How often is this feature used and what is its application?

Looks pretty much like rocket science.

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Do you want the make a double exposure in which you overlay your first image?

Without it, the fist exposure will look washed out or like a ghost under the second exposure.

Post-processing and staking of images might provide a better result.

George
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My advice is to try it both ways. Usually when I'm doing multiple exposures, I use auto gain, since often one wants all of the various contributing exposures to be semantically equal. But sometimes I really do not want the exposures to be equal, so it's easier to get the correct result without auto gain. That means doing some calculation, usually mentally, and that can be pretty error prone. At least it is for me. But virtually any multiple-exposure image, at least in my experience, is a very deliberate kind of thing, and there is nearly always ample opportunity to reshoot if I get the calculations wrong.

_____
Brian... a bicoastal Nikonian and Team Member

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But why use multiple exposures in the first place? I don't want to be Man Ray with his photo collages.

I thought it was a remedy for high noise when shooting in dark places. Camera on a tripod. Two or three underexposed (intentionally) images, each having little noise. But adding up to correctly exposed, and noiseless single image. I guess this would suggest high ISO, or long shutter speeds.

I'm asking, because I don't know a thing about his and just came across a posting discussing some of the little-known treasures in the D7000 Shooting Menu.

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>But why use multiple exposures in the first place? I don't
>want to be Man Ray with his photo collages.
>
>I thought it was a remedy for high noise when shooting in dark
>places. Camera on a tripod. Two or three underexposed
>(intentionally) images, each having little noise. But adding
>up to correctly exposed, and noiseless single image. I guess
>this would suggest high ISO, or long shutter speeds.

This would be an interesting experiment as I have not heard of this use before.

I have heard that you can use the multiple exposures to get the milky water effect when you cannot get the single long exposure.

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Joseph K
Seattle, WA, USA

D700, D200, D70S, 24-70mm f/2.8, VR 70-200mm f/2.8 II,
50mm f/1.4 D, 70-300mm f/4.5-5.6 VR, 18-70mm f/3.5-4.5 DX

What is the advantage of doing this in camera instead of stacking the images in post?

EDIT: After seeing Brian's post above, I get it. Thanks.

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I don't know the advantage. That's why I'm asking about this feature.

Moreover, some of us do no PP modification. I don't have a computer that will run the modern programs. At least, not yet.

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>Moreover, some of us do no PP modification.

There's your answer - the Multiple Exposure facility can be useful for people who want to combine images - say, a full moon into a featureless dark sky - but like to do as much as possible in-camera in an automated way.

Brian
Welsh Nikonian
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Yes, that occurred to me shortly after I posted the question. Thanks.

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> But why use multiple exposures in the first place? I don't want to be Man Ray with his photo collages.

There's more than one way to use multiple exposures.







Yes, it is possible to do this in post. One reason I do some of these this way, frankly, is that I'm tired of the criticism I sometimes get for "non-photography." So for things like this, I sometimes do it in-camera. Honestly, it's really a terrible reason. I should just do it the way that's best, and forget what other people say. In these three cases, it's probably just as good or possibly even better to do it in the field with the camera. I'd say it's better to do it in-camera since one can easily judge the result in the field and reshoot. Each of these is one of a number of attempts - usually four or five at a time - and they're not exactly precision craft. This is particularly true of stuff like #2 which might be emphasizing things like flowers blowing in the wind.

> I thought it was a remedy for high noise when shooting in dark places.

You could do that, although it's better to do it with some other software, which assumes that the images are supposed to be equal, thus eliminating noise - which would be different in every exposure. Sort of like the Fuji x10/x20 do.

The difference between that and your proposal is that you're assuming a tripod, but frankly if you can do that, you can probably just expose it properly in the first place.

_____
Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

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Beautiful, beautiful, beautiful. That's all I can say. We get all the 'realism' we need on the evening news. Artistic vision is sadly lacking. And one of the seductive delusions of photography is that we are accurately recording the reality around us with our cameras.
Bank clerks keep accurate recordings of reality and, in my case at least, the results are not inspiring.

It is an old argument. Realism versus imagination. I didn't mean to put down Man Ray in my earlier post. My professor of photography at UCLA in the early '60s was Edmund Teske (of Chicago). He studied with Man Ray, and was a resident at Taliesin West with Frank Lloyd Wright for 10 years. Cold photographic realism is too easily usurped by journalism. That's what the wisdom he urged in his young students. Who were, in the main, architecture students.

