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canon noise reduction setting

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#1 keithlt

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Posted 04 May 2014 - 03:34 PM

hi all, there is a setting for noise reduction in my xsi (450d) is any using this for a/p ?

#2 jgraham

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Posted 04 May 2014 - 04:35 PM

There are two basic options. Leave all of the noise reduction functions turned off and use stand-alone darks. This is pretty standard faire. Plan-B is to turn the long exposure noise reduction on (leave the others off) and let the camera take and apply the darks for you. This is far less common, but it can be very effective. I quit taking darks a couple of years ago and I let the camera do it for me. Either way works.

#3 keithlt

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Posted 04 May 2014 - 05:13 PM

thanks John, i will give it a go tonight with noise reduction on.

#4 Mike Clemens

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Posted 04 May 2014 - 05:15 PM

That plan will half your sky-time, right?

#5 torsinadoc

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Posted 04 May 2014 - 05:18 PM

Maybe combine dithering and internal canon noise reduction?

#6 keithlt

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Posted 04 May 2014 - 06:34 PM

so the noise reduction is the same as pause in byeos?

#7 piaras

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Posted 04 May 2014 - 08:48 PM

so the noise reduction is the same as pause in byeos?


No. The pause in BYEOS is more of a let things cool etc.

#8 keithlt

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Posted 04 May 2014 - 09:26 PM

i was just reading the canon manual on the noise the reduction setting, its for exposures over 1 sec. and it will be as long as the exposure before it was .so a 30 sec exposure will cause a 30 sec wait. it might not work nice with byoeos.

#9 jgraham

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Posted 04 May 2014 - 09:37 PM

BYEOS detects when the long exposure noise reduction is turned on. You will see a message "Noise Reduction" displayed while the camera takes and applies its dark frame. Pretty painless.

#10 Ralph Paonessa

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Posted 05 May 2014 - 01:24 PM

I recently discovered a useful Long Exposure Noise Reduction feature in my EOS 6D. (Poorly documented; I believe the 5D's have this as well; you'll have to check your camera.)

With LENR on, the camera can record several "light" frames before it records its "dark."

From the 6D manual:

During noise reduction, shooting is still possible as long as the maximum burst indicator in the viewfinder shows "1" or higher.



So you can shoot a, say, 2 min exposure. At the end of this. the camera will be "busy" recording the 2 min dark. But you can interrupt this and shoot another light. On my 6D, I can shoot 3 lights in a row. After this the camera will record the dark frame, and apply it to all 3 lights. (During this final light, the camera is "busy" and you can't take another shot until it's done.)

If my math is right, this way you only lose 25% of your shooting time to darks, instead of 50% if each shot required one light.

I believe the 5D's shoot more lights before needing a dark, but someone will have to check this.

I'm not sure yet how BackyardEOS handles this.

#11 Moromete

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Posted 05 May 2014 - 01:35 PM

I recently discovered a useful Long Exposure Noise Reduction feature in my EOS 6D. (Poorly documented; I believe the 5D's have this as well; you'll have to check your camera.)

With LENR on, the camera can record several "light" frames before it records its "dark."

From the 6D manual:

During noise reduction, shooting is still possible as long as the maximum burst indicator in the viewfinder shows "1" or higher.



So you can shoot a, say, 2 min exposure. At the end of this. the camera will be "busy" recording the 2 min dark. But you can interrupt this and shoot another light. On my 6D, I can shoot 3 lights in a row. After this the camera will record the dark frame, and apply it to all 3 lights. (During this final light, the camera is "busy" and you can't take another shot until it's done.)

If my math is right, this way you only lose 25% of your shooting time to darks, instead of 50% if each shot required one light.

I believe the 5D's shoot more lights before needing a dark, but someone will have to check this.

I'm not sure yet how BackyardEOS handles this.



Good point, you are right!

I've read this too in 6D's user manual somewhere hidden. It's just one line about this unfortunately.



Have you tried to see how long can be those 3 exposures before the dark frame is taken?

Also what difference does it make if one sets Canon LENR to Auto instead of On?

#12 mmalik

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Posted 05 May 2014 - 03:15 PM

So you can shoot a, say, 2 min exposure. At the end of this. the camera will be "busy" recording the 2 min dark. But you can interrupt this and shoot another light. On my 6D, I can shoot 3 lights in a row. After this the camera will record the dark frame, and apply it to all 3 lights. (During this final light, the camera is "busy" and you can't take another shot until it's done.)


Ralph, can you list the actual steps you take to combine 3 lights with one dark? I have been wanting to know this information but no avail so far. Details will be appreciated. Regards

#13 Thirteen

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Posted 05 May 2014 - 05:24 PM

The 6d just lets you keep shooting immediately when LENR is turned on. I assume it is until the burst buffer is filled then it takes a dark, applies it to each, and writes everything to the card.

I assume that's what it's doing anyway.

#14 mmalik

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Posted 05 May 2014 - 07:01 PM

Thanks! Does anyone know how large is the multiple exposure buffer; does it matter how long is each exposure? In other words, does same amount of buffer get used if one were taking 10sec exposure vs. 1000sec individual exposure? My question is mainly about AP; is multiple exposure implementation compatible with longer length RAWs typical of AP instead of very short length JPEGs used in day time/burst mode photophraphy? Regards

#15 Thirteen

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Posted 05 May 2014 - 07:38 PM

I can run an experiment, I haven't yet. I can't figure any other way it is doing the dark subtraction. I just am speculating on how it is applied here but I figure the length of sub isn't going to matter. Since the buffer is a fixed size, a raw frame is a raw frame?

