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New REDCAT 61

Observing Eyepieces Equipment Reflector Visual
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#1 Mikano

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Posted 01 December 2023 - 11:09 AM

The New REDCAT 61 from William Optics is a solid build scope and takes clear sharp Pictures.

I'd like to used this scope for visual Viewing and Astro as well.  I can't seem to find the right Diagonal erect prism eyepiece to go with this scope. I place my old REDCAT 51 erect prism eyepiece holder and it works the focus is clear. but its doesn't fit.  I also brought the William optic 2" Dura-Bright dielectric diagonal and can't get a focus. 

 

Any help would be appreciated

 

Thank you.  


Edited by Mikano, 01 December 2023 - 12:27 PM.


#2 UnityLover

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Posted 01 December 2023 - 02:24 PM

The New REDCAT 61 from William Optics is a solid build scope and takes clear sharp Pictures.

I'd like to used this scope for visual Viewing and Astro as well.  I can't seem to find the right Diagonal erect prism eyepiece to go with this scope. I place my old REDCAT 51 erect prism eyepiece holder and it works the focus is clear. but its doesn't fit.  I also brought the William optic 2" Dura-Bright dielectric diagonal and can't get a focus. 

 

Any help would be appreciated

 

Thank you.  

why cant you focus? Is the point where focus is reached too far in? Or too far out? How much are you out of focus? Like you see giant circles? Or are you just out of it?


Edited by UnityLover, 01 December 2023 - 02:26 PM.

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#3 rblackadar

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Posted 01 December 2023 - 02:27 PM

Welcome to the forum!

 

I'm a bit surprised that no Redcat owners (which I'm not) have stepped up to answer this yet. I'd have to guess, but in general terms it's not hard to see what's going on. Your 2" diagonal has 3 issues, compared your old diagonal, that all contribute at least to some extent to lack of focus:  (1) it's bigger overall, so the optical path in the right-angle section is longer, (2) the EP holder is also probably longer, to accommodate 2" nosepieces that are typically longer than on 1.25" EPs, and (3) it's mostly air inside, as opposed to the prism which is mostly glass. (Converging rays come to focus over a shorter distance in air than they do in glass, so in other words, you have less room to play with, with a mirror diagonal.) And by the way, if you're using a 1.25" adapter with the 2" diagonal, the thickness of the adapter has to be considered as well. In short, your optical path is just too long. If you can see an easy way to shorten it, give it a try!

 

Otherwise, if you can live with a 1.25" diagonal, it should be possible to find an adapter with the proper thread size to make your old one fit.


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#4 rgk901

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Posted 01 December 2023 - 03:16 PM

looked it up and little word about back focus or visual use with this astrograph...

Give the manufacturer an email to see what they say, maybe a redcat 61 diagonal is in the works!?
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#5 Mikano

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Posted 01 December 2023 - 09:54 PM

why cant you focus? Is the point where focus is reached too far in? Or too far out? How much are you out of focus? Like you see giant circles? Or are you just out of Way out of it

It's way out of focus, I'm thinking the spacing between the diagonal to scope is to long.  


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#6 Mikano

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Posted 01 December 2023 - 09:59 PM

Welcome to the forum!

 

I'm a bit surprised that no Redcat owners (which I'm not) have stepped up to answer this yet. I'd have to guess, but in general terms it's not hard to see what's going on. Your 2" diagonal has 3 issues, compared your old diagonal, that all contribute at least to some extent to lack of focus:  (1) it's bigger overall, so the optical path in the right-angle section is longer, (2) the EP holder is also probably longer, to accommodate 2" nosepieces that are typically longer than on 1.25" EPs, and (3) it's mostly air inside, as opposed to the prism which is mostly glass. (Converging rays come to focus over a shorter distance in air than they do in glass, so in other words, you have less room to play with, with a mirror diagonal.) And by the way, if you're using a 1.25" adapter with the 2" diagonal, the thickness of the adapter has to be considered as well. In short, your optical path is just too long. If you can see an easy way to shorten it, give it a try!

 

Otherwise, if you can live with a 1.25" diagonal, it should be possible to find an adapter with the proper thread size to make your old one fit.

I'm going to do this again, The Redcat 51 diagonal thread doesn't  fit it has a smaller thread then the New Redcat 61. And has no extension tub on diagonal.  I need  to work on getting the right thread.


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#7 Mikano

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Posted 01 December 2023 - 10:02 PM

It's way out of focus, I'm thinking the spacing between the diagonal to scope is to long.  

It's defiantly the spacing.  There's no information on what size or eye diagonal that will fit.  The Redcat 51  diagonal was simple to find. it gets frustration.


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#8 SporadicGazer

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Posted 01 December 2023 - 10:28 PM

I don't know, but I notice the latest version of the Redcat  51 explicitly will not work visually.  (The current 61 doesn't say one way or the other as far as I see.)

 

Is it possible your 51 is an older version that did work.  But your 61 is a newer version that also doesn't work visually?

 

I'd guess contacting William Optics and asking might be your best bet.

 

Good luck.


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#9 Yerman

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Posted 02 December 2023 - 10:23 AM

In order to understand your focus issues try the following. In daylight point your scope at a distant object a tree a house. Just the scope nothing else no adapters no diagonal no eyepiece. Hold a piece of white card up behind the scope. Move it until you see a focused image projected on the card. Measure from the estimated middle of the objective (middle of the thickness not the centre of the objective) This should correspond to the published focal length of your scope. It may be slightly off what the manufacturer says regardless this is what yours is. Make a note of that dimension. Now you can see how much space you have between the back of the focuser and the focal plane. Simple mathematics should show if you can fit your accessories into this space in order to achieve focus. If you want to stay with the practical approach start adding your accessories diagonal etc. each time project an image onto the card. If you run out of space before you are finished adding your accessories then you can never achieve focus.
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#10 Foobaria

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Posted 03 December 2023 - 09:51 PM

Just got my new Redcat 61 under the stars tonight.  So far, first frames coming in are looking stellar.   Will publish results here. 

Things I like so far:  

  • Well machined, nice color 
  • Easy to handle, light weight, center of mass toward the center, doesn't lean like my old GT71
  • Easy to mount/focus, though already hit the big focus knob on the AM5  (no focus tube!!), what's the answer, put a Losmandy dovetail?
  • Well color corrected
  • Easy to PA 
  • EAF works with it

Here it is, First pic on Redcat61:

 

NGC7000 / North American Nebula. 

IMG 0265 ngc7000


Edited by Foobaria, 03 December 2023 - 11:14 PM.

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#11 Foobaria

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Posted 04 December 2023 - 05:23 PM

How to get the Redcat61's focuser to clear the AM5 mounting plate?   I fastened two vixen dovetails together (one simply on top of the other, to make a "double" height rail) with 1/4-20 x 3/4" cap head screws.  This gives extra clearance for the focuser knob to clear the AM5.   I'll post pictures shortly. 




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