I am ready to purchase Chroma filters for photometry but do not have the experience to decide between a set of Bessell or Classic Bessell. I read that both sets are considered Johnson-Cousins. An advice on this topic would be greatly appreciated. Of note, the two models have very different light curves.
If I wanted to buy Chroma filters today I would get the version with passbands which closely followed the classic UBVRI prescription. As far as I have seen, there has been no information or guidance in the AAVSO forums about how well the Chroma flat top, i.e. non-standard, UBVRI filters perform. You don't need to buy a full set, and you certainly don't need a U. I'd suggest just a V for a starter. If you eventually decide to transform your magnitude measurements you will also want at least a B in addition.
The Chromas are high quality filters but expensive. You may also want to consider the Optolong filters. Arne Henden's review of the Optolong UBVRI filters is here: https://www.aavso.org/optolong-ubvri-filters .
Interesting, I didn't realize Chroma starting making a "Classic' line, these are new. I still have some of their original filters with the JC shapes, but these new ones look to be much higher transmission. I had some issues with the coatings failing so have replaced with Optolongs.
I have standard-cluster images now with most of the possible filter choices:
- Schuler colored glass
- Astrodon interference
- Optolong interference
- Baader interference
- Chroma flat-topped
- Chroma classic
I'm on vacation now, but about mid-January, I'll give the transformation results from all of these.
have you been able to analyze your standard-cluster images through the various filter sets you mentioned in your post?
I am about to put a new photometry rig together and would appreciate any information on how well each of the currently available options perform. Cheers,