53 replies to this topic

[Jeff B]

No, it's not mine.

 

It belongs to a friend and gentleman who has graciously loaned it to me for my testing and use while he travels for a month or so abroad.  He previously had lent me his latest generation AP 130GTX under similar circumstances:

 

https://www.cloudyni...-serial-no-746/

 

And, like with the 130GTX, I've already sold his 110GTX to six people............

 

Jeff

 

 

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[Jeff B]

This scope is a well thought out package.   I was struck by how compact the basic scope is and the thought put into how it fits all nice and tidy into the Pelican case.

 

I was also struck by how light weight it is, especially compared with my Stowaway, which I find to be a very stout scope.  Did I say the 110GTX is compact?

 

Fit and finish of the scope and rings are superb, just like the Stowaway.  The focuser is awesome and obviously set up for imaging ease and adaptability.  All visual/photographic back connections are robust, smooth and tight, but allow easy change outs with machined knobs that are easy to identify and use with gloves on.

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Edited by Jeff B, 15 June 2023 - 11:31 AM.

[PhotogTom]

Take your time with this baby - a few people will be very interested in the results and observations.

 

Interesting how short it is compared to the Stowaway. Just a touch, maybe an inch longer.

[Mike Sandy]

My Precious  

[Jeff B]

Part of my evaluations typically include a couple of items I always relate to quality of construction.

 

The first is the focuser alignment, which I check with my Glatter (RIP sir) laser mounted in the focuser/visual back and firing down the tube, through the objective, and, hopefully, out through the center hole of the paper mask I place over the objective.  The 110GTX "passed" this test with an "A+". The laser not only went right through the mask center hole, but stayed there throughout the entire range of focuser drawtube travel.  But the 110GTX also gets some "extra credit" as it accomplished the same feat each time I removed and reinstalled the laser and visual back.   That's excellent machining and fit.

 

The second is using my Cheshire "eyepiece" to examine how the reflection dots off of the back surfaces of the objective's elements lie up with each other and the Cheshire's inlet aperture.  Ideally they should all fall on top of each other, forming a single dot/bullseye when viewing through the Cheshire.  And that's exactly what happened.  While not an optical quality check, like in DPAC or a star test, I like as a reference of sorts and a starting point for my own refractor ATM work.  

 

Of course, no "review" or evaluation of a scope is complete without the "money shot" of the objective with the coatings and interior baffling.   The coatings are just beautiful and even stand up under the glare of a camera flash.   Just beautiful.  

 

As you can see from the machined baffling, the scope has a very large fully illuminated FOV to accommodate the big sensors, but it's certainly appreciated by us visual folks as well.  Staring down the tube from the focuser end showed the baffling to be very effective with no scatter I could see when pointing the scope out a window in daylight.  Just the objective surrounded by blackness. 

 

Jeff

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[Jeff B]

Yeah, yeah, yeah it's beautifully built so what about the optics!?   

 

Well, like Scott said about his Tak FSQ-85 he recently DPAC tested.....it's rather boring.  Nothing to see here .....

 

Very well corrected LCA (mild blue/red fringing at the tips of the L/R lines in the white light images) with some small amounts of spherochromatism in red and blue of the color montage images (mild bowing of the lines in opposite directions), and at green focus, a narrow, uniform, small "plateau"  by the edge, a mild center zone with a good polish (if you look cross eyed at the darker, really hyped up contrast at focus image you can catch out a very subtle "quilted" texture.).     

 

Rather boring which means truly excellent.

 

Jeff

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Edited by Jeff B, 15 June 2023 - 06:29 PM.

[RichA]

I'd have to know the exposure times of the Tak vs. this one, but it looks like this has more colour error than the FSQ.  Also, it appears there is a Chinesesque central "zone" in as well as something going on at the edge.  Odd.

[PhotogTom]

I can't even pretend to completely decipher the testing - it appears that the primary design goal was in the center of the spectrum - the green area, with very slight over or under correction towards the extremes of the optical range (blue, red), but nothing outlandish. All pretty close. 

 

How does it fare against other refractors of a similar speed and aperture? 

[Jeff B]

I can't even pretend to completely decipher the testing - it appears that the primary design goal was in the center of the spectrum - the green area, with very slight over or under correction towards the extremes of the optical range (blue, red), but nothing outlandish. All pretty close. 

 

How does it fare against other refractors of a similar speed and aperture? 

Well said Tom, certainly with less words and without the "....twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was...".  

 

And funny you should ask Tom.

 

Here is a side-by-side-by-side of three 110MM "APOs".  From left to right, the 110GTX F6, an older WO 110FLT F6.5 (TEC FPL-51 ED oiled triplet) and my trusty Orion 110ED F7 (FPL-51 doublet).  The 110 GTX is the "best" color corrected of the bunch, with the WO a tiny bit "worse" (or, perhaps more accurately, different) with the older Orion falling off in blue focus a bit (LCA/Secondary Spectrum).  I suspect you would be hard pressed to see any substantive visual difference between the AP and WO scopes in color error in the visual range.  Unfortunately, I was unable to view through the WO/TEC scope, but I've had plenty of eyepiece time with the Orion 110ED doublet.  It's color error for me visually is really rather benign with a very mild purple tint on the moon at higher power and some red/blue splashing around bright star airy disks, again, at higher power (over ~150x).  But the scope is very sharp despite the blue miss!  

