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Best 90mm APO

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#1 Kon Dealer

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Posted 15 September 2019 - 01:02 PM

Just to start the ball rolling.

TS Optics 90mm triplet, f6.7.

Perfectly symmetrical star test both sides of focus. Zero colour on any object.

Quite cheap.



#2 WilburTWildcat

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Posted 15 September 2019 - 01:34 PM

I've got one and I like it so far! I've also got a WO Megrez 90FD Im comparing it to; I know you had a poor experience with that scope.

So far, I like the focuser and snap-to focus point of the TS90. The case is quite poor. The Megrez doublet has markedly increased contrast, but the TS 90 shows less color on bright objects being a triplet.

The TS90 is VERY tail heavy vs the Megrez which is nose heavy. You read that correctly...the triplet is tail heavy and the doublet is nose heavy. . It's due to the small dew shield and 2.5" focuser on the TS90 vs the Mergez's generous dew shield and shorter overall length (I have a Feathertouch on mine).
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#3 25585

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Posted 15 September 2019 - 07:25 PM

Borg 90FL? http://scopeviews.co.uk/Borg90FL.htm



#4 junomike

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Posted 15 September 2019 - 07:35 PM

For Planetetary/lunar ~ SVR90T

For RFT ~ WO88


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#5 Scott in NC

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Posted 15 September 2019 - 08:33 PM

My former SV90TBV fluorite.  Oh why oh why did I sell it??? :bawling:


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#6 desertlens

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Posted 15 September 2019 - 09:36 PM

Best? Who knows? But, I've had some rewarding experiences with this one, excellent resolution, no CA that I can see, above average focuser and robustly built.

 

AT92m2c.jpg

Astro-Tech AT92


Edited by desertlens, 15 September 2019 - 09:40 PM.

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#7 gnowellsct

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Posted 01 November 2019 - 06:59 PM

CFF f/6.9 92 mm, here wearing solar attire

 

I'm not sure how wee would establish "best" but I can tell you a three inch FT, 175 mm back focus on a CFF triplet really rocks.

 

cff fast tpod set up - cn size - edit.jpg


Edited by gnowellsct, 01 November 2019 - 07:42 PM.

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#8 ken30809

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Posted 01 November 2019 - 08:56 PM

Best? Who knows? But, I've had some rewarding experiences with this one, excellent resolution, no CA that I can see, above average focuser and robustly built.

 

attachicon.gif AT92m2c.jpg

Astro-Tech AT92

It looks pretty "Best" to me. Awesome IMO. I'm considering one to fill the gap in my lineup


Edited by ken30809, 01 November 2019 - 08:57 PM.

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#9 CHASLX200

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Posted 02 November 2019 - 07:43 AM

I've got one and I like it so far! I've also got a WO Megrez 90FD Im comparing it to; I know you had a poor experience with that scope.

So far, I like the focuser and snap-to focus point of the TS90. The case is quite poor. The Megrez doublet has markedly increased contrast, but the TS 90 shows less color on bright objects being a triplet.

The TS90 is VERY tail heavy vs the Megrez which is nose heavy. You read that correctly...the triplet is tail heavy and the doublet is nose heavy. . It's due to the small dew shield and 2.5" focuser on the TS90 vs the Mergez's generous dew shield and shorter overall length (I have a Feathertouch on mine).

My 90 FD was very good.



#10 Paul Hooper

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Posted 02 November 2019 - 11:03 AM

CFF f/6.9 92 mm, here wearing solar attire

I'm not sure how wee would establish "best" but I can tell you a three inch FT, 175 mm back focus on a CFF triplet really rocks.

cff fast tpod set up - cn size - edit.jpg


Great setup! What is that mount/tripod?

#11 areyoukiddingme

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Posted 02 November 2019 - 12:33 PM

92 A-P stowaway is not terrible.



#12 25585

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Posted 02 November 2019 - 01:17 PM

Baader Travel Companion 95mm CaF2  https://www.baader-p...-companion.html



#13 gwlee

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Posted 02 November 2019 - 01:58 PM

92 A-P stowaway is not terrible.

Ignoring the objective cover that has an unfortunate tendency fall off far too easily, I have no complaints about the 92mm Stowaway. It’s expensive and hard to get, but seems to approach “sensible perfection” with respect to its optics and mechanics. Haven’t done side-by-side testing of scopes with equivalent aperture though, so there might be something else as good for less. 