.

#16 Alex McConahay

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Posted 05 May 2014 - 08:36 PM

Please do run that experiment.

Are you saying that the camera takes a light, then starts a dark. But you interrupt the dark to start another light. You do that repeatedly, and finally, the camera gets to take its dark. And then it subtracts the dark from all the lights? Do you have some information to back that up?

I can see it interrupting the dark. But I cannot see it waiting until it finally gets a chance to take one, and then going back and applying. May be that way, but I would like to know for sure, not just an assumption.

Alex

#17 Thirteen

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Posted 05 May 2014 - 09:02 PM

Please do run that experiment.

Are you saying that the camera takes a light, then starts a dark. But you interrupt the dark to start another light. You do that repeatedly, and finally, the camera gets to take its dark. And then it subtracts the dark from all the lights? Do you have some information to back that up?


I think that is what is happening. The 6d manual p129 alludes to this. I'm not going to claim I can definitively say.

I ran the experiment. With 10s, 60s, and 300s, and an intervalometer on a 5s delay between frames. In all cases it never threw up the "busy" until it took 3 frames and then came a dark time-out "busy" signal. After the dark it took longer to write to the card with progressively longer exposures. Maybe up to 10-15s with the 300s exposures. After that it was ready to go for another 3 and then another timeout, and so on....

I don't have information backing up what is actually happening, only my speculation as I said. I will try to get it under the sky soon to check the effect of the noise reduction.

#18 mmalik

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Posted 05 May 2014 - 09:49 PM

Reading the 6D manual, here is my understanding:


1. 'Multi Shot Noise Reduction' can ONLY be set with 'High ISO Noise Reduction' where for a single photo, four shots are taken in a burst and merged into a single JPEG image. [Page 126]


2. 'Multi Shot Noise Reduction' can NOT be set for 'Long Exposure Noise Reduction' typical of Astrophotography. In short, if 'Long Exposure Noise Reduction' has already been set, 'Multi Shot Noise Reduction' can NOT be set. [Page 127]


3. You can shoot two to nine exposures to be merged into one image in 'Multiple Exposures'; but my understanding is that 'Long Exposure Noise Reduction' is what's NOT happening here and can NOT happen. Multiple Exposures are just being added or averaged but are NOT being 'Long Exposure Noise Reduced' per se. [Page 158]


So much for all the enthusiasm regarding 'Multiple Exposures' :(

#19 keithlt

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Posted 05 May 2014 - 10:13 PM

Yes it works seamlessly with Byoes exactly is you mentioned.

#20 Thirteen

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Posted 05 May 2014 - 10:59 PM

mmalik... I'm confused by what you are trying to say. I just went out under the sky and took some samples. When I take a "burst" of three images with LENR turned on, each of those light RAWs has a dark applied. That dark has to be the one taken at the end of the series. There is no other explanation.

There is no setting that has to be manipulated to get this to happen. If you press the shutter during "dark frame time", it abandons it and takes an exposure. I can only figure it saves the light images in the buffer until it fills, then forces a dark.

I don't think it writes to the card and then post-processes it. So, in this way you can't set up a series of more than 3 lights with the intention of using a single dark.

#21 Alex McConahay

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Posted 05 May 2014 - 11:13 PM

I still think it worth the try.

I did read the manual, though. I can see Keith's logic in it.

There is a distinct difference between what my T3i manual says and the 6D manual says on the issue. The T3i says you cannot take another picture. The 6D says you can continue to shoot. What does it mean that "shooting is still possible" if Keith's interpretation is not correct? How could it take another shot if it is exposing a dark at the time?

But I agree, that it sounds like we have the multi-shot reduction noise (averaging out several exposures?) confused with long exposure noise reduction (taking a dark frame and subtracting it).

Run the experiment, Keith. Tell us what you find?

Alex

#22 mmalik

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Posted 06 May 2014 - 12:01 AM

When I take a "burst" of three images with LENR turned on, each of those light RAWs has a dark applied.


How long are your individual exposers when you say "burst" of three?


I am trying to decipher myself what the manual says. Please read the pages I referenced and elaborate if you have a different understanding.


As Alex said, averaging multiple exposures is different from applying dark to multiple exposures. In astronomy we care more about the later than former, don't we? Regards

#23 Thirteen

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Posted 06 May 2014 - 12:11 AM

See my earlier posts for the exposure lengths and the section of the manual that pertains to the feature on the 6d

I am not referring to averaging at all. I am only referring to LENR.

#24 mmalik

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Posted 06 May 2014 - 01:02 AM

Well, all this means is that 6D manual is written quite badly. If LENR is possible with multiple exposures, manual doesn't say it out right and has a very convoluted way of saying it. Let's get more testing done and get this sorted out. Regards

#25 Thirteen

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Posted 06 May 2014 - 06:34 AM

Not trying to hijack this more so perhaps a new thread is in order. What additional testing are you guys proposing on the 6d?


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