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back focus on evostar 150 ed

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#1 thebonz

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Posted 14 October 2020 - 02:07 PM

I am considering an evostar 150 to match with a binoviewer.

Does anybody know the back focus of the 150 ed in standard or delux version.



#2 bob midiri

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Posted 14 October 2020 - 02:12 PM

Not sure I have dx, ill try my denks hopefully tonight and see...will get back



#3 sg6

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Posted 14 October 2020 - 02:25 PM

A scope doesn't have a back focus, it has a focuser with some degree of travel.

What you want to know is: Is there sufficent travel on the focuser of an Evostar 150 to accomodate a binoviewer.



#4 thebonz

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Posted 15 October 2020 - 12:20 AM

Thanks Bob

The APM 152 advertises that it has a back focus of 180mm. I would prefer the APM but they are very expensive to export to Australia. The Evostar is currently on  sale here but it does not state the backfocus. I have the baader maxibright with the short diagonal plus a binotron.



#5 tonyt

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Posted 15 October 2020 - 01:15 AM

The basic Evostar 150ed has very short backfocus while the DX has more, probably not quite 180mm though. I don't have a measurement but a binoviewer with corrector in front of the diagonal would be fine on the DX.

 

I bought the basic Evostar and added a WO focuser later; I'd advise going straight for the DX while it's on sale - the extras are worth it.



#6 Mitrovarr

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Posted 15 October 2020 - 02:07 AM

My Evostar 150 ED doesn't work with my binoviewer without a barlow.

It is very rare for any refractor to work with a binoviewer with no barlow unless it was specifically designed to.

#7 bob midiri

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Posted 15 October 2020 - 09:34 AM

Thanks Bob

The APM 152 advertises that it has a back focus of 180mm. I would prefer the APM but they are very expensive to export to Australia. The Evostar is currently on  sale here but it does not state the backfocus. I have the baader maxibright with the short diagonal plus a binotron.

I tried but not enough in travel to focus!!



#8 SteveG

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Posted 15 October 2020 - 06:23 PM

I tried but not enough in travel to focus!!

Did you try it with a 1.25" diagonal? 



#9 SteveG

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Posted 15 October 2020 - 06:27 PM

The basic Evostar 150ed has very short backfocus while the DX has more, probably not quite 180mm though. I don't have a measurement but a binoviewer with corrector in front of the diagonal would be fine on the DX.

 

I bought the basic Evostar and added a WO focuser later; I'd advise going straight for the DX while it's on sale - the extras are worth it.

The DX uses the Esprit focuser. It is advertised as "100mm backfocus" on the 6" version. I don't know if it's the same for the Evostar though.



#10 bob midiri

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Posted 15 October 2020 - 07:32 PM

Did you try it with a 1.25" diagonal? 

No with a 2"?




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