Calculad
Affiliation
British Astronomical Association, Variable Star Section (BAA-VSS)
Wed, 08/16/2023 - 22:21
My scope, mount and accessories are here so now my thoughts turn back to suitable filters.
Are these suitable to get started in CMOS photometry. Does anyone in AAVSO have experience of using them?
I wondered because they are cheaper than other makes(but still eye-wateringly expensive)
Baader UBVRI Bessel Photometric Filters.
Sorry to hog the forums. So many questions on the learning curve.
They are ideal. I use them.
Ray
As a beginner you don't need to buy a full set. If you find a retailer that will sell you individual filters you can spread the cost out over time to match your experience level. The most important filter is the V.
A second filter will be necessary when you get to transforming your measurements. Usually, this would be the B filter. It's best if all your filters come from the same maker (so you don't have to refocus for each filter) so you might consider just getting the V and B together for starters. The I filter (often written as Ic for Cousins I) is usually the next step , then the R. You may never need a U filter.
Phil
Have you considered Optolong? Quite a bit cheaper than Baader, but you have to buy the full UBVRI set unfortunately. I did, and sold the U.
Keith
Yes, this is another good choice, and the prices are much lower. As Keith commented the U filter can be resold (to people who want images of Venus). It would be interesting to compare the price of two Baader filters (B and V) vs a full set of Optolongs minus, say $100, if you sell the U.
Phil
I can vouch for the Baader filters because I and at least two other observers have independently measured them.
I guess the Optolong filters would be fine, But I have not seen independent measurements of them.
It is always best to begin with as many of the BVRI as you can afford.
Ray
You can see Arne's comments here:
https://www.aavso.org/optolong-ubvri-filters
https://www.aavso.org/baader-photometric-filters
Phil