Understanding Noise

[cjcampbellphoto]

Hi Canon Community,

I'm an amateur photographer looking to improve my skills and I'm struggling in low light situations.  I recently took some photos of my friends using a Canon 7D (the oldest model) and an EF 100-400mm f4.5-5.6L IS USM with the settings of:
ISO250 at 100mm f/4.5 and 1/125 sec.  The picture shows up with a TON of grain and I'm confused. The ISO isn't that high at all.  I bumped up the exposure by +2 in Lightroom just to show how much grain is in the photo:

Any tips would be greatly appreciated!

Best,

CJ

[cjcampbellphoto]

I'm an amateur photographer looking to improve my skills and I'm struggling in low light situations.  I recently took some photos of my friends using a Canon 7D (the oldest model) and an EF 100-400mm f4.5-5.6L IS USM with the settings of:
ISO250 at 100mm f/4.5 and 1/125 sec.  The picture shows up with a TON of grain and I'm confused. The ISO isn't that high at all.  I bumped up the exposure by +2 in Lightroom just to show how much grain is in the photo:

Any tips would be greatly appreciated!

Best,

CJ

[Waddizzle]

I admit to having bad eyes, but I think others would agree that your photo does not have a lot of grain or noise.  What part of the image shows the worst grain?  The LL Bean logo looks good, as does the dark area on the upper right.

If you are using LR, then you should be able to remove just about all noise in a properly exposed image.  With the latest subscription version of LR Classic your exposure can be off by a whole stop, and it can still clean it all up.

[ebiggs1]

There are several reasons why you see "noise" or "grain" in a photo.  Noise is always pixel size and is caused by the sensor.  However, you an get grainy photos from other sources.  Like the lens you use and you chose a poor lens for that shot.  What you are seeing as noise is actually the resolution ability of the lens.

BTW, noise shows up worse in dark areas and shadows and is worse in underexposed photos. Some or most of it can be fixed in PS/LR but lens resolution can not for the most part. Select a better lens for that type work.

[Tronhard]

Looking at your photo, and taking into account that you say you have increased exposure of the image since taking the shot by +2 EV, I would say that the original was under-exposed to begin with.   Your subject's face still seems a little under-exposed to me. Noise will certainly occur when you are underexposed and boost exposure during PP.

What was you metering setup - i.e. what did you meter on, and what kind of metering system did you use: Evaluative Partial,  spot, Centre-weighted Average..?

[ebiggs1]

" Noise will certainly occur when you are underexposed and boost exposure during PP."

Absolutely but I don't think what he is seeing or I see is noise.  It looks more like resolution of the lens which was not the best for that shot. Exposure is a problem certainly.

[Waddizzle]

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@ebiggs1 wrote:

" Noise will certainly occur when you are underexposed and boost exposure during PP."

Absolutely but I don't think what he is seeing or I see is noise.  It looks more like resolution of the lens which was not the best for that shot. Exposure is a problem certainly.

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I did not see significant noise, either.  It might be the lens.  It might be the APS-C sensor.  The original shot may have been off, but I think the photo does not descend to the level of bad.  I think it is pretty good.

[Tronhard]

I agree about the noise.   I had been looking on a monitor that was not my own or up to scratch.  Now that I have had a chance to see it under better conditions I think that the image is a bit under exposed but not terribly noisy.

I am surprised that the lens would be the culprit as the 100-400 has always been regarded in its two versions as a bad lens - certainly that has not been my expeience...

[cjcampbellphoto]

I've heard differing schools of thought. I've heard that under exposing slightly is ok because you can bump up in the exposure, but I've also heard that overexposing and bringing down the exposure is better, as it results in less grain.  What are your thoughts on that?

[cjcampbellphoto]

I admit I was editing on a large monitor that isn't necessarily built for it so I believe the accentuation of noise came from the large 4K monitor.  I would like to ask how I can determine the best lenses for clarity. Is it strictly the glass of the lens? 

[cjcampbellphoto]

Thank you!