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Review: William Optics Star 71

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#26 Orion58

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Posted 15 July 2014 - 07:53 AM

How is the focuser on it, I have the WO 81 GTF and there is a little sag from my ccd camera.


I've only got about two nights worth of imaging on mine but have not noticed any problems - the focuser seems rock solid. I was imaging the Crescent Nebula so I was oriented within 45 degrees of the zenith, not close to the horizon.

I have a filter wheel and Atik 460ex mounted on it. The 460ex is longish, moving the center of gravity farther back but the focuser shows no sign of sag. Here is a link to the image if you are interested: http://www.meadowlar...bservatory.com/

#27 rjweng

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Posted 16 July 2014 - 08:21 AM

Well I sold my WO81GTF and will be ordering a WOS71, they are 2 weeks out and then another week for deliver so in a month I hope to have mine.

#28 timmbottoni

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Posted 16 July 2014 - 12:57 PM

I'm hoping to get out again this weekend. The days are so long right now that I can't really stay up late enough on work nights to really do any imaging. The initial pictures I took with it using a Canon 60D looked quite good, and I tried some both with and without my Astronomik CLS clip filter.

I want to find a really good wide field object. M31 would be perfect but its not a good time of year for it. Any other suggestions? I need to be near Zenith.

Timm

#29 nodalpoint

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Posted 16 July 2014 - 01:18 PM

North American nebula is in good position for what you want.

#30 timmbottoni

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Posted 16 July 2014 - 08:16 PM

North American nebula is in good position for what you want.


Thanks for the tip. I will see if I can capture it.
Timm

#31 rjweng

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Posted 18 July 2014 - 01:37 PM

Well I ordered mine from William Optics, hope to have it by first week of August, can't wait.

#32 gatsbyiv

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Posted 19 July 2014 - 08:16 AM

Hi - see this post where I commented on how to adjust the focuser to get rid of any sag due to the rotation mechanism - http://www.cloudynig...6621825/page...

Timm


The same treatment to the focuser's rotator may need to be applied to some Star 71s. I got sharp images the first time I took one of mine out. The second night, the top 30% of the field was out of focus. I had loosened the rotator to turn the camera 90 degrees, then re-tightened it.

There is about a millimeter of play in the ring that facilitates rotation when the screw is loosened. This can allow the camera to "sag" or hang at a very slight angle. This put the top of the sensor about a millimeter further back than the bottom. At f/4.9, the zone of critical focus is narrow.

You have to be careful that when you re-tighten, you don't lock in that small amount of sag. I found that when adjusting rotation, I can simply push inward on the camera while re-tightening the rotator screw to prevent sag, but your solution sounds more permanent.

#33 Astrofotografen

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Posted 07 August 2014 - 06:13 AM

Any dude here tried this scope with full frame dslr?

 

I have: http://www.cloudynig...71-first-light/



#34 lakeorion

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Posted 19 August 2014 - 05:35 AM

Looks VERY interesting, but how do you attach anything to it? 48mm thread? The included Cannon adapter is not much use to me, I have a Nikon body, and I'm not about to spend more money on another diagonal when I have a perfectly functional Baader prism (that uses a t-thread). More connection options please! Or am I missing something simple?

#35 zsb04

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Posted 19 August 2014 - 09:56 PM

i have one coming in any day now, i got it from their ebay store, it was listed as a star party demo, i figure since they ised it for a demo it must be a very good example :)  



#36 zsb04

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Posted 19 August 2014 - 10:30 PM

question for you guys, i have the special diagonal for the scope, it has a 1.25" eyepiece cap/cover, but nothing to cover up the m48 end. Does anyone make an m48 attachment cap/cover? i don't think it is good idea to leave the diagonal in the case or elsewhere uncovered like that?



#37 lakeorion

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Posted 22 August 2014 - 07:15 AM

Question for those who have one of these in hand.  Does a 2" eyepiece nose fit in the focuser?  Or does the focuser just terminate in that 48mm thread?

 

I'm investigating being able to attach a Borg filter holder http://www.sciencece...s/html/7519.htm in front of a Nikon DSLR body.  This device has an M57 front thread and Borg does not carry an M48 -> M57 adapter.  They do have a 2" eyepiece nose -> M57 adapter...



#38 Gary BEAL

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Posted 23 August 2014 - 02:48 AM

The draw-tube end finishes in a male M48 thread. If you want you can screw on most 2" to 1.25" adaptors, as they usually have a 48mm thread on the front (for filters). Then you can slip a 1.25" eyepiece in. I use mine like this with the webcam, tried a couple of solar shots yesterday.

I doubt you'd be able to use a 2" though sorry. Plus, it's an imaging scope.

Loving the FOV though. Imaging with mine as we speak.

Gary



#39 lakeorion

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Posted 23 August 2014 - 06:16 PM

Thanks.  But it looks like this probably isn't the scope for me then.  I'm looking for a small imaging refractor, but with other features:

 

I need to work with a Nikon.  It's nice they include a Cannon adapter but that's a toss out item for me.

 

I need to be able to install 2" filters, not clip-in, and not as a structural member.

 

Again, thanks all for the info.



