ASI 290 mini mono and SC problems

Discussion of using SharpCap for Deep Sky Imaging
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edgar619
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Joined: Sat Jan 13, 2018 4:43 am

ASI 290 mini mono and SC problems

Post by edgar619 » Mon Nov 05, 2018 2:05 pm

Robin

I am an experienced SC Pro user Using a Touptek 224. I have purchased a ASI 290 mini mono.i downloaded the proper ASI drivers. Verified all my laptop drivers are up to date. I have done daylight tests , using my Acer E 15, to establish all is working and obtain proper number of focusing turns and direction with a .5 GSO FR correctly spaced @ 51mm. This distance verified by Agena techs. I can come to focus in the daylight. Using 3.2 , When I observe at night I can not get any stars to appear on the screen ( with the exception of very bright stars like Vega) until i reach 8-10s exposure. My gain is set at 350. My screen is set to auto. I have checked on the USB troubleshooting ..up to date drivers , changed ports , etc .....experimented with turbo USB settings..currently 80 ..cable is less than 5m

Another example of my problem is my focusing tecnique will not work. I GoTo an object. Center a bright star in the field. Set exposure to 500ms , gain 350 and Zoom to 200 % then reduce exposure until it is just visible and then focus. Since I can’t see any stars in the field @ 500ms i can’t use this, ..I have had to use Vega to focus.

I have successfully taken images at 8-10s..of something as bright as M57. but this was by trial and error chance experimenting with back and forth exposure vs gain settings

I wonder if my sky conditions are so marginal that a sensitive camera like the 290 is having trouble with that. ..or if somehow the combination of my Laptop, SC and ASI is not compatable ...although as I said the setup comes to focus in daylight using a .5 or a .63 focal reducer.

What am I doing wrong.....approaching wits end ..

Thanks

Edgar

BlackWikkett
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Joined: Sat Jun 23, 2018 8:48 pm

Re: ASI 290 mini mono and SC problems

Post by BlackWikkett » Mon Nov 05, 2018 3:26 pm

- Double check your drivers for ZWO cameras. The latest version is 3.0.0.5, you can find this version number easily in the the Windows uninstall program list.
- you say you can get focus in daylight, how far are the objects your get focus with? Rule of thumb for daylight focus is 1 mile or 1.5 KM
- in SharpCap set color space RAW 16, exposure 2-4 seconds, max gain, brightness 10-20 (same as offset) then in the display histogram click the auto stretch
- If you're very much out of focus you may see nothing and have to rack your focus in one direction quit a bit. Just take note of your focus starting point so you can go the other direction if need be
- if you use my suggestion of 2-4 second exposure give SharpCap time to capture the frame and display on you screen. When I started with SC not giving the screen time to update caused me endless headaches.

This process works for me hope you have good results.
-Wikkett

edgar619
Posts: 21
Joined: Sat Jan 13, 2018 4:43 am

Re: ASI 290 mini mono and SC problems

Post by edgar619 » Mon Nov 05, 2018 4:10 pm

Thank you Wickett for these suggestions

I reinstalled the latest driver version just to be sure

I have been daylight focusing on an object more than a mile away ..but I will
I k another object and recheck

This is a mono only camera....so only two choices mono 8 and mono 16..I have chosen 16 based in reseqrch on cloudy nights

I moved my brightness setting to 20..it has been higher through trial and error

I will move gain to max and use auto stretch when I can again observe at night

And use 2s exposure

I wonder if there is something wrong with the camera ?

The trial and error journey continues

Thank you!

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admin
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Re: ASI 290 mini mono and SC problems

Post by admin » Mon Nov 05, 2018 7:33 pm

Hi,

it sounds as though you may have got your settings into a bit of a mess. If you hold down <CTRL> while opening the camera then SharpCap will not re-load the settings saved last time you used the camera and you will go back to defaults.

Not sure quite what exposure values to expect to work as you don't mention the scope you are using and a long focal ratio scope like an SCT will require longer exposures. Still, 2-4s exposures and max gain should show a good selection of stars except in very long focal length systems.

One trick to test sensitivity - use the new 290 and the old 224 in the same situation in daylight at minimum gain and check they require roughly the same exposure to reach 50% histogram level.

cheers,

Robin

edgar619
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Joined: Sat Jan 13, 2018 4:43 am

Re: ASI 290 mini mono and SC problems

Post by edgar619 » Mon Nov 05, 2018 8:10 pm

Robin thank you

I am using a Celestron SCT NexStar 8” F/10...since I have both a .5FR and a.63 I can lower the F ratio. I will try a reset and max gain...never tried that as I was told and saw so many cloudy nights posting using 350 gain. 8s exposure and 350 gain produced acceptable image the other might. I have to solve this since trying to focus and find an object is tough at 8s. I get the relationship between gain and exposure I will work on this

Edgar

edgar619
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Re: ASI 290 mini mono and SC problems

Post by edgar619 » Mon Nov 05, 2018 8:32 pm

Robin

If I follow you on sensitivity and am doing this properly the 290 needed exposure is 9.9ms and the 224 is 2.0ms .This gets the histogram for both to 50%

I will need your coaching to tell me how these two exposure settings tell me what to do with other SharpCap settings

Thx

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Re: ASI 290 mini mono and SC problems

Post by admin » Mon Nov 05, 2018 8:53 pm

Hmmm,

is your 224 a mono camera by any chance and the 290 a colour? That difference would be around right for the difference in sensitivity between the two.

cheers,

Robin

edgar619
Posts: 21
Joined: Sat Jan 13, 2018 4:43 am

Re: ASI 290 mini mono and SC problems

Post by edgar619 » Mon Nov 05, 2018 11:42 pm

Robin

Other way around ...so the results bothered me too

I may not have done the “test” correctly though

Don’t fret about this ...I will work on 2s exposures and high gain to start with and see where the this goes

Thx

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