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Old 06-05-2018, 03:26 PM
LewisM
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FSQ-85 flattener spacing

Fiddling to get all my astro cams correctly spaced for the Tak FSQ-85 Flattener (specifically for larger than APS-C sensors). The below is an aberration shot for the full-frame DSLR through the FSQ with the flattener.

Does this appear to be too far OUT as I suspect, or too far in? It seems pretty even in all the corners, so tilt can be ruled out. Tak is not exactly open with the spacing dimensions, as you are supposed to use their CA-35's and cam adaptors Not me....

I later put the STF-8300 on, and that seemed spot on, so compared distanced to chip, shim thickness etc, and then removed one of the shims from the DSLR. I hope I went the right way! I use 1mm delrin shims.

Opinions appreciated on too far out or too far in.
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Old 06-05-2018, 05:02 PM
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Looks pretty close Lewis

Dunno about in or out (or shaking it all about) though...not a problem I've had with my Esprit
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Old 06-05-2018, 06:29 PM
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Originally Posted by Camelopardalis View Post
Looks pretty close Lewis

Dunno about in or out (or shaking it all about) though...not a problem I've had with my Esprit
You must have gotten the Esprit instruction manual with the 4th spacer information revision (my Esprit 80 spacing was wrong in the manual - had to get it from SW :lol).

This flattener is so bloody uncommon that Claude at AEC didn't even know it existed! I had to have it special ordered in after consulting Tak directly.
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Old 06-05-2018, 06:47 PM
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Hi Lewis,

After having a close look at your image I believe you have some tilt as well. The top right corner has definitely better stars than the other 3 corners. Also, the stars in the middle right part of the image are all slightly elongated towards bottom right (instead of being elongated in a horizontal plane).

As for the spacing, I feel you are out by more than a mm, perhaps several mm. I would add a few mm spacer and see if stars get better or worse. Then you will have an idea which way to go.

Please keep us posted.
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Old 07-05-2018, 08:38 AM
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Quote:
Originally Posted by LewisM View Post
You must have gotten the Esprit instruction manual with the 4th spacer information revision (my Esprit 80 spacing was wrong in the manual - had to get it from SW :lol).

This flattener is so bloody uncommon that Claude at AEC didn't even know it existed! I had to have it special ordered in after consulting Tak directly.


Yeah trial and error I reckon...
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Old 07-05-2018, 08:59 AM
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After having another look at your image, it seems that the top rig corner is close to the right distance, as the stars are most pinpoint in this section. Sometimes just tightening the focuser can fix the tilt.

Could be useful to point the scope into a busier star field and take another shot to have a more uniform distribution of stars across the entire image.
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Old 07-05-2018, 09:20 AM
LewisM
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There was some solidified grease in the camera rotator. I think that was pushing the tilt as my prelim day tests don’t show much if any tilt now. The focuser body was also loose by an eight of a turn so tightened that up. Also reinstalled my custom thicker cross section adaptor so will be stiffer.

All fun...frustrating but fun . I don’t need the flattener with the 8300 since it is smaller than APS-C but I purchased it for use with the APS-C M26C I got (that’s still being a problem child).

BTW I am recording my RMS in arc sec now Suavi I’ll post a pic one day. It’s exceedingly better in MaxIM - the only time it moves off baseline is during a dither It’s not pushing much weight though
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Old 07-05-2018, 09:22 AM
LewisM
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Originally Posted by Camelopardalis View Post


Yeah trial and error I reckon...
I think Iíll just use the 8300 - no flattener needed.

The new model FSQ85 apparently is now fully corrected to APS-C with no additional flattener - that is if I am translating Tak right. All confusing.
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Old 07-05-2018, 09:34 AM
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Yep just confirmed it was the rotator. The tilt exactly follows the rotator orientation in several of my composition shots. So here’s hoping cleaning and regreasing helps. Moves very smoothly now. The hard black crud was very thick and was even stubborn to alcohol and acetone.
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Old 07-05-2018, 12:26 PM
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Glad to hear you rectified the issue Lewis. I'm confident your baby Q will be a joy to use and will provide best data in this aperture class.

Happy to hear your guiding is smooth as

I may one day investigate MaxIm - thanks for the hint.
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Old 08-05-2018, 08:56 AM
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Quote:
Originally Posted by LewisM View Post
I think Iíll just use the 8300 - no flattener needed.

The new model FSQ85 apparently is now fully corrected to APS-C with no additional flattener - that is if I am translating Tak right. All confusing.


Yeah the larger chip might be tantalising but itís mostly extra width (?) and only advantageous for so-shaped objects
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Old 09-05-2018, 12:52 PM
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Originally Posted by Slawomir View Post

Happy to hear your guiding is smooth as
Hey Suavi, not posting the figures - I'll let your mathematical mind try to guesstimate...then I'll post the figures (MaxIM 6 graph)
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Old 09-05-2018, 03:02 PM
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Hey Suavi, not posting the figures - I'll let your mathematical mind try to guesstimate...then I'll post the figures (MaxIM 6 graph)
Awesome! Both axes are in arcseconds so the guiding looks really great, unless the scale is set incorrectly, which I'm sure is not the case
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Old 09-05-2018, 03:03 PM
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You always have a rejection clause
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