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best 90mm refractor under $2,000?

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#1 tlogan6680

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Posted 12 November 2012 - 09:15 PM

I have a Televue 60mm with very good optics and a 105 mm Stellarvue which is great but big (I also have a 10in dob). I am looking for a grab-and-go larger than 60mm and want refractor contrast for visual use only. any suggestions- something with a short f number, under 7.
Thanks
Tom in clear CA

#2 tomharri

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Posted 12 November 2012 - 09:22 PM

Don't go under f/7 with an inexpensive refractor.
That is why you see all those made in Chinas for sale used.
Use 'em once and yours will be for sale too.

#3 idealistic

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Posted 12 November 2012 - 09:55 PM

I dont consider 2K inexpensive for a small refractor. How 'bout the TMB 92ss?

#4 jtaylor996

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Posted 12 November 2012 - 10:29 PM

If you want to see nebulae, then the 92SS or 92L (light is its own benefit on that thing!). The short focal length hurts it on a lot of grab and go targets (read: planetary), and I ended up selling it.

I ended up getting a 102/800 LOMO triplet, and wouldn't go back. It's a little hairy getting it all out in one trip, however. Maybe it's the 3" FT focuser on that thing!

Anyways, I think one of the best GnG scopes of all time is are the 80/600 and 80/480 LOMO triplet scopes. These are TMB designed, and sold under brands like Teton, Stellarvue, APM, etc. For grab and go that's easier than your SV105, I don't think you'll beat one of those.

For me and my light polluted skies, I'd go with the longer focal length version at 80/600.

#5 Lane

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Posted 13 November 2012 - 01:00 AM

If you want to see nebulae, then the 92SS or 92L (light is its own benefit on that thing!). The short focal length hurts it on a lot of grab and go targets (read: planetary), and I ended up selling it.



WHAT :question:

I have the 92L and it does a great job on planets. It is not going to show quite as much detail as a 4" obviously, but the short focal length does not cause any problems for me when viewing planets. I have been using a 2x Televue Powermate with a 7mm UO Ortho for high power planet and moon viewing and have been very pleased with the detail I am seeing. It is so good in fact that I went ahead and bought a 3.5 Pentax XW last week to give me a wider view and make it bit easier to track planets with my push-to Stellarvue M2 mount.

Under very good skies I have used a 3x Televue Barlow on a 9mm Ortho with good results as well.

The only issue I see with an F5.5 Refractor is field curvature. It is difficult for me to find 16mm to 40mm eyepieces that can deal with the curvature. I have been using a 16 Nagler and a 31 Nagler which do very well, but if I did not own them already that would have been a pricey add-on. The Delos 17.3 might be even better than the 16 Nagler but I don't own that one so I can't be sure. Shorter focal length eyepieces don't seen to have problems in this scope, even my cheap TMB Planetaries work well and produce a flat enough view that I cannot see any curvature. And my eyes don't deal with curvature well at all.

#6 M44

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Posted 13 November 2012 - 01:01 AM

Takahashi Sky 90

With Takahashi Extender-Q, it can be used at high mags.

No affiliation to the Seller.

#7 hottr6

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Posted 13 November 2012 - 08:21 AM

For visual, a worthy contender is the 90mm f/11 achro class. With the money you save, you can find and buy everything in my sig, AND 3 Naglers!

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#8 snommisbor

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Posted 13 November 2012 - 10:11 AM

Why not look at a TV 101 or NP101. A world class scope and it is not very heavy or big. You can get them for a great value used. I just sold mine for 1,800. But the only reason I got rid of mine is because I have a TEC 140 coming any day now. You would have the extra 10mm of aperture and a awesome imaging scope should you ever want to dive into that part later.

#9 jtaylor996

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Posted 13 November 2012 - 12:33 PM

If you want to see nebulae, then the 92SS or 92L (light is its own benefit on that thing!). The short focal length hurts it on a lot of grab and go targets (read: planetary), and I ended up selling it.



WHAT :question:

I have the 92L and it does a great job on planets. It is not going to show quite as much detail as a 4" obviously, but the short focal length does not cause any problems for me when viewing planets. I have been using a 2x Televue Powermate with a 7mm UO Ortho for high power planet and moon viewing and have been very pleased with the detail I am seeing. It is so good in fact that I went ahead and bought a 3.5 Pentax XW last week to give me a wider view and make it bit easier to track planets with my push-to Stellarvue M2 mount.

Under very good skies I have used a 3x Televue Barlow on a 9mm Ortho with good results as well.

