting conditions and times of day will require a 1 stop rather than a 3 stop, or a 2 stop rather than a 3 stop.

Ultimately, I don't think grad placement is really the problem. If you use the right strength of grad, over a subject which doesn't have such a dramatic change in light levels, then a little bit of bad placement shouldn't really be a problem.

Lastly, If you still think grad placement is a real problem for you - then Lee Filters now have a Rangefinder ND grad set, with a special holder with markings on it, to aid in the correct placement of the filters. I'd give that a go, if my advice doesn't help you in any way.

BIG STOPPER

I've been in contact today with Robert White, a fantastic camera shop here in the UK about buying the new Lee Filter Big Stopper. If you've not heard about the Big Stopper yet, it's a 10 stop full ND filter which basically greatly reduces the amount of light coming into your lens, so you can go crazy doing long exposures.

I'm a big fan of the Lee filter ND Grads and full ND's. They are very neutral. Over the past two years of doing my workshops, I've seen many people come on trips and try to cut corners by buying Cokin filters. Only to be disappointed by the poor filter holder and the colour shifts that are apparent in the filters.

So as much as Lee filters are expensive, they're very worth it in my opinion. But what I didn't know was just why the filters are so expensive, and when you hear how they are made, you'll have a better appreciation for the costs that they sell them at.

As usual, I got into a discussion about the terrible waiting times for any of the Lee Resin and Glass filters and the chap at Robert White started to tell me about the filter making process. He said that it takes roughly 1 hour to make a resin or glass filter. They're hand made and dipped into boiling dye. Depending on how hard or soft the graduation should be, they are dipped in at different rates. Then each filter is checked against a spectrometer for colour shifts and the filter is re-applied to another vat of dye to correct the colour shift. At each stage, they have to monitor the light fall off for each filter. It really is a long process.

When I considered this, it made me realise that the filters are pretty cheap considering how much time and effort goes into making them.

I've got a big stopper on back order (4 to 6 weeks). I love using full ND filters in the early morning light, but a 10 stop filter is more a requirement for mid day shooting (for me anyway - I shoot film, so I can't really go more than a few minutes on Velvia before something horrible happens).

Metering for dynamic range

It's a cold hard fact, but in case you didn't know it - photography is not 'real'. We don't capture reality as it is with a camera. You might wonder what I'm on about, but let me explain further. Firstly, a camera sees in 2D, whereas we see in 3D. But also, our perception is a lot more different than a camera sees because we have far greater 'dynamic range'. We are able to register detail in shadows and highlights that a film or digital camera can only dream about.

sekonic.jpg

ISO 50, f4 = average reading of 1/4 second, 5 stop dynamic range where shadows are at 2s and highlights are at 20th of a second

This point is mainly the reason for why we often get images back from the lab, that looked nothing like how we perceived the scene at the time. It takes skill and patience to be able to get to a point where you are confident you are going to capture what you saw, and you may need to use neutral density graduated filter to squeeze the the entire range of tones from highlights right down to shadow onto your film/sensor.

So I thought I'd explain a bit more about dynamic range.

Our eye is capable of seeing over a range of 24 f-stops. But a digital sensor or film can see roughly 3 to 6 f-stops depending on the medium (negative film has a higher latitide and can often record over a wider range than slide film can). So it's very common to want to record a scene that the camera simply cannot handle. You are either going to have an image with underexposed ground, or over exposed sky, or a bit of both.

Now, your camera simply meters everything and works out an average of 18% grey. For instance, if you point your camera at a black wall, the meter will make an exposure which will make the black wall grey. The same is conversely true for a white wall; your meter will make a white wall grey. This is why you need to add or subtract exposure compensation for situations when you know that the overall scene is too bright or dark.

So how do you get the right exposure?

Well the truth is that there is no such thing. It is purely about what you consider important to record, and what you are willing to sacrifice, but there are times when using an ND graduated filter will allow you to squeeze an entire scene which has a dynamic range greater than your film/sensor can record, and here's how I do it.

