I wrote about polarizing filters once: “Using a cross polarizing filter”. It was a long time ago and I was using flash for all my macro photography, so it was an article on a technique that involves flash.
I mentioned that I wanted to try something: The use of polarizing filters in natural light. Last weekend I had the opportunity to test this.
As a reminder, polarizing filters are attached to the front of the lens and can be rotated. As the filter rotates, it cuts polarized light coming from certain angles. This makes it possible to photograph behind shiny glass or inside water that reflects like a mirror. We just need to turn the filter to the appropriate angle and cut the reflections.
In macro photography, the harsh light reflected from the shells and eyes of insects hides colors and details from us and creates a photograph that disturbs our eyes. To prevent this, we put a diffuser between the light source and the object to prevent the light from hitting directly. Thanks to the diffuser, the diffused light from various angles reveals the hidden colors with a very soft illumination. At some point, it’s not about using lenses, bodies, etc., but about how to make better use of ambient light.
Of course, laziness haunts us. A diffuser means difficulty in setting up in the field. It means a mini tripod with an additional holder. If I compare the times when I use a diffuser and when I don’t, there is a big difference. I can see that I don’t prefer a diffuser in the field, so what do I do?
First of all, I never work in the sun, I always need to be in the shade. It’s much easier to create these conditions during the golden hours of macro shooting, morning sunrise or evening sunset. There’s shade everywhere. And the insects are calm. And what’s better if it’s cloudy? Clouds are the best diffusers. Is it possible to improve these conditions?
Even if I shoot in the shade, the direction of the sky or between the trees where the main light is coming from is too bright. This brightness shows up on the surface of the insect facing that way. In some cases it creates a nice look because it brings out the natural glossy texture, but sometimes it bothers me to the point that I can’t get a good result without a diffuser.
At this point, the use of polarizing filters starts to arouse curiosity.
This is not the first time I have used a polarizing filter. I and some of my friends have already tried it in macro shooting. The master photographers I follow on the internet have tried such experiments. But for some reason the general opinion was not very positive. There are several reasons for this.
Problems with the CPL filter
- Polarizing filters are dark. When we put a dark glass in front of the lens, we naturally get less light inside. The exposure time is longer.
- The viewfinder gets darker for the same reason. If there is no good lighting, it is a bit more difficult to focus.
- The angle of the filter is used to block reflections. It is useless if we cannot sense the change that occurs when rotating the filter. Unfortunately, it is very difficult to perceive this because the light will already be soft and in shadow and in a setup prepared for macro shooting. It is almost impossible just by looking through the viewfinder.
- While sharpness is everything to us, we take the risk of reducing sharpness with the glass we put in front of the lens. If a light reflection occurs between the filter and the front glass of the lens, it causes unwanted haze in the image. Different filter brands stand out here. The Marumi brand, which is quite expensive and high quality compared to ordinary filters, is successful in overcoming reflection problems with its DHG and Super DHG coatings. Quality lenses are as if they do not exist, they do not cause a loss of sharpness.
- Low quality filters can cause color shifts. For example, an old polarizing filter I tried had a blue shift in tones.
- You have to be careful if you have a lens whose front rotates while focusing. If you change the focus after adjusting the filter, the filter in front of it will rotate with the lens and the adjustment will be lost. You will have to deal with it again. Otherwise you will not get efficiency. Fortunately, such lenses are in the minority.
For the reasons I wrote above, I didn’t use polarizing filters much. My cousin Kerem took a harsher decision and said he would never use them again. In short, polarized filters are not very popular in macro.
So what changed? Why did I try again now?
I switched to a mirrorless body. Mirrorless has so many advantages. Personally, I don’t want to go back to the old mirror system anymore.
- There is no darkening of the image when a polarizing filter is installed. Mirrorless bodies measure light continuously and always present the image at the appropriate exposure value. What we see on the screen is the same as the photo we take. There are no problems until very low light levels that are not suitable for shooting. As the light decreases, the preview image becomes grainy, but we still see it as bright. The only adjustment I have to deal with is exposure compensation. I just decide how bright I want it.
