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1.25" LRGB filters opposed to 2" LRGB Filters using a ASI2600mm Pro Camera

ZWO ASI2600MM Pro Filters LRGB Buying Advice
Narrowband imaging •16 replies•578 views
Anthony Fuller avatar
Anthony Fuller avatar
Hello, fellow astrophotographers!

I really could use some advice on LRGB filters. So far I'm using ZWO 2" LRGB filters, and thinking of purchasing Chroma LRGB filters.

My question is, would LRGB filters that are 1.25" cause issues (vignetting), with using my ASI2600mm pro camera, which has a wide sensor?
Or should I go for 2" LRGB filters instead?

Going with the 1.25" is a lot cheaper, but it also means buying a new EFW also and Ha, OIII & SII filters as well. 

I live in Bortle 6-7 skies. 

Thank you in advance!
Bruce Donzanti avatar
Bruce Donzanti avatar
What scope are you using?  

This calculator will also tell you best size to get.   https://astronomy.tools/calculators/ccd_filter_size
Anthony Fuller avatar
Anthony Fuller avatar
I have several but for the most part I'll use TPO RC 304mm F/8, Explore Scientific ED165mm APO Triplet and once in a while the Explore Scientific ED102mm APO triplet refractor
Anthony Fuller avatar
Anthony Fuller avatar
Anthony:
I have several but for the most part I'll use TPO RC 304mm F/8, Explore Scientific ED165mm APO Triplet and once in a while the Explore Scientific ED102mm APO triplet refractor

*** Awesome, thank you!***
Stan Smith avatar
Stan Smith avatar
I believe at 31mm/1.25 inch filters you will have some pretty severe vignetting. I am getting away with 36mm filters on my QHY268M with the same sensor as your asi2600 with no vignetting. If you are forced to change filter wheel and filters it's not much more expensive to go to 36mm from 31.

Stan
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Bruce Donzanti avatar
Bruce Donzanti avatar
I also have the ASI2600 and then bought the ASI6200.  So, I sold my 1.25" and got all 2" filters and the larger filter wheels.  I know it is a big leap in price, but you can sell the 1.25" filters easily enough and once done, you are finished even if you decide to get a full frame sensor down the road.
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Anthony Fuller avatar
Anthony Fuller avatar
That is what I was afraid of,  vignetting.
The calculator from above is showing the minimum filter size of 30.28mm, equivalent to a 1.25" filters size for the TPO RC 304mm.

Anthony Fuller avatar
Anthony Fuller avatar
Yeah, I think the 2" LRGB and narrowband Ha, OIII & SII is where I'll head. @Bruce Donzanti , where did you sell your equipment? I have equipment I purchased years ago, some used and unused.  

Covid19 is cooped up and buying frenzy. 
Bruce Donzanti avatar
Bruce Donzanti avatar
Astromart- check out the website.  Great place to sell stuff
Lynn K avatar
Lynn K avatar
I have the QHY268M.  You will need 2".  And, with the IMX455, more likely 50mm. The Astronomik's are  a good choice.  I use the Astronomik MaxFR Ha & SII 6nm and the Chroma OIII F3 3nm. You don't have to go with Astrodons or Chroma.  Baader has a bad reputation of halos with the OIII as do cheaper manufactures. Search on Cloudy Nights for filter reviews.

Lynn K.
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Anthony Fuller avatar
Anthony Fuller avatar
@Lynn K, I appreciate the input, Lynn! I was looking at Astronomik and wasn't sure. I did review Cloudynights yesterday and lots of input, no one really used Chroma. There was Astrodon, Astronomiks, and one other. 

I'm going to take it slow, these filters are just as costly as purchasing a NexDome, Lol!!
Bruce Donzanti avatar
Bruce Donzanti avatar
Be careful- many folks use Chroma filters and you can see that on this site.   Also, Astrodon does not make a 2" filter.  Many folks will buy Baader, Astronomik, and Antlia filters but also get the Chroma OIII filter.  That is one way to save a lot of money and not get frustrated with halos around bright stars using an OIII filter not from Chroma.
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Michael J. Mangieri avatar
Michael J. Mangieri avatar
I know this is a bit late to the game to make suggestions, but … I just went with 2" filters for use with my ASI2600.  I was going to get the Chromas, but my finances wouldn't allow it.  So I purchased the new Optolong 3nm 2" set.  I was a bit afraid of the halo on the Oiii, but it turned out not to be too bad at all (actually testing the filters for the first time tonight as I write this).  You definitely need 2" filters for this camera and your OTAs.
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Tom Engwall avatar
Tom Engwall avatar
I use 32mm Chroma Filters with my ASI2600MM Pro on my Esprit 150 with no vignetting.
Well Written
Alex Nicholas avatar
Alex Nicholas avatar
Tom Engwall:
I use 32mm Chroma Filters with my ASI2600MM Pro on my Esprit 150 with no vignetting.

I dub thee - Adrenosine...

Reviving a thread that was last posted in almost 2 whole years ago.. ;)
JohnAdastra avatar
JohnAdastra avatar
I bought 2" Astronomik filters for my ASI2600MM and they were not needed. I was thinking I'd be safe when I went to an ASI6200MM with the larger sensor, which I never bought. Save yourself some $$ and get 36mm or 31mm as people are saying and get better filters, not larger size. smile
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SonnyE avatar
SonnyE avatar

I have an 8 position EFW that came with my ASI1600MM Pro camera (full of filters).

When I got my ASI2600MC Pro camera I of course tried the 1.25” filters. I’m a try it before I buy it sort, since I already have the investment in filters.

My results where the vignetting was unacceptable to me. I’ve outgrown doing excessive filtering in my imaging. In my experience, it is not worth all the extra time and processing to get a web presentable image. The web is a fickle mistress about our images. I do not need images capable of billboard projection for the myriad of small displays or TV’s viewing my captures.

I fell back on the old experience of using a larger filter for the “Sweet Spot” of it. Since the only thing I’ve left to fight with is my local light pollution, I’ve invested in two great LP filters in 2” mounted versions. And they are my first adventures into multi-band filters. I was always a single band filter fan. But for the crap my ignorant neighbors shine into the night, enshrouding myself with walls and doing a blanket filtering is my best course.

I’ve chosen a new avenue for me, a Filter drawer in 2”. Since I no longer need to program NINA to do multi-series filter changes. I basically decide to use the Quad LP filter, or the Dual 3 nm narrowband, depending on what my outcome desires are. Then shoot my series overnight.

But to the Delema of filter size, better to err on oversized, then to deal with vignetting or misalignment issues, in my experience.

As always, YMMV.

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