multiple images

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RodAstro
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multiple images

Post by RodAstro » Sun Nov 12, 2017 12:17 am

Ha image 700mm inside.jpg
Ha image 700mm inside.jpg (76.13 KiB) Viewed 2969 times
Hi new to the forum
I have been reading for a while and trying to glean info on the Omega H-alpha filters
I have been trying to build a system using these filters and am having problems with the front filter etalon.
It seems to have multiple images in one direction all the same size but progressively fading.
The images rotate with the filter if I rotate it so fixed.
No amount of tilting makes any difference to them.
I started with the filter system just in front of the diagonal and the images are close together but today I have moved them 700mm up the tube and they spread out not quite as intrusive.
I am using on a 150mm f15 refractor stopped down to 70mm by ERF so working just over f30.
Just wondering if anyone has come accross this? Omega seem to sell enough of these filters.
I have added a drawing of what I am seeing to help.
Thanks for any help

download/file.php?mode=view&id=29720&si ... 0a443fc866



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Re: multiple images

Post by marktownley » Sun Nov 12, 2017 4:20 am

Post a pic / drawing of your optical setup.


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Re: multiple images

Post by RodAstro » Sun Nov 12, 2017 10:02 am

Ok simple diagram as it is a simple setup
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Ha filter position in zeiss.jpg
Ha filter position in zeiss.jpg (41.89 KiB) Viewed 2964 times



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Re: multiple images

Post by marktownley » Sun Nov 12, 2017 11:01 am

I see. Looks to me like it's reflections in the different layers of the Omega filter. I've tried the Omegas before a couple of times, IMHO they are nowhere near good enough for solar astronomy. Try sending it back and asking for a replacement.


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Re: multiple images

Post by RodAstro » Sun Nov 12, 2017 12:04 pm

Yep thanks for the reply Mark that is the conclusion I am coming to. I have two sets of these and both are the same, although the reflections in one is slightly closer than the other. It is a pity the elements could not be separated and mounted separately then the reflections could be removed.
What problems did you have with yours?



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Re: multiple images

Post by marktownley » Sun Nov 12, 2017 12:32 pm

Ghosting, lack of contrast, very wide band pass. They're basically trying to get an interference filter to act as an etalon, and the two are quite different things.


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Re: multiple images

Post by RodAstro » Sun Nov 12, 2017 12:53 pm

yep ghosting is a problem but I have found CPL filters can remove nearly all but these secondary images then the contrast improves, band pass I am not sure about yet, I am getting good prominences but surface detail is not good yet I can see some.
Im not sure how good my seeing is and there is little on the surface to look see at the moment.
But in contrast I think the only other system that would work on my scope is a Quark or a second scope and cost becomes a bit prohibitive.



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Re: multiple images

Post by RodAstro » Sun Nov 12, 2017 4:27 pm

Has any one other than Dave G and P Zetner had success with these filters?



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Re: multiple images

Post by Montana » Mon Nov 13, 2017 10:00 am

Doesn't P Zetner have the Omega CaK and not the Halpha?
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Re: multiple images

Post by RodAstro » Mon Nov 13, 2017 10:18 am

Hi Alexandra
Yes I think he does now but his original Omega was a Ha system and he also had trouble with the first filter and reflections and from what I can gather he used some different pre filtering and two of the rear filters that do not have the UV/IR protection filters. It seems to me that it is these two or three plates stuck together that is the cause of the reflections.
By the way did you ever get your Baader prominence viewer working? I am interested as the original design was for my scope and made by Zeiss Jena yours was probably made by Zeiss as many of the Baader optics were and from what I can gather some still are. It should show lovely proms when working it was not an amature unit when made.



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Re: multiple images

Post by RodAstro » Mon Nov 13, 2017 10:47 am

Hi Alexandra
Just been on your solar nutcase blog and see you did get it working, nice!
Surprised you have not seen the pollen before, maybe modern filters are to narrow. I have seen them and many other high altitude objects in other solar filter systems thousand oaks, PSTs it is a common thing to see. Another reason to get to high altitude. Interestingly it also makes you realise how many species can spread around the earth.



