Doublestack for mod

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Re: Doublestack for mod

Post by EGRAY_OBSERVATORY »

Yes I agree James, where clearly China have been well involved over the last decades in producing much of what goes into astro-gear for various manufacturers around the globe. Presumably allowing prices to be kept lower due to the lower production costs in China.

I wonder how many of us really know that the Synta Technology Corporation of Taiwan actually own much/or all of the Orion/Meade, SkyWatcher, and Celestron, companies and no doubt manufacture part for many other companies too, with their main operation in China.

https://telescopenights.com/celestron-v ... kywatcher/ confirms this.

Whether it is a good thing that Synta have taken over this major part of the telescope manufacturing world, albeit maybe keeping some prices to the end-user lower for some, is one matter. And whether that affects the other manufacturers such as Vixen, Takahashi and so on, as far as their abilities to produce and sell their excellent products at the usually higher-prices is another matter, where competition may-not be a good thing.

Terry


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Re: Doublestack for mod

Post by DeepSolar64 »

Synta and Sunny dominate the amateur telescope market with companies like Celestron, Sky-Watcher, Orion and Meade but they are not the only Chinese manufacturers. Astro-Tech, Astronomics brand of ED-APO refractors are Chinese manufactured but not by Synta or Sunny. I read this somewhere but I cannot remember who the manufacturer is. SharpStar is another ED-APO brand that is Chinese but not Synta or Sunny.

I hated the Chinese optics at first. Quality was very hit or miss when compared to Japanese, American or European optics but in recent years they have gotten much better. But I must admit, they have made amateur astronomy much more affordable. I would be really curious what they could do with narrow band solar.

But now Meade has their Coronado scopes made in Mexico!


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Re: Doublestack for mod

Post by Ivan »

Hi, everybody,

I want to share with you a small mod that (as I would like to believe) works.

I dreamed of doubling the stack for about a year, but for financial reasons I postponed the purchase of an aperture DS from Coronado, as Bob advised, and then, for all known reasons, such a purchase and delivery to my country became impossible. I had to look for options in the domestic market and settled on another Lunt50.

I knew that Vladimir (CSVE), very successfully implemented DS PST+Lunt50, working under F10, but my already modest short-focus tube WO Megrez90 works under F7, besides, when I decided to buy used solar telescopes on sale, there was nothing.

Then there was an unsuccessful attempt to buy a great copy in Cyprus, I tried everything I could and realized that I had hit a wall. As a result, I persuaded my friend to sell me his Lunt50. Ohhh

Connect two etalon Lunt50 it was risky, but Brian's experience gave hope

After receiving the second etalon, I ordered an adapter so that there was a minimum distance between them. In case of a ghost, the adapter provided a thread for the filter (fortunately, the ghost did not come and the filter was not needed).

When assembling the first mod to find the etalon position, I used the camera technique described by Filip. But it was not possible to focus two standards on the Lunt50 lens at once, because its pipe interfered. Perhaps I should have unscrewed the lens and built something like an optical bench, but I did not dare to take this step.

I did this: focused each etalon separately, connected them together, and screwed them to the Megrez90. An adapter was installed on the telescope (the length of which was determined by the method described by Filip). I assumed that there would be no focus, as it was not on Lunt50, but it was worth checking. As a result, the old adapter was unscrewed, and I, holding the camera with etalons in my hands, manually found the focus. Then a new adapter was ordered, the production of which was delayed, and only a couple of weeks ago I received it.

The setup process is quite original, (I haven't dealt with DS). I thought it would be easy to set up, and I completely unscrewed the second tuner, believing that I would tune the first one first, and then the second one would simply improve the picture. But I was very surprised when I turned the first one almost completely, I found only faint traces of the chromosphere, I was out of the band. Only after starting to twist the second tuner, the picture improved. It turned out that both filters work only in pairs. I wonder if this is a feature of all systems with internal DS?

My impressions are very contradictory, I can't say I'm happy, but I'm not disappointed either. I see that the double limb has almost disappeared, but I also see the unevenness of the band. Some part of this problem lies in the sagging of the focuser under the weight of the camera, this can be solved if everything works optimally, and I'm not sure about that. In addition, the picture does not look crisp and contrasting, although it may be a matter of processing.

