Graininess...

Started 2 months ago | Discussions thread
FingerPainter Senior Member • Posts: 7,532
Re: Graininess...
3

rubybgold wrote:

Hi all. I'm a newbie to this forum and look forward to folks' thoughts on this. I recently upgraded from my D3300 to the 7500 and took it for a spin yesterday with a Tamron 100-400 lens. Part of why I bought the 7500 was because of its reputed performance in low light situations and the number of ISO options available with supposedly far less visual noise/graininess

I don't know where you get the "far less" from. The difference in noise performance between the two cameras at ISO 800 is about 1/3 stop.

. I also got the Tamron 100-400 as an upgrade from my old kit lens 55-200 that I had with the 3300.

So at max focal length the slower Tamron lens eats up all that 1/3 stop advantage the D7500 give you. You should expect no difference in noise performance.

I was out at the end of the day, hour or so before sunset, sky still quite light,

EV 11?

shooting migrating birds.

Tough subject

In manual mode,

why?

set my shutter speed to 1250 (to capture fast flying, erratically moving birds),

OK

Ap was 6.3, which was the widest I could get with the lens fully extended to 400mm,

Most lenses are not at their sharpest when shot wide open. You lens woudl be sharper at f/8.

and I set ISO to 800.

Why?

Happily, I was able to capture some really great looking shots of the migrators in low light,

Remember that "low light". Ti will come up below.

but, at even close to full size, all of them had too much grain

Noise, not grain. Grain is something film has.

for them to be good images. I was disappointed, given that 800 was not a very high ISO for this camera,

All digital photos have noise. It's just the natural result of the random arrival of photons at the sensor. The more light you capture, the more the variation caused by that randomness cancels itself out. You shot at a fast shutter speed in low light. Noisy image are the expected outcome.

The fact that you shot at ISO 800 doesn't mean you should expect the noise performance reported for ISO 800. If you are underexposed at ISO 800, you will get more than the rated noise. Since you used all manual exposure, and haven't told us how you arrived at your ISO setting. there remains the possibility that your proper ISO is higher.

and, given the reputation of both the camera and the lens,

This lens is less sharper than either Nikon's or Canon's xx-400mm lens, and they aren't all that sharp.

I expected the images would be much sharper.

"Sharper" is a different matter than "less noisy". There can be several possible causes for lack of sharpness. You didn't use the sharpest aperture for the lens. You might have had the wrong VC setting. Maybe your holding technique needs work.. Maybe you missed focus. Depending on how many birds and how far away they were, maybe some were outside the field of acceptable sharpness.

I welcome thoughts on why I got so much grain, and how to get sharper images in a similar situation next time. Thanks in advance!

Post one of your images, with EXIF intact. It might give us some more information to help. See how many "Maybe"'s there were in my previous paragraph?

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