Horsehead from Dec 29th

Hey all,

Been an age since I've been on the boards due to the ol' bad weather gremlins being let loose for the past 6 months. Finally getting to use the QHY6 now that we got a couple of clear nights. First target was the horsehead with a Baader h-alpha filter. Didn't get a chance to shoot through the rgb filters so this is false colour.



Focus is off a bit + I'm having strange guiding issues with my mount. PE is causing slight trailing despite gpusb.

Does anyone run into problems with ice? I've had to leave the peltier off the last two times I used the camera as it seems to get ice crystals on the sensor window even though there's a "cold finger" which should prevent this. I may try putting some silica packs in the body but not sure if this will help at all.

Cheers,

Trev

Trevor,
apart from focus (a very minor issue there) you've got a very lovely red-coloured image of a popular target I never get bored of seeing. Well done! The only thing I can suggest, and it is down to preference I guess, is that (on this screen at work any way) it looks a bit dark. Some lightening of the red-end might not be a bad idea. The filament structure is superb, and it still looks like there's a glow behind the Head, somtehing even the big boys always get - great job!

Seanie.

Trev,

Thats a lovely image. Lovely structure, and nice striations in the nebulosity behind B33.

Focus doesn't look too bad to me mate.

I think I can answer both your questions.

Dew spot forming on camera optical window: I get exactly the same with my ATIK16HR. The reason is the enclosed air either between the objective and the optical window of the camera, or between a flattener lens and the same opt window. What I do is before I start I run the camera for 5 minutes before imaging. Almost inevitably there is a dew sopt on the OW. I blast it with a hairdryer and then blast some warm air inside the scope and quickly put them back together before the warm air escapes. The warm air is less humid than the surrounding air and after doing that you will get no more dew spots for the rest of the night. Where the OW is exposed to the open air, you should not get this. The function of the cold finger is to transfer heat from the CCD to the peltier cooler. It does not prevent spot dew on the OW, nor is it supposed to.

Guiding. I'd say your guiding is not too bad. What software and mount are you using. The stars look slightly diamond, which suggests that the mount is over compensating in bothe RA and DEC. Try reducing the agressiveness on both axes. Another thing to look into is that any anti-backlash settings are not too high. Also check the balance of the scope and ensure that the scope has to slightly lift the counterweight side. i.e. make the counterweight side very slightly too heavy. I'm alm ost 100% certain that your issue is not PE but guider settings. Really only trial and error and spending some time staring at the screen and understanding whats going on will truly solve the problem.

Now a tip: If you want to turn this into an LRGB, just take blues and greens and use some of the HA as the red channel. Use as many HA frames as you do blue and green, you'll end up with a really nice LRGB composite with less work. Note. This only works for nebulae. Doesn't work as well on other discreet objects.
Anyway congrats again on a really nice image.

Excellent Image there Trevor, well done. I believe there is a user group for the users of the QHY camera range, available at qhyccd.com/ccdbbs/index.php

Best regards

Steve Roche

That's very good detail.
Excellent!

Michael.

Thanks for the tips Dave. I misunderstood the function of the cold finger. Will definitely give this a go on the next night out.

I think you are correct about the aggresiveness of the guiding. I'm using PHD and will play around with this. About 1/3rd of the shots show a large trail on the Dec access so I will also look at the backlash settings on the CG5GT as I am guessing this is also adding to the problem.

Great tip in relation to using some of the h-alpha exposure for the red channel. I must try that out.

Thanks again,

Trevor