Extremely low FPS with ASI224MC

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Blade71
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Extremely low FPS with ASI224MC

Post by Blade71 » Sun Aug 26, 2018 7:39 am

Hello, when trying to do DSO EAA, I’m getting extremely low FPS rates during my previews, 0.5 to 2 fps. I have tried using 2 different Win10 laptops, my primary is an i3 and just installed SC on an i7 w 16GB ram and both PCs have SSD drives and connected the camera directly into the USB 3.0 port. My settings are 2 sec exposures @ 350 gain. I have tried RGB24, RAW8 and 16 and I’m using the native ZWO drivers. I’m using a WO GT71 f/5.9 refractor to capture M51 and M31. I don’t have any issues when going through my focusing and was able to do a bit of planetary some time ago with my 8SE but I don’t recall the FPS when I did that. This doesn’t seem correct to me so I’m reaching for any help and suggestions. Thanks

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turfpit
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Re: Extremely low FPS with ASI224MC

Post by turfpit » Sun Aug 26, 2018 9:04 am

Fps=1/exposure(in seconds)

For a 2s exposure, fps=1/2 which gives a fps of 0.5. Low fps will always be the case for deep sky.

For lunar/planetary a typical exposure will be 20ms

Fps=1000/exposure(in ms)

For a 20ms exposure, fps=1000/20 which gives a fps of 50. High fps will be the case for lunar/planetary.

Hope this helps.

Dave

Blade71
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Re: Extremely low FPS with ASI224MC

Post by Blade71 » Sun Aug 26, 2018 1:25 pm

Thanks Dave, then it seems the FPS is ok for DSO. My next step is to figure out why I’m not aligning when doing live stack. Hopefully it’s just sky conditions.

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turfpit
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Re: Extremely low FPS with ASI224MC

Post by turfpit » Sun Aug 26, 2018 1:42 pm

Have a look at docs.sharpcap.co.uk, live stack section, troubleshooting. Try turning on the stars SHarpCap is using for alignment.

If this doesn’t help, then start a fresh piston the live stack forum detailing your issue. A picture of the screen and settings would help.

Dave

cuivenion
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Re: Extremely low FPS with ASI224MC

Post by cuivenion » Mon Aug 27, 2018 4:18 am

After you've got good focus try 8-15 second exposures with raw 16 at high gain (375). This may be more than you need for some targets. Here's an example of EAA with the ASI224, 10 x 8 second exposures, 135 gain, the scope was a Skywatcher 200P:
Stack_10frames_80s_WithDisplayStretch.jpg
Stack_10frames_80s_WithDisplayStretch.jpg (518.7 KiB) Viewed 1348 times
Last edited by cuivenion on Mon Aug 27, 2018 6:08 am, edited 1 time in total.

Blade71
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Re: Extremely low FPS with ASI224MC

Post by Blade71 » Mon Aug 27, 2018 5:04 am

Awesome thanks for the tip. I’ve been usually at gain 350. I was trying M31 and I did get the center of it but I wasn’t sure I was doing things right because of the low FPS. I’ve read more that I should increase the gain to be able to see. I’m going to try the 8-15 second route. I was only seeing 3-5 during last night’s viewing. I’ve got to keep remembering this isn’t a sprint and I need to have more patience, but one thing is I’m not sure how long I should expect it will take to see the targets.

cuivenion
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Re: Extremely low FPS with ASI224MC

Post by cuivenion » Mon Aug 27, 2018 5:50 am

If you're using the live stacking function you need to use the histogram and colour balance functions to get the best image. A single exposure of the above image would have just shown a few stars. You can use autostretch in the mini histogram to make sure you're on target, it will give you a good idea what you're looking at. Don't forget to switch it off before your start live stacking.

The live stacking histogram also has an autostretch function, as does the colour balance but you may get the best results by adjusting manually. M31 is a very large target and with your scope/camera you will only get the center in the field of view. I would try some more compact targets like M51, M63, M57 or M27.

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turfpit
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Re: Extremely low FPS with ASI224MC

Post by turfpit » Mon Aug 27, 2018 7:28 am

I would class M31 as a hard target. I had a year of elapsed time before I captured something reasonable for that object and only then with a 66ED refractor and 183C camera running at 5000x3000. M31 is huge.

I would agree with the previous post that M27 and M51 are good compact objects to start with. M27 has rich colour and the faint domes as as a challenge. With M51 there is the bright core and faint dust lines to aim for.

Astro imaging takes longer than people imagine to start to produce decent results.

Dave

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