I am attaching some photos so that you can evaluate whether this device works as a DS and maybe you can advise me something.

In all photos, except for the mosaic, I used only deconvolution for processing.

It is better to open the first 2 photos in a new window:

ImageComparison_1 by Ivan Sirotin, on Flickr

Image24.10.22_DS_3 by Ivan Sirotin, on Flickr

Image24.10.22_DS_2 by Ivan Sirotin, on Flickr

Image24.10.22_DS_1 by Ivan Sirotin, on Flickr

Image27.10.22_DS by Ivan Sirotin, on Flickr

The first experience of a mosaic shot on DS already published here earlier:
ImageFD_24.10.22 by Ivan Sirotin, on Flickr

Telescope Photo:
Image20221024_134836 by Ivan Sirotin, on Flickr

Image20221024_135310 by Ivan Sirotin, on Flickr

Thanks,
Ivan

ps
Since I was shooting at the end of October, seeing was very bad, besides there were so few gaps in the clouds that I could not shoot the same areas in the Sun on SS for a more correct comparison.


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Re: Doublestack for mod

Post by marktownley »

Great mod Ivan!


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Re: Doublestack for mod

Post by DSobserver »

I've tried too to DS lunt50.

Despite many newton rings...I came to the conclusion that the picture is darker and gives an impression of higher contrast

No real new info on the "DS" picture Vs "SS" picture

Would be interesting to compare your mod with a camera, the same day with DS vs SS...


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Re: Doublestack for mod

Post by Ivan »

marktownley wrote: Mon Oct 31, 2022 8:21 pm Great mod Ivan!
Thank you Mark!
I would like to hear criticism and advice :) although this season I will hardly be able to see the Sun through it again.

Ivan


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Re: Doublestack for mod

Post by Ivan »

DSobserver wrote: Tue Nov 01, 2022 9:03 pm I've tried too to DS lunt50.

Despite many newton rings...I came to the conclusion that the picture is darker and gives an impression of higher contrast

No real new info on the "DS" picture Vs "SS" picture

Would be interesting to compare your mod with a camera, the same day with DS vs SS...
Hello,
Unfortunately, I won't be able to make photo comparisons this season. We have already had the first snow, and although it has melted, the weather promises nothing but heavy, low clouds.

Ivan


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Re: Doublestack for mod

Post by Bob Yoesle »

Hi Ivan,

I'm not sure how it looks visually, but via the images, your DIY double stacking system looks like it's performing much better than I would have estimated it would - and you're especially fortunate that you're not having to deal with internal reflections and use of a circular polarizer to suppress them. The full disc mosaic image is wonderfully detailed, and I see little to no trace of a double limb on it. I think it would take considerable resources and effort to improve on what you've accomplished, and the improvements would be incremental...

Congratulations!

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Re: Doublestack for mod

Post by Ivan »

Bob, thank you so much for your feedback, I really appreciate it. You made my day!
:bow :bow :bow

Ivan


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Re: Doublestack for mod

Post by DeepSolar64 »

Ivan,
Congratulations on your doublestack mod! You mention tuning. I usually have to tune BOTH my etalons to get on band. One is internal and one external. The same on both Coronados. Also I find the primary etalon without stacking gives a more evenly tuned and illuminated disk on my scopes. I tend to use doublestack more for visual use and single stack more for imaging. But it could be in part from my imaging inexperience.

I await your results once the sun rises higher again and warm weather returns. Keep us posted!

James


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Re: Doublestack for mod

Post by OlegLviv »

Nice Ivan congratulations!
Sorry friends all serial numbers models Lunt 50Tha have F7 and they doublet telescopes?
Thank you!


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Re: Doublestack for mod

Post by OlegLviv »

Sorry friends all serial numbers models Lunt 50Tha have F7 and they doublet telescopes?
Anybody say me?
Ivan whitc is the camera diagonal and pixel you have QHY?
Thank you!


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Re: Doublestack for mod

Post by marktownley »

My LS50 is a doublet Oleg


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Re: Doublestack for mod

Post by Ivan »

OlegLviv wrote: Tue Jan 03, 2023 11:58 am Sorry friends all serial numbers models Lunt 50Tha have F7 and they doublet telescopes?
Anybody say me?
Ivan whitc is the camera diagonal and pixel you have QHY?
Thank you!
Oleg, sorry for the long answer. I haven't been in this topic for a long time.

