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Old 22-12-2018, 10:13 PM
SuperG
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Skywatcher ED80 and Televue 0.8X FF/FR

I've had a Televue 0.8x reducer for a little while now and I am seriously not happy with the results. The vignetting observed with the FF/FR is seriously bad. Is there anyway I can resolve this ? I'll submit an example later.
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Old 23-12-2018, 11:50 AM
casstony
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Which camera? I imagine the reducer should be fine up to APS-C.

Something else to check is the length of the drawtube - make sure it's the shorter one for the ED80 rather than the long one for the ED100. From memory it's about 8cm travel for the ED80. Sometimes focusers get swapped around on used scopes.
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Old 23-12-2018, 07:15 PM
SuperG
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This is an unmodified Skywatcher ED80 that I've had from new with the standard (albeit poor performing) single speed focuser. I am using a Canon 60D.

The TV FF/FR is quite heavy so I wonder if the single speed focuser that came with my ED80 is sagging a bit to cause the vignetting. Alternatively, I don't know anything about spacing. Do I need a spacer between the FF/FR and the Canon.

Check out the image and that is with some compensation in Photoshop to remove some vignetting.
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Old 23-12-2018, 10:16 PM
casstony
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The focuser might be struggling to stay straight and the vignetting seems excessive, but looking around the 'net it seems the TRF-2008 is not particularly well matched to the f/7.5 ED80. It does seem to work very well with some small scopes.
http://www.pbase.com/snowlep/reducer

https://astro.ecuadors.net/refractor...equinox-80-ed/
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Old 24-12-2018, 06:46 AM
SuperG
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Thankyou Casstony. The TRF-2008 does indeed look to be a terrible match with the SW ED80. It is unfortunate that this was recommended as the 'bees knees' in reducers by a local supplier.

I may just have to sell it on and try for a different reducer since I so love the ED80.
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  #6  
Old 24-12-2018, 11:00 AM
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Have you tried flat calibration?
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