- We have great aids in focusing. We can see the sharp area both painted and marked. And what I like more is that we can magnify a small part of the image, say 10 times, and we can watch it and get a very precise focus. We can move this magnified area to the part of the image we want and focus wherever we want.
- When rotating the filter, we again use a zoomed-in bright area to see how much it cuts the reflection. This way, getting the right angle on the filter is no problem at all.
My friend Bayram, who uses a DSLR body with a mirror, mentioned that he uses a different method when adjusting the filter angle. First he removes the filter, holds it in front of his eye and changes the angle while looking through it. At the point where he can reduce the reflection on the insect to the desired level, he looks at the angle of the CPL filter, places it in front of the lens in that way without changing it at all and starts shooting. I’ve tried this too, it’s a clever method that can be used when it’s difficult to adjust.
Testing macro shooting with CPL filter
Let’s get to our story:
The hottest days of August. It’s 38 degrees Celsius and I’m in the middle of the field at noon, looking for some shade to escape to. When it seems like I have no chance, the clouds that are the precursors of the torrential rain that will start in a few hours start to gather rapidly in the sky. Long lasting cloud shadows suitable for shooting are formed. I go exploring again, aiming to try the polarizing filter.
To escape the unstable light conditions created by the passing clouds, I find a spot behind a tree that provides constant shade and set up the camera. It’s time to find a model that will fill the holder on the target and stay still despite the hot weather. Insects are plentiful. Dragonflies everywhere, all kinds of flies and bees. But they are all very active. My wife helps me in the search. Together we take a romantic tour of the fields… We are a bit nervous and noisy during the blackberry break by the stream. We try to drive the snakes away.
My wife calls out as we pass the sunflowers. The model we are looking for is standing there. A crab spider, dressed in colors matching the flower, is on the watch for its prey. It is motionless. Just what I was looking for. I take out the garden shears and carefully cut the sunflower head without shaking. The spider is calm.
It’s a bit far from where the camera is set up. Now I have to carry the sunflower there without shaking it. I’m sure I look strange and funny as I tiptoe like a ballerina across the uneven field. With the same care I attach the sunflower to the clamp at the top of the stem, at the strongest part. Cut plants wilt very quickly in hot weather. If we don’t secure it firmly in the holder, the frame will slide down as the plant loosens during the shooting. You have to be very careful with this. If necessary, it would be wise to fix it with a double clamp from both top and bottom.
After I get behind the camera and make some minor adjustments, I realize that the wind is a bit stronger than I thought. I even complain as quietly! as possible before I can shoot for about 10 minutes! There is no other solution but to increase the ISO. In an environment where I would normally use ISO 160 and take a long exposure, I am forced to go up to ISO 640 and reduce the exposure time to 1/25 s at f6.3 aperture. Otherwise, the wind makes it impossible to get sharpness.
To measure the effect of the filter, I use f16 aperture to slightly increase the depth of field in single frame shots. Then the exposure increases to 1/3sec. I take the shots when the wind dies down. These two photos, which measure the effect of the CPL, are the reason for writing this article. Let’s look carefully at the 2 photos below. In the first one, the filter angle is set to have the least effect. In the second photo, the filter is rotated 90 degrees to cut the reflections.
There is a noticeable improvement. Although both photos were recorded by the camera at exactly the same color temperature, there is a tonal difference. The colors are more saturated in the photo where the reflections have been reduced. Again, I have treated both images slightly and exactly the same, leaving them almost exactly the same as they came out of the camera.
Let’s crop the areas where the difference is more pronounced and examine them side by side.
If we pay attention to the reflections, there is a big reduction. But something interesting stands out. When we change the angle to eliminate the original reflections, some reflections appear in the opposite areas where there were none before. This shows that the CPL filter is reducing the reflections on one side and increasing them on the other. But since these new reflections are already quite weak, they do not disturb the balanced situation.
CPL filter provides the desired effect
Finally, I photograph this frame from beginning to end with an aperture value of f6.3 and complete the focus stacking work. This work, in which the CPL filter is used effectively, is also a first for me. I am publishing the final version with a resolution of 4000 pixels with a link. If you click on the photo, you can view the larger version.
If or when you have experience with polarizing filters in macro photography, I would be very happy to hear your ideas. May your light be bright.