Why so much noise?

After a long time I shot at dusk with my 7D and 28-135mm lens. SOOC the photo is very noisy even if it is shot at ISO 100 and f/8, f/10, f/22, f/29. The 100% crop sample shown below was captured at f/29.

Why is there so much noise?

That looks incredibly good (noise wise) for a 13-second exposure!

absplastic wrote in post #12892239
That looks incredibly good (noise wise) for a 13-second exposure!

Yeah, and for a %100 crop too! LoL

When you have to increase exposure in post production to compensate for under-exposure at the time the photos was taken, you amp up noise a lot.

Also with longer exposures you are likely to see some noise in shadows and dark sections of the photo. Some form or noise reduction is likely to be needed. NR be done in camera or in post production.

But I have to agree with the other responses... there's almost no noise in your image. It's pretty amazingly clean considering. I'm guessing you have long exposure noise reduction turned on or set to automatic in the camera.

Another subject...

Using f29, very likely you are getting a lot of loss of detail due to diffraction. The Diffraction Limited Aperture on a 7D is something like f7.1... I try not to use smaller than f11. I can see diffraction effects as f16 and f22... so have little doubt you lost a whole lot of fine detail using such a small aperture.

amfoto1 wrote in post #12892602
Another subject...

Using f29, very likely you are getting a lot of loss of detail due to diffraction. The Diffraction Limited Aperture on a 7D is something like f7.1... I try not to use smaller than f11. I can see diffraction effects as f16 and f22... so have little doubt you lost a whole lot of fine detail using such a small aperture.

Really...
@ ISO 800, F8 you'd be shooting @ 1/2 - 1/4 second or so, not 13 seconds...
The "noise" you see is just a soft image due to defraction and subject motion during the long exposure.

f29?! is there such an 'f'?

led hed wrote in post #12892636
f29?! is there such an 'f'?

Not on every lens, but some (esp. macro lenses) support very small apertures.

led hed wrote in post #12892636
f29?! is there such an 'f'?

1/3 F-stop wider than F32...F22, F25, F29, F32...

Why in heavens name would you choose F29?!

Were you trying for a longer shutter? That's what ND filters are for.

led hed wrote in post #12892636
f29?! is there such an 'f'?

Of course. For example, the 100-400 L has a minimum aperture of f/32 at 100mm and f/40 at 400mm. f/29 is one click (1/3 stop) up from f/32.

csondagar wrote in post #12892215
After a long time I shot at dusk with my 7D and 28-135mm lens. SOOC the photo is very noisy even if it is shot at ISO 100 and f/8, f/10, f/22, f/29. The 100% crop sample shown below was captured at f/29.

Why is there so much noise?

Dude, --- 100% crop, f 29 , 13 seconds
Why so little noise

And you were shooting at f/29 because... ?

You should read this thread: https://photography-on-the.net …/showthread.php​?t=1077162

That is actually really good..


ALL cameras will show noise, even at ISO 100.

csondagar wrote in post #12892215
...very noisy...

I think you're fine

JonK wrote in post #12893482
Why in heavens name would you choose F29?!

Were you trying for a longer shutter? That's what ND filters are for.

I regularly shoot at f/16 with long night time exposures at 100 ISO..

A typical exposure could be 30 seconds at f/16 at 100 ISO..

Back to the OP's question.. You'll always get more noise in areas of solid tone like the sky for example.