What is a likely cause of this glow in my photos?

Question

I have been using a Nikon D5200 with a Tamron 100-400 zoom for wildlife photography. It's admittedly a budget setup (in some sense of the term "budget"), so I don't expect amazing results. I'm also not a trained photographer, and I've pretty much learned by reading the internet and youtube (not ideal, I know). Recently, I decided to rent a different Nikon body for an expedition (which ultimately got canceled due to COVID-19).

I decided to rent a mirrorless Nikon Z6 to see how I would like a mirrorless camera, and to try a full-frame sensor, and also just to get a newer sensor and body and see how the quality compares, using the same Tamron lens.

I made a lot of mistakes in using the new body, but ultimately I'm stumped still. The photos are displaying the same annoying glow that I've seen with the old body. I don't know what is causing it, but it seems like I can narrow it down to "operator" or lens errors.

In the image above, a heavily cropped section of a photo of a bird, you can see the glow. It shows up similarly using either body. This is shot at 400mm, ISO 320 f/6.3, 1/500 sec.

I handhold the camera most of the time because I just can't use a tripod for most of these photos (the birds are up in a tree, jumping around, etc.)

Does anyone have any suggestions for what I should do here? Should I use faster shutter speed and higher ISO? I've tried that and found that I get a lot of noise, but maybe the newer sensors can handle it? I'd be willing to spend some $$ on a book or read any references people might recommend.

Thanks!

EDIT This image is uncorrected, straight out of the camera, though (sadly) I took it as a JPG originally. I usually shoot raw, but had my settings incorrect for this new body that I'm renting. I see the same effect whether it's RAW or JPG though, it was just that this photo showed the effect more strongly so that I could illustrate my question.

Answer 1

You appear to be using your lens (100-400/5-6.3) with the aperture wide open. I would expect the glow in your photos to be significantly reduced or absent stopped down to about F8.

Many lenses "glow" when used wide open, especially in bright light with high contrast. It is likely associated with spherical aberration and is typically reduced or completely gone when the aperture is closed a stop or two. Increased familiarity with the lens' behavior and characteristics will allow you to predict when the glow will and won't be present. You will then be able to select apertures to match your artistic intent.

Answer 2

The fact you're seeing this with two very different bodies suggests to me it's in the lens. Long zooms tend to have a bunch of elements (anywhere from a dozen to twenty, in my experience). No lens coating is perfect, and no lens surface is perfect. Every time light passes through an air-glass or glass-glass interface at an element surface, there's a small amount of reflection and a small amount of scattering.

Put enough elements in the light path, and you'll get flare. Flare is not the huge reflections you see in photos with the sun in frame -- it's a general, overall loss of contrast due to light scattered at the lens surfaces. Flare can also cause small halos at light-dark boundaries -- like what you're seeing here where the bird's bright feathers meet the relatively dim background.

It might be worth renting a top-end lens, perhaps even a mirror lens (the better ones have only a couple transmissive elements and a couple reflective surface) to see if the problem stays in your Tamron zoom.

Answer 3

You've got a dirty lens.

First, alcohol. IPA, ethanol. Use that with a microfibre cloth. That should dissolve the oils, but you want the cloth to pull it off of the glass and into the cloth. Don't reuse sections of the cloth.

Then, a little Deionized water and soap- a tiny tiny tiny smidgen. Again, just enough to be a surfactant. Wipe the lense elements again, not reusing the sections of cloth.

Then back to alcohol, and wipe.

Now the surface should be pristine. If you were REALLY pedantic you could use a specialize tape from 3M to 'pull' material off, but by now I think you should be good.

You'll need to do this to the back of the lense (rear lense element as well), as it can get dirty too.

Finally you need a realistic test- so print out a series of black&white lines on paper and photograph it. That should help with determining if it's there or not anymore.

Oh, and if you have a filter- that can be bad too.

Sadly... sometimes lenses can 'out-gas'. Silicone is notorious for this, and one of the reasons anything with silicone is banned in commercial clean rooms. It would contaminate all the optics and material. Those stupid silicone wrist-bands have caused millions of dollars in rework in cleanrooms. So if the oils have seeped into the lense and are on internal surfaces, you're stuck.

Answer 4

All lenses are debased by aberrations, two of which deal with color. The lens maker endeavors to mitigate by crafting the lens using multiple lens elements. Most commonly, chromatic aberration displays images with a rainbow colored edge effect. This is caused by the fact that each color has a slightly different focal length. The violet image falls closer to the lens followed by blue, green, yellow, orange and then red. The longer the focal length, the larger will be the projected images. Thus the lens projects an image consisting of multiple colored images, each slightly different in size, thus we see a fringe of color about the edges of objects.

The halo effect you are asking about does not display the typical rainbow edge effect. This tells me that your lens is well corrected for chromatic aberration. What you are seeing is commonly called a halation. This is seen as a white edge effect surrounding objects. The origin of this is in the CCD image sensor. It is an optical effect whereby light spreads (bleeds) inside the CCD due to internal reflections and blooming. The camera’s imaging chip is covered with millions of light sensitive sites that gain an electric charge during the exposure. The amount of this charge is related to image brightness. Halation is due to the leaking of some of the charge into adjacent sites. This produces a bright halo edge effect surrounding bright objects.

Answer 5

It could be lens lost calibration. Try this and tell us. Use f5.6 or greater number like f8 etc... Take a photo of a white text with black background, this will show you ghosting effect in the edges of the letter. If this happens, one of the components of your lenses is out of the center. This can happen due to a hit, etc...

Let us know.

Regards