Why is this image soft?

Rudy Pohl
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p.3 #1 · p.3 #1 · Why is this image soft?

Imagemaster wrote:
I have seen it and others, and never said I disagreed. I said the effects are easily avoided in the first place, and it is easy to quickly remove the warm air in seconds.

What I was referring to is distance to the subject, which is nowhere similar. The first shot was no way to test if a TC was faulty.

OK, thanks for the clarification.

Regarding the first shot of the Short-eared owl, I was not testing the TC, rather I was out for a drive and happened upon a couple of Short-eared owls and started shooting with the gear I had with me and I had just bought the TC 2 days before. When all my shots turned out soft I had no idea why and thought that the new TC might be the problem as I had not tested it yet.

The static shot was taken to test that the TC could take a sharp photo.

Anyways, thanks for your input.

Feb 24, 2024 at 10:26 PM

rscheffler
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p.3 #2 · p.3 #2 · Why is this image soft?

jpeter wrote:
Interesting point about the lens hood trapping warm air. That's one I never thought of. It would seem like a quick swing of the lens might stir the air up and clear it out. My 500 has such a long hood, I could see it being an issue.
Jay

It's not just warm air brought by the hood from a warm environment to a cold one. It's the temperature difference between the hood and the cold air. If the hood is quite warm, it will take longer to equalize its temperature with ambient. Meanwhile, heat from the hood is radiating from it, warming the air inside it in front of the front element, for longer than a few seconds. How long this lasts will depend on a number of factors. The larger, denser hoods for super-tele primes likely take longer to equalize than the thinner plastic hoods for lenses like the 100-500.

Feb 24, 2024 at 10:27 PM

juststeve
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p.3 #3 · p.3 #3 · Why is this image soft?

If the problem is warm air trapped in the lens hood, perhaps a smaller lens hood might help. I have been using the lens hood for the RF 50/1.2 L. It is much smaller and of a flower petal design. I live in MT and cold weather is part of life and don't seem to have much problem with warm air entrapment with the 100-500.

Feb 26, 2024 at 11:33 AM

rscheffler
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p.3 #4 · p.3 #4 · Why is this image soft?

IMO there were too many variables at play for the example image in the OP's first post to blame it just on warm air in the lens hood. OP was apparently sitting in a car where it's bound to be warmer inside than outside, which I think would have been a much bigger factor. To my eyes at least, that photo looked like shooting through atmospheric disturbance (I see a lot of this photographing field sports). And there was a filter on the lens. AFAIK, OP hasn't since done test photos in a controlled situation with the filter on and off to determine how much it might be a factor.

Feb 26, 2024 at 12:52 PM

Rudy Pohl
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p.3 #5 · p.3 #5 · Why is this image soft?

rscheffler wrote:
IMO there were too many variables at play for the example image in the OP's first post to blame it just on warm air in the lens hood. OP was apparently sitting in a car where it's bound to be warmer inside than outside, which I think would have been a much bigger factor. To my eyes at least, that photo looked like shooting through atmospheric disturbance (I see a lot of this photographing field sports). And there was a filter on the lens. AFAIK, OP hasn't since done test photos in a controlled situation with the filter on and...Show more →

Sorry if it wasn't clear, but in one of my first posts I wrote that I was not shooting from inside the car but outside and by the time I took the posted image I had already been outside for about 25 minutes. As well, I had left all windows open in the car for the previous 30 minutes. I would imagine that the lens was completely acclimatized by the time I took the image I posted.

I have not been able to reproduce this in a controlled setting because the temperatures here have gone up considerably.

However, I have removed my filter since then, but I will continue to keep my lens hood on in order to protect the front element.

Thanks for your input.
Rudy

Feb 27, 2024 at 09:05 AM

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