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  #21  
Old 07-12-2016, 11:23 AM
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Merlin66 (Ken)
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You can check the reducer by focusing the sun on a piece of paper and measuring the focal length - it should be close to 240mm.
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  #22  
Old 07-12-2016, 12:08 PM
sharptrack2 (Kevin)
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Is it correct that with the most common design used, that focus would be achieved at that length in only one direction? In other words, the reducers are not typically simple positive lens and behave like a typical refractor objective lens? Referencing this explanation... https://starizona.com/acb/basics/equ...1_optical.aspx
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  #23  
Old 07-12-2016, 12:14 PM
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Merlin66 (Ken)
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Kevin,
Generally you are correct.
Just measure what you have before worrying.
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  #24  
Old 07-12-2016, 08:24 PM
sharptrack2 (Kevin)
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Reducer confirmed, approximately 240mm focal length. Didn't have the sun to work with but putting my eye right up to the glass and moving the lens up and down a ruler while focusing on an Anzac biscuit worked as well, and I got a treat afterwards.

Scope check tomorrow definitely, don't have time tonight to try. I'm kicking myself for not getting the mount out right when I got home... looking like a reasonable evening to have done some more testing or observing.

One of my T adaptors is roughly 40mm long. I'll try to finagle something with that to test with an EP. My other T adaptor is about 60mm, I might be able to fit one of my Meade HD EPs in such a way as to have the first element near 40mm distance from the reducer.
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  #25  
Old 09-12-2016, 02:17 PM
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redbeard (Damien)
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Hi,

I have a Meade 10" SCT and I also have no issues with focus using the 6.3 FR.

I use a Moonlite focuser with the large flange that screws directly to the back of the scope, it has the .95 draw tube and the focal reducer screws inside this and only screws on one way so you can't get that wrong.

I have heaps of travel in both ways in relation to focus from the telescope itself. Then I fine adjust with the Moonlite.

I have also used the small flange with a 2" diagonal and the focal reducer this time was put after the diagonal and before the camera. Again, no issues with focus.

One thing mentioned is the distance from the camera to the FR. On my scope, the distance is about 110mm but the only thing the distance is for, is to how close to 6.3 it is, It does not have an affect on focus from my experience in this situation.

Cheers
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  #26  
Old 11-12-2016, 10:35 PM
sharptrack2 (Kevin)
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Operator error!

Good evening,

Amazing what can be accomplished when you start with a plan and take your time.

Obvious human error in this one. Don't know where I erred but it had to be me.

The moon was my target and the test setup was the original Celestron visual back, with a spacer/adaptor that came with my Bintel 2" diagonal. Not really sure why it was there, I think it was to connect the diagonal directly to the focus back. Anyway, its about 30mm long, and a 32mm EP was used to check where the focus point of the mirror was. Which was about 10 turns clockwise from the stop (fully counter clockwise). See photo #1.

Inserted the reducer into the path, at the focus back. Focus reached at approximately 8 t (CW from CCW stop). See photo #2

Connected Moonlight focuser directly to focus back, focus tube racked all the way forward. Mirror focus was achieved at ~8 t CW. Racked the focus tube all the way back and the mirror movement was approximately 1 t CCW. See photo #3

Installed the reducer in the focus tube, focuser racked all the way out and short flange installed. Mirror focus achieved at ~6-7 t CW.

I did look through the scope without an EP and managed to get focus with my eye at roughly 5 cm away from the EP holder (visual back), but I didn't count the number of turns. However I can say anecdotally, it was about the same number of turns as with the EP +/- 1 t.

So all appears to be working correctly so far. I ran out of time so haven't captured the number of turns with focuser and diagonal. I'm expecting it to be considerably higher, between 15-20. Hopefully I'll get that done tomorrow evening after work. Then on to the camera and making measurements to see what I need to make it work, hopefully nothing as it should work. Still going to order the proper flange to use with the reducer, might make a difference although I don't readily see how it could.

for everyone's input. I'll put this one to bed but will update when I get the flange and test with the diagonal.
Attached Thumbnails
Click for full-size image (32mm EP_ 30mm spacer.JPG)
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Click for full-size image (32mm EP_ 30mm spacer_reducer.JPG)
54.6 KB18 views
Click for full-size image (32mm EP_moonlight_reducer installed in focal tube.JPG)
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Last edited by sharptrack2; 11-12-2016 at 10:42 PM. Reason: Wording update
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  #27  
Old 12-12-2016, 03:04 AM
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Merlin66 (Ken)
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All's well that ends well.
Glad you got it sorted out.
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