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Old 23-09-2021, 09:36 AM
Emuhead (Andrew)
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Guiding with a Red filter

To anyone doing this, does this help?

Red should produce the smallest stars from my SVBony 60mm guide scope as it's def not an apochromat.

If so, assume we need to use an imaging red filter, and not just a planetary viewing red filter.

Thanks

Last edited by Emuhead; 23-09-2021 at 09:58 AM.
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Old 23-09-2021, 12:59 PM
JA
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Originally Posted by Emuhead View Post
To anyone doing this, does this help?

Red should produce the smallest stars from my SVBony 60mm guide scope as it's def not an apochromat.

If so, assume we need to use an imaging red filter, and not just a planetary viewing red filter.

Thanks
Hello Andrew,

Star size aside, the red filter will drastically reduce light transmission by some 2 or 3 stops depending on filter type. That's a huge loss (75 to ~90%) and may make picking up the stars, or as many stars, much more difficult.

Best
JA

Last edited by JA; 23-09-2021 at 01:42 PM.
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Old 23-09-2021, 03:40 PM
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The_bluester (Paul)
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So long as the stars are as well focused as you can get, it is likely that a bit of bloat will have no measurable effect.

The stars in one of my early scopes (Very much not an Apo) looked pretty awful at the guiders image scale with quite a bit of blue bloat, but it guided just fine.

Last edited by The_bluester; 23-09-2021 at 04:33 PM.
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Old 24-09-2021, 07:23 AM
Emuhead (Andrew)
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Ok thanks, I'll not rush out to try this. I'm getting great guiding anyway just thought I'd heard it somewhere as a thing to do. Cheers
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Old 25-09-2021, 06:47 PM
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PRejto (Peter)
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I think you might be confusing guiding in red vs guiding in near IR (like the ONAG provides). If you read the innovations Foresight website there is an excellent article on this subject:

https://www.innovationsforesight.com...-infrared-nir/

Experimenting with an IR filter in front of the guide camera might give a similar result.

Peter
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Old 25-09-2021, 09:36 PM
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multiweb (Marc)
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Quote:
Originally Posted by Emuhead View Post
To anyone doing this, does this help?

Red should produce the smallest stars from my SVBony 60mm guide scope as it's def not an apochromat.

If so, assume we need to use an imaging red filter, and not just a planetary viewing red filter.

Thanks
There is no doubt red is less affected by turbulence than green or blue so it can't hurt. I suspect guiding could be better.
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Old 27-09-2021, 11:53 AM
Emuhead (Andrew)
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Thanks @Peter, perhaps that might have been it. Probably something for the pros, happy with the guiding im getting at the moment

@Marc will probably try a red filter at some stage if i can get my hands on one, and ill update the results here.
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Old 27-09-2021, 12:05 PM
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multiweb (Marc)
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Thanks @Peter, perhaps that might have been it. Probably something for the pros, happy with the guiding im getting at the moment

@Marc will probably try a red filter at some stage if i can get my hands on one, and ill update the results here.
I did a lot of imaging in infrared (both telescopes and wide field lenses) from home and I can confirm guiding is significantly better (with a lodestar). Never tried red which is more broadband but I'd say it'll help too.
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