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Helen

Fill a focal length gap??

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It is ☁️ and my birthday is coming up... so musing about telescopes.  I have a 'few' scopes.  My main imaging combination is a WO 123 with a atik 460c.  That has 720 fl, and fov of 1x0.75 degree.  I've got a couple of smaller refractors for wider views, and then a C11 (fl 2800) currently with a ZWO1600 mono giving fov 0.36 x 0.27 degree.  I find it a bit daunting imaging at such a long focal length though, and so usually it only gets used for planetary and lunar.  (I also find collimation a challenge).

 

So.... any recommendations for a scope to slot between the fl of the two scopes?  

Thanks

Helen

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Rather than buying yet another telescope have you thought of  first trying a focal reducer on the C11 and/or a powermate/good quality barlow with the WO123.  The Celestron .63 focal reducer would bring the focal length down to 1764 and also reduce exposure times.  You do need to get the right spacing but I think it is more forgiving than most reducers for refractors.  A x2 powermate would bring the WO123 to a focal length of 1440.  The pair would close the gap.

 

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14 minutes ago, pmlogg said:

Rather than buying yet another telescope have you thought of  first trying a focal reducer on the C11 and/or a powermate/good quality barlow with the WO123.  The Celestron .63 focal reducer would bring the focal length down to 1764 and also reduce exposure times.  You do need to get the right spacing but I think it is more forgiving than most reducers for refractors.  A x2 powermate would bring the WO123 to a focal length of 1440.  The pair would close the gap.

 

Has my husband knobbled you???

But seriously, thanks for the input!   That would certainly be easier and cheaper than the alternative.  I've currently got a field flattener on the refractor, so may need to think about how the image train would work with a barlow.  And then of course there will be longer exposure times.  But worth a go.  

If I was to do deep sky with the C11 I might be tempted to pick up a colour camera (I know that mono theoretically gives better results, but Welsh weather is not good, so getting usable images more easily works better for me 😎)

Helen

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To fill that gap I'd be thinking of another reflector, possibly a GSO RC10, or if budget allows, an ODK10. I think anything bigger / longer would be pushing up against the C11.

What camera would you be putting on it?

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Thanks Dave.  I was thinking about a refractor/cat maybe an Edge.  Like you I think bigger is closer to C11 and therefore not much advantage.  So I think as a start I'll put the 6.3 reducer on the C11 and a AP barlow/flattener on the 123 (with the atik 460) - and see where that gets me.  The camera question has just been answered - I bought the ex-demo 1600 colour that FLO posted earlier -_- (cheaper than ODK!!)  to try with the C11 (looks a good match using FLO calculator)

Rain for weeks now.....

Helen

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On 12/02/2019 at 01:13, Helen said:

 That would certainly be easier and cheaper than the alternative.  I've currently got a field flattener on the refractor, so may need to think about how the image train would work with a barlow.  And then of course there will be longer exposure times.  But worth a go.  

 

Helen

F ratio myth? Life is full of surprises: 

Olly

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Thanks Olly, I picked that link up yesterday - and now have the said Barlow on order 😉

I've also just put the 6.3 fr on the C11 along with the zwo 1600 colour.  The weather must have been odd today as my counterweights were covered in condensation and the corrector had problems too.  My dehumidifier has become a bit temperamental,  so time for a new one I think.  Will give everything a quick going over tomorrow and then hope for clear skies for galaxy hunting 😎

Helen

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