SharpCap Forums

Andy

Darks - have a look at viewtopic.php?f=16&t=1347. This was processed with and without darks. Always worth considering if you are time pressured.

With the QHY10, I think you have setpoint cooling which means you will be able to build a darks library.

Dave

Nice dave,
Here is a couple from the QHY10.
But with several hours for each.

Andy,

If you have a cooled cam then definitely build a darks library, it gives you more time under the stars taking lights instead of wasting precious time doing darks. I am quite certain that your Altair cam, like my Altair cam, is not cooled. If you continue to use your Altair cam for deep sky then make sure that you take darks BEFORE lights. Don't try reusing darks from a previous night. The temperatures will not match and you will end up injecting a lot of Dark noise into your stack.

Next time you use the Altair for deep-sky back off the exposure from 80 seconds to 30 seconds but by all means experiment.

Brian

Andy,

Those are awesome shots! Can you share the exposure information?

Thanks,
Brian

Actually Brian, looking at my notes, they were all done in a rush , and less than an hour a piece.
All in the same nighht.

Altair Astro RC8, with Revelation 0.75x reducer, QHY10, EQ6.
Guided with 60/285 finder, PHD2 and Altair GPCAM2 AR0130.
7 x 360s , darks and flats.
Taken with ATP, calibrated in DSS, stacked in nebulosity, processed in Startools.

I much prefer the image scale of the CMOS imaging train, and with everyones help, I’m keen as mustard.

the mono cam is a lot noisier than the colour cam, which surprised me.
But of course the colour cam is probably only half as sensitive if that.

Read noise for the QHY10 is 7.1 e.
Colour CMOS is 1.6e@ 200 gain
mono CMOS is 5.2e @ 200 gain.

How many dark frames do you take and average?
And any dithering involved?

Andy,

With these cool ambient temperatures I strive for 20 darks but in the heat of the summer I like to get 50 darks.

I am not a ditherer. In fact I don't actively guide. I have a 50 year old mount with just a stepper motor on the R.A. axis using a controller and software that I designed. I rely on precise polar alignment and periodic error correction. I call it "passive" guiding. I can get up to 200-second exposures with reasonably good results. That's the exposure I use for narrowband.

Here is a stack of 32x 200s in 7nm Ha of M101. As you can see the tracking is reasonably good.

Brian

That’s a great result for unguided mate.

Andy

A search on astrobin.com for your QHY10 will give you an indication of the camera's capability and some ideas for settings for different objects.

https://www.astrobin.com/search/?q=qhy10 go to the site and put QHY10 in the search field at the top.

Dave

Looks like you are already on astrobin - if its you?

Dave