#14 Brollen

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Posted 02 November 2019 - 02:13 PM

For Planetetary/lunar ~ SVR90T

For RFT ~ WO88

+1 for the SVR90T .. my SVR90T is a wonderful balance of size, weight and awesome views


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#15 areyoukiddingme

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Posted 02 November 2019 - 02:52 PM

Ignoring the objective cover that has an unfortunate tendency fall off far too easily, I have no complaints about the 92mm Stowaway. It’s expensive and hard to get, but seems to approach “sensible perfection” with respect to its optics and mechanics. Haven’t done side-by-side testing of scopes with equivalent aperture though, so there might be something else as good for less. 

Actually, A-P fixed the objective cover somewhere in the series. Mine fits very nicely and has no tendency to fall off (mine's #202).

 

I suspect that it would be very hard to tell the difference between the A-P and (say) the CFF and Baader offerings.

 

I've compared my Stowaway with 80mm F6 Orion triplet and Televue 101. The A-P is the better scope, but it does give me appreciation for how good the little 80mm is for the money, and what a bargain a used Televue is.



#16 Heywood

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Posted 02 November 2019 - 03:27 PM

Actually, A-P fixed the objective cover somewhere in the series. Mine fits very nicely and has no tendency to fall off (mine's #202).

I suspect that it would be very hard to tell the difference between the A-P and (say) the CFF and Baader offerings.

I've compared my Stowaway with 80mm F6 Orion triplet and Televue 101. The A-P is the better scope, but it does give me appreciation for how good the little 80mm is for the money, and what a bargain a used Televue is.


My Stowaway's objective cover falls off easily, and AP never offered me a solution.

#17 gwlee

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Posted 02 November 2019 - 03:28 PM

Actually, A-P fixed the objective cover somewhere in the series. Mine fits very nicely and has no tendency to fall off (mine's #202).

 

I suspect that it would be very hard to tell the difference between the A-P and (say) the CFF and Baader offerings.

 

I've compared my Stowaway with 80mm F6 Orion triplet and Televue 101. The A-P is the better scope, but it does give me appreciation for how good the little 80mm is for the money, and what a bargain a used Televue is.

Mine is #204, and the objective cover has fallen off repeatedly. For the moment, I am securing it with blue masking tape to prevent any damage to the cover or the optics. If AP doesn’t come up with a fix soon, I will try modifying the shims inside the cover. 

 

Have owned an NP101 previously and had been searching for a used NP101 for a couple of years when the Stowaway became available, and I bought it although I was mildly concerned about the effects of aperture loss. In what way do you consider the NP101 to be a better scope? 



#18 gwlee

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Posted 02 November 2019 - 03:52 PM

My Stowaway's objective cover falls off easily, and AP never offered me a solution.

I suspect that the dimensional tolerances of the cover, shims, and dew shield stack up, so that some covers work fine and others fall off, which is a not an unusual quality control problem to have when a product is only manufactured in small quantities.

 

However, if the cover comes loose in cased transport, the loose cover has the potential to rattle against the objective and damage it, so it’s not something to be ignored by AP or the owner. When I received mine the cover seemed to work fine, but after using it nightly for a few weeks, it became loose as a goose, so I am temporarily securing the cover with a bit of blue masking tape until AP acknowledges the problem and comes up with a fix. 
 


Edited by gwlee, 02 November 2019 - 04:24 PM.


#19 areyoukiddingme

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Posted 02 November 2019 - 03:53 PM

Mine is #204, and the objective cover has fallen off repeatedly. For the moment, I am securing it with blue masking tape to prevent any damage to the cover or the optics. If AP doesn’t come up with a fix soon, I will try modifying the shims inside the cover. 

 

Have owned an NP101 previously and had been searching for a used NP101 for a couple of years when the Stowaway became available, and I bought it although I was mildly concerned about the effects of aperture loss. In what way do you consider the NP101 to be a better scope?

Huh, that's surprising, as mine has a very nice fit. The only time I've had any issue is wedging it into the case (the cover can come off when pushed at an angle). I have no need to tape on the cover. It only has a strip of glued on felt or something holding it on, so it should be a pretty easy DIY fix. Though given it is brand new and premium, I agree that A-P should be offering you a solution.

