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Time For Single Frame

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#1 JAS62

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Posted 19 February 2020 - 11:10 PM

I use Astrophotography Tool to control a Nikon D5300. If I take an 180 second exposure, the total processing time for a single shot is just over six minutes. It breaks down like this:

* 3 minutes for the exposure.
* 20 seconds for dithering (PHD2)
* 3 minutes to transfer the raw file for display in APT.

This means I am able to generate about 10 lights an hour. Is this normal performance?

Thanks folks!

#2 Gipht

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Posted 19 February 2020 - 11:48 PM

Saving a file should not take 3 minutes. I am not familiar with the software, but with my astronomy camera run by Sharpcap, dithering, and that exposure time, I  would get probably 15+ frames per hour.


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#3 Astrola72

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Posted 20 February 2020 - 12:14 AM

Agree with Gipht.



#4 Chuckwagon

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Posted 20 February 2020 - 12:34 AM

Agree that it should not take that long to copy the file, unless perhaps you are using USB 2 connection shared for both cameras (like through a hub) and it's blocked on the dithering part and the bandwidth is bogged down. 

 

Just a maybe, but does the Nikon have a "Long Exposure Noise Reduction" or similar feature like the Canon cameras do?  If so, make sure it's off.  If it's on, at least with the Canon cameras, that feature takes a dark exposure of the same length (the extra 3 minutes) and removes the noise it detects from the light exposure.  A nice feature if you are taking one shot, but not needed if you are processing dark exposures separately when you stack your light frames.


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#5 17.5Dob

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Posted 20 February 2020 - 12:34 AM

In BYN, using my D5300, a dither takes ~ 20"..... and 1" to download......for a 180" sub or a 480" sub...


Edited by 17.5Dob, 20 February 2020 - 12:36 AM.


#6 JAS62

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Posted 20 February 2020 - 12:43 AM

Thanks all. I think I will download the BYN demo and see if it makes a difference. I am using USB 2, but not through a hub. The D5300 and guide can are on different ports.

Now that I know this is not normal performance, I'll try changing out a few things to see if I can get better times.

Clear skies!

#7 TelescopeGreg

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Posted 20 February 2020 - 01:37 AM

Nikon does have a LENR setting.  It's suspicious that the display time is the same as the image time.

 

BUT, the image is not considered done (available for download) until both the Light and Dark images are taken and processed within the camera.  So the sequence of image, then dither, then display would be incorrect.  It would be 6 minutes for the image, and then dither and a quick display, unless you're listening to the camera and have the sequence rotated one position in your head.

 

I've tried tethering my D3200 over USB to my Raspberry Pi controller, and it does take a while to download an image.  But it's on the order of 10 seconds or so, not minutes.

 

Where is the image going when you download it?  Does it have to traverse a WiFi link back to the computer for display?  Just a thought.



#8 DaveB

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Posted 20 February 2020 - 08:35 PM

I wonder if you have dark frame subtraction (or whatever it is called) enabled on your camera? That function takes a second frame of the same duration as the first frame but with the shutter closed and then subtracts the second frame from the first one. That eliminates any hot pixels from the image before downloading it. But you're better off doing that yourself in post-processing, both because of the time issue that you're seeing and because you will liklely do a better job of it than your camera.

 

Besides checking the menus, you can just try changing the exposure time to 120 seconds and seeing if the "transfer" time goes down to ~120 seconds. If it does, then it really isn't the "transfer" time because that should be the same whether it is a 180 second frame or a 1/180 second frame.

 

EDIT: Sorry, I didn't read TelescopeGreg's reply closely. He is saying the same thing that I am, I just didn't know that it was called LENR.


Edited by DaveB, 20 February 2020 - 08:40 PM.


#9 JAS62

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Posted 20 February 2020 - 08:59 PM

I'm going to work on it this weekend. The skies look to be getting cloudy. :(

All of the suggestion are reasonable and easy to check. I'm sure I'll get this solved. I can't believe I've lived with it as long as I have.

I really like the camera. The sensor takes very good shots with a reasonable amount of interference.

I'm eventually going to have it moded[sic]. Just need to dialed it in all the way.


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