As far as I know, all Lunt50 duplets and f7.

I have a very old qhy img0s CCD, the diagonal is 7.6 mm, the chip size is 5.8×4.95 mm, the pixel size is 4.65 microns.

Ivan


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Re: Doublestack for mod

Post by OlegLviv »

Ivan thank you for your answer!
I have focal lenth 900 mm and camera 432mm the diagonal 14mm the chip size is 14x9 and am scary sweet spot will be small that you.....


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Re: Doublestack for mod

Post by Ivan »

Hello everyone This animation shot on July 26 shows the difference between SS and DS.

ImageDS vs SS by Ivan Sirotin, on Flickr

Several months of operation revealed both the pros and cons of this installation, I will write about them a little later.

Ivan


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Re: Doublestack for mod

Post by Ivan »

ImageDS vs SS by Ivan Sirotin, on Flickr


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Re: Doublestack for mod

Post by OlegLviv »

Today was a good weather and test my double stack with two lunt 50mm etalon! Thank you Ivan for idea!
But I see that sweet spot less with two etalons that one and me need do it big focus lenth :cry:
A few photos test double stack without lens barlow with 432mm and 429mm cameras.
A photo viber_2024-02-26_11-44-39-412.jpg with one stack!


But have a few questions!

1.Why sweet spot less with two etalon?
2.Why when two etalon near sweet spot its too dark? But when 1 etalon bright near sweet spot.
3.On photos this is really DOUBLE STACK??? If yes what is the bandwidth there now I have 0.6A?
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Re: Doublestack for mod

Post by marktownley »

The rear etalon is not square (orthogonal) with the first etalon, you can see that in the photo of the scope. This is the reason the sweet spot is not central. As bandpass decreases then also does sweet spot size. You need to zoom in further!

No such thing as a free lunch! ;)


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Re: Doublestack for mod

Post by OlegLviv »

Thank you Mark seeing on winter not good but on photos this is really DOUBLE STACK???
If yes what is the bandwidth there now I have 0.6A?
Between the two lunts I put filter ND 0.6 to avoid unwanted glare and double suns but bought Baader 2" polarisation filter too.
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Re: Doublestack for mod

Post by MalVeauX »

Hi Oleg,

What is the base scope you're using (aperture, length, etc)? Are you using collimating lenses internally or a telecentric?

The jacquinot spot will shrink as bandpass becomes more isolated in a collimated system. If they were front mounted, it wouldn't be noticed. If they were behind a true telecentric it would not be noticed. In those two situations, the field & acceptance angles are more similar, so there is less of a noticed jacquinot spot or outright not jacquinot spot at all.

Your system is coming on band, and it is indeed double stacking well, you can see features in high contrast, somewhere around 0.5~0.6A FWHM probably in your best areas. The next steps are to perfectly tune both etalons together so there's uniformity. And if you want to increase the jacquinot spot size or eliminate it, you need to revisit the above ideas of using a telecentric if these two etalons are internal or rear mounted.

If you're using the stock collimating lens, it's probably not the correct position for two etalons like this, as it was designed with a length meant for one. If you're using a stock collimating lens, the rear lens is before your 2nd etalon and so that etalon is not in a collimated light cone, so it will develop a very small jacuiqnot spot as you see in your images.

It's likely the collimating lens relative to your donor scope parameters. A telecentric would solve both.

Very best,


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Re: Doublestack for mod

Post by OlegLviv »

MalVeauX thank you for answer!

1.About my telescope.
I use a Ts Optics 150/900 f5.9 telescope, but before the first lunt 50 etalon I screwed in the Baader Glasspathcorrector 1:1.25 to get to f 7.5 so that the aperture is not cut.
Am using collimating lenses internally because I'm afraid to disassemble the lunt 50 for the telecentric circuit and my balcony is short for telecentric system.

2.About not the correct position for two etalons.
Yes, I use a standard collimating lens and I know about the incorrect position of one etalon relative to the other,
but I made an experiment and put another Baader Glasspathcorrector 1:1.25 between the two etalons at the measured distance, accordingly, the distance should be correct.