I have a rather nice little Sekonic meter which allows me to take many spot readings around my scene and from that I can see the entire dynamic range that the scene contains. For example, I will take a spot reading of the darkest part of the scene and then a spot reading of the highlights in the scene, and from that I will perhaps see that there is a 10 stop difference between these extremes. I know that my Fuji Velvia film won't handle this and that I really need to get the scene down to around 6 stops of a difference. If I put on a 3 stop ND graduated filter to compress the sky (highlights) down by 3 stops, I've reduced the entire dynamic range from 10 to 7 stops. Which is a bit more manageable, but I also have to determine what in the scene is going to appear 18% grey. Remember that when I meter the dark areas of the scene, the meter is telling me what the exposure would be if I wanted the dark areas to be grey. And the same is true when I meter the highlights. So I need to decide where in the middle of the range I want to be my mid tone. This is the bit that is subjective, but if I find for example some rocks in the scene that I think are 18% grey, I will decide that is my exposure point. I will then set this exposure manually (to stop the camera's meter from changing the exposure when I add on the grad), and take the shot.

With an SLR, it's a lot easier than this - sure it's nice to have a meter that shows you the entire range so you can figure out what difference in exposure latitude you need to make, but often, the camera will work out a nice average for you - if you have already placed a grad on the scene anway. So it's much more of a point and shoot approach to it, and if you are using a DSLR, you can check the exposure to see if you over did the grad - often for example, I tend to find that 3 stop grad is too much and 2 stops is more appropriate.

Placement of ND Grads on a Mamiya 7

I've been asked a few times now, how I manage to use graduated neutral density filters with my Mamiya 7II. So I thought it was about time I wrote an article about it to explain ND grads and how to place them on a range finder camera. iceland-version-2.jpg

What the human eye sees, and what a camera see are two different things. The human eye is capable of capturing a dynamic range (brightness values from dark to light) that is wider than what a camera can capture. This is why often you will see a shot where the sky is burnt out while the ground is exposed correctly, or the sky is ok, but the ground is underexposed (almost black). Film and digital sensors cannot cope with such a difference in light values between the sky and ground, yet our eyes are able to handle this difference in contrast and make it appear to us as though the brightness is the same between the sky and the earth. In order to bring this contrast or 'latitude' down to a manageable level, so we can 'squeeze' the entire scene into the dynamic range that a camera can record, we use Neutral Density Filters. Neutral means that they do not affect the colour of the scene in any way, they simply darken down an area of the scene (typically the sky) so we can get a good exposure in camera. I use these all the time for landscape work.

With a rangefinder camera, you do not view your scene through the lens. In the case of the Mamiya 7II, the lens contains the shutter and so is permanently closed, until the moment of exposure. There is also no prism or mirror. Which means the camera is a lot more compact and more silent too. But the draw back is that you don't get to see what you'll get when you expose. Most range finders have a side window showing you an estimate of what you'll get with some dotted lines at the edges to compensate for different focal lengths.

Anyway, the problem with using ND filters on a range finder is that most folk think it's very hard to judge the correct placement in front of the lens.

Above are two Lee 0.9 (3-Stop) grad filters. The left hand one is a soft grad, while the right hand one is a hard grad filter (one of my most used grads). As you can see - the graduation of the hard grad is rather dramatic in the middle of the filter. Most folks think that placement needs to be precise, but to be honest with you - it doesn't. When you put something so close up in front of the lens, it becomes diffused. This means that the graduation effect of the hard grad becomes less pronounced. Unless you are really way off with your placement, you're not going to see a problem.

So how do I place the filter? Simple - I guess. If the scene I'm shooting has a sky that is using 1/3 of the area of the scene, then I place the filter roughly 1/3 of the way down. If the sky takes up 1/2 of the scene, then I simply place the filter half way. Etc, etc.

The other thing that I tend to do is take more than one shot of the same scene. If I'm uncertain about the filter placement, I'll take the scene a few times, each time with a subtle adjustment, moving it up or down by a few centimeters. But I've often found that it's been unnecessary.

My favourite ND Grads are made by Lee in the UK. I've tried others such as the Cokin system but found them not as effective. But they are considerably cheaper. As in everything - you get what you pay for.

One last thing, if you feel that placement on a range finder sounds problematic - what I love about such a system is the 'visualisation' process that I go through. I like to 'imagine' the final image, and not having direct feed back (via an LCD screen) is a benefit, also being able to imagine the scene in my head and place the filter accordingly, allows me to remain in the 'creative-mode'. Being confronted with real world feed back takes me out of this 'creative-mode' and into 'editor-mode' which is something that I feel kills my creative flow when out shooting scenes. So yes, it's a benefit to me rather than a hindrance.