Which Filters?

I I know you can get RGB filters for photography that include an IR blocking element. But I suspect these filters are not going to do anything for visual work.

Any idea as to a rough cost of those Dave?

It might be real hard to get a set of 3 filters that suit both astrophotography and visual observing. Likewise, the filters you mention above (other than the IR one) will do little if anything for your webcam (in terms of correct colour balance etc).

Cheers

Dave

The filters I was looking at were by TS. A quote from their site reads:

"You can use the filters both visually and photographically without reservations.

TS Quality:
- the filter housing is made of metal and as thin as possible to avoid vignetting.
- the glass used in our filters is very homogenous and parallel
- we promise a very good image quality!
- filter threads on both sides allow you to combine different filters. For example, a blue filter and a yellow filter combined resemble a green filter."

On the IR side, I've just checked and they also do an IR Cut filter:

"Astronomik IR Cut Filter
An important tool for CCD imaging. The transmission of visible light is 97% with maximum transmission at H-Alpha (656.3nm). All infrared light is cut out completely up to over 1200nm. The filter has a dielectric coating, is scratch-resistent and doesn't age. You need this filter whenever there is any glass element (objective lenses, barlow lens, corrector lenses, eyepieces) between the camera and the object.

ASIR1 Infrared cut filter - 1.25" €49.- "

This IR filter is more expensive than the combined three colour filters, but it sounds like an essential piece of kit for webcamming - what do you think?

Just been googling IR Cut filters and found an interesting article:
www.astro-imaging.de/astro/webcam_imaging_6.html
Sounds like I need to at least use an IR filter for Webcam imaging.
I'll probably purchase as follows:
IR Cut, Light Red, Light Blue and Light Yellow.

Where would we be without the Internet?

Anyway I'm off to Youghal on Monday on a weeks sojourn, at least the skys should be darker there, and hopefully I'll get a couple of clear ones.

John,
Thanks for that link, it answered a few questions that I had. As for colour filters, I got a set of 4 celestron filters a few years ago but only occasionally use them. They do allow you to see more of one particular type of feature but at the expence of all other features and colour but I prefer the "real" view.

I also got a single polarising filter for which I have yet to find a real use apart from when viewing Venus in the daytime where it can darken the blue of the sky.

The other filters are #21 orange, #80A light blue and #15 deep yellow. These would probably be too dark for you but are ok with my 222mm dob.

I have tried some webcam imaging (see www.kerryastronomyclub.com/gallery-plan.htm ) but do not have an IR cut filter yet.

Michael Scully

Hope this helps

John - I guess I was referring to the usual imaging colour filter set of RGBL and taking images with a monochrome CCD. You then process the four images and combine them to give a realistic colour image.

I guess the RGB filters would have limited visual use.

Likewise, if you bought the filters you suggest (light red, blue and yellow) I'm not sure how you would combine those images to give a realistioc color.

However, you may be coming from the view of taking images that highlight a particular feature using a particular filter - and I guess your choice of filters will be based on the features you want to highlight...

Let us know how you get on and I'd be interested to see how the imaging goes for you.

Cheers

Dave

Thanks to all for their comments, this has been an interesting discussion.
I have an old Panasonic GP-MF602 from which I can remove what I believe is an IR filter and try to fit that to my Philips NPC900NC (Toucam replacement), although the fit will be tricky. I'll try that setup before I purchase any filters.
Anyway I have a lot of setup and modification to do. I'm not going to do a long exposure mod until I've gained more experience with planetary imaging first.