 

Color errors in DPAC are twice reality, as are other features/distortions/artifacts seen on the wave front.  The artifacts seen above are exceedingly small, and IMO, functionally trivial and completely invisible outside of the testing environment.  In the hundreds of refractors I've passed through DPAC, including completely domestic US ones, mild center zones are the rule and not the exception.  This is an excellent lens in double pass.

 

Jeff

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Edited by Jeff B, 15 June 2023 - 06:30 PM.

[PhotogTom]

Well said Tom, certainly with less words and without the "....twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was...".  

 

And funny you should ask Tom.

 

Here is a side-by-side-by-side of three 110MM "APOs".  From left to right, the 110GTX F6, an older WO 110FLT F6.5 (TEC FPL-51 ED oiled triplet) and my trusty Orion 110ED F7 (FPL-51 doublet).  The 110 GTX is the best color corrected of the bunch, with the WO a tiny bit "worse" (or, perhaps more accurately, different) with the older Orion falling off in blue focus a bit (LCA/Secondary Spectrum).  I suspect you would be hard pressed to see any substantive visual difference between the AP and WO scopes in color error in the visual range.  Unfortunately, I was unable to view through the WO/TEC scope, but I've had plenty of eyepiece time with the Orion 110ED doublet.  It's color error for me visually is really rather benign with a very mild purple tint on the moon at higher power and some red/blue splashing around bright star airy disks, again, at higher power (over ~150x).  But the scope is very sharp despite the blue miss!  

 

Color errors in DPAC are twice reality, as are other features/distortions/artifacts seen on the wave front.  The artifacts seen above are exceedingly small, and IMO, functionally trivial and completely invisible outside of the testing environment.  In the hundreds of refractors I've passed through DPAC, including completely domestic US ones, mild center zones are the rule and not the exception.  

 

Jeff

The WO is slightly not as great, but still very good. The Orion doublet - well, even my eyes can see that it doesn't do well with the color correction. Looking at the Orion with its FPL-51 glass, I'm seeing that it is somewhat different from my AT-102 EDL with its FCD-100 and Lanthanum glass. Then again, in use, you can really see what's up, and the difference is amplified X2 in the twice-through test.

 

I'll go back to my Group-W bench now.

[RichA]

Well said Tom, certainly with less words and without the "....twenty seven eight-by-ten color glossy photographs with circles and arrows and a paragraph on the back of each one explaining what each one was...".  

 

And funny you should ask Tom.

 

Here is a side-by-side-by-side of three 110MM "APOs".  From left to right, the 110GTX F6, an older WO 110FLT F6.5 (TEC FPL-51 ED oiled triplet) and my trusty Orion 110ED F7 (FPL-51 doublet).  The 110 GTX is the best color corrected of the bunch, with the WO a tiny bit "worse" (or, perhaps more accurately, different) with the older Orion falling off in blue focus a bit (LCA/Secondary Spectrum).  I suspect you would be hard pressed to see any substantive visual difference between the AP and WO scopes in color error in the visual range.  Unfortunately, I was unable to view through the WO/TEC scope, but I've had plenty of eyepiece time with the Orion 110ED doublet.  It's color error for me visually is really rather benign with a very mild purple tint on the moon at higher power and some red/blue splashing around bright star airy disks, again, at higher power (over ~150x).  But the scope is very sharp despite the blue miss!  

 

Color errors in DPAC are twice reality, as are other features/distortions/artifacts seen on the wave front.  The artifacts seen above are exceedingly small, and IMO, functionally trivial and completely invisible outside of the testing environment.  In the hundreds of refractors I've passed through DPAC, including completely domestic US ones, mild center zones are the rule and not the exception.  

 

Jeff

110 AP beats fluorite (is it?) triplet and the FPL-51 doublet, like most of them is an achromat.  Interesting!

[Dean J.]

The gentleman who made this telescope has seen this thread and has commented about the design of the AP 110GTX and has posted the actual interferogram for this particular scope on the Astro-Physics User Group if anyone is interested:

https://ap-ug.groups...277447225254251

 

 

 

[Dean J.]

… and I continue to check my emails frequently in the event that one of the fine folks over at AP wants to let me know that the computer spit out my name in the 110GTX drawing.

[Jeff B]

110 AP beats fluorite (is it?) triplet and the FPL-51 doublet, like most of them is an achromat.  Interesting!

Rich, the old WO/TEC scope does not have a fluorite crystal element.  The ED element is FPL-51.  Years ago WO got taken to task for that.

 

The Orion is an ED doublet.   I would avoid the use of words like "beats", "bests", "superior" or whatever.  That to me implies a quantitative measure, something that DPAC is not.   It's a simple tool to have a look at the figure in one glance.  The indoor star test also showed no indication of coma or astigmatism that I could subjectively detect, all the way to 330x.  That's subjective too and more on that later but very impressive.

