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

[cjcampbellphoto]

There was no flash involved in the taking of this photo

[cjcampbellphoto]

Thank you so much! I'll definitely utilize YouTube University!

[kvbarkley]

Bracketing is taking multiple exposures at different settings around what you think is correct. That way you are more likely to get a correct exposure.

You don't need a light meter*. The one in the camera should do fine - you can even set it for spot readings.

*Unless you need it for flash photography, but that is a whole nother kettle of fish.

[RobertTheFat]

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@cjcampbellphoto wrote:

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?

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It's rarely such a simple choice. But all else equal, underexposure is better. You can correct, more or less, for underexposure in post-processing, and most editors will give you some control over the contrast. But if you overexpose enough to cause blown highlights, there's no corrective method available; the information just isn't there.

[ebiggs1]

Correct exposure is best. However, sometimes it is better to expose a scene to be as bright as possible, without blowing out the shot's highlights and losing data. Then in LR/PS you darken the image so that it looks how you want.

The hardest part is you must be careful to avoid exposing too far to the right.  If you shoot jpg, there is no (little) benefit from shooting to the right. This is also where bracketing becomes your best friend.

[Tronhard]

In terms of exposure I agree that there are several variables to consider.  The degree of contrast, the performance of the sensor and lens to render tone, and whether one shoots in JPG or RAW.

I have been told several times to shoot slightly to the right for RAW as long as I am not blowing out elements of the photo that I consider significant (some would say at all).  Since RAW captures all the data, then more shadows can be brought up without too much noise. 

I have also been told to shoot to the left or as metred for JPGs but choose carefully my point of exposure metering - I tend to use spot metering, lock it and then compose.

I consider to use all of these considerations when I shoot, but I tend to start from the metred value as my default.

With regards the Canon 100-400L lens:   I had the MkI model and must have had a good one as I got acceptable results from it, although I must admit I never used it as a portrait lens. The MkII 100-400L is a step up again and is, IMHO, a superb lens.  That said, the 70-200L, which is considered a great portrait lens by many, has a decent overlap.  But for portraits I would tend to use something closer to the 80mm mark and with less complicated and heavy glass.  

[cjcampbellphoto]

This is very interesting! As a beginner photography, my lens inventory is very limited as I own a few, cheap lenses.  I was actually testing out my friend's lens during this shot so I can see how I didn't know which lens would be best, only that I was trying something new I had never used before.  I think it will help me to do some more research into lens types and learn which ones are best for certain situations.

[cjcampbellphoto]

Thank you for the insight! What is bracketing??

[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..?