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Archive 2013 · Using 5d3 multi exposure to reduce noise.
  
 
ben egbert
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p.1 #1 · Using 5d3 multi exposure to reduce noise.


I tried this yesterday, you set multi exposure for several shots up to 9, set the multi-exposure to average, save source as result only. I also enabled long exposure NR and used silent live view with a cable on a tripod. This could be a nice process for deliberate tripod work in dark situations. It can also be used with burst mode.

I then did some ISO1600 shots in a dark basement. The noise of the multi shot RAW was much cleaner than a single shot. It still needed a tiny bit of NR but cleaned up very nice.

I wish I could bracket the exposure as I can do with HDR but that is not an option. The HDR function only produces a jpg. The multi exposure produces a raw file.



Feb 26, 2013 at 08:52 PM
Rickuz
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p.1 #2 · Using 5d3 multi exposure to reduce noise.


So the camera really produces a single raw file from the multiple exposures? (from up to 9 different exposures?)


Whats the difference between this function and HDR function? To me it sounds like they are the same thing.

Edited on Feb 26, 2013 at 09:21 PM · View previous versions



Feb 26, 2013 at 08:58 PM
ben egbert
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p.1 #3 · Using 5d3 multi exposure to reduce noise.


HDR is a method to autoblend different exposures. You can save all the raw files, but the result is only saved as a JPG.

Multi exposure is more like what we used to do with film cameras, it is designed to get different stuff in the same image. You could do an eclipse of the moon sequence for example and get the moon in different locations with everything else stationary.

The method I am describing is probably not an intended use, or at best undocumented. But by averaging several images, it enhances real detail while cancelling out random noise.

The average setting keeps the exposure constant. Other options are additive, bright and dark. Additive would build the exposure. I have not explored the others.



Feb 26, 2013 at 09:12 PM
abqnmusa
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p.1 #4 · Using 5d3 multi exposure to reduce noise.


that is interesting Ben. thanks for the heads up


Feb 26, 2013 at 09:15 PM
Pixel Perfect
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p.1 #5 · Using 5d3 multi exposure to reduce noise.


Or you could merge the multiple shots in PS and use the median filter and greatly reduce noise. It's also a way to remove pesky people/cars etc from a shot as long as they don't stand in the same place for all the shots.


Feb 26, 2013 at 09:33 PM
ben egbert
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p.1 #6 · Using 5d3 multi exposure to reduce noise.


I just found that you can bracket in multi exposure. You need to do it manually between shots. You need to wait for it to compute results before changing exposures. But the result is no different than a single shot in the middle of your bracket. It just averages back to the mid point.


Feb 26, 2013 at 09:37 PM
ben egbert
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p.1 #7 · Using 5d3 multi exposure to reduce noise.


Pixel Perfect wrote:
Or you could merge the multiple shots in PS and use the median filter and greatly reduce noise. It's also a way to remove pesky people/cars etc from a shot as long as they don't stand in the same place for all the shots.


I also wonder if this is a way to simulate a long exposure water shot to blur motion? I need some moving water to test that idea. I am thinking it will take too long to get the sequence. Maybe a 2 shot burst?



Feb 26, 2013 at 09:39 PM
Pixel Perfect
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p.1 #8 · Using 5d3 multi exposure to reduce noise.


ben egbert wrote:
I also wonder if this is a way to simulate a long exposure water shot to blur motion? I need some moving water to test that idea. I am thinking it will take too long to get the sequence. Maybe a 2 shot burst?


I think you could, but you might need several shots for a good effect.



Feb 26, 2013 at 09:46 PM
Monito
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p.1 #9 · Using 5d3 multi exposure to reduce noise.


ben egbert wrote:
I also wonder if this is a way to simulate a long exposure water shot to blur motion?


Yes. If you want to have an 18 second exposure but can only ND it down to two seconds, average 9 two-second shots. I think it would be best to minimize the time between shots or randomize it to avoid catching rhytmic action like waves at the same point on the cycle preferentially.

You have to set the options to avoid the camera trying to counteract the motion, but it can easily be done. I have not done it since my camera does not do in-camera averaging.



Feb 26, 2013 at 09:48 PM
Monito
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p.1 #10 · Using 5d3 multi exposure to reduce noise.


Here's a tutorial (a real one, a written one) on how to do the averaging in Photoshop, so you can shoot multiple Raws or HDR Raws: http://www.verdantvista.com/gallery.php?doc=tut9-3



Feb 26, 2013 at 09:50 PM
 

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Fred Miranda
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p.1 #11 · Using 5d3 multi exposure to reduce noise.


