DIY Solar Wedge ND3.0 alternatives for Imaging only

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Martin_S
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DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by Martin_S » Tue May 21, 2019 9:40 pm

Hi, I'm building a Herschel wedge for white Light solar Imaging. I am sourcing a ND3.0 ND filter at a reasonable cost . Most of my parts I buy from Asia,as the postage and exchange rates from the UK or USA to Australia can be expensive. There was a nice set of ND filters from Svbony . but they have been discontinued. I have a UV /IR cut and a variable polarising filter and a #58 green filter and Moon filter in my collection.

Any suggestions for filters for imaging only would be most welcome.

Thank you

Martin
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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by MalVeauX » Tue May 21, 2019 9:54 pm

Heya,

Is this strictly for refractors?

What aperture range do you want to have on it?

You really do not have to make a Herschel wedge for imaging only. Wedges kill transmission, which is ideal for visual use, but for imaging, you don't have to do that. You just have to have transmission low enough to not saturate the sensor, and thermal load handled to not melt everything, so you can make an imaging only platform a lot better. Again, no need to make a wedge.

Very best,

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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by Martin_S » Tue May 21, 2019 10:05 pm

Marty , I'm using refactors up to 100mm , I just need a grab and go solution for travelling with my small refactors. I have tried film but thought I might do better with a wedge.

Martin

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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by MalVeauX » Wed May 22, 2019 1:18 am

Heya,

All good, you mentioned this is for imaging only right? A UV/IR block filter and a KG3 with any sort of colored dielectrically coated imaging filter would effectively mitigate any serious heat issues and allow upwards of a 150mm refractor's aperture without any problems with the camera sensor... again, if this is for imaging only. For visual that's not safe. So if this is strictly for portable imaging, you could make a high transmission system. Then again, a Lunt wedge isn't that much more expensive. The cheapest thing is of course solar film and apertures this small its still a portable solution to carry a film filter in a cell around likely.

A single 2" Baader Red CCD-IR block filter would handle all thermal load in refractor apertures up to 150mm no problem.

https://agenaastro.com/baader-2in-r-ccd ... 8475r.html

A colored (red) filter behind that would further cut down transmission and left over thermal load. A Baader 610nm long pass filter comes to mind. You can mount both right into a diagonal and you have your own high transmission wedge. Wedges have low transmission, this would be way, way, way higher transmission. If that matters. Again, I assume it does if this is strictly for imaging.

Very best,

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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by Martin_S » Wed May 22, 2019 1:35 am

strictly Imaging...... my eyes are shot from working as a welder for over 45 years

Thanks Marty

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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by Martin_S » Mon Sep 23, 2019 3:48 am

Hi everyone , Here's a follow up from my original post. I managed to get a ND 3.0 filter off Ken (Merlin66),so today I gave my wedge it's first light.
The wedge is a made from a Meade diagonal prism reverse mounted in two plastic star diagonal holders. The prism is held in place by pieces of foam rubber. no attempt was made to suppress stray light or align the prism this was just an exercise to see if it would work. I am happy with my initial results so now I will be making a wedge mounted in an aluminium case so I can collimate the prism, control stray light and diffuse the heat from the back of the wedge. Here are a few pictures from today's session, My Image train is as follows ED100 - Wedge - IR cut filter - ND 3.0 filter- Wratten #58
green filter - 2 x barlow - ASI120 mm camera.

The solar pictures are raw unprocessed stacks to show the difference in resolution I obtained using a wedge compared to solar film.


Martin
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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by marktownley » Mon Sep 23, 2019 5:51 am

Nice looking rig!
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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Re: DIY Solar Wedge ND3.0 alternatives for Imaging only

Post by Martin_S » Mon Sep 23, 2019 6:16 am

Thanks Mark

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