Cause of graininess in my images

rubybgold

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

I was out at the end of the day, hour or so before sunset, sky still quite light, shooting migrating birds. In manual mode, set my shutter speed to 1250 (to capture fast flying, erratically moving birds), Ap was 6.3, which was the widest I could get with the lens fully extended to 400mm, and I set ISO to 800. Happily, I was able to capture some really great looking shots of the migrators in low light, but, at full size, all of them had too much grain for them to be good images. I was disappointed, given that 800 was not a very high ISO for this camera, and, given the reputation of both the camera and the lens, I expected the images would be much sharper. 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!
 

480sparky

Senior Member
It's not grain you're seeing.... it's noise. Although visually similar, they are radically different. The former is an analog function of the actual silver granules in film emulsion, the latter is a result of electronically amplifying a digital signal.

Every image will look bad when you're pixel-peeping, especially at 100% and higher.
 

mikew_RIP

Senior Member
Welcome to the forum, first thng to say is dont panic:D

The best results come from the best light, you where at the end of the day which can have a lot less light than you think,ime sure if you go out in good light all your fears will melt away, you have good gear perfectly able to produce great results.
 

nickt

Senior Member
If the light is poor and/or you are underexposing a bit, you will see more noise. Post some pictures here for folks to see what is going on.
I like to shoot in manual mode with auto iso. For birds in the sky, I might dial in +.3 exposure compensation.

Are you doing any post processing? Iso 800 should not be a big deal, but you might need to clean up some noise depending on light.

You could also shoot some tests to see how your lens does wide open at f6.3. Sometimes its worth stopping down 1 stop from wide open to get a sharper image. At some point you can check for front or back focusing. That can be tweaked in the menus, but I'd put it last on my list.
 

rubybgold

New member
Thanks Nick. I will post something here as soon as I have time to download some of the images. I was concerned that stopping down wd not let enough light in, but it's a good suggestion. Perhaps I could have slowed the shutter speed slightly from 1250 and still captured the movement, but not introduced as much noise in that lowlight situation.
 

rubybgold

New member
Thanks for correcting the semantics. :chargrined: I do like the phrase 'pixel-peeping,' and, guilty, as charged. Though, I disagree that every image looks bad at 100%. Some of my images with my old gear looked great - sharp as a tack - at 100%.
 

mikew_RIP

Senior Member
Unless i have missed it you dont say if your shooting raw or jpeg, ime not one of these that say raw is the only way to go.

If its jpeg the settings need to be right, in camera noise reduction off,D lighting off, the only things that would need setting are the picture controls like sharpness contrast etc.

As i said before dont despair, show us what your talking about and i bet there is an answer, the very high ISOs may not make 100% crops but it depends on what you want to do with the images.

As far as i know the lens should be good wide open but knock it down to f7.1.
 
Top