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Transit of Mercury in the Spicule Layer. Phil took this great image with his Quantum 6 Scope, Solar Spectrum etalon and PGR Camera.

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Two PST etalons doublestacked

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bart1805
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Two PST etalons doublestacked

Post by bart1805 » Sun Aug 11, 2019 11:38 am

For some time I am trying to doublestack two PST etalons. Here is more information about the adapter Gerd Neumann made for me and the older experiments:
viewtopic.php?f=9&t=25524&p=229597&hili ... ck#p229597

Two weeks ago the adapter arrived, today first try. Here are the different components of the current train:

Image20190807_152317_resized by bart moors, on Flickr

From left to right:

1) adapter SCT to front thread of etalon.
2) first etalon
3) Neumann filter drawer with the correct threads to couple both the etalons. On the back you can see a ring so I can mount the back etalon in every position I want it to be.
4) Above the drawer the circular polariser
5) second etalon
6) adapter from back thread etalon to sct
7) JMI EV1 SCT focuser

Here is how it looks when coupled:

Image20190807_152837_resized by bart moors, on Flickr

And attached to the Intes:

Image20190807_095710_resized by bart moors, on Flickr

Seeing was terrible this morning, so try not to look at the quality of the image. 160mm D-erf on a 7 inch Intes Rumak. ASI290mm, UV/IR cut. No gamma, no gain, exposure 5 ms. Had to use a lot of LR and UM in IMPPG to get something out of it.

Image10_05_20_l5_ap2102_IMPPG2 by bart moors, on Flickr

The combination is very stable. Now waiting for some decent seeing to experiment more:
- how to position the etalons exactly to eliminate the double limb some more
- how to position the etalons "against eachother"
- position of the CP (at first glance there was no difference visible with the different positions of the CP)
etc.

Thanks for looking! Bart.

ps. some reflected sunlight with the 9 inch Rumak and a 742nm filter on august 7, very early in the evening with the sun above the horizon.

Image20_44_13_l5_ap2456_RS2_PS_V2 by bart moors, on Flickr

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Re: Two PST etalons doublestacked

Post by ffellah » Sun Aug 11, 2019 11:57 am

I find your etalon experiment very interesting, Bart. Great moon shot !

Franco

bart1805
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Re: Two PST etalons doublestacked

Post by bart1805 » Sun Aug 11, 2019 6:09 pm

Thanks Franco, will post here how it evolves. CS! Bart.

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Re: Two PST etalons doublestacked

Post by Starry Jack » Sun Aug 11, 2019 7:44 pm

Excellent DS work and the moon is terrific. I have found that using a 12nm HA filter is fantastic in the moon. Makes my achro look like an apo.
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Re: Two PST etalons doublestacked

Post by marktownley » Sun Aug 11, 2019 7:58 pm

Good adaptors and good result. I pursued this method some years ago but gave up in the end because of uneven illumination.
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Re: Two PST etalons doublestacked

Post by MapleRidge » Sun Aug 11, 2019 10:26 pm

Hi Bart...

The DS assembly looks good, and I'll be keeping an eye out for images as you refine it!!! The DS image shows lots of potential, and the lunar pic is tack sharp. Well done :bow

Brian
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Re: Two PST etalons doublestacked

Post by MAURITS » Mon Aug 12, 2019 5:14 am

Excellent results Bart.
Regards,
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Re: Two PST etalons doublestacked

Post by Carbon60 » Mon Aug 12, 2019 5:28 am

Nice engineering, Bart. Looks great.
As Mark says, it can be tricky to achieve even illumination with two PST etalons. It’ll be interesting to see how this develops.

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Re: Two PST etalons doublestacked

Post by bart1805 » Mon Aug 12, 2019 5:41 am

Thanks guys!
Starry Jack: it is a trade off between resolution and seeing. And if I could choose, I would choose a good seeing. And then image with a green or blue filter. (-;
Mark and Stu: problem of uneven illumination will be one of the biggest problems, will let you know if I find something to deal with it.

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Re: Two PST etalons doublestacked

Post by Montana » Mon Aug 12, 2019 9:04 am

Wow! well done, still a fabulous image :bow :hamster: great Moon too!

Alexandra

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Re: Two PST etalons doublestacked

Post by Merlin66 » Tue Aug 13, 2019 1:20 am

As I've mentioned before - double stacking PST etalons isn't the easiest challenge to attempt.
I'm currently using the SM60/ED80 with a PST etalon as a double stack system, with good results.
(The SolarMax II DS is basically the same arrangement but with the RichView tuning)
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