CaK with 250 mm RCT- REWORKED!

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Carbon60
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CaK with 250 mm RCT- REWORKED!

Post by Carbon60 »

Inspired by Alexandra's Ca K images with her C11 I thought I'd take an opportunity on a sunny lunch break to see what I could do with my 250 mm RCT. Previous attempts were a complete failure (for whatever reason) and although lunchtime isn't the best time of the day for hi-res work I wanted to undertake a trial run to see if the previous issues remain. I think better collimation and a B1800 CaK module (as opposed to a B600) may have made the difference, plus improved processing knowledge, but the results this time around are a world away from the previous mess.

Anyhow here's the result in mono and colour. By no means perfect and much room for improvement, but the scope shows significant promise under optimal seeing conditions. I need to somehow brighten the image (by modifying the CaK module) to significantly reduce the exposure time and freeze in the air movements..... my next project :)

Image20200901_CaK_x2.7_2 by Stuart Green, on Flickr

Image20200901_CaK_x2.7_2_Colour by Stuart Green, on Flickr

Thanks for looking.

Stu.
Last edited by Carbon60 on Wed Sep 02, 2020 6:24 pm, edited 1 time in total.


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Re: CaK with 250 mm RCT

Post by pedro »

Beautiful HR Ca-K images Stu, well done


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Re: CaK with 250 mm RCT

Post by EGRAY_OBSERVATORY »

Excellent images Stu.

Terry


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Re: CaK with 250 mm RCT

Post by marktownley »

You're being ambitious there Stu, 250mm at CaK is the equivalent of imaging at 400mm in Ha. Have you ever tried your 150mm scope for CaK? at f10 you should be a winner, or is it a faff taking the Ha rear end off? When you can get results at 250mm in Ha, then 150 in CaK is equivalent in resolution.


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Re: CaK with 250 mm RCT

Post by Montana »

Wow!! amazing Stuart!! :bow :bow :hamster:

Did you stop the aperture down? did you use the 2.5x powermate?

Alexandra


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Re: CaK with 250 mm RCT- REWORKED!

Post by Carbon60 »

Same images as above, but reworked using different settings in ImPPG.

Image20200901_CaK_x2.7_3 by Stuart Green, on Flickr

Image20200901_CaK_x2.7_3_colour by Stuart Green, on Flickr

I guess these are too ‘fluffy’ for CaK, which should be more ‘flaky’ according to images from DOT, if this is the benchmark.

Thanks for looking.

Stu.
Last edited by Carbon60 on Thu Sep 03, 2020 6:19 am, edited 1 time in total.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: CaK with 250 mm RCT

Post by Carbon60 »

marktownley wrote: Wed Sep 02, 2020 4:48 am You're being ambitious there Stu, 250mm at CaK is the equivalent of imaging at 400mm in Ha. Have you ever tried your 150mm scope for CaK? at f10 you should be a winner, or is it a faff taking the Ha rear end off? When you can get results at 250mm in Ha, then 150 in CaK is equivalent in resolution.
Hi Mark,
I completely understand what you mean because of the shorter wavelength of Ca II K compared with Ha and it would be interesting to try the 150 mm, but the main issue is the internal ERF which really would be a faff to remove every time.

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: CaK with 250 mm RCT

Post by Carbon60 »

Montana wrote: Wed Sep 02, 2020 1:36 pm Wow!! amazing Stuart!! :bow :bow :hamster:

Did you stop the aperture down? did you use the 2.5x powermate?

Alexandra
Hi Alexandra,
Many thanks. I figured I'd try it at full aperture to see what I could get. No, the PM gives a central image that is far too bright. Instead I image in CaK using an APM 2.7x Barlow from Rupert at Astrograph, with good transmission at 393.4nm.

Cheers

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: CaK with 250 mm RCT

Post by marktownley »

Carbon60 wrote: Wed Sep 02, 2020 6:38 pm
marktownley wrote: Wed Sep 02, 2020 4:48 am You're being ambitious there Stu, 250mm at CaK is the equivalent of imaging at 400mm in Ha. Have you ever tried your 150mm scope for CaK? at f10 you should be a winner, or is it a faff taking the Ha rear end off? When you can get results at 250mm in Ha, then 150 in CaK is equivalent in resolution.
Hi Mark,
I completely understand what you mean because of the shorter wavelength of Ca II K compared with Ha and it would be interesting to try the 150 mm, but the main issue is the internal ERF which really would be a faff to remove every time.

Stu.
I thought there were constraints that meant the 150 wasn't feasible.


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Re: CaK with 250 mm RCT- REWORKED!

Post by Montana »

Stuart, to use the 2.5x powermate all you have to do is add 4cm to the end of it before the camera, works a treat.

Alexandra


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Re: CaK with 250 mm RCT- REWORKED!

Post by grimble_cornet »

Great images Stu and overall very interesting stuff. I can use my 100mm f10 Tal most days for CaK and with two x2 Barlows stacked together I have had very sharp results on days of really good seeing. I have tried using the CaK1200 unit on my 152mm f5.9 scope with promising results - I have a near full aperture erf which just sits on the end of the tube (thanks Mark) so its easy for me to swap between Ha with the Quark, white with a Baader wedge and CaK. Look forward to seeing more results in high res CaK from you and Alexandra.


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