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Old 13-12-2020, 07:02 AM
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OneCosmos (Chris)
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UV/IR Filter with a modified camera?

I have an EOS Ra and recently also purchased the drop-in filter lens adapter for use with my EF lenses and a hot filter from Kolari which promises to allow normality for say time shots.

Stupidly I was too quick to sell my basic lens adapter because afterwards I remembered that when using my Sigma 105mm f/1.4 EF lense for Astro imaging (which I’ll do sometimes instead of the fsq-85), the drop in filter adapter only works at all with a filter. For daytime it will be my new hot filter but Astro now the only option would be the clear filter. That filter with holder costs $159 so I may as well have just kept my original adapter for Astro (they cost about $189). I have to now buy one of the other -the question is which?

Is it advisable anyway to use a clear filter anyway (because I think and assume is probably also a UV/IR filter) or am I better off with no extra glass between the lens and sensor? It is annoying because it money I didn’t need to spend -that’ll teach me to be too quick to sell!

When I use the same camera with the Takahashi of course there will be no lense adapter and this no UV/IR filter anyway.

Thanks in advance for your advice.
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Old 13-12-2020, 08:46 AM
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Camelopardalis (Dunk)
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Chris, Canon employs a UV/IR cut on all their cameras from the factory. The Ra, and Da models before it, just had slightly modified LP filters that passed more in the near IR.
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Old 13-12-2020, 12:31 PM
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OneCosmos (Chris)
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Quote:
Originally Posted by Camelopardalis View Post
Chris, Canon employs a UV/IR cut on all their cameras from the factory. The Ra, and Da models before it, just had slightly modified LP filters that passed more in the near IR.
Thanks Dunk -makes sense and means I shouldn’t have sold my adapter abc will now have to buy another to use my lens as a telescope ��

PS given that I have thd drop-in filter for daytime use I only need something basic for Astro use so I have taken a punt with a non-Canon one: https://au.kentfaith.com/KF06.383_ca...iABEgIBGfD_BwE

Only $55. The price of the Canon one is insane given there is no glass involved.

Last edited by OneCosmos; 13-12-2020 at 02:29 PM.
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Old 18-12-2020, 09:21 PM
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OneCosmos (Chris)
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The hot filter from Kolari arrived but it appears to not work with the EOS Ra -everything is horribly green. Sure setting a white balance may correct for it but the purpose and point of this filter was to avoid needing a custom white balance.

Without any filter at all the EOS Ra produces quite normal daytime photos even without a custom white balance. With the filter it looks like the world is on drugs.

Kolari said it did work with the 60Da and the assertion it would therefore work with these Ra was more of an assumption!

Chris.
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Old 13-01-2021, 03:28 PM
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Hi Chris,

you'll need to set up a custom white balance.

A few years ago, I had a Canon DSLR modified and used a B+W 489 IR blocking filter and a custom white balance so that I could take 'normal' photos. I also tried a 486 filter, which also worked well, although this is an interference filter and not suitable for wide angle lenses due to the angle at which the light comes in.

With a filter on, take a photo of a white sheet of paper and use that as the basis for a custom white balance template. You may need to do a few iterations to get it right. I had a few custom white balances - sunlight, cloudy, tungsten etc.

Unfortunately the camera was stolen - I wonder if whoever ended up with it managed to figure out why all the colours were so strange if they used a lens without the filter and white balance set correctly...
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Old 16-01-2021, 12:49 PM
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OneCosmos (Chris)
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Quote:
Originally Posted by Suzy_A View Post
Hi Chris,

you'll need to set up a custom white balance.

A few years ago, I had a Canon DSLR modified and used a B+W 489 IR blocking filter and a custom white balance so that I could take 'normal' photos. I also tried a 486 filter, which also worked well, although this is an interference filter and not suitable for wide angle lenses due to the angle at which the light comes in.

With a filter on, take a photo of a white sheet of paper and use that as the basis for a custom white balance template. You may need to do a few iterations to get it right. I had a few custom white balances - sunlight, cloudy, tungsten etc.

Unfortunately the camera was stolen - I wonder if whoever ended up with it managed to figure out why all the colours were so strange if they used a lens without the filter and white balance set correctly...
Thanks I did exactly that and it did work but can you believe I then sold the camera (and explained everything to the new owner). I am instead buying a QHY268C
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