I applaud a photographer imposing his ideas on realism. In the camera. In post. In a darkroom with smelly chemicals. It's all good.

Thanks, I've learned more than I had hoped for.

Gary - Santa Monica

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This is the photo that prompted me to post a question. It came on the D7000 Tips forum. And included descriptive text on how the image was achieved. Multiple images shot at reduced exposure. Merged with Auto Gain turned on.

The camera, by the way, had no noise reduction set. Photos were merged in the camera. No post.

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Bravozulu
Might be helpfull for a bunch of us if you could post a link to the D7000 how-to
I love the image of the boats in the harbor

Thanks

Jeffcs

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Again, I'm hard-pressed to imagine how this would be better than simply getting the exposure right in the first place. You'll have motion artifacts either way. Shooting it at base ISO - and correct exposure - will surely result in no more noise than a regular daytime snapshot.

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Brian... a bicoastal Nikonian and Team Member

My gallery is online. Comments and critique welcomed any time!

Here's a link to the original tip. Scroll down to Tip #7.

http://forums.photographyreview.com/nikon-camera-equipment/nikon-d7000-tips-78038.html

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>Again, I'm hard-pressed to imagine how this would be better
>than simply getting the exposure right in the first place.
>You'll have motion artifacts either way.

Actually if that sample was a multiple exposure merge, it's pretty good in that there is to me little appearent motion artifacts especially in the masts.

But there is an advantage in stacking multiple shots with regard to SNR I believe.

The predominate noise source in images is shot noise. The benefit of multiple stacking is that the stronger signal will be accumulative and show little difference, but the lower signal will be averaged and shot noise would be improved (especially in fine gradient areas such as the sky).

At least I think I got that correct!!

Pete

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Pete, I believe you have the theory correct, but the question -- and I think this is what Brian is driving at -- is whether the SNR will be reduced more by taking three high-ISO shots and merging them compared to taking one low-ISO shot, albeit at a longer exposure. Either way, you have to consider motion effects. Either way, you'll improve the SNR. I think the jury is out as to which way would be better, but I'm with Brian in thinking you probably won't gain that much with the multiple-exposure technique.

-- Jon
Wethersfield, CT, USA
Connecticut High School Sports Photos

>-- and I think this is what Brian is driving at -- is whether
>the SNR will be reduced more by taking three high-ISO shots
>and merging them compared to taking one low-ISO shot, albeit
>at a longer exposure.

I think it depends on what the Gain in “AutoGain” means.

You are taking it to mean ISO or A/D amplification where it could mean a setting in post capture processing.

For example I shot these test images at base ISO of 100 (the D7000 has no Lo ISO settings).

This is single capture.



This is a three shot multiple exposure with AutoGain enabled.




They are NEF's using LR3 for conversion, using the Auto button (there was an apparent difference in exposure between the two) and a 71 sharpening setting only. Then I handed off to PS for cropping to 100% and saving.

To me there is significant difference in the darker background.

This technique has been used in Astrophotography for some time to improve overall image quality. The only limitation I see with the in camera process is that you are limited to only 2 or 3 shots. In Astrophotography they might often use 10 to 30 exposures (or more).

Pete

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>Two or three underexposed (intentionally) images, each having little noise. But adding
>up to correctly exposed, and noiseless single image.

I don't believe that's necessarily so.

There are two types of noise, fixed pattern and random. Shot noise is random and best dealt with through blended multiple exposures. But while several underexposed images might improve shot noise, I believe it will make fixed pattern noise such as read noise more apparent.

So in that sense it won't be noiseless, but instead random noise will be improved while fixed pattern noise will be worsened.

At least I think I got that correct.

Pete

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Interesting. I'll have to play with that. I must say, though, that I'm not used to seeing that much noise from the D7000 at ISO 100.

-- Jon
Wethersfield, CT, USA
Connecticut High School Sports Photos

>Interesting. I'll have to play with that. I must say, though,
>that I'm not used to seeing that much noise from the D7000 at
>ISO 100.
>

Don't forget that is a 100% crop. That's like looking at a door sized print from an 8x12 viewing distance. Under normal viewing and printing that noise would not be visible.

Pete

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