Yes, it offers similar S/N ratio increase you get when taking 9 shots and stacking them in Photoshop or other stacking software. The difference is that Canon's Multiple Exposure does the work in-camera and has the option to save only one "enhanced' RAW file as a result.
This can also be used for astrophotography stacking as well. See this thread here:
http://www.fredmiranda.com/forum/topic/1192050/1#11372841

I don't believe Canon intended this feature to be so useful. You can even use it to mimic a ND filter with very natural results. I used it a lot when shooting with my 17 TS-E.
Fred



Feb 26, 2013 at 09:55 PM
ben egbert
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p.1 #12 · Using 5d3 multi exposure to reduce noise.


Pixel Perfect wrote:
I think you could, but you might need several shots for a good effect.



Just tried it on a kitchen faucet. Poor choice as the light was so low it was blurred with one shot. But I tried two anyway just to get the idea of it. My preferred water blur is about 1/4 to 1/10 second. But even in burst mode and a fairly fast shutter, it is slow because it does a calculation between shots.



Feb 26, 2013 at 09:57 PM
ben egbert
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p.1 #13 · Using 5d3 multi exposure to reduce noise.


Fred Miranda wrote:
Yes, it offers similar S/N ratio increase you get when taking 9 shots and stacking them in Photoshop or other stacking software. The difference is that Canon's Multiple Exposure does the work in-camera and has the option to save only one "enhanced' RAW file as a result.
This can also be used for astrophotography stacking. See this thread here:
http://www.fredmiranda.com/forum/topic/1192050/1#11372841


That's where I got the idea to test it. Thanks for the idea.



Feb 26, 2013 at 09:58 PM
snapsy
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p.1 #14 · Using 5d3 multi exposure to reduce noise.


Here's a comparison I did: http://www.fredmiranda.com/forum/topic/1120557/0


Feb 26, 2013 at 10:30 PM
ben egbert
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p.1 #15 · Using 5d3 multi exposure to reduce noise.


snapsy wrote:
Here's a comparison I did: http://www.fredmiranda.com/forum/topic/1120557/0


Matches my tests yesterday. I am not willing to show what my basement looks like however.

I see one guy does not understand this can produce a raw not just a jpg.



Feb 26, 2013 at 10:55 PM
Larate
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p.1 #16 · Using 5d3 multi exposure to reduce noise.


The pros of in-camera averaged multi exposure to reduce noise : have the results as a raw file. The cons : no alignment is performed before the "blending" (which de facto implies a tripod at least for me).
Well it is how the multi exposure is implemented in the 1Dx. I guess the 5D3 is similar.

Larate



Feb 26, 2013 at 11:17 PM
ben egbert
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p.1 #17 · Using 5d3 multi exposure to reduce noise.


Larate wrote:
The pros of in-camera averaged multi exposure to reduce noise : have the results as a raw file. The cons : no alignment is performed before the "blending" (which de facto implies a tripod at least for me).
Well it is how the multi exposure is implemented in the 1Dx. I guess the 5D3 is similar.

Larate


This is a very deliberate method. Not sure how I will be using it. For sky shots without a tracking device I am stuck with long single exposures up to 20 seconds or so. I have done astro stacks before, but not real happy with the results. The problem is blending in the foreground shot of land afterward. I want to get the whole thing in one shot.

I am heading out east of Provo tonight for a full moon illuminated shot. For this trip I will probably just do long exposures.



Feb 26, 2013 at 11:34 PM
cputeq
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p.1 #18 · Using 5d3 multi exposure to reduce noise.


Oh wow, I had no idea this multi-exposure would save a RAW as the result. Hrrrrrrmmmmmmm...thanks for this thread (I missed the other one apparently)



Feb 27, 2013 at 12:17 AM
Beni
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p.1 #19 · Using 5d3 multi exposure to reduce noise.


Strangely the manual says that using multi exposure will increase noise.


Feb 27, 2013 at 10:12 AM
dhphoto
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p.1 #20 · Using 5d3 multi exposure to reduce noise.


ben egbert wrote:
it enhances real detail while cancelling out random noise.


Does it, or does it just mean there is noise upon noise which makes it look like less noise but at the expense of detail?

Certainly in Snapsy's example it seems there is an apparent loss of detail in the lettering

I can't help thinking skillful use of PS layers and good noise reduction software would be both quicker and better

YMMV



Feb 27, 2013 at 10:20 AM
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