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Meade ACF f/8 OTA?

catadioptric Meade
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#1 Jim Seargeant

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Posted 23 June 2015 - 03:20 PM

Has anyone out there used one of the Meade ACF f/8 OTAs?

 

I have a 14" ACF OTA that I'm pretty happy with but see that Meade has a sale on that includes the 16" ACF f/8 OTA.

 

I'm especially interested in how well the "internal zero image shift Crayford-style focusing system" works on the f/8 design.  Is the image really held steady during focus and as the scope is waved around the sky?

 

Jim Seargeant



#2 BWAZ

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Posted 23 June 2015 - 04:07 PM

It's exactly as advertised on my 10" f/8, save for being a bit stiff with the coarse adjustment. 



#3 Spacetravelerx

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Posted 24 June 2015 - 12:23 PM

Jim,

 

I have used the Meade 14" f/8 OTA heavily for two years now and I am here to tell you it is a wonderful instrument.  The focuser system is excellent and works 100% as advertised. Unlike other SCT's you will not need to "replace" the focuser at purchase.  Now a nice add on is a remote focuser and/or auto-focuser,  but you can definitely get by with the focuser that comes with the OTA.  

 

And yes, the image is steady as the telescope is "waved around the sky".  



#4 Rob Dog

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Posted 25 June 2015 - 05:09 AM

I recently purchased a 10" Meade ACF f/8 OTA.  

 

The coarse focuser is stiff and I do get some image shift while coarse focusing although it is minimal. No image shift with the fine focuser.

 

I have also placed a moonlite high res stepper motor focuser on it.

 

Cheers

 

Rob



#5 RAKing

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Posted 25 June 2015 - 11:17 AM

I loved my old Meade 10 inch ARC and have often thought about replacing it. But at f/8, it seems like these new Meade scopes have a huge CO.

 

Is anyone using these for visual observation? How is the contrast?

 

Cheers,

 

Ron

 

EDIT - Welcome, Jim and Rob to Cloudy Nights! :woohoo:

 



#6 Spacetravelerx

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Posted 25 June 2015 - 11:36 AM

I loved my old Meade 10 inch ARC and have often thought about replacing it. But at f/8, it seems like these new Meade scopes have a huge CO.

 

Is anyone using these for visual observation? How is the contrast?

 

Cheers,

 

Ron

 

EDIT - Welcome, Jim and Rob to Cloudy Nights! :woohoo:

 

 

Ahhh, the ever famous "huge CO".

 

I do use my f/8 ACF for visual and the views are absolutely wonderful.   Folks are welcome to take a look and see for themselves.

 

Meade has a great optical system in the f/8 ACF.  I think it is very smart of them to sell it as an OTA.



#7 KevH

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Posted 25 June 2015 - 12:01 PM

I often wonder why they don't offer the f10 ACFs as OTAs too.  


Edited by KevH, 25 June 2015 - 12:01 PM.


#8 Spacetravelerx

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Posted 25 June 2015 - 12:17 PM

I often wonder why they don't offer the f10 ACFs as OTAs too.  

 

 

I agree that is a big mystery to me too.  I am quite certain they would sell a few of those.



#9 Rob Dog

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Posted 25 June 2015 - 07:01 PM

I loved my old Meade 10 inch ARC and have often thought about replacing it. But at f/8, it seems like these new Meade scopes have a huge CO.

 

Is anyone using these for visual observation? How is the contrast?

 

Cheers,

 

Ron

 

EDIT - Welcome, Jim and Rob to Cloudy Nights! :woohoo:

 



#10 Dunkstar

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Posted 26 June 2015 - 04:28 AM

Jim,

 

I have used the Meade 14" f/8 OTA heavily for two years now and I am here to tell you it is a wonderful instrument.  The focuser system is excellent and works 100% as advertised. Unlike other SCT's you will not need to "replace" the focuser at purchase.  Now a nice add on is a remote focuser and/or auto-focuser,  but you can definitely get by with the focuser that comes with the OTA.  

 

And yes, the image is steady as the telescope is "waved around the sky".  

 

Not sure what "other" SCTs you're referring to but my C11 has a nice large rubber focuser that makes it easy to get precise focus and then a quick twist of the mirror lock screw and the mirror also stays where it is told. I didn't feel the need to replace the focuser at purchase either  :shocked:



#11 Spacetravelerx

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Posted 26 June 2015 - 04:44 AM

 

Jim,

 

I have used the Meade 14" f/8 OTA heavily for two years now and I am here to tell you it is a wonderful instrument.  The focuser system is excellent and works 100% as advertised. Unlike other SCT's you will not need to "replace" the focuser at purchase.  Now a nice add on is a remote focuser and/or auto-focuser,  but you can definitely get by with the focuser that comes with the OTA.  