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Re: multiple images

Post by Montana » Mon Nov 13, 2017 12:05 pm

Glad you saw my results, I was just going to say yes I did get it to work, it is great for visual :) Perhaps Wolfgang may be able to help with the placement of your filters or how to overcome the issues, but only if you speak German :)

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Re: multiple images

Post by RodAstro » Mon Nov 13, 2017 12:31 pm

Do you know if Wolfgang worked for Zeiss at any time?
Oliver Smie of Bel Optik did and he also makes a very similar unit.
Lots of excellent opticians were put out of job when the Berlin wall came down and Zeiss west managed to take over the Jana factory.



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Re: multiple images

Post by Montana » Mon Nov 13, 2017 2:44 pm

I am sorry but I don't know, you could ask him :)
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Re: multiple images

Post by marktownley » Tue Nov 14, 2017 10:18 am

I don't think you're going to get anywhere near what you can get even with just a PST compared to these Omega filters...


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Re: multiple images

Post by RodAstro » Tue Nov 14, 2017 10:38 am

Yep Mark I am coming to that conclusion
Peat Z ended up using two of the rear filters and other blocking filters in his scope, he even mentioned in one of his posts that he tried to separate the front filter but it could not be done.
So after spending a £100 or so on fittings other filters and aluminium plus hours of machining the filters are packed up ready to go back to Omega. Now my friend who ordered them has all the hassle with customs to get their hefty charges back.
From looking around the internet it seems Dave Gs is the only one that works no one else posts anything about what they can see and no images.
What did you end up doing with your filters?



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Re: multiple images

Post by Merlin66 » Tue Nov 14, 2017 10:55 am

I’m currently testing a combo of the CaK Omega filters. So far the results are looking good.
Haven’t tried any of the Ha options.


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Re: multiple images

Post by RodAstro » Tue Nov 14, 2017 11:39 am

Hope they work well there does seem to be a lot of success CaK filters is it possible to use them visually or are they just for imaging?



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Re: multiple images

Post by RodAstro » Tue Nov 14, 2017 11:42 am

I have had a PST but found although the views were good I wanted to get closer in and study areas more but found it very limited for that so didn't use it much. I must admit though imaging and processing has come on so much since then I probably go more down that road now.



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Re: multiple images

Post by Montana » Tue Nov 14, 2017 12:03 pm

Why not do a PST modification then?
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Re: multiple images

Post by RodAstro » Tue Nov 14, 2017 12:28 pm

I did think of that when I had the PST that was before any one had done it but didn't have the guts to have a go, (very unusual for me) I wanted to keep my eyes. My PST was one of the first ones.
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Re: multiple images

Post by marktownley » Tue Nov 14, 2017 6:12 pm

RodAstro wrote:
Tue Nov 14, 2017 10:38 am
What did you end up doing with your filters?
I chucked them away...


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Re: multiple images

Post by RodAstro » Tue Nov 14, 2017 8:50 pm

Thats expensive
I have taken great care with them especially after seeing the first image and not being able to move the false images by tilting thought they may have to go back.
Very expensive in time and money for me so I don't feel inclined to try any other Omega filters at the moment and Bob who sells the filters on ebay does not seem to accept or understand the problem. I can understand if they have been damaged in the post or at customs as they did take weeks to get here and they were only in a jiffy bag but that would be Bobs problem for not packing them sufficiently.
Now I am starting moan.
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Re: multiple images

Post by RodAstro » Sat Nov 18, 2017 2:45 pm

Well after thinking we will send the filters back, I thought about Peter Zetner's Omega Ha scope and also Filips Scope both using the rear blue filters etalons. Peter used two and Filip used just one because he had the same problem with his red one.
I decided to have a go with the two blue filters (etalons), I had to re machine one of the mounts as the red filter is smaller put it all together and hay presto no multiple images, Prominences all around the edge and surface detail wow. Now needs a bit of work to get rid of the faint ghosting and bring up the contrast. The detail could be better as the two blue filters are not well matched for tuning so will have to sort that out with Omega.
I also used a Kg3 UV/IR blocker to make it safe as well as the ERF.
I can now see the potential so will keep you updated
Cheers for the help/suggestions.



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Re: multiple images

Post by marktownley » Sat Nov 18, 2017 2:58 pm

Let us know how you get on


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