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Would you replace the Built in UV/IR cut on a 2600MC with AR glass?

ZWO ASI2600MC Pro CMOS UV/IR Cut Blooming
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Would you replace the Built in UV/IR cut on a 2600MC with AR glass?
Single choice poll 23 votes
26% (6 votes)
74% (17 votes)
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Itto Ogami avatar
Itto Ogami avatar

Hello All,

I am looking to replace the built in UV/IR cut window on a 2600MC-Pro with AR window and using a better UV/IR cut filter with better cutoffs in the UV and IR (Baader cmos optimized UV/IR cut filter) so i get less UV and IR and better glass, coatings etc.Been seeing slightly bloated stars and halos with the built in ZWO UV/IR cut and someone at starfront said they saw an improvment after replacing the built in filter with the AR window and using a high quality filter.

I am sending an Ultracat 108 to starfront in the next few months. I already have a spacecat 51 rig there. I am looking to get the ultracat 108 setup as maximized as possible. The reason I’m considering the swap is i see a little blurriness/softness and haloing on my stars. Want to get them tighter. Thnking a better UV/IR cut will help or is stacking the 2 suffficient?

I am very nervous to mess with the camera. Has anyone done this replacement? Also I see some forums just saying to leave the built in UV/IR filter and to use the better UV/IR cut together with no impact to image quality, athough I dont know the level of imaging expertise for those suggesting to do this. To use both seems like it wouldnt be as good as using a clear AR window and a good filter. I would surmise that having more glass and inferior glass in the built in filter used in combination with a high quality filter would not be what I would want to do.

I really dont know what to do here. Should i just use both UV/IR cut filters for a slightly better cutoff ? Others have noted that when doing dualband I already am using 2 filters (built in UV/IR plus the dualband) ant thoughts and suggetsions would be appreciated

Any advice would be appreciated!

Regards,

Itto (Jim)

andrea tasselli avatar
andrea tasselli avatar
Just use a "better" (i.e.,  stricter) UV/IR filter ahead of the camera and you're done. No risk of messing up the sensor with dust (unless you have a clean room this a clear and present danger.) I can't see any downside to this course of action.
V avatar
V avatar

Replace it in a clean room, it’ll do great. My 2400 has an AR window installed. It allows for much better filter variety into the IR and UV wavelengths, and a little bit more reds, but honestly the IR does more harm than good when unfiltered. If you are not using a reflector, and even with a reflector, it tends to wash out colors and provide greyish or redder images of further objects. The upside is it acts like a built-in luminance frame against the rest of the image, unaffected by light pollution.

Tony Gondola avatar
Tony Gondola avatar

Having an AR window will give you greater flexibility in the long run. I’d do it if it were a choice I had to make.

Well Written
Alan Brunelle avatar
Alan Brunelle avatar

If for some reason you were using the camera on a RASA, then I would do the replacement if the quality of the window was important to you. Celestron claims that the number of glass elements before the sensor is critical to optimal performance for the RASA. That said, I have done some swapping of glass elements prior to the sensor when I had my RASA and I could not see any real differences. Ultimately, you could test this with your setup and in the end report back here to tell us if it was important or not. I am interested.

One risk to doing the swap is breaking the seal into the sensor chamber and thereby causing issue with needing to deal with frost or dew appearing on the sensor.

Helpful Insightful Respectful Concise
Itto Ogami avatar
Itto Ogami avatar

Thanks everyone for your help. I am asking because I contemplated doing the ar swap on an ultracat 108 soon. I have seen some haloing and a lack of star sharpness/softness in my stars on my spacecat 51 at starfront using just the built in filter. I was thinking this was due to the ZWO filter letting in a little UV/IR from what i have read. I wanted to eliminate this by using the baader with better cut offs on the new ultracat setup. I would prefer not to mess with the camera and dont know if just using a better UV/IR filter in front of the built in one would fine or if replacing it with an AR window and using a better filter would be a better option. I just assumed more glass or an inferior filter mixed with a better one would not be optimal.

I am using this strictly for broadband imaging, no UV IR imaging at all. I have used dualband filters but have used them with the ZWO UV/IR in place (since its built in).

Neil Everall avatar
Neil Everall avatar

I was thinking about this myself, but more from the perspective of the harm that not having an AR coating on the window could be doing. Losing quite a lot of light and generating a back reflection that could cause problems depending on what other filters you have earlier in the imaging train?

SonnyE avatar
SonnyE avatar

It’s your camera, roll those dice!

Of course, once you do you are stuck with it.

As for me, I voted NO.

YMMV

(Also a very happy ASI2600MC Pro owner/user)

Tim Ray avatar
Tim Ray avatar

From a practical point of integration and backspacing. I always use a filter in the filter drawer or FW in front of the camera as not to effect backspacing from the reducer/flattener… That filter is the UV/IR when shooting RGB with the MC’s instead of an ALP-T or a Lum filter when using a MM camera…

As a side effect I am unaware of any issue I might be having with the optical window on the camera. If I would ever have to replace any of the optical windows in the MC’s I would probably use the window for the MM camera because of filter use…

It is my understanding that all of the optical windows are AR (Anti-Reflective) coated. The MM window is full spectrum pass thru and a MC window has a UV/IR cut filter instead of a full spectrum glass. ( I hope I’m correct on this…)

Rick Krejci avatar
Rick Krejci avatar

Itto Ogami · Sep 19, 2025, 09:21 PM

Thanks everyone for your help. I am asking because I contemplated doing the ar swap on an ultracat 108 soon. I have seen some haloing and a lack of star sharpness/softness in my stars on my spacecat 51 at starfront using just the built in filter. I was thinking this was due to the ZWO filter letting in a little UV/IR from what i have read. I wanted to eliminate this by using the baader with better cut offs on the new ultracat setup. I would prefer not to mess with the camera and dont know if just using a better UV/IR filter in front of the built in one would fine or if replacing it with an AR window and using a better filter would be a better option. I just assumed more glass or an inferior filter mixed with a better one would not be optimal.

I am using this strictly for broadband imaging, no UV IR imaging at all. I have used dualband filters but have used them with the ZWO UV/IR in place (since its built in).

The Ultracat 108 is very well corrected, much tighter than the cat 51 with little in the way of blue bloating. I’d stick with what’s there and minimize the amount of glass in front of the sensor.

Well Written Concise
Itto Ogami avatar
Itto Ogami avatar

It seems that the concensus is to leave the UV/IR cut alone and that the 108 will be just fine. I really appreciate all the responses an Ill leave it alone for now :)

Thanks everyone for your input!

Regards,

Itto (Jim)

Neil Everall avatar
Neil Everall avatar

Tim Ray, re your earlier note, I don’t think that the UV- IR cut window on the 2600 MC pro is AR coated; if you look at ZWO’s transmission curve for the window on this device , the D60 UV IR Cut see (https://i.zwoastro.com/wp-content/uploads/2023/04/5875bb92023c162b4c80286c9a1773b2-1.jpg) , it has losses of between 5 and 10% in the visible region, which suggests no AR coating to me ( unless they are absorption rather than reflection losses). I’ve asked ZWO to clarify.

There are UV IR cut filters around with much lower losses in this region, it’s a shame if ZWO have used a poorly performing window on such an expensive camera. Hopefully they will respond to my question.