The only issue I see with an F5.5 Refractor is field curvature. It is difficult for me to find 16mm to 40mm eyepieces that can deal with the curvature. I have been using a 16 Nagler and a 31 Nagler which do very well, but if I did not own them already that would have been a pricey add-on. The Delos 17.3 might be even better than the 16 Nagler but I don't own that one so I can't be sure. Shorter focal length eyepieces don't seen to have problems in this scope, even my cheap TMB Planetaries work well and produce a flat enough view that I cannot see any curvature. And my eyes don't deal with curvature well at all.


Yup, just calling it like I saw it, even in side by side comparisons. The LOMO 102/800 blew its socks off. I was using TMB supermonos, radians, etc... results were pretty consistent. The contrast is better in the LOMO, and the color correction is a hair better (especially out of focus, in focus is almost undetectable).

#10 jtaylor996

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Posted 13 November 2012 - 01:11 PM

I think I did some comparisons on the 92SS and GT-LOMO on this thread, FYI:
http://www.cloudynig...3987110/page...

#11 jtaylor996

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Posted 13 November 2012 - 01:20 PM

Sorry, wrong link. Jupiter obs are here, before I got a new tube:
http://www.cloudynig...3747237/page...

#12 Lane

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Posted 13 November 2012 - 05:05 PM

I am not saying a 102 isn't better than a 92, my 106 APO blows away the 92 as well on planets. And a 127 blows away my 106 and so on. What I am saying is that there is nothing wrong with using the 92 for viewing planets. You seem to be saying that the short focal length made it bad for some reason and that is simply not true. The OP is looking for grab and go and a 92L is better for that than the 102. I can use a much smaller tripod and mount and still get steady views. I can also carry it around as a spotting scope in the daytime. It is much more versatile than a 4".

#13 t.r.

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Posted 13 November 2012 - 06:31 PM

I'll second the 92L recommendation. I had it set-up on a CG-4 for the ultimate one handed, one trip out the door, scope/mount combination. No 4 incher is gonna do this. Very capable planetary performer with better color correction than the Tak Sky 90 I had. Yep, a 102 will show more, as will a 115, as will a...BUT none will go out the door so easily but show almost what a 4 incher does. I'm not satisfied with the detail an 80mm shows...90 gets it!

#14 jtaylor996

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Posted 13 November 2012 - 07:41 PM

Part of the comparisons I made is due to the fact that I had the (extremely heavy) SS version, which weighs almost the same as my 102.

I found myself not using the scope without barlows or powermates. I looked att observing, and my site, and I just found that I didn't need such a wide FOV for just about any reason. Getting a better FL match to my targets means less glass is involved, hence, higher contrast, this better planetary performance.

Like I said, if you put the scopes side by side like I did, you would have seen the differences I observed. It was not much of a contest, to be honest. Looking at performance for the weight, it was an easy choice to make.

As far as it being better just because of the aperture difference, 10mm is like nothing. This LOMO replaced both the 92SS, and my C11. Clearly, the C11 wins on aperture, but the LOMO had more visible detail on planetary targets due to its much better contrast (although lower resolution).

If I had $2k to spend, like the OP, I'd be looking hard at the LOMO triplets in 80 and 95mm apertures. The 92L would be my second choice.

#15 Lane

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Posted 13 November 2012 - 08:56 PM

I'll second the 92L recommendation. I had it set-up on a CG-4 for the ultimate one handed, one trip out the door, scope/mount combination. No 4 incher is gonna do this. Very capable planetary performer with better color correction than the Tak Sky 90 I had. Yep, a 102 will show more, as will a 115, as will a...BUT none will go out the door so easily but show almost what a 4 incher does. I'm not satisfied with the detail an 80mm shows...90 gets it!


I narrowed my selections down to the TMB 92SS, TMB 92L, and the Tak Sky 90. I read some things about the Sky 90 I did not like and tossed it off my list and then I decided against the 92SS because of size and weight. The 92L hit the spot just right. It is still a bit heavier than I like but it will work on a "sturdy" photo tripod with a Stellarvue M2 and that makes it great for daytime and nightime use.

I agree that 80mm is not a good idea. The jump from the OP's 60mm up to an 80mm is probably going to be disappointing. Better to go at least to a 90 or a 92. I was never happy with my 80mm which is now over in the corner collecting dust. In fact., I use to use my TV Pronto 70mm more often than the 80mm just because of the size. The smaller scope was a lot easier to toss in the car and its DSO performance was practically equal to the 80mm on most objects. Planetary views in both a 70mm and 80mm are rather puny to say the least.

