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Backfocus & spacing

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Not a question but a post to help alleviate pain & suffering 

So I've been helping some members in Facebook astro groups with their backspace issues. All flatteners/reducers require backfocus - typically 55mm.  This isn't a religion but a guide. Last night was 1st light dialling in my Altair 130EDT-F.

I added 0.5mm to the image train & the difference was profound. 

See the comparison images using abberation inspector


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Interesting comparison Andy. I'm sure it will help others out to experiment with backspacing rather than just rely on default. All my WO telescopes have adjustable spacing on the flatteners and it is easy to do without dismantling anything. I have experimented in just such a way and have the spacing tuned.

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