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Old 21-01-2015, 06:38 PM
garymck (Gary)
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garymck is offline
 
Join Date: Aug 2005
Location: Geelong
Posts: 695
Hi,
on my TSA120 I use the TOA35 Reducer at a distance of 83.7mm

With TOA35-RD reducer
Focal length 672mm
Focal ratio F/5.6
Image circle 40mm (60% non-vignetted)
Photo field 3.4░ @ 40mm image circle
Spots size 4Ám RMS @ center of field
6Ám RMS @ 10mm off-axis
13Ám RMS @ 20mm off-axis

specs here:
http://www.buytelescopes.com/t/takahashibackfocus
System chart here:
http://www.takahashi-europe.com/en/T...stemcharts.php
There appear to be a couple of versions, mine is cat no: TKA31580S
The difference is a sort of extension on the reducer.
Fields are essentially flat and stars are round to the edge of my ST8300C camera. I haven't tried any bigger chips.

Hope this helps
cheers
Gary

Last edited by garymck; 21-01-2015 at 06:50 PM.
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