3.Yesterday the weather was good and tried do it double stack and have question about this photo tell me this good because as for me this seet spot its too dark when rotated two etalons or not plese tell me because I'm afraid that I left the lane HA that's why it's so dark.
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Telescope: TS 152/900/Bresser 102/1350
Baader D-ERF 160MM
2xBaader 1.25 GPC
2xLunt 50mm
Lunt Cak B1200
Coronado BF15
Camera: Apollo Max 432M/ Apollo Mini 429M/Player One Mars II 462M/QHY 290MM
Mounh: 2xSky Watcher AZEQ6
Telecentric Lense: Televue Powermate 2/2.5x/4X/5X
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Re: Doublestack for mod

Post by MalVeauX »

Hi,

Well, the fact that you have an obvious jacquinot spot makes it apparent that whatever measurement you used for collimating lens placement for both etalons is simply not positioned correctly. I'm not sure which etalons you're using, but many of the internal ones have a collimating lens set before and after the etalon chamber that you cannot remove without destroying the pressure system of the chamber. So when you add that 2nd etalon behind that, unless it has its own collimating lenses, I'm not sure how its seeing a collimated light cone since the 2nd lens after the first etalon returns the light cone to normal (a cone, rather than cylinder).

The presence of that jacquinot spot and how small it is means your field angle and acceptance angles are not similar, they're rather divergent. Since the etalons are not front mounted, this then becomes a relationship of the objective aperture relative to the aperture of your etalons, and so you're seeing the result here. Even a collimating lens will not fix this. When you do this with a large aperture and a tiny etalon with collimating lenses, the jacquinot spot will be there and be small, so the instrument becomes a high res system and basically only good with a small camera sensor to only use that FOV within the jacquinot spot. If you want to increase the jacquinot spot or remove it, you need to move to true telecentrism. If you cannot do this due to collimating lenses, then see previous comment about just using a smaller camera sensor and working within your jacquinot spot size.

If your first etalon is correctly positioned with its collimating lens you should have a pretty good FOV; similar to what you would see in the results in my thread on the Lunt 60 mod. You can then add a telecentric after this and a 2nd etalon behind the telecentric to further the setup, as you've seen in my current system. The jacquinot spot will be small (not full disc) but it will be big enough to use a smaller sensor FOV and do moderate to high res imaging, which is what you're interested in with a 150mm lens anyways.

But, it depends on what kind of etalon you're using as the double stack and if it has collimating lenses or not.

Overall this is why front mounted tilting etalons are the easiest ones to do this with, no lenses.

Very best,


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Re: Doublestack for mod

Post by OlegLviv »

Hello friends a few days ago will be good seeing and want see a few photos my and Ivan modification 2xlunt50 pressure tune!

Ts150>first lunt>first part adapter (inside adapter 2.0 Baader ND.06)>second part adapter have tilt and shifter and Baader Glasspathcorrector 1:1.25 >second lunt>focuser 1.25>bf15>Powermate 2.5x>429mm camera. 2850mm focus/f19

Have a fun!
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https://www.facebook.com/oleg.lavigne/
https://www.astrobin.com/users/RamonLviv/
https://www.astroclub.kiev.ua/forum/ind ... ic=46758.0


Telescope: TS 152/900/Bresser 102/1350
Baader D-ERF 160MM
2xBaader 1.25 GPC
2xLunt 50mm
Lunt Cak B1200
Coronado BF15
Camera: Apollo Max 432M/ Apollo Mini 429M/Player One Mars II 462M/QHY 290MM
Mounh: 2xSky Watcher AZEQ6
Telecentric Lense: Televue Powermate 2/2.5x/4X/5X
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Re: Doublestack for mod

Post by Martin_S »

Wow that's amazing , well done.


H alpha : ,Skywatcher 120mm F8 open frame refractor, a tilted 2" 7nm H-alpha filter as a sub energy rejection filter, Baader TZ4 telecentric focal extender, Player One energy rejection filter, Combo Quark Chromosphere, Naked PST etalon for double stacking, ASI74mm camera
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Re: Doublestack for mod

Post by marktownley »

That works Oleg!


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