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jcm

First Go With QHY8

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My QHY8 arrived today. I cannot believe it but there is a clear sky. I decided to use Nebulosity to control the camera. The drivers loaded OK. I set the gain to 0 and the offset to 112. (suggested by Bern who had tested the camera ). The leads all seemed to fit OK and are not loose. ( common earlier problem )

I attached the camera to the C9.25 at F6.3. The field of view with the 130mm APO at F4.8 will be amazing. Can't wait to try it out.

I just took 5 X 2mins using a CLS filter. No Darks , Bias or flats.

Not bad for 10min total.

John

post-13061-133877354913_thumb.jpg

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Thanks for that , Kevin.

It seemed a bit strange setting the gain to 0 , might try setting it to (1) as most others seem to use this setting.

John

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You will get great results I am sure John, as that pic shows.

As for the gain, i'd recommend you read Craig Starks tutorial, and then try and find the settings yourself, and then see how they compare to the written ones you have. I found other settings to the ones supplied by Bern worked well for me.

You really need to test the camera in the daylight, to ensure that you are getting the full dynamic range, without overdoing any of it. For instance, I found the settings on my qhy8 work well for me at 31 gain (49%) and 30 offset.

The tutorial is a little vague as to exposure times to be used for the tests, but I am under the impression you would use that which gave you a properly exposed image. The offset is easy to find, just decide how far off zero you want your pics to start, and then set accordingly. Holding your mouse over the pixels in Nebulosity will give you their ADU value. Also in the image properties the max pixel value will be recorded.

if you get flumoxed, send a pm or something, and we could figure it out together :(

How did you get on with the dewing problem? Are you using the standard 12v power supply for the TEC? After a suggestion by SteveL I have spoken with Bern about using a lower voltage supply, which may indeed help to alleviate the problems experienced. For now I assemble my camera rig under warm air from a hair dryer, and whatever you do, dont undo the filters once the camera is running!!! (Ice aint nice!)

Looking forward to some dazzling results now John!

Cheers

TJ

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Hi TJ ,

I am placing the camera in a sealed box with silica gel after use. I used the camera for about an hour tonight and did not notice any icing. ( I do have an obs so this might help)

I am a little confused about the gain/offset - I will try at the weekend to check what are the most suitable ones for my camera. There are some instructions for this in the nebulosity manual.

John

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The usual problem comes on the centre of the IR nosepiece filter. Silica gel will help. Dont forget to give the camera 10 - 15 mins to settle itself when you test it.

As for Nebulosity, what a great little program. I can still make sense of it after a night out and frozen brain :(

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Right out of the blocks John, excellent!

bern

Yep , it was a surprise how easy it was to get the camera up and running.

Even the weather played ball by being clear.

John

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TJ ,

I think I am starting to agree with your figures.

I am using 65 for the offset , and at present imaging the Rosette neb. At the moment I am using a gain of 20 , thats 31%. It seems to give a reasonable image with a 4 min exp.

John

I do have a CLS filter on which increases the exp slightly

After a lot of messing about I have ended up with , Offset - 65 , Gain - 26 (42 %)

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Hmm, I do all my QHY camera tests using Maxim, I've just read on the QHY forum that you need to use different values with Nebulosity. I'll have to check that out when I get a chance.

bern

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Hmm, I do all my QHY camera tests using Maxim, I've just read on the QHY forum that you need to use different values with Nebulosity. I'll have to check that out when I get a chance.

bern

The offset of 55 gives about 850 ADU's this was confirmed by roughly the same value in Photoshop.

John

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I was tempted by a QHY8 but the gain and offfset plus the icing problem concerns me. I`ll stick to mono for the time being i think. Great first light though!!!!

PC :(

I have had no trouble - so far. I store the camera in an air tight box with silica gel this seems to stop the ice. The gain and offset are easy to set up.

John

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Alan, if you want to have a good look close up, come round and see mine in action. Although didn't Steve just get one too? There are murmurings about being able to stop the nosepiece centre icing up by using a lower voltage power supply to the TEC.

Thats interesting about maxim and Nebulosity Bern. It would indicate that each program uses the drivers in a different way perhaps? Or that the numbers are arbitrary and defined by each app.

My camera will give an offset of 1000 ADU with a figure of 30 in Nebulosity. I could test that in maxim if you like.

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