Hi all,
I have filters since long time ago at size of 1.25”, i bought them at good old prices, and i will not sell o give up them, but now having APS-C sensor cameras, how to use those filters then? I don’t like that 1” square sensor or even smaller one with IMX585, so what solution i can have t use those filters without selling them?
The filters are: Astrodon Ha 5nm 1.25”, Chroma OIII/SII 3nm 1.25”.
The clear area of a 1.25” filter is between 24mm and 27mm. The average diagonal measurement of an APS-C senser is 28mm. You are going to have clipped corners even with a very slow system. I guess you have a choice, wait until a small senser that you like is developed or learn to love the 533/585 class of sensors.
When I first got myASI2600MC Pro Itried using my 1.25” filters and frankly it as dismal failure. The ASPC sized sensor needs a 2” in my opinion.
Some say they use 1.36”. I like to go for the filters sweet spot so I got 2” for my camera.
I only use a couple of 2” filters, both for light pollution. One is an Antlia quad, and the other is an Sbony SV220. I use the Antlia Quad the most. But the SV220 is a dual filter and works best for Ha spectrum.
Between to two I don’t want for any others. I use them in a filter drawer on mine.
Tony Gondola · Apr 23, 2026, 01:18 PM
The clear area of a 1.25” filter is between 24mm and 27mm. The average diagonal measurement of an APS-C senser is 28mm. You are going to have clipped corners even with a very slow system. I guess you have a choice, wait until a small senser that you like is developed or learn to love the 533/585 class of sensors.
How long we have waited since they made those new sensors [IMX: 455/571/533/585]?
I will definitely wait until a smaller size but not so small will be released as new sensor version.
SonnyE · Apr 24, 2026, 11:33 PM
When I first got myASI2600MC Pro Itried using my 1.25” filters and frankly it as dismal failure. The ASPC sized sensor needs a 2” in my opinion.
Some say they use 1.36”. I like to go for the filters sweet spot so I got 2” for my camera.
I only use a couple of 2” filters, both for light pollution. One is an Antlia quad, and the other is an Sbony SV220. I use the Antlia Quad the most. But the SV220 is a dual filter and works best for Ha spectrum.
Between to two I don’t want for any others. I use them in a filter drawer on mine.
I also went with 2” filters for my IMX571 cameras, in fact, even in the past when i have that Panasonic sensor of 4/3” the one from QHY they recommended to go with 36mm sizes over 1.25” due to the slight larger back focus of that camera compared to ASI1600mm, so i bought Optolong 36mm filters, but for my APS-C i definitely bought 2”.
I asked about what i can do with my 1.25” size filters, i still use them with ASI1600MM camera for small setup, i could buy something like 533 or 585 to be used with that small setup, but for another setup say 70mm up to whatever size i will use APS-C mainly or only, not sure with RC10 yet, so i just don’t want to ignore those 1.25” at all and because they are from high end brand i won’t sell or even upgrade due to prices.
Tareq Abdulla · Apr 25, 2026, 04:38 PM
SonnyE · Apr 24, 2026, 11:33 PM
When I first got myASI2600MC Pro Itried using my 1.25” filters and frankly it as dismal failure. The ASPC sized sensor needs a 2” in my opinion.
Some say they use 1.36”. I like to go for the filters sweet spot so I got 2” for my camera.
I only use a couple of 2” filters, both for light pollution. One is an Antlia quad, and the other is an Sbony SV220. I use the Antlia Quad the most. But the SV220 is a dual filter and works best for Ha spectrum.
Between to two I don’t want for any others. I use them in a filter drawer on mine.
I also went with 2” filters for my IMX571 cameras, in fact, even in the past when i have that Panasonic sensor of 4/3” the one from QHY they recommended to go with 36mm sizes over 1.25” due to the slight larger back focus of that camera compared to ASI1600mm, so i bought Optolong 36mm filters, but for my APS-C i definitely bought 2”.
I asked about what i can do with my 1.25” size filters, i still use them with ASI1600MM camera for small setup, i could buy something like 533 or 585 to be used with that small setup, but for another setup say 70mm up to whatever size i will use APS-C mainly or only, not sure with RC10 yet, so i just don’t want to ignore those 1.25” at all and because they are from high end brand i won’t sell or even upgrade due to prices.
That is exactly what I do with mine, Tareq. They live in the ZWO EFW mounted to my ASI1600MM Pro.
But I don’t use it, I set it up to try using it for Galaxy’s and such. But went back to the ASI2600 MC Pro because it does much better than my 1600 for me. I guess the 2600 spoiled me. But, I’ve always liked color cameras anyway.
SonnyE · Apr 26, 2026, 06:31 PM
That is exactly what I do with mine, Tareq. They live in the ZWO EFW mounted to my ASI1600MM Pro.
But I don’t use it, I set it up to try using it for Galaxy’s and such. But went back to the ASI2600 MC Pro because it does much better than my 1600 for me. I guess the 2600 spoiled me. But, I’ve always liked color cameras anyway.
I will use ASI1600MM and QHY163M with my small setup, they are still usable, also bought Touptek equivalent sensor to 1600mm but in color, so i have three cameras of same sensor, i also have QHY294M Pro so four cameras at 4/3” size, i already found a camera in color same size format of ASI1600MM without that issue we see on 1600/163 cameras, if i knew about that i could buy it over a Touptek of 1600 OSC, i still can buy if i want but APS-C took my interest.
I will hold on the filters for a while and see, if i won’t use that of 4/3” cameras much in future then i think i might sell them, unless they can make a new camera with 4/3” sensor, or, i change my mind and go with 1” sensor or smaller.
I was in the same position as you. I sold one set and kept my second. I use them with the 294MM Pro. An underrated camera that is amazing in bin1 mode with widefield optics.