I had the exact same reflection with my QHY8, I got it when imaging with a a 2 different refractors, my C11, and a newtonian, all with and without flatteners/reducers etc.
I did the same thing that Doug did, removed the standard QHY8 nose piece, put a 2" to T-Thread adapter on it, and a 2" Baader U filter... Instantly cured the problem.
Alex I agree you can remove the halo. Did you get these donuts ever with your different configurations?
Hi Duncan, I was more referring to the halo Doug has mentioned, as I have got that problem also. The one caused by the MPCC isn't so bad to deal with in Photoshop.
Thanks Marc, looks like my dear lady is going to be short one hair dryer!! I'll have another go!
Thanks for the confirmation on getting rid of the halo, Alex.
Ps - Square stars can be undersampling... If a stars light falls onto a very small amount of pixels, (between 1 and say, 5 pixels) you'll get irregular, blocky shaped stars.
Yes Marc. I got doughnuts like that with the C11.. Reflections That I'd believed were from the corrector plate (as it had the shaddow of the secondary in the reflection...
Yes Marc. I got doughnuts like that with the C11.. Reflections That I'd believed were from the corrector plate (as it had the shaddow of the secondary in the reflection...
I'll see if I can dig up an image..
On the C11? Wow, that's interesting... Yeah please do post the pic. I'd like to get to the bottom of that.
Hi Marc. Ummmm....I had a very quick play with your piccy of M45(sorry if you do really mind), so it's not perfect, but your reflections have gone. Have you tried this before, I'm sure you would have, you seem rather knowledgable?
Grey - I dont think long exposures would overcome this.. What I can say though from the image of the horse head that you've posted... It looks like the spacing for your flattener is perfect to me.. The stars look very well focused from the center to the edges, what I'm seeing in that image is field rotation caused by a polar alignment error..
Marc, I'll find one.. I have one of M42 somewhere here where I got the little doughnuts from the C11...
Grey - I dont think long exposures would overcome this.. What I can say though from the image of the horse head that you've posted... It looks like the spacing for your flattener is perfect to me.. The stars look very well focused from the center to the edges, what I'm seeing in that image is field rotation caused by a polar alignment error..
Oh! Really? Ummm....I'll look into that too! Thanks!
Hi Marc. Ummmm....I had a very quick play with your piccy of M45(sorry if you do really mind), so it's not perfect, but your reflections have gone. Have you tried this before, I'm sure you would have, you seem rather knowledgable?
Ok. Who needs an anti-reflective coating when you've got decepticon powers. What's the trick? I'm all ears!
Ok. Who needs an anti-reflective coating when you've got decepticon powers. What's the trick? I'm all ears!
Yeah, spot healing brush is all. Set the brush diameter to just larger than your reflection and then it uses the pixel info around it to clean up the area under the brush when you click your mouse button.
Enjoy
Doug
How long was the null extender that you used with the QHY8 to remove the reflections?
And a merry Xmas to you and others in IIS
G'Day Allan, I just use a 2" Camera adapter. I also blow the camera out with a hot hair dryer and seal it up very quickly. I have just aquired a bottle of Argon gas which I can now purge the camera and adapter with in a plastic bag then assemble and use.
Quote:
Originally Posted by TheDecepticon
Hi guys. I too have experienced some of these problems, and as I was following the threads I decided to experiment also. If I dont have a filter down near the chip, it freezes over straight away! I can then open up the camera and put a filter there and the freezing is gone, with out trying to dry the inside of the camera with warm air or what ever. How do you guys stop this from happening? I have tried storing it in a plastic bag with dessicant or with the heater and it still happens.
The only shot I have done that didn't give me a reflection was a Horse's Head shot with the Megrz110 and a Flat II(which I just can't seem to get the spacing right still!) with which I used the original noise piece with no glass>an Astronomik UV/IR>a version of Marc's adjustable spacer(thanks for the diagram)>Flat II>extension>IDAS LPS P2 filter on the end in that order.
I then ended up with blocky stars- is that what is called undersampling?
I would like to find an answer, as I'm getting ticked off and am considering selling the QHY8, or perhaps we need some collective pressure on QHY to help resolve the problem.
Thanks Alex, I'll try again and see. Can you expose longer to overcome this and saturate the pixels a bit more?
PS: Perhaps this thread should be moved to Cameras, etc??
Graham, if the star shape bothers you try selecting all brights stars in photoshop, then, select,modify,expand. enough pixels to select more than just the star. Then select,modify,feather about the same as the expand pixels. Then filter,gausian blur and var the blur to give your star a faint edge.
Should help make the image a little softer. Just remember any sharpening without a star mask will sharpen the stars and may make them appear blocky.
I'll have another go!
Ok. Who needs an anti-reflective coating when you've got decepticon powers. What's the trick? I'm all ears! 
