I bought a Askar M54 filter drawer.
The plan was to get some Baader photometric filters and use the filter drawer to swap them during an observing run.
Most of my previous filters (non-photometric) did NOT fit the Baader drawer. I asked a friend to bring his ZWO filter drawer and though slightly "higher" than the Askar most of my filters again did not fit.
I called Alpine Astro and the Baader photometric filters will not fit in either drawer.
I did call Starzona and their filter holder will accept filters up to 8.2mm which should accept the Baader filters.
Has anyone else ran this issue into a corner??
BTW....a large number of those filters also did not fit the SBIG filter wheel for the ST8XE.
I am not hung on on the Baader filters, but will like to have a plan that will allow me to use the filter drawer.
Are there any photometric filters in stock and available for purchase TODAY, other than the Baaders?
Vladimir
Chroma is a supplier
https://www.chroma.com/products/product-families/astronomy-products/astronomy-filters
Ray
What about the Optolong photometric filters....they are much cheaper.
Type Chroma or Optolong or Baader or Custom Scientific or Filter into the search function box at the upper right of the home page.
A lot can be learned, many of your questions already answered.
Happy reading.
Ray
Hi Vladimir,
Optolongs are thin. I don't remember exactly the thickness, but they fit easily into my SBIG CFW-10. They give good transformed results for me. Arne Henden posted some comments about the Optolongs on one of the forums.
I haven't tried them in an SBIG CFW-5, but if thickness is the only problem with Baader filters the Optolongs should work.
The problem with filter drawers for photometry is that you really should take a new flat with every filter change. This is just not a good way to go.
Phil
Thanks for all…
Hi Phil,
Thanks for all your help in getting me started. I would not have continued without your help.
I showed your message to my astrophotography friend.
The issue was that removing the filters and reinserting would introduce dust to the system according to him.
He did make an interesting comment, that he did not think filter wheels were all that great for variable star measurements simply due to repeatability issue in getting the filter in the exact same position.
I guess it doesn't matter if the filter is perfectly made without any imperfections.
So far I am still shooting V filter only, so the filter drawer would be handy at the end of an observing run when I could simply remove it and go back to taking pretty pictures.
The other part, is I want to get away from any "pressure" adapters to hold things tight. I would like to shift everything to threads to hold things tight.
Vladimir
Changing filters…
Vladimir,
Changing filters in a drawer is no different, dust wise, than changing filters in a FW. In either case you are assured to end up with a small number of dust "rings" that get removed through taking flats every session, or at least every time the filters are exposed to outside atmosphere. Precise placement from a FW is also not normally a problem.
Also, if you do RGB imaging using a FW, you can replace the RGB filters with BVR photometry filters and get similar results. Or just replace the G with your V initially..
Remember: Perfect is the enemy of the "good enough"!
Peter
BPEC
When I mentioned taking new flats with every image after a filter change I was not intending to recommend that, I was trying to illustrate why using a filter drawer for photometry is such a bad idea. I see now the might have been easily misunderstood.
Standard operating procedure for photometry is to shoot new flats whenever anything has changed (or has been monkeyed with) in the optical system. Modern, decent quality filter wheels are usually good at accurate positioning
"So far I am still shooting V filter only, so the filter drawer would be handy at the end of an observing run when I could simply remove it and go back to taking pretty pictures." Yes, but this would mean taking a new flat for the V every time you made the switch.
If you want to do both V filtered photometry and RGB photography I think you would be better off with a 5 slot FW: VRGB or VB photmetric and RGB photographic. This way your flat would be good much longer and you wouldn't be opening up the system to dust as well.
Phil