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ASI1600 and SGPRO - Reducing Time Between Exposures


Andyb90

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Hi everyone,

I was out imaging last night and I ended up with 2 hours of L data from 4 hours imaging. I was doing 30s subs at gain 75 in SGPRO. I was unguided and used the direct mount guider option for a medium dither every 5 frames.  Apart from a couple of pauses for re-focusing the sequence ran continually for the 4 hours. So the gap between subs is more or less the same as the sub length at 30s.

Is there anything I could do to reduce the gap as it's cost me nearly half my imaging time :(

I could try increasing my exposure time, but probably not by that much as it's easy to over expose when doing L with the 1600.

Andy.

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Possibly a silly question, but are you running this on usb2 or 3?

The length of time for download should be the same whatever the sub-length (the files are still 32MB). Last night my 1600 subs were taking about 1s to download over usb3 (I was getting a 2s sub every 3s).

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15 minutes ago, Demonperformer said:

Possibly a silly question, but are you running this on usb2 or 3?

The length of time for download should be the same whatever the sub-length (the files are still 32MB). Last night my 1600 subs were taking about 1s to download over usb3 (I was getting a 2s sub every 3s).

I'm using USB 3. Will time how long it takes to download a sub, but I think it must be several seconds at least.

Andy.

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I can manage 512 frames in about 12 minutes (flats and flat darks), that roughly gives around 1.4s download time - which is what it feels like when I look at it (regular subs, watching progress bar for download) - just over a second.

That is over USB3.0

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1 hour ago, vlaiv said:

I can manage 512 frames in about 12 minutes (flats and flat darks), that roughly gives around 1.4s download time - which is what it feels like when I look at it (regular subs, watching progress bar for download) - just over a second.

That is over USB3.0

Ah right. What usb setting are you using in the camera settings?

I'm wondering if it could also be an issue with my laptops performance. What spec machine do you use for capture?

Andy.

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Just now, Andyb90 said:

Ah right. What usb setting are you using in the camera settings?

I'm wondering if it could also be an issue with my laptops performance. What spec machine do you use for capture?

Andy.

I don't think it has anything to do with USB speed setting in my case. I recently fiddled around with those settings (read somewhere that it has an impact on dark current / amp glow - and it indeed does). But I did not see any difference in download speed over minimal setting of 40 and the one I'm currently using - 64.

I did think that it might help and increase download speed because this cam is capable of almost 15fps at max resolution and 12bit ADC. That would mean download time of around 70ms! That would be in line with max theoretical USB 3.0 speed which would allow for max 20fps (640MBps for frames of around 32MB), but one never reaches theoretical max communication speed.

It turns out that speed limit is either due to ASCOM drivers or SGP itself (program does statistical calculations / histogram / stretch and star count statistics on frame download, not sure if those are part of reported download time).

My laptop is Macbook pro 2015 - i5 dual core, 8 gigs of ram and 512ssd, running Windows 10 under bootcamp. I get same performance on my desktop machine - i3 / 8gb ram / 256 ssd running windows 7.

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My guess would be laptop performance as my laptop takes around 24 seconds to download a single sub, irrelevant of exposure time which makes taking lights and calibration frames a right headache. That's using a qhy183c and USB 3. 

I'm trying to find a decent laptop that will perform very quickly at both downloading subs and stacking but as I'm not very technologicaly minded, I have no idea what to look for. 

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On 21/04/2018 at 16:56, geordie85 said:

My guess would be laptop performance as my laptop takes around 24 seconds to download a single sub, irrelevant of exposure time which makes taking lights and calibration frames a right headache. That's using a qhy183c and USB 3. 

I'm trying to find a decent laptop that will perform very quickly at both downloading subs and stacking but as I'm not very technologicaly minded, I have no idea what to look for. 

I am seeing a spike in CPU activity when each image is downloaded from the camera. I think it is also taking several seconds to save the image files to the hard disk. So I think I'll look at a laptop upgrade.

I think I'll go for one with an i3 or i5, SSD and 8gb RAM. Possibly a refurbished laptop.

Andy.

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On ‎21‎/‎04‎/‎2018 at 09:50, Andyb90 said:

Hi everyone,

I was out imaging last night and I ended up with 2 hours of L data from 4 hours imaging. I was doing 30s subs at gain 75 in SGPRO. I was unguided and used the direct mount guider option for a medium dither every 5 frames.  Apart from a couple of pauses for re-focusing the sequence ran continually for the 4 hours. So the gap between subs is more or less the same as the sub length at 30s.

Is there anything I could do to reduce the gap as it's cost me nearly half my imaging time :(

I could try increasing my exposure time, but probably not by that much as it's easy to over expose when doing L with the 1600.

Andy.

Are you keeping an image history, ie. HFR / star count statistics? When I was using an ASI1600 I seem to remember that was taking longer than the actual download on my very low spec (but USB3) laptop until I disabled it. You can tell how long it takes by seeing how long the "Analyzing Star Data" message is displayed at the bottom.

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12 minutes ago, Chris-A said:

Are you keeping an image history, ie. HFR / star count statistics? When I was using an ASI1600 I seem to remember that was taking longer than the actual download on my very low spec (but USB3) laptop until I disabled it. You can tell how long it takes by seeing how long the "Analyzing Star Data" message is displayed at the bottom.

Yes I had image history enabled and turned it off. I tested and its definitely helped to reduce the interval between images.

Also I think generating the image preview takes up some time too. Ideally I'd like to turn that off as I don't really need it, but I don't think that is possible in SGP.

Andy.

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