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Old 21-07-2009, 10:24 PM
TheDecepticon
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Filters for QHY8

I suppose I'm going to answer my own questions here, but 1.25" filters are going to be too small for a QHY8 with a 1.8" diagonal chip size, aren't they.
I will need 2" filters, wont I?
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Old 21-07-2009, 10:37 PM
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Yep
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Old 22-07-2009, 12:04 AM
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Talking

Asked and answered all in one
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Old 22-07-2009, 02:57 AM
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But you can just crop the image.

Theo.
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Old 22-07-2009, 08:49 AM
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Quote:
Originally Posted by Gama View Post
But you can just crop the image.

Theo.
What about vignetting? Field of view also a concern as I use an 8" reflector.
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Old 22-07-2009, 10:21 PM
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which is why i said crop it.

You can also do a little flat field to help extend the size of you field a little before croping.

Theo
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Old 22-07-2009, 10:33 PM
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How where you planning to put a 37mm filter in front of a QHY8? 1.25" nosepiece or wheel?
I could try this week-end and see what happens. What F ratio?

Last edited by Tandum; 22-07-2009 at 11:57 PM.
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Old 22-07-2009, 11:49 PM
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Filters for QHY8

Hi

I bought a QHY9 and held off buying the filter wheel in order to see if I could get away with still using my 1.25" set.

Glad I did - at f/7 I get very little vignetting. If you crop you loose very little of the image and it will flat field out if you want to.

What F ratio are you imaging at?

Rob
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Old 22-07-2009, 11:52 PM
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It would probably be an F5 reflector.
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Old 23-07-2009, 09:34 AM
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I would certainly try it with what you've got to see how much of the field of view you loose before forking out loads of cash on a new wheal and filters
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Old 23-07-2009, 09:43 AM
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Thanks for the help, it is an F5 reflector, 200mm aperture. Eventually I was going to get a 2" wheel, but if I can get away with the 1.25" filters, they are in a 1.25" filter wheel.

Last edited by TheDecepticon; 23-07-2009 at 09:56 AM.
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Old 27-07-2009, 05:33 PM
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Did anyone do these tests?
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Old 27-07-2009, 05:37 PM
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Your going to get at least 1/3 blocked, so still plenty of ccd chip left...

Theo
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Old 29-07-2009, 05:26 PM
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Quote:
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Did anyone do these tests?
No, Twas overcast most of saturday night and I've only just unpacked

But here's a couple of daytime shots from today. One of a couple of hi-voltage pylons about a kilometer away shot through a red filter and one of my light box shot through a blue filter.

The qhy8 nosepiece was coupled directly to the wheel via a 42male -> 42male adapter and the scope was at F8.

I tried in the dark for F6 but I don't have the adapters on hand to achieve focus.
Attached Thumbnails
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Click for full-size image (flat-blue.jpg)
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Last edited by Tandum; 29-07-2009 at 08:09 PM.
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Old 30-07-2009, 01:01 PM
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Thanks!
That, at least, looks workable, I suggest. If I wanted to do a larger area than the chip size, I would have to do a mosaic anyway, and the crop area is not hugely restrictive.
Gray.
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Old 30-07-2009, 06:06 PM
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Never hurts to try these things!!
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