Filters for QHY8

[TheDecepticon]

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.:shrug:
I will need 2" filters, wont I?

[DavidU]

Yep

[renormalised]

Asked and answered all in one:P:D:D

[Gama]

But you can just crop the image.

Theo.

[TheDecepticon]

What about vignetting? Field of view also a concern as I use an 8" reflector.:eyepop:

[Gama]

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

[Tandum]

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?

[sootyandsweep]

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

[Tandum]

It would probably be an F5 reflector.

[sootyandsweep]

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

[TheDecepticon]

Thanks for the help, it is an F5 reflector, 200mm aperture.:thumbsup: 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.

[TheDecepticon]

Did anyone do these tests?:shrug:

[Gama]

Your going to get at least 1/3 blocked, so still plenty of ccd chip left...

Theo

[Tandum]

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.

[TheDecepticon]

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.:thumbsup:

[AlexN]

Never hurts to try these things!!