Noise and ETTR

Started 10 months ago | Questions thread
Anders W
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Re: Noise and ETTR
In reply to roperc3, 10 months ago

roperc3 wrote:

Dear fellow forumites,

I have a question regarding noise, and how best to avoid it. I'm aware of the usual preventative measures - using as low an ISO as possible, improving it in PP etc. - but I was wondering, having seen mention of noise and ETTR (exposing to the right) are there are any other ways of reducing noise at the time of shooting?

I might have got the wrong end of the stick, but I recall reading that noise is reduced if you expose to the right - is this correct?

Yes.

I don't normally change the EV in camera before taking a shot and rely on making exposure adjustments in PP, is this a bad thing? I've never had an image (yet) that couldn't be recovered in Lightroom using the appropriate sliders, but I've a sneaky suspicion that making these adjustments in PP might actually exacerbate noise.

Your sneaky suspicion is correct. Changing the "exposure" (or rather the brightness, the exposure remains what it was) in PP affects the visibility of the noise (although the noise itself, just as the exposure, remains what it was). If you push in PP (increase the brightness), you will make the noise more visible. If instead you pull in PP (decrease the brightness), you will make it less visible.

Should I be making sure the image is as perfectly exposed as possible before taking the shot rather than relying on my trusty OMD-EM5's assessment?

Yes you should try to make sure the image is as perfectly exposed as possible when out shooting. The E-M5 will help you do that if you use the tools it provides right. See below for further information.

And, what exactly does exposing to the right mean? Sorry for being such an ignoramus - I have hitherto assumed it would benefit my pictures, but I don't actually know what it means.

"Exposing to the right" refers to the histogram. It simply means that you should give the image enough exposure to bring those highlights that you care to preserve right up to the clipping point (in RAW) but not beyond. Depending on how contrasty the scene is, this may sometimes mean that you "overexpose" (expose such as to make the OOC jpeg look overly bright) and decrease the brightness in PP and sometimes that you "underexpose" (expose such as to make the OOC jpeg look overly dark) and then push the shadows in PP.

In addition to the link to the article you already got from GeorgianBay1939, you might want to have a look at this recipe for exposure with the E-M5 specifically:

http://www.dpreview.com/forums/post/51169217

What I should mention in addition to what is said in that post is that I have my highlight warning level set to 255.

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP). The two images below, were both produced by such means. Both have greater dynamic range than any current camera could give you in a single shot.

Some info about me:

- I always shoot RAW, but find the JPEG results from the EM5 sometimes surpass my ability to alter RAW images and manipulate noise/contrast etc.

This may mean that you have to improve your PP skills. Although the OOC jpegs of the E-M5 are certainly not bad, you should be able to get better results from LR across the board.

- I find that the histogram in LR during PP is almost always bunched up (and touching) in the left hand side, before I've made any adjustments - could this be chronic underexposure?

Yes, that may be a sign that you are systematically giving the camera less exposure than it can take (and you can give it). A histogram like the one you describe is not always wrong (if there are prominent highlights that are close to clipping at the other, right end) but as a rule it should look different.

- I use the exposure, recovery and fill light sliders in LR with blinkies for highlight/shadows to asses what I need to correct

Your mention of the "fill light slider" suggests that you are still on LR 3.x. I would strongly advice you to upgrade to a later version. For example, the effect of the highlight slider improved noticeably in LR 4.x as did the ability to deal with CA (chromatic aberration). There are significant improvements in version 5.x too.

 Anders W's gear list:Anders W's gear list
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