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Benno

New focuser for 8" SCT

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Good afternoon, l am considering replacing the focuser on my Celestron 8" SCT.

I am not too bothered about having a powered unit, I would just like something that would have a finer adjustment than the standard unit fitted.

Any views or experiences with replacement focus units would be appreciated.

Best regards,

Steve.

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How bothered are you by mirror shift? If it's not a problem for you then the FeatherTouch microfocuser would be great. If it is, then there are a number of secondary focusers you can buy to fit on the visual back so you leave the mirror focus alone (or locked if it has that capability), and just use the rear focuser.

I use a Baader SteelTrack, mainly because it came up used with a SteelDrive at a good price. It is excellent, but there are quite a few options around for varying budgets

https://www.harrisontelescopes.co.uk/acatalog/Revelation_SCT_Crayford_Focuser_Dual_Speed.html

http://www.firstlightoptics.com/moonlite-focusers/moonlite-cs-dual-rate-sct-crayford-focuser-with-standard-2-inch-thread.html

http://www.firstlightoptics.com/starlight-instruments-feather-touch-2inch-crayford-focusers/feathertouch-2-inch-crayford-focuser-sct.html

The FeatherTouch is the pick of the bunch, but they all basically do the same thing.

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Hi Steve,

In my Edge 14" SCT I've replaced the main mirror focuser with a MIcroTouch and a Feather Touch focuser in the visual back. As BigSumorian says the MT focuser will not eliminate mirror shifting, it will just make focusing a lot accurate but backlash will still be there. My main reason for replacing the stock main focuser was because my obsy is remotely operated. From the other hand installing  an FT focuser, Baader or MoonLite in the visual back in my opinion is a must especially if you doing long Deep Sky sessions. By focusing the primary mirror in a suitable focus star "near" your working target area, locking it after that and then micro-adjust only the visual back focuser at your main target there will be no backlash anymore all night long and refocusing will be a snap ! 

IMHO if you're only doing visual with your SCT you don't need any of this.

Clear skies.

Edited by seo
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I have just put a moonlight on my sct and it is lovely but agree for visual only don't bother. My stock focused was fine for visual and gave great focus ability with little mirror shift. I now do planetary imaging which is why I added a moonlight

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I guess I must be fussy, and too used to lovely FT focusers on my fracs then. I'm purely visual but did not enjoy the focusing on my EdgeHD 8". With the SteelTrack on the back it is far more accurate and enjoyable. Everyone is different though.

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Hi, thank you for your swift reply's

I agree that for visual use, the standard focuser is fine, but as a few of yor reply's have mentioned, it is for my imaging that I would like a little more control. My main issues are mirror flop and the lack of fine adjustment.

Having looked at the recommendations I think the unit that replaces the visual back would suit my needs best.

Would I be right in assuming that this type of focus unit would also fit onto the back of a focal reducer ( I sometimes image with the Celestron f/ 6.3 focal reducer in place of the standard visual back).

Best regards,

Steve.

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Hi Steve,

I don't know about your 8" SCT and Moonlight but in my Edge 14" the Celestron reducer has the same thread dimensions as the visual back as also the same focus distance. So the  FT coupled with its adapter for my scope fits both with and without the reducer.  

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