#16 RA-DEC

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Posted 13 November 2012 - 09:00 PM

Judd you make some valid points but the OP asked for the best 90mm under 2K and further added under f/7. A LOMO 102 as well as his current SV 105 do not qualify for any of those constraints. Without concessions in the criteria the TMB 92 is the only option (to my knowledge) available new and a Tak Sky 90II or LOMO 95 (maybe) used...let's leave out the AP Stowaway's cause, well, good luck even finding one for sale. Anyway, I'll give the 92L the nod. Mine rides on a Bogen 3060 tripod with 3047 head and all my eps, filters, etc. in the case. Because of the overall portability/aperture/optical quality I'd say I use it by a factor of 10:1 over any scope I have ever owned.

#17 Lane

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Posted 13 November 2012 - 09:08 PM

Hey I use the Bogen 3060 too. An oldie but a goodie.


Stellarvue has a couple of 90's in $1650 range. Both APO's I believe. But I think that they are not under F/7 they are exactly F/7. At least they would have no field curvature to mess with.

#18 jtaylor996

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Posted 13 November 2012 - 10:39 PM

There was a lomo 102/800 for $1800 just a few days ago. They also have the F6 version at 102/650, and I think the 95 was F6 ish, all definitely within the price range used, possibly even new.

My point was partially that it was the short FL itself of the 92 that didn't work out for me, which is something I thought the OP should consider for himself. Also, lomo triplets rock and are in that $ range. And don't forget, we're talking about "best" here.

Sometimes a discussion is allowed to go beyond rubber stamp or yes/no answers. I was in exactly the same boat as the OP a short time ago, with nearly the exact same scope he is considering. I don't think adding my personal experiences here is detracting or confusing anything. I'm just suggesting questions that I wish I had known to ask before spending that kind of money.

#19 maknewtnut

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Posted 14 November 2012 - 12:48 AM

If you want to see nebulae, then the 92SS or 92L (light is its own benefit on that thing!). The short focal length hurts it on a lot of grab and go targets (read: planetary), and I ended up selling it.

I ended up getting a 102/800 LOMO triplet, and wouldn't go back. It's a little hairy getting it all out in one trip, however. Maybe it's the 3" FT focuser on that thing!

Anyways, I think one of the best GnG scopes of all time is are the 80/600 and 80/480 LOMO triplet scopes. These are TMB designed, and sold under brands like Teton, Stellarvue, APM, etc. For grab and go that's easier than your SV105, I don't think you'll beat one of those.

For me and my light polluted skies, I'd go with the longer focal length version at 80/600.


Sure as heck not nitpicking, but rather just an FYI for all reading...

The LOMO's are not TMB designed. That's based on a compilation of information compiled since the late 1990's.

When Tom and Markus began they enlisted LZOS to produce Tom's first designs. I was lucky enough to own one, an exceedingly rare LZOS made 80/600 housed in an equally rare WO "Yang" style tube. It was tremendous.

They (or at least Markus) contacted LOMO as well, who provided 80mm objectives based on LOMO designs. After evaluation, they concurred that the LOMO 80's met or exceeded their expectations, and even slightly edged the LZOS 80's based on Tom's design.

After success in marketing high quality, Russian made refractor lenses to Western astronomers, the pair opted to farm out the lenses to SV. That went well for a short time. Apparently, Vic Marris of Stellarvue learned he could purchase LOMO lenses directly, rather than being supplied by TMB (essentially APM). That move put an end to a supply of larger aperture TMB designed/LZOS made lenses.

I most definitely concur that anyone interested in the very best 80mm apo triplet ever made (so far), the 80/600 is it. That's despite the 80/480 being the higher volume seller.

As for the relatively rare LOMO 95/650..at f/6.7, curvature of field is relatively well controlled. Light grasp vs size and weight is excellent. I've compared performance and attributes with the Takahashi Sky 90, A-P f/7 Stowaway and Traveller, LOMO 102/650, LZOS 105/650, and Zeiss 100/640. Some phrase about cold, dead hands comes to mind, although YMMV.

FWIW, some of the 90mm f/7's coming from China (under various brandings) were pretty darn good too.

#20 RA-DEC

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Posted 14 November 2012 - 12:49 AM

Like I said Judd, you made some valid points. If he considers his SV105 "great but big" then a LOMO in 102 or the 95 would pretty much be redundant. That 95/650 was well over 10 lbs just like the 92 with the FT. The LOMO 80/480 (in keeping with the sub f/7)..yeah I agree that's a good option and one I considered before buying the 92. However, after having the 92 beside a LOMO TMB 80/480 at a star party last spring I'm very happy with my choice. Not that I wouldn't take the LOMO too...

