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Old 02-01-2012, 02:54 PM
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BlackWidow (Mardy)
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What filters for Horse Head with Colour CCD

I have posted a shot a few weeks ago that I took of the Horse Head. Never tried this target before and was happy to have captured it with my QHY8 ccd.

I had trouble with the star Alnitak that was causing a band of light through my image. No matter what I did I could not stop this band of light from effecting my shot. I have seen others taking nice shots without this problem??

What filter should or could I use to assist in removing this problem? Should I use a Hbeta filter? I have not used filters in my imaging at this point, so help would be great on this subject.

I am using a colour CCD QHY8. I have O111 and other filters for 1.25, but nothing for 2" at this stage so I want to ask as 2" filters get pricey.



Mardy
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Old 02-01-2012, 09:25 PM
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BlackWidow (Mardy)
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Can anyone Help
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Old 03-01-2012, 10:27 AM
Poita (Peter)
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What length of subs were you taking? I find around 10-15 minute subs seems to tame Alnitak.
It could be a reflection issue from the nosepiece filter as well. Can you post a picture and your settings?
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Old 03-01-2012, 11:01 AM
gbeal
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Martin.
The QHY8 is a one shot colour camera, but having said that it does work OK with an Ha filter, so that would be the initial suggestion. You will need longer subs though, something like 10 - 15 minutes each. And given my past experience with a QHY8 sized sensor, it will need to be 2", not 1.25", sorry.
The filter will not really help with the "band of light" though, as Peter said, it will be a reflection from within your imaging train somewhere. You are not alone with this issue, so track down some older posts where others have suffered in a similar fashion and find out how they resolved it.
Gary
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Old 03-01-2012, 08:48 PM
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BlackWidow (Mardy)
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Thanks guys.. I have attached a sample image that has been streched the heck out of to show it more... I am using all 2" and have a Peterson Eyeopener also. the only thing in the tube is a 6.3 focal reducer and the IR filter on the QHY8 itself. so I have Eyeopener visual back, then Meade electric focus, Field Reducer, 10mm spacer, then the QHY8.. The length of the subs were around 5 mins if I remember correctly.
I was also using a non reflective flex dew filter on the front of the scope to help shield stray light..


Regards
Mardy
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Old 03-01-2012, 08:53 PM
Mighty_oz (Marcus)
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It's a trial and error process to find the culprit, take out everything except the camera, no other stuff if u can and see if it's there ? Then if it's not add 1 at a time till u get it back. U could shine a bright light down the tube from the eyepiece end and see if u get any shiny bits ?

Marcus.
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Old 04-01-2012, 10:36 AM
Poita (Peter)
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Yeah, take out the IR filter and see if the problem goes away, if it does then changing its position can often solve the problem.
If the problem doesn't go away, remove the reducer and see if it is causing it.
If the problem is still there then a filter to tame Alnitak might be in order.
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