TS flattener -- good for visual?

[YKSE]

There're talks in the other forum about visual use of this falttener:

http://www.teleskop-express.de/shop/product_info.php/info/p1010_TS-Optics-Universal-APO-Flattener-TSFLAT2-for-refractors.html

Not much details mentioned though, not in TS site either. I've seen it on ABS from time to time, hoping memebers who have used it can share their experiences about:

1. How's the flattening effect (the scopes you've tried)?

2. Any visible dimming of image?

3. How's the installation of this flattener? any adapter needed? any impact on focus travel distance? any fiddling or things to look up?

4. Some I forget to ask?

[Astroframer]

Hi

I cannot comment on the questions you ask.

But i can tell you there is one in the for sale section here on SGL

Hope this helps

Mark

[Stu]

Yong, I did use one of these with some success on some faster fracs such as TV76 where field curvature was very noticeable with widefield eyepieces such as the 31mm Nagler. My eyes would not accommodate the range, so it was a problem for me.

If I recall correctly I either replaced the barrel of the diagonal with it, or added it to the barrel. It did not cause me inwards focus issues as the focusers on the scopes were able to take any additional length.

In terms of results, it definitely improved things, let's say 70 to 80% improvement, I would think with some of your diligence in terms of spacing you would get it better.

There was another post from @Louis D with what I think would be a better solution. If Louis sees this, perhaps you could link to the post, although I will try to find it myself.

EDIT Found it!

 

[Louis D]

53 minutes ago, Stu said:

Yong, I did use one of these with some success on some faster fracs such as TV76 where field curvature was very noticeable with widefield eyepieces such as the 31mm Nagler. My eyes would not accommodate the range, so it was a problem for me.

If I recall correctly I either replaced the barrel of the diagonal with it, or added it to the barrel. It did not cause me inwards focus issues as the focusers on the scopes were able to take any additional length.

In terms of results, it definitely improved things, let's say 70 to 80% improvement, I would think with some of your diligence in terms of spacing you would get it better.

There was another post from @Louis D with what I think would be a better solution. If Louis sees this, perhaps you could link to the post, although I will try to find it myself.

EDIT Found it!

 

Yes, it gives quite an improvement.  The outer part of the field of low power wide field eyepieces in my AT72ED looked comatic rather than just blurry from field curvature.  Now, they look pinpoint or close to it to the edge.  There's no vignetting even with a Meade 40mm SWA 5000 that I could discern.  Because my focuser doesn't allow the 2" tube to be inserted beyond the clamping area, it does require some addition in-travel with the focuser.  If your focuser does allow 2" barrels to be inserted past the initial clamping area, there's no change in focus point because it doesn't change the focal length.

Just screwing it onto the front of my 2" diagonal provided overcorrection.  My 14mm Pentax XL actually looked perfect to the edge in this mode!   To get better correction for all my other eyepieces, I added an SCT to M48 threaded adapter to the front of my GSO diagonal (doesn't thread all the way on, so there's a slight difference in thread).  I then thread the 15mm spacer that came with it onto this and then the FF.  It sticks out no more than 20mm extra over my old diagonal nose piece.  If you needed less distance than screwing the FF directly into the SCT to M48 adapter, you'd be out of luck.

It's a very well made piece that doesn't seem to degrade from the image quality even in the center when curvature isn't an issue.  I consider it a necessary piece of equipment for short refractors like a coma corrector for a fast Newt.

[Louis D]

I should add I am using the Starguider version.  It comes with more bits and pieces for a better price when purchased with USD shipped to the states.

[YKSE]

Thanks guys, very helpful information.

Just need to sleep over the the pros/cons.