 

Jeff

[Jeff B]

… and I continue to check my emails frequently in the event that one of the fine folks over at AP wants to let me know that the computer spit out my name in the 110GTX drawing.

I'll check my email.  Thanks for the heads up.

 

Jeff

[PhotogTom]

… and I continue to check my emails frequently in the event that one of the fine folks over at AP wants to let me know that the computer spit out my name in the 110GTX drawing.

The computer at AP reads these threads too.

[41lat]

Nice to see Mr Christen himself give his input on this.

Wish I could get my traveller in to him for an oil change and the front end greased..

[PhotogTom]

Nice to see Mr Christen himself give his input on this.

Wish I could get my traveller in to him for an oil change and the front end greased..

You can grease the front end yourself, but the results won't be so nice. 

[Kitfox]

I read RC’s response, and it made me even more curious about this scope. He said the three element compressor/corrector (actually it may be differentiated from a focal reducer/flattener in more than name?) is analogous to the rear elements in a petzval.

 

Jeff, did you get the C/C on loan along with the scope?  Sure would be intriguing to see that stuck into the optical train in front of your Ronchi screen…  Mr. Christen makes it sound like there may be an improvement in performance with the C/C…which would be amazing on a 110 f/5. That would be impressive, and certainly makes me swing way towards the decision to buy if I am ever blessed with the opportunity.

 

I will only add that nothing that Jeff B has posted here has made me think this scope is inferior to anything else in its class, and I didn’t read any follow-on posts here that alluded to that conclusion, especially not anything the OP said. I am not exactly sure what prompted Mr. Christen’s response, and especially not his feeling pressured to break tradition and publish IF data. All I have seen is results that still support my intent to buy one of these. Period.  Maybe even more so after the nugget that the C/C is more than just an FR/FF. 

Edited by Kitfox, 15 June 2023 - 05:22 PM.

[Jeff B]

I read RC’s response, and it made me even more curious about this scope. He said the three element compressor/corrector (actually it may be differentiated from a focal reducer/flattener in more than name?) is analogous to the rear elements in a petzval.

 

Jeff, did you get the C/C on loan along with the scope?  Sure would be intriguing to see that stuck into the optical train in front of your Ronchi screen…  Mr. Christen makes it sound like there may be an improvement in performance with the C/C…which would be amazing on a 110 f/5. That would be impressive, and certainly makes me swing way towards the decision to buy if I am ever blessed with the opportunity.

 

I will only add that nothing that Jeff B has posted here has made me think this scope is inferior to anything else in its class, and I didn’t read any follow-on posts here that alluded to that conclusion, especially not anything the OP said. I am not exactly sure what prompted Mr. Christen’s response, and especially not his feeling pressured to break tradition and publish IF data. All I have seen is results that still support my intent to buy one of these. Period.  Maybe even more so after the nugget that the C/C is more than just an FR/FF. 

Thanks for the support Kitfox. Most appreciated.

 

Please read the last paragraph of Roland's posting very carefully.  He explains that the corrections associated with use of the compressor/corrector will differ from those of the base objective and are designed specifically for imaging where smallest spot size over a broader portion of the spectrum is very important compared to visual use, where best optical correction in the visual wavelengths is very important.  That's a very important distinction.  He also explains exactly this on the 110GTX section of the AP website as well.  The 110GTX is designed to be superb at both visual and imaging (with the CC), which is nothing new really, as his other scopes, like my Stowaway,  have the same dual function with the optional field flattener and TC.

 

But to answer your question, no, I do not have the CC.  And even if I did, I would not DPAC test it in that configuration as my DPAC testing is over the visual spectrum and I've a feeling the ronchi screen would require very careful setup for spacing, tilt and other stuff, judging by what I read on the imaging forums.

 

Jeff

[weis14]

Excellent post Jeff.  Thanks to all of you that do these tests and gather the data.  I was very surprised to see Roland's response.  I know of no other scope that he's made where we have his interferometer data tied to a specific scope serial number.

[900SL]

As far as I know, RC designed this for near flawless polystrehl imaging over a full frame sensor. That's what I'm waiting to see.

If only AP would stop doling these out to visual observers..

[900SL]

Roland's response reminded me of that of a Michelin starred Chef after reading a restaurant review by a park time food critic in the local rag.

Bonus points for the use of 'starred'

[edif300]

Control of opinion by timeless intervention.

[Ihtegla Sar]

 

I was also struck by how light weight it is, especially compared with my Stowaway, which I find to be a very stout scope.

I am surprised by this comment. By the numbers, the 110 weighs 71% more than the Stowaway.  I will be interested to hear what mount you use for visual with this scope.

 

As an air travel scope, being able to use it with a small, light weight mount is important. I would expect that at 12 pounds, the 110 would require a beefier mount than the 7 pound Stowaway. 

 

Now that you have your hands on one, I would be interested in hearing what is the smallest mount that can be used with the 110 for visual without excessive vibrations.