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.

Colour Neutrality Guatanteed: Hitech Firecrest Full-ND Filters

For the past few months, I've been using the new Hitech Firecrest range of Full-ND filters and I thought I would share some of my insights into using them with you in this post today.

Rio Serrano & Paine Massif, Torres del Paine National Park, Chilean Patagonia, 2015

Rio Serrano & Paine Massif, Torres del Paine National Park, Chilean Patagonia, 2015

I use many kinds of colour neutral filters in my work:  ND-grads are used to control the contrasts between sky and ground, and I also use Full-ND (neutral density - i.e no colour filtration - just darker) filters in my work to control the shutter speeds so I can get the effects I'm looking for, regardless of what the light levels are at.

For a long while I've used the Lee filter system. I've found the system to be one of the best out there, and for most things I've been very happy. The filter holder is well designed (unlike some of the other brands I could mention) and the filters - especially the grads are all hand made. I've also found that compared to other brands, they are less prone to introducing colour casts when compounded together. With most other filters I've tried, I find that combining a 3-stop full-ND filter along with a 3-stop ND-grad filter can introduce a very obvious magenta colour cast in the final images. With the Lee filter system, the colour cast isn't completely gone, but it's certainly the least pronounced and most of the time I am happy with being able to tune it out later on.

One of the filters I don't use by Lee, is the Big Stopper. The main reason being that I seldom require 10-stops of ND for what I do. This is because I am a film shooter who finds that during low light photography the reciprocity effects on my film mean I'm into long shutter speeds without needing to add anything more than a 3-stop Full-ND filter. For example, Fuji Velvia becomes less sensitive after 4s. An exposure of 4s with a 3-stop Full-ND filter applied becomes 32s. Once I apply reciprocity to this (the film loses it's sensitivity the longer its exposed, so I need to compensate for this by adding more exposure time) the exposure is already down to 1m 6 s.

So a Big Stopper has never been needed, or wanted for what I do. But I do however use 6 stops of Full-ND from time to time, and that means compounding 2 x 3 stop Full-ND filters along with a 3 stop ND-grad. Which often means I'm introducing a real magenta cast into the image - which is uneven - it's very pronounced in the sky and less so in the ground, but it's still there. I've avoided using the Lee Little Stopper, because it has the same very pronounced blue cast that is evident in the Lee Big Stopper.

So I was interested when I heard this year about the Firecrest Full-ND filters from HiTech (thanks Jeff for making me aware of them). I decided to buy two filters from them: one 3-stop NFull-ND filter and one 6-stop Full-ND filter. Now that I have images back from the shoots I used them on, I'd like to discuss their neutrality and also their physical attributes in today's post.

Colour Neutrality

They are completely colour neutral. Phew, it took me a while to get to this point, but there you are. Worth every penny and a remarkable technological step forward.

Filter physical build and thickness

This is a description from the Hitech website:

"Rather than dyed resin, Firecrest is a carbon metallic coating used to create hyper neutral NDs. The filters are made from 2mm thick Schott Superwite glass, and the multicoating is bonded in the middle to increase scratch resistance. Firecrest Filters are neutral across all spectrums, including UV, visible, and infrared."

The Firecrest filters a slightly slimmer than the Lee's, so there's been some discussion that they may fall through the Lee filter holder. I've found that the filters are indeed a little bit slimmer, but I've not had any worry about them falling through. I would say however, that it's dependent on the age of your Lee filter holder. I find over time that the little rubber parts that hold the filters in place tend to get loose or soft. So it might be worth checking this out before using the Firecrest filters in your Lee holder. I think the fix for a loose filter holder is simply to buy some new spacers for it, or a new holder (I've always got a spare one anyway).

Glass Filters and Fragility

The last concern for me about using any glass filter is its fragility. It's well documented that the Lee Big and Little stoppers may break just being stowed away in a normal camera filter bag. So for the past several years they've been released with little metal cases to avoid the chance of this.

With the Firecrest filters, they come in rather large plastic cases. Too big in my opinion for storing in most camera bags, so if I had some recommendation to Hitech - it would be to produce a smaller set of cases please. But maybe this is a moot point, because I chose to see if the filters would break if I put them in my normal filter case. After six weeks of traveling on really rough unsealed roads in Patagonia and the Altiplano of Bolivia, the filters are still intact and I feel confident that they're not too fragile at all (they won't bounce if dropped, but at least they aren't going to break too easily if placed in a normal filter bag).

Summary

If you tend to compound ND-grad filters with Full-ND's  a lot, then using the Firecrest Full-ND filters in your mix of filters is definitely the way to go. They will cut down the possibilities of colour casts and allow you to be more free with the combination of grads with Full-ND's you use. 

If you use the Lee Big or Little stopper, then I would recommend you replace these filters now with the Hitech Firecrest equivalents. The Big and Little stopper filters have a very pronounced blue cast whereas the Hitech ones are completely neutral. (On a side note - you may feel that you can 'tune out' the blue cast from the Lee's during raw conversion, but please bear in mind that the blue cast may not be uniform across the entire visible spectrum. So I'm not convinced that tuning the colour temperature fixes the issue entirely, and may introduce cross-over casts in other tonal ranges of the image).

For me, since I tend to compound filters (an ND-grad + several Full-ND filters)  I've replaced my 3-stop Full-ND filter for one 3-stop ND firecrest filter and I've bought an additional 6-stop Full-ND firecrest filter (to get round those times when I previously used 2 x 3-stop Full-ND's).

I see that Hitech have also released some soft grads in the Firecrest range, which means we now have the possibility to use completely neutral ND-grads as well, but I haven't tested them yet, but have now placed an order for them. So I hope to tell you in a few months time once I've used them a fair bit. Until then I will continue to use the Lee ND-grads as I still maintain that they are the most colour neutral resin filters on the market.

For any full-ND requirements, I will now be using the Hitech Firecrest range with no reservation from now on. I'm delighted with the results :-)