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Old 08-10-2019, 12:17 PM
meellor (Jack)
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ASI1600MM without a filter

I own an ASI1600MM-Pro and have been using it with my 80mm triplet.
I'd like to try out a bit of super wide-field stuff, ranging from 85mm-200mm with my Sony E mount lenses. There is an inexpensive ASI1600 to Sony E adapter I can purchase, however because of the tiny backfocus distance with Sony E lenses I won't be able to use any filters with my 1600MM (thus only obtaining mono images).
This doesn't phase me, however I am wondering how the camera will perform with NO filters in front of it, meaning not even a UV/IR cut filter.
Does anyone have any examples of images taken without a UV/IR cut in place?

Thanks,
Jack
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Old 08-10-2019, 12:44 PM
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Hi Jack,

You could try some basic red, green and blue photographic filters on the front filter thread of your various Sony E-mount lenses to get you some of way there. Not as good as the precise bandwidths of a matched astro filter set for sure, but can be had reasonably enough for a trial. Just try to standardise on one or two thread sizes if possible. You can also add a UV/IR if required.

Best
JA
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Old 08-10-2019, 01:33 PM
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The_bluester (Paul)
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If the ASI1600 responds in anything like the same way as my ASI294, I would certainly look at a UV-IR filter on the front filter thread.
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Old 08-10-2019, 09:29 PM
meellor (Jack)
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Quote:
Originally Posted by JA View Post
Hi Jack,

You could try some basic red, green and blue photographic filters on the front filter thread of your various Sony E-mount lenses to get you some of way there. Not as good as the precise bandwidths of a matched astro filter set for sure, but can be had reasonably enough for a trial. Just try to standardise on one or two thread sizes if possible. You can also add a UV/IR if required.

Best
JA
I actually didn't even think of using a threaded lens filter! It's been too long since I've used my Sony, been so focused on astro
Finding plenty of UV/IR threaded filters out there, should be easy enough to find some coloured/astro ones!

Thank you
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Old 08-10-2019, 09:30 PM
meellor (Jack)
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Quote:
Originally Posted by The_bluester View Post
If the ASI1600 responds in anything like the same way as my ASI294, I would certainly look at a UV-IR filter on the front filter thread.
Does your 294 just respond with overly saturated stars? Or are there other undesirable effects?
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Old 09-10-2019, 07:41 AM
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The_bluester (Paul)
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I can’t comment directly on the 1600 as I don’t have one and have not seen images taken with one without any filter at all, but on both my scopes the biggest issue for the 294 was major reflections that a bit of calculation nailed down to reflections between the sensor and the AR window on the camera, presumably the camera was sensitive into wavelengths that the AR windows anti reflective treatment was ineffective.

There were some issues with blobby stars at both ends of the spectrum and increased background brightness but the biggest problems were some really spectacular reflections.
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Old 09-10-2019, 10:16 AM
meellor (Jack)
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Originally Posted by The_bluester View Post
I canít comment directly on the 1600 as I donít have one and have not seen images taken with one without any filter at all, but on both my scopes the biggest issue for the 294 was major reflections that a bit of calculation nailed down to reflections between the sensor and the AR window on the camera, presumably the camera was sensitive into wavelengths that the AR windows anti reflective treatment was ineffective.

There were some issues with blobby stars at both ends of the spectrum and increased background brightness but the biggest problems were some really spectacular reflections.
I see, definitely a huge hit to image aesthetics. I've managed to find a decent UV/IR cut threaded filter, hopefully this will do the trick!

Thank you for your help
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Old 09-10-2019, 10:52 AM
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To give an idea what the reflections were like, this is Alnitak without and with my UV-IR filter using my ED72.
Attached Thumbnails
Click for full-size image (Alnitak without.JPG)
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Click for full-size image (Alnitak with.JPG)
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Old 11-10-2019, 12:20 AM
meellor (Jack)
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Originally Posted by The_bluester View Post
To give an idea what the reflections were like, this is Alnitak without and with my UV-IR filter using my ED72.
Yikes, okay that is an enormous difference. Thank you again for the help, this has been exactly what I needed to see/hear!
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Old 11-10-2019, 07:57 AM
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The 1600 may or may not suffer from the same sort of reflections with no filter before it, I have not yet been able to find examples of subs shot with no filter at all.

The sizing and position of the various reflections suggested strongly that it was light bouncing around between the front face of the sensor and the protective window at the front of the camera.
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