Gina's DIY All Sky Camera - Mark3 - with QHY5L-II-C

[Gina]

And this is really pushing hard on curves and levels - about the limit for the corrected image and exactly the same amount on the plain image as a fair comparison.

Plain.

Corrected.

The corrected image has been pushed until the random noise is starting to show.

[Gina]

Could get a small chance to test this out tonight but the trouble is it doesn't really get dark until 11pm and starts getting light again by 4am.

[Horwig]

just finished work here, still light!

Huw

[Gina]

Yes, the clouds came in before it got dark just as forecast.  An overnight AVI showed it stayed overcast all night. 

The darks I took earlier seem to have disappeared by the time long exposures were practical.  Maybe they are time limited or they may get wiped if the software is restarted.  I wonder if they are simply saved in memory and that's why there's no sign of them on HD.

[Gina]

Done some testing and I can report that the dark frames are lost on restarting the software.  ie. after restarting the software for any reason you need to retake the dark frames before dark frame subtraction will work.  I guess the dark frame stack is stored in memory.  While EZPlanetary was running and subtracting dark frames I tried to find dark files on the HD but didn't find them/it.

[Gina]

3 hours later and the dark frame subtraction is still working, using 20s exposures which is enough to show hot pixels easily. 

[Gina]

Thunder storms ahoy

[DrRobin]

Shame Gina, did you catch any lightning strikes? Still nice and clear up here, going to have another go at Saturn tonight.

Robin

[Gina]

Not yet but I think there's a good chance for later   Good luck with Saturn   That was the first planet I imaged

[Gina]

No sign of a thunderstorm but the rain has started.  Raindrops on dome.  Heater switched on.

[Gina]

I've now attached the pole to the observatory corner post.  The angle of the pole allows clearance from the roll off roof when open.

No more clearance than necessary

This view is from a distance with telephoto lens which makes the distant trees look almost in touching range   It shows the ASC and roof from as near horizontal as I can get without climbing a ladder.

Some image captures from this afternoon.

[Gina]

Some clear sky tonight and I'm recording an AVI - also taking a snap every so often.  Took a stack of 10 60s darks and now taking 60s lights with dark frame subtraction.  Here's a couple of examples, captured in TIFF format and enhanced in Photoshop.  The Milky Way is showing but the dew is very bad tonight and I need to increase the dew heater power.  I think the focus has gone off a bit too - have to set that up in the daylight as one adjustment per minute would take all night

[Gina]

Last night's AVI was too dark and being only 8 bit coundn't be enhanced with curves without posterisation.  I think this camera needs more than 60s exposures.  I think the focus was slightly off though and getting good focus will increase brightness of the stars.  EXPlanetary seems to take as long to process the image as it does to take it - ie. 60s exposures take 2m plus to capture.  To take a stack of 10 darks of 90s takes over half an hour.  Dark frame subtraction is pretty much perfect though.  I'm thinking of trying a smaller stack of maybe 4 or 5 dark frames.

The old QHY5 mono camera seems to be slightly more sensitive but the larger sensor area meant pushing the lens beyond its spec and caused considerable aberrations.  Of course, other things being equal, you would expect a colour camera to be a lot less sensitive than a mono one and clearly a mono version of the new camera would do better for capturing stars (as long as you're not interested in what colour the stars are ).

This project is still at the experimental stage but results are looking good.  Next to do is to change the sketch to control the dew heater automatically to maintain a given teperature in the dome.  Then the required temperature can be ascertained from the dew point calculated from data from a DHT22 housed in a small Stevenson Screen mounted slightly lower down on the pole.

[Gina]

Brought whole assembly indoors and pointed camera out of open window for setting focus.  It was out by 6 steps.

[Horwig]

What gain do you run at Gina, I've been using 50% gain and somewhere about 10 to 30 seconds.

Huw

[Gina]

About 2 or 3%.

[emadmoussa]

I have to say, quite impressive, Gina! Hats off!! 

[Gina]

Thank you Emad

[Gina]

Contrails galore!

[Chris]

Wow Gina I've not checked in on this project for a while but it looks like you've really cracked it with the mk3. 

The shots looks really impressive, especially like the ones showing the Milky Way!

[Gina]

Thank you Chris

More contrails lit by the setting sun.

[Pan Euro]

This project just gets better and better.

[Gina]

Thanks

I'm going to try Huw's settings tonight - 30s exposures and 50% gain.  Longer exposures produce oblong stars so no advantage.  This can be seen when using the focus tool in EZP.

[Gina]

At last a clear night   ASC is mounted on observatory.  Focus was found to be 15 steps out using EZPs Focus Aid.  Remote focussing is definitely needed with this lens.  I'm recording an AVI file overnight.  Exposures of 20s with dark frame subtraction (stack of 10), gain of 50 and gamma of 0.7.

Here is a Snap capture in TIFF format, cropped and levels applied in Photoshop, saved in PNG format.

[Horwig]

That is very nice, clean and very sharp Gina. Is the light at 2 o clock yours?

H