Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 12/28/2022 - 17:28

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.

Francois.

 

Affiliation
American Association of Variable Star Observers (AAVSO)
Which Chroma Filters?

Francois,

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 .

Phil

Affiliation
American Association of Variable Star Observers (AAVSO)
Interesting, I didn't…

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.

 

Keith

Affiliation
American Association of Variable Star Observers (AAVSO)
photometric filters

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.

Arne

photometric filters

Hi Arne,

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,

Mark

Affiliation
American Association of Variable Star Observers (AAVSO)
Got the Optilong

I was going to get the Baader but saw the optilong 1.25 set on sale for $550 at highpoint last week and grabbed them. 

Was waiting for some definitive, quantifiable data but not finding that,  I bought them based on some comments in another thread that they appeared to be decent for the price.  

Haven't used them yet so guess I can return if they don't cut the mustard.  

Affiliation
American Association of Variable Star Observers (AAVSO)
I posted my coefficients not…

I posted my coefficients not long ago on these (SBIG CCD, soon to be replaced with a Player One 533 CMOS). 

Keith