 

And yes, the image is steady as the telescope is "waved around the sky".  

 

Not sure what "other" SCTs you're referring to but my C11 has a nice large rubber focuser that makes it easy to get precise focus and then a quick twist of the mirror lock screw and the mirror also stays where it is told. I didn't feel the need to replace the focuser at purchase either  :shocked:

 

 

@Dunkstar,

 

Several folks have written on CN about needing to purchase an aftermarket focuser to replace their Celestron SCT stock focuser due to image shift focusing issues, not as much precise focusing.  You may have not replaced your focuser, but it has been a common theme discussed on the CN board. 

 

Celestron claims an image shift in focusing for the Edge telescopes up to 30 arc seconds.  The tolerances are larger for non-Edge OTAs.

 

So your claim is the image does not shift when focusing on the Celestron SCT?

 

Yes, Mirror flop (this is different than image shift) is removed by locking two screws on the Celestron.  The Meade 14" f/8 ACF requires only one locking screw.  The 10" and 12" f/8 ACFs do not require locking screws.



#12 Dunkstar

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Posted 26 June 2015 - 06:21 AM

Besides sounding desperate to bash Celestron, what's your point exactly?

 

I just shared my personal experience that with my "other" SCT I could easily find focus and keep it that way, contrary to some other folks and/or their common themes. I guess I got lucky.

 

Maybe if f/8 discussion was a more common theme here we'd have more data points to work with. Two reports of working scopes in the wild is not statistically significant.



#13 RAKing

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Posted 26 June 2015 - 08:05 AM

 

I often wonder why they don't offer the f10 ACFs as OTAs too.  

 

 

I agree that is a big mystery to me too.  I am quite certain they would sell a few of those.

 

 

Meade used to sell the f/10 ARC (then ACF) as separate OTAs - that is how I bought mine. But they now limit their OTA sales to the f/8 models.

 

Thanks for the visual impressions, I'll look into one of the f/8 models.

 

Ron



#14 Hilmi

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Posted 28 June 2015 - 12:35 AM

One thing to note when purchasing a Meade f8 OTA. Check if your mount can handle the weight. The Meade OTAs are very heavy. I did a lot of research when I was planing to buy a replacement OTA and this is the only significant negative point I found.



#15 Jim Seargeant

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Posted 28 June 2015 - 01:21 PM

Thanks to Andrew and others for the comments!

 

Andrew - have you found a focus motor setup that works on the ACF f/8?  There is most always a way to hook something up but it's nice to have a debugged solution.  

 

Jim Sgt



#16 Spacetravelerx

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Posted 28 June 2015 - 01:34 PM

Thanks to Andrew and others for the comments!

 

Andrew - have you found a focus motor setup that works on the ACF f/8?  There is most always a way to hook something up but it's nice to have a debugged solution.  

 

Jim Sgt

 

Jim,

 

I am using the Zero Image Shift Electronic Microfocuser from Meade which came with my LX850. It works quite well and accommodates all my instruments.

 

I am investigating a range of remote focusers, but I am not pleased with ASCOM/PC only units. (I am 100% Mac based).  I am very tempted to start developing a wifi/USB based remote focuser once I have wrapped up my next three flights.  Stay tuned as they say!



#17 Jim Seargeant

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Posted 02 July 2015 - 08:19 PM

Rob, in re-reading the posts in this thread I finally saw that you've added a Moonlight focus motor to your Meade f/8.  Can you post some pictures of your installation?

 

I assume the motor drives the fine focus, not the course.

 

Jim Sgt



#18 baggywrinkle

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Posted 06 January 2019 - 03:18 AM

I have just bought the LX850 with the 12" OTA and the immediate thing I noticed was how stiff the course focus control is. I have had experience with the SW 127 MAK, the Celestron 9.25 SCT and the CPC8

 

There is no mirror flop on either the MAK or 9.25 but I did upgrade the 9.25 focuser for a Featherlight one and as its name implies it is very smooth and easy to rotate in course mode.

 

I bought a CPC8 secondhand for outreach work and the mount is fine for this. However that did suffer from bad mirror shift. So rather than add £300 for the Featherlight for this I bought a Baader Steeltrack which screws directly onto the back of the OTA. Lovely piece of kit at < half the Featherlight cost. Course focus on the normal focus knob then fine focus on the Steeltrack and no mirror flop.



#19 carolinaskies

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Posted 07 January 2019 - 05:34 PM

The F/10 OTAs have been available for years.  Not sure where the idea that only the F/8s were offered.   Of course this is now 2019 and this is an old thread, but I never saw the OTA alone in F/10 not being available. 




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