which filter wheel and why?

[Robert_T]

Hi all, filter wheels, I don't know how many of you have them out there, but I'd welcome any comments or advice, even hearsay, on what's good, what's not, especially motorised wheels. Costs and sources would also be welcome.

My interest is planetary imaging, but I'd guess most users have them for deep sky and assume the experience is still relevent.

thanks,

[iceman]

Depends how much you want to spend, and whether you want manual or motorised.

You can get wheels with 4, 5 or 7 filter slots, and with 1.25" or 2" filter slots.

For planetary, you only need 1.25" slots, and you only need the 4 or 5 slot one, for IR, R, G and B filters.

In terms of manual wheels, I've got the Atik one which appears to be the cheapest/best value for money at US$199. You'll need to include a bit extra for adapters.

For motorised wheels, I can't comment on the makes and models, except that the Andy Homeyer one is apparently the cheapest at US$499. Quite a few people have and use this quite successfully. You can spend a lot more on other motorised wheels. Gary Beal recently bought one and might be able to offer some advice.

[gbeal]

Robert,
I am in deep with CFW's. When I first had this hair-brain idea of getting a mono camera, I found the cheapest wheel I could get, a Sirius Optics wheel, which had RGB filters in it. I bought it from Adorama in NY via an e mail friend. It was the simplest way to buy it, but this friend has been slow in posting it, so I have yet to see it. The Sirius is a manual wheel, but at US$200 complete (with filters) I felt it was great value.
BUT........ in between times I found a used Homeyer MFW (Motorized Filter Wheel). It was US$450, and had the True Technology filters installed. Given that I reckoned on about US$150 for filters, and about US$350 for a motorized wheel I grabbed it.
Now I have both the manual (well I will when it arrives) and the motorized.

OK, to your query.
I would not want to do too much imaging with a manual wheel. The image sits pretty good at about 6 -7 metres focal length as I image, (OK it is on an AP600E mount) but the window of opportunity with Jupiter seems to slam shut quickly.
Mike has the ideal setup to suggest yay or nay for a manual wheel. I suspect that it will suffice this Jupiter apparition, but by the next he will have either motorized this one, or found a motorized one. I recall him imaging without a tracking platform, but that changed after a while!!!!

The Homeyer is simple, but nice. It has/had some quirks.

Both sides of the wheel have a simple 35mm approx female thread. Andy Homeyer is a great guy to deal with and provided that they were in fact 1 3/8th"x40 threads. He was more than happy to supply whatever adaptors I needed. In the end I visited a local old codger who makes threads and stuff for me. He made the required C to Homeyer thread and also the required Homeyer to 1.25" adaptor. I am set. The DMK is mounted, and stays on the wheel.
Second quirk is that the wires/cabling Andy Homeyer uses is stiff, hell is it stiff. It does not want to bend at all. The cold freezing temperatures I have been imaging in this week are not helping either. I have replaced the 12 volt wire, and also the serial input wires, these being simple two core and within my basic wiring ability. The main 7 core one will have to wait until Robby returns home.

So..........
The options are about this, off the top of my head.
True Tech Supa Slim like Rumples has.
SBIG CFW8 or CFW10.
Homeyer MFW.
Optec IFW (find a price first, and make sure you are seated).
Manual wheels, like the Atik, Sirius, Apogee and others.
The Sirius I have (or don't have as the case may be), will be available if/when it arrives. I am sure they can be modified, heck Davo is the guy to ask there.

There will no doubt be others, but that may help with whatever you are contemplating.
Gary

[Robert_T]

Thanks Mike and Gary, especially appreciate your experience on this Gary, the trials and tribulations of filter wheels.

Something that puzzles me, is that when someone makes a filter wheel for astronomy you'd think for pity's sake that they would just include a garden variety 1.25in fitting as standard equipment. I notice the ATIK is similarly lacking. I'm sure manufacturers are just like toying with people like me who are to hapless or lazy to go to extra effort of sourcing such things.:D I used to view such things as just one of the joys of the hobby, but these days all I care about is getting the light on the pixels in the quickest and easiest way possible:P

[Striker]

Dont forget about the limicon filter selector.

I dont know how it will perform against the rest but its very simple to fit.
http://www.lumicon.com/mfs.htm

Just wont take the really deep sided filters like the Baader.

[gbeal]

Good point Tony.
But it like the Meade DSI slide leaves the filters exposed to the elements, correct?
Heck, even my secondary dewed up last night, couldn't work out why the images were needing more and more gain. It was foggy at the time and I put it down to that, but no.

[Striker]

True a simple shower cap or something homemade can fix that.

I leave the shower cap on permanantly and being flexible you can slide to what ever filter you need whilst leaving the cap on.

Having a sealed unit is the way to go, this is just an option that is simple to fit with out having all these adapters needed.

Thier isn't too much in the 2" range that is cheap.

[gbeal]

Heck I nearly took that you wore the shower cap while using the filter slide, now I understand.
I must admit to thinking to build a filter slide, within the tube of the 10" newt. OK, it will mean getting 2" filters, but there is only a couple that you need, and the advantage of not having to take them on and off each eyepiece is a boon.
Gary

[Robert_T]

hmmm, shower cap... nice idea, that would work Tony... us planetary types only need 1.25in filters which brings costs down a bit (they're still mental though if you ask me, some things just don't make sense cost-wise and this is one of 'em)