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RedCat as a starter AP scope

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9 replies to this topic

#1 damarks913

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Posted 23 February 2021 - 11:41 AM

For someone presently using a Nikon D600 with camera lenses, what challenges would a RedCat pose? I have heard that focusing and temp differentials are sometimes frustrating.

 

Would an Apo doublet (72 or under) be more forgiving for a newbie?



#2 jonnybravo0311

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Posted 23 February 2021 - 11:44 AM

The cat will be very similar to your existing camera lenses. Same helical focuser style. I think the cat would be considerably more forgiving than the 72 doublet.



#3 bobzeq25

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Posted 23 February 2021 - 11:46 AM

Either the 51 or the 72 would be an excellent choice.  It's easier to mount the 51, it's easier to setup a 72 for autofocus.  There is someone selling a 3d printed adaptor for a ZWO focus motor and the Redcat.

 

People here will have their favorites, I'd call this a personal choice.



#4 durak

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Posted 23 February 2021 - 12:00 PM

Sharpstar 61 would be a good choice too. Or the Radian Raptor if you wanna be fancy. 

 

I much prefer traditional r&p focusers over helical/camera lens style. Like Bob said, it is much easier to automate focus if you decide to (you probably will) in the future.



#5 qswat72

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Posted 23 February 2021 - 12:07 PM

Sharpstar 61 would be a good choice too. Or the Radian Raptor if you wanna be fancy.

I much prefer traditional r&p focusers over helical/camera lens style. Like Bob said, it is much easier to automate focus if you decide to (you probably will) in the future.

I believe the SS has CA issues. Might only be for particular units, but I know there have been people finding issues with them.

#6 scadvice

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Posted 23 February 2021 - 12:16 PM

Having used one, I believe the RedCat is a better choice. It's basically plug and play no flattener needed.. When you buy one a Bahtinov focusing mask is also included. I never had problems focusing it and got great images. I used Backyard EOS  (there is also a BackyardNikon) very simple to use with a cheap laptop and a trouble free system.

 

I highly recommend using the BackyardNikon starting out and a laptop. I  never regretted it, even though I've now moved on to a more sophisticated program. Here is a very long video about BackyardEOS and Nikon well worth watching as you will know how to use it right away.

 

https://www.youtube....h?v=z3gkw8bx7Aw

 

Also here is a short one on using a Bahtinov mask :

 

https://www.youtube....h?v=k0FIluj9ndQ


Edited by scadvice, 23 February 2021 - 12:28 PM.


#7 Wei

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Posted 23 February 2021 - 12:55 PM

It all depends on the mount. If your mount is no good even a 200mm won't work well. If you mount work well you have not constrains on the scope you use. If you don't have a good mount or guiding system, that would be the first thing to look at.

 

Advantage of Redcat or petzval scope are the "build in" flattener. Thats all.

 

Temp differential is an issue if you take photos for long hours with huge temp fluctuations. At 200mm I don't think you have to worry too much about it. If you worry about temp changes affecting focus, just get some auto focus system to account for that and refocus.

 

200mm wide field is very forgiving. At 200mm you can probably do unguided easily, may be even hand held..just kidding.



#8 acommonsoul

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Posted 23 February 2021 - 01:17 PM

I currently use the Redcat51 with a t3i and my D610. Its a fantastic scope. The one issue I would have with pairing the full frame sensor to it, is that it will be greatly undersampled. You won't notice on full images, but you will when zooming in and cropping tightly. Overall, I love it though and will save to pair an 183c camera to it for better pixel sampling.



#9 scadvice

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Posted 23 February 2021 - 01:24 PM

He has a good mount. At 200mm and F/4.9 the imaging is as Wei said, very forgiving. I mostly used my RedCat on the iOptron SkyGuider Pro with good polar alignment was able to do up to 90 second images. without ever seeing trailing.

 

Undersampling can be a problem but I never really felt it was something other than for top end imagers to be concerned about.

 

This image was with the RedCat and a modified T3i Canon.

 

https://www.astrobin...r0mgon/?nc=user



#10 acommonsoul

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Posted 23 February 2021 - 01:35 PM

I was concerned with undersampling only when I was trying to image something I really shouldn't have been lol, like the moon or say M42 (and cropping in tight). Then I see the blocky stars and such. Some of this can be avoided by drizzling some dithered data in post processing.


Edited by acommonsoul, 23 February 2021 - 02:47 PM.



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