Does sensor size matter? Well if you’re using a graduated filter then it’s definitely important to keep in mind.
A graduated filter is an important tool in any photographers’ toolbox. They are very popular among landscape photographers in particular, as they can be used to cut down the exposure of bright skies, whilst leaving the ground intact. Along with neutral density graduated filters, you can also get different colors like blue and sepia, making for some interesting visuals. These filters come in various strengths, from super-soft to very hard gradients.
When looking to purchase a graduated filter, however, an often-overlooked factor is the size of the camera sensor. A single filter will give you varyingly different results depending on whether you have a small or a large sensor, and everything in between. Therefore, it’s vital to be aware of this before making your purchase.
LEE Filters has shared some tips on Facebook, via its parent company, Panavision. These quick tips illustrate how much the look of your image changes depending on your sensor, and provide advice on how to pick the right filter for your camera. It mentions how a camera sensor size can alter the perceived softness of a filters' gradient. Generally speaking, the smaller the sensor size, the softer the gradient will appear, and vice versa. This is because a small sensor, like Micro Four Thirds, has a tighter crop, comparatively. Therefore, a smaller section of the filter is being used, softening the appearance of the gradient. This is something to note as if you do not take it into consideration, you may not get the desired effect you’re after.
Thankfully, companies like LEE Filters have created graduated filters for specific sensors, allowing for maximum control. The 150 x 170mm Very Hard Graduated Neutral Density 0.75 Filter is specifically designed for a hard gradient on a large sensor. If you used this on a smaller sensor, however, the gradient would not match. But not to worry, as there are graduated filters available in various sizes and strengths. This means that hard gradients are possible with even the smallest of sensors. There are other great options for graduated filters out there, too. Tiffen and Scheider both offer high-quality filter options for photography and cinematography.
Some may not take sensor size into consideration while buying a filter. However, as LEE Filters has demonstrated, it’s important for getting the right look out of a graduated filter. Luckily, there are many options and alternatives out there, all with their own specific purposes.
You won't get the same effect even when using the same sensor size across different focal lengths, or even the same focal lengths and sensors but different physical lens lengths. It would be more accurate to say it depends on the viewing angle (or the effective focal length) and the physical length of the lens.
Hi! Thanks for your comment :) You're 100% right - there are so many variables to consider.
I've noticed that if I take a picture with a FF sensor and then another one with a smaller sensor (leaving the lens firmly mounted on the tripod as if I was in a Tony Northrup video) the 2nd image is substantially different regardless of whether or not I used a filter of any kind. For example I recently took pictures of a ruler and in the first picture the part from 3 to 9" was 50% of the height of the image, but in the second it was 80% of the height. In fact, I've noticed that the smaller sensor makes everything in the scene bigger. And some of the stuff around the edges was just plain gone. Weird, huh?
After a great deal of thought I'm thinking that if a transition of any sort in a filter affects some portion of the image with a smaller sensor it's going to affect a larger portion (hypothetically, lets say 60% more) of the height/width/diameter of an image taken when the only thing different is the size of the sensor. OTOH, switching to a shorter focal length (again using a hypothetical, let's say 100mm instead of 160) is going to makes things in the image small again (and it magically brings back all that edge stuff, too). Now this part is just wild, crazy speculation, but wouldn't that also make the effect from the filter much more similar similar to the effect in the first image?
And what about switching lenses on the same camera instead of switching cameras? Again I'll use my hypothetical 100 and 160 mm lenses. What's that going to do to the effect? Not on the sensor, but on the rulers of which I'm so fond of taking pictures. Won't that longer lens also make the ruler look bigger and therefore put the effect over a larger portion of the ruler?
I'm going to have to ponder this for awhile. When I'm done maybe I'll start a filter company and try to sell photographers a set of filters for every lens and camera combination they have. Ooh, and f stops, too. If all the light captured for the image comes through only half of the lens diameter that should make a difference, too.