#21 Shawn H

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Posted 14 November 2012 - 04:56 AM

I am not saying a 102 isn't better than a 92, my 106 APO blows away the 92 as well on planets. And a 127 blows away my 106 and so on. What I am saying is that there is nothing wrong with using the 92 for viewing planets. You seem to be saying that the short focal length made it bad for some reason and that is simply not true. The OP is looking for grab and go and a 92L is better for that than the 102. I can use a much smaller tripod and mount and still get steady views. I can also carry it around as a spotting scope in the daytime. It is much more versatile than a 4".


I have been reading this thread with interest, I work in Africa and travel back & forth all the time to Florida, Boston & France. My Dobs are only getting used now when I have a clear night on vacation (read not too much)! I desperately need a travel scope and have decided on buying the TMB92 this Christmas basically for its short foot print (won't take up much room in my carry on bag), versatility for planets, nebulae, wideviews and daytime use for African wildlife. When Judd said the short FL didn't work well on planets I was a bit stressed! But the following statements make me feel I'm still making the right decision. :p

#22 moynihan

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Posted 14 November 2012 - 10:49 AM

I have been thinking about the AT90EDT. Is it the weight that keeps it from being mentioned, or...

#23 jtaylor996

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Posted 14 November 2012 - 11:34 AM

If you want to see nebulae, then the 92SS or 92L (light is its own benefit on that thing!). The short focal length hurts it on a lot of grab and go targets (read: planetary), and I ended up selling it.

I ended up getting a 102/800 LOMO triplet, and wouldn't go back. It's a little hairy getting it all out in one trip, however. Maybe it's the 3" FT focuser on that thing!

Anyways, I think one of the best GnG scopes of all time is are the 80/600 and 80/480 LOMO triplet scopes. These are TMB designed, and sold under brands like Teton, Stellarvue, APM, etc. For grab and go that's easier than your SV105, I don't think you'll beat one of those.

For me and my light polluted skies, I'd go with the longer focal length version at 80/600.


Sure as heck not nitpicking, but rather just an FYI for all reading...

The LOMO's are not TMB designed. That's based on a compilation of information compiled since the late 1990's.

When Tom and Markus began they enlisted LZOS to produce Tom's first designs. I was lucky enough to own one, an exceedingly rare LZOS made 80/600 housed in an equally rare WO "Yang" style tube. It was tremendous.

They (or at least Markus) contacted LOMO as well, who provided 80mm objectives based on LOMO designs. After evaluation, they concurred that the LOMO 80's met or exceeded their expectations, and even slightly edged the LZOS 80's based on Tom's design.

After success in marketing high quality, Russian made refractor lenses to Western astronomers, the pair opted to farm out the lenses to SV. That went well for a short time. Apparently, Vic Marris of Stellarvue learned he could purchase LOMO lenses directly, rather than being supplied by TMB (essentially APM). That move put an end to a supply of larger aperture TMB designed/LZOS made lenses.

I most definitely concur that anyone interested in the very best 80mm apo triplet ever made (so far), the 80/600 is it. That's despite the 80/480 being the higher volume seller.

As for the relatively rare LOMO 95/650..at f/6.7, curvature of field is relatively well controlled. Light grasp vs size and weight is excellent. I've compared performance and attributes with the Takahashi Sky 90, A-P f/7 Stowaway and Traveller, LOMO 102/650, LZOS 105/650, and Zeiss 100/640. Some phrase about cold, dead hands comes to mind, although YMMV.

FWIW, some of the 90mm f/7's coming from China (under various brandings) were pretty darn good too.


Thanks for clearing that up, Mark. Seems there's some conflicting information around on this. I was seeing some older info last night that was leading me to think it was the TMB design. Apparently at that time, TMB/Markus thought it was! This post seems to sum it up pretty well.

#24 Traveler

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Posted 14 November 2012 - 11:52 AM

"I've compared performance and attributes with the Takahashi Sky 90, A-P f/7 Stowaway and Traveller"

Comparing a Takahashi Sky 90 and an AP Traveler the difference between these two are substantial on planets.

#25 RA-DEC

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Posted 14 November 2012 - 02:05 PM

I have been thinking about the AT90EDT. Is it the weight that keeps it from being mentioned, or...


I think mainly the weight. At almost 13 lbs. it's heavier than all the aforementioned scopes. It seems to be a good performer otherwise.






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