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]

Thank you! I was looking on a monitor that wasn’t so great either and I think that’s where the major problem was too

[Waddizzle]

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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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Assuming the camera is not being fooled by a wide DR scene, for me setting AEC sometimes depends upon where the ISO will be for a "correct" exposure, I am not going to ETTL when ISO is at 25600.

I like to shoot in M mode with ISO set to Auto, which means any AEC will raise or lower the ISO.  If the ISO is going to be super high, then I add negative compensation to keep ISO from introducing a lot of noise.  When ISO Is going to fall within a more normal range, 100-1000, then I may dial in positive compensation to capture more details in shadows.

Also, my Sekonic light meter tells me that my camera tends to typically overexposed by 1/3 of a stop, so I have been conducting an experiment.  I have been using -1/3 Ev as my normal setting for shooting most of the year, just to see what images look like.  The images do have a slightly different look, most especially images with a lot of bokeh.

Subjects tend to really stand out from the background, and contrast seems a little higher.  Images also seem to look a little under exposed, which the histogram usually confirms. My eyes like it when I add 1/2 stop of exposure in post.  The first photo is without any exposure added.  I had forgotten to add it in.  The second photo has +1/2 stop of exposure.  The experiment continues.

[ebiggs1]

"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 ..."

Having owned the first version and using a borrowed 2nd version, IMHO, the second is very much a better lens. Version 1 is not one of the best lenses I have ever used. Don't get me wrong, it is OK but just average.

The single reason I don't buy version 2 is it doesn't have 401 to 600mm.

Again, IMHO, I don't see either as indoor, up close, lenses and that is what the OP is seeing.  There are better choices. Shoot to the right is correct.

[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.  

[jrhoffman75]

Welcome to the forum CJ.

I opened your image in Lightroom and lowered the exposure by -2. Here is the image.

As you can see from the istogram it is significantly underexposed.

Then I increased the exposure until a small specular highlight on her galsses just started to give a highlight warning.  Here is the image.

AI consider this a well exposed image for the subject - it is +3.45 over your original.

Were you letting camera select the exposure or were you in manual mode?

The settings you presented are an EV of 12 2/3.

The daylight basic setting of Sunny 16 would be an EV of 14 2/3. (f/16, ISO 100, shutter 1/100).

An interior room, that you described as dark, would generally be darker than two stops below daylight.

What was the metering setting in the camera?

To me there is no obvious reason why the camera shouldn't give you a proper exposure in Program AE in that setting. Then you could refine it. The camera would use program shift - if you were to decrease the ISO to lessen noise then the shutter speed would slow down. IS on the lens could help with camera shake.

The jpeg you posted is only 1.2MB. I personally wouldn't be making any judgements about lens quality from enlarging that image. 

[ebiggs1]

"I personally wouldn't be making any judgements about lens quality from enlarging that image"

I would!  There are only two ways to go here is it noise or resolution.  We mostly agree there isn't any, too very little, noise in the photo.

Now, probably not the best use of a 100-400mm zoom.  That and a small exposure error add up to what the OP got. Actually not too bad considering and 100% fixable in LR/PS.

[cjcampbellphoto]

Forgive me, as I'm unfamiliar with the terms AEC and ETTL.  I'm assuming AEC is Automating Exposure Compensation.  I'll have to invest in a light meter to help get some of this information.  I'm still very new to photography so learning these skills is definitely necessary.

[cjcampbellphoto]

Thank you for the insight! What is bracketing??