#40 timmbottoni

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Posted 24 August 2014 - 08:14 PM

Thanks.  But it looks like this probably isn't the scope for me then.  I'm looking for a small imaging refractor, but with other features:

 

I need to work with a Nikon.  It's nice they include a Cannon adapter but that's a toss out item for me.

 

I need to be able to install 2" filters, not clip-in, and not as a structural member.

 

Again, thanks all for the info.

You'll want to look at something 80mm and up to get the full 2" accessory options you are requiring.  I don't think its practical or sell-able in a 71mm because it would make it too expensive.  Maybe someone has one, not sure.  Just don't recall ever seeing one.

 

Timm



#41 kmparsons

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Posted 25 August 2014 - 04:39 PM

Excellent review. Thanks. This scope is favorably reviewed in the latest issue of Astronomy Technologies Today. They make a useful comparison between the WO scope and the SV 70mm ED "Travelhawk" from a few years back. I have one of these and have always thought that it performed admirably, with effective color correction, a flat field, and good contrast. According to the review, the WO's 5-element lens array definitely gives it an edge over the ED doublet. 



#42 timmbottoni

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Posted 25 August 2014 - 07:01 PM

In case anyone is interested, for a Nikon camera you would need this... For a Nikon you would need something like this...

https://www.astronom...ras_p19497.aspx

 

Timm



#43 timmbottoni

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Posted 25 August 2014 - 09:22 PM

Hi all - I just learned something new to pass on about this scope.
 
The inside tube piece where the last lens element is, is threaded for 48mm filters.  
 
I took a picture to show everyone what I found.
 
Timm

Attached Files


Edited by timmbottoni, 25 August 2014 - 09:23 PM.


#44 timmbottoni

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Posted 26 August 2014 - 08:26 PM

Posting an update - there are actually 2 places that are threaded that could accept a 2" filter.  

  1. The inside of the tube where the last optical element is located
  2. The inside of the cone shaped photo adapter 

Attached Files



#45 zsb04

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Posted 26 August 2014 - 10:10 PM

looks pretty intense inside hahaha i will not be messing with the insides of mine, but cant wait to go use it



#46 liors

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Posted 27 August 2014 - 06:16 AM

Hi Charlie,

Recently I bought the WO GT81 Apo to use it as a guide scope with my Lodestar guide camera.
I found this scope to be pretty heavy more than I thought, guiding through this scope is awesome compering to my previous Orion ST80.
The focuser is by far no match to the Orion one, actually how can I compare between the two.
All I can say is that WO scopes are wonderful.
I had thoughts that cross my mind to use it for wide field imaging but decided to keep this option for the future.

Lior



#47 timmbottoni

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Posted 27 August 2014 - 12:37 PM

looks pretty intense inside hahaha i will not be messing with the insides of mine, but cant wait to go use it

It's simple actually.  All you are seeing is the insides of the two pieces that screw together.  The cone shaped photo adapter piece is easily unscrewed and replaced with the special 1.25" WO dielectric diagonal for switching between photo and visual use.

 

There isn't anything to worry about, except maybe dropping something, or getting a fingerprint on the lens element.  It's amazingly solid and quite attractive looking!

 

Timm



#48 Astrofotografen

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Posted 29 August 2014 - 05:16 AM

Hi,

I actually screwed a Lumicon Deepsky filter in place of the cone shaped adapter yesterday. I was easy and no risk that the back lens could be touched.

Now it's sitting there and the good thing is that it prevent dust from getting to the lens.

Regards

Jonas


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#49 Denimsky

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Posted 04 September 2014 - 01:18 PM

I'm using a CCD camera and I'm not sure how the lens groups are configured.

Is this scope similar to Petzval design such as NP101 or FSQ meaning that the last lens element is not moving with focusing change?

In those scopes, you don't have to worry about the optimal distance between the sensor and the flattener. Is this scope like that or is there optimal distance between the last element and the camera sensor?

 

Thank you.



#50 timmbottoni

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Posted 05 September 2014 - 12:21 PM

I'm using a CCD camera and I'm not sure how the lens groups are configured.

Is this scope similar to Petzval design such as NP101 or FSQ meaning that the last lens element is not moving with focusing change?

In those scopes, you don't have to worry about the optimal distance between the sensor and the flattener. Is this scope like that or is there optimal distance between the last element and the camera sensor?

 

Thank you.

The configuration of the lenses isn't like a Petzval, but in this scope you are correct in that you don't have to worry about the optimal distance between the sensor and flattener.  There is a triplet in front, followed by 2 single lenses.  I have not seen any other refractors like this.  The lenses are all fixed, none move with the focuser. So the optimal distance is fixed at the focal point, and you don't have to worry, just get it in sharp focus and you have a flat field. 

 

My initial tests are the same as those of others, and there is no field curvature with my Canon 60D (APS size sensor), and being such a fast scope requires focus to be precise.  The 2 speed focuser is very nice, and I use the live view mode in 10X to get the best precision focuse on a bright star that I can and then lock it down as I move around.  That what seems to work best for me so far, but I'm really just starting to use it due to the cloud curse imposed on me this summer.

 

Timm


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