 

As for the highlighted part of your post, I see the A-P as the better scope.

 

My Televue is the 101 (i.e., pre-NP model). It's longer and heavier than the newer NP version, but optically said to be very, very close.

 

They show up in the 1300-1500 range, which is a steal, especially compared with close to 4k for a new Stowaway with taxes. I have not had a good look at planets with the A-P, but on the moon they are very close in performance.



#20 scooke

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Posted 02 November 2019 - 04:39 PM

Another vote for the AT92.  Resolution of a 4", size of an 80mm.

Totally different, but the Celestron 90mm fluorite I had years ago was incredible as well.  Much longer but lighter weight than the AT92.

I've never observed with a Stowaway or CFF 92 but I know they have to be two of the best as well.



#21 ryderc1

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Posted 02 November 2019 - 04:57 PM

I suspect that the dimensional tolerances of the cover, shims, and dew shield stack up, so that some covers work fine and others fall off, which is a not an unusual quality control problem to have when a product is only manufactured in small quantities.

 

However, if the cover comes loose in cased transport, the loose cover has the potential to rattle against the objective and damage it, so it’s not something to be ignored by AP or the owner. When I received mine the cover seemed to work fine, but after using it nightly for a few weeks, it became loose as a goose, so I am temporarily securing the cover with a bit of blue masking tape until AP acknowledges the problem and comes up with a fix. 
 

I can understand why a loose fitting dewshield cap would be frustrating.  But why not buy a LensCoat Hoodie or something similar to replace it?  Besides fitting correctly it would remove any risk of the metal cap falling and becoming dinged or dented or chipping paint or removing the finish on the edge of the dewshield from repeated contact.

A Hoodie of the proper size can be had for under $15 plus a few dollars for shipping.


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#22 gwlee

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Posted 02 November 2019 - 05:08 PM

My Televue is the 101 (i.e., pre-NP model). It's longer and heavier than the newer NP version, but optically said to be very, very close.

 

They show up in the 1300-1500 range, which is a steal, especially compared with close to 4k for a new Stowaway with taxes. I have not had a good look at planets with the A-P, but on the moon they are very close in performance.

We are fortunate to have so many nice refractors to choose from these days. The better ones are so similar in performance (sensibly perfect) that it becomes a matter of selecting the one with the combination of features that’s best suited to your observing interests and observing site. 



#23 gwlee

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Posted 02 November 2019 - 06:07 PM

I can understand why a loose fitting dewshield cap would be frustrating.  But why not buy a LensCoat Hoodie or something similar to replace it?  Besides fitting correctly it would remove any risk of the metal cap falling and becoming dinged or dented or chipping paint or removing the finish on the edge of the dewshield from repeated contact.

A Hoodie of the proper size can be had for under $15 plus a few dollars for shipping.

Not so much frustrating as potentially damaging to the optics. I use my scope almost daily, and a few times I have opened the case to find the objective cover has come adrift, which looks like it could allow it to come in contact with and damage the objective in transport.

 

A bit of blue masking tape securing the cover isn’t an elegant solution, but seems to be an adequate temporary  preventative measure until AP acknowledges and fixes the problem. A hoodie are other aftermarket cover is might be permanent solution to consider that doesn’t depend on AP’s timely performance though. 

 

It could be something as simple as the shim stock that AP uses inside the cover taking a set and the cover becomes loose after few weeks of regular use, which could explain why AP isn’t seeing the problem in the shop and hasn’t fixed it yet. Whatever the cause, AP needs to take these reports seriously and fix the cover though. 

 

 

 

 

Attached Thumbnails

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Edited by gwlee, 02 November 2019 - 08:09 PM.


#24 gnowellsct

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Posted 02 November 2019 - 08:13 PM

92 A-P stowaway is not terrible.

Yeah just ring em up you'll have one by the end of the week



#25 gnowellsct

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Posted 02 November 2019 - 08:15 PM

My Stowaway's objective cover falls off easily, and AP never offered me a solution.

Just get some velcro and take cut some small strips of the fuzzy part, put them at  12-3-6-9 o'clock positions, and you can ditch the tape.

 

SCT experience counts for something here.

 

Greg N


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