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C90 + focal reducer 6.3+ zoom eyep.8x24mm?

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#1 paulsky

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Posted 25 July 2021 - 07:15 AM

Hello, 

How much magnification range have this combination? 

Worth? Advantages? 

Thanks, 

Paul. 



#2 petert913

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Posted 25 July 2021 - 08:11 AM

You would effectively have a zoom eyepiece with a new range of 13mm to 39mm.  I'm not sure of the quality of the view.  I may try it myself :)


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#3 luxo II

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Posted 25 July 2021 - 08:18 AM

An 80mm f/6 … f/7 refractor would be better…


Edited by luxo II, 25 July 2021 - 08:19 AM.

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#4 Tapio

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Posted 25 July 2021 - 08:31 AM

That reducer is meant for SC scopes so quality may not be so good.
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#5 erin

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Posted 25 July 2021 - 08:38 AM

I use the reducer on my 102 mak and it gives nice lower-powered views. It doesn’t make the Mak a wide-field instrument, but it helps fit more open clusters. Then you just remove the focal reducer to get the nice longer focal length performance on planets and doubles. The advantage of this combo is that you have a versatile, lightweight, easy to mount grabngo set up.

 

It depends on what the OP is looking for. If you want grabngo and wide views, a short refractor with the zoom is the way to go.


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#6 rmollise

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Posted 25 July 2021 - 08:45 AM

The problem with this is the focal reducer. The little scope has a small baffle tube, and that will cause considerable vignetting. I tried a reducer with my ETX125, and for that reason, vignetting, found it was better just to use long focal length eyepieces if I wanted lower magnifications. 


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#7 Echolight

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Posted 25 July 2021 - 01:51 PM

I’m planning to get a focal reducer, with maybe the end game being used on a C5 on a lightweight mount.

 

But I’ll certainly try it on my f/11 C90 with an eyepiece featuring a 23-24mm-ish field stop, for close to 3 degrees TFoV....I think.

Surely it won’t be an optimized widefield. But maybe a cool little useable setup. I’m considering a Baader 32mm T2 with helical focusing 1.25 eyepiece holder for fine tuning as the scope’s helical focuser is itself a little fast.


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#8 erin

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Posted 25 July 2021 - 03:09 PM

The problem with this is the focal reducer. The little scope has a small baffle tube, and that will cause considerable vignetting. I tried a reducer with my ETX125, and for that reason, vignetting, found it was better just to use long focal length eyepieces if I wanted lower magnifications. 

Hi Uncle Rod! I’ve only used small eyepieces-BST flat fields. The lowest power is 27mm at 53 degree FoV. I haven’t noticed vignetting but wasn’t looking for it either. It’s good to know you have seen it. Were you using eyepieces like these or larger FoV ones?




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