What is a high end 110-115 refractor?

[gregbradley]

I am starting to get the itch to use another high end 4inch plus refractor.

I have had a couple of FSQ106 (106N and 106EDX 111) and they are lovely instruments for imaging. For visual not so much.

I had a TEC 110 F5.6 fluorite triplet which was fabulous. The focuser though was a bit on the weak side but could be made to handle a FLI Proline 16803 which is about as heavy as CCD cameras get.

107-115mm would be good, a triplet, a good focuser that can hold a decent load and illuminate a 16803 sensor corner to corner with a decent flattener.

Availability of a reducer would be nice too.

Am I dreaming thing a 4 inch scope could be good as a visual instrument?

I had a Tak FS102 scope as one of my early high end refractors. It was way too dim to be interesting as a visual scope. 140-150mm seems good for that but now its heavy and expensive.

At some point an AP130mm GTO with the quad compressor would be ideal as it would probably match or beat an FSQ130 which I would love to have but at $20K its not happening.

There are some Chinese scopes that are high quality these days. Stellarvue is a contender. Sharp star, Rover, CFF (expensive) are contenders.

What would you suggest?

Perhaps all roads lead to another FSQ106ED! Except I want also a scope for visual.

APM have a 140mm APO doublet for US$2990 which is amazing value.

Greg.

[Atmos]

I’d throw a TSA-120 into the mix and a contender.

[gregbradley]

Yes. Reading about TSA102 sounded great and I well remember Paul's fabulous series of TSA102 images. A 120 could only be better.


Odd size though 120mm. I wonder why they didn't go 130? I suppose they have the TOA130 for that.

Greg.

[Slawomir]

Hi Greg,

APM should have some nice telescopes with LZOS lenses.

I have been thinking of pulling a trigger on CFF 135mm with 3.5FTF (limited run of 4 only) which is nicely priced, relatively speaking, and has a 55mm imaging circle. But it is bigger than 4" you are after.

[glend]

Hmm, Doublets, they just can't compete as imaging platforms, although the new TS125 with a FPL-53 & a Lanthanum glass element (not just coated, it is actually the glass) , look pretty good.. The Stellavues, Sharp Star, are the pretty much the same as the TS Triplet Apos and currently TS is more cost effective as a direct import. Stick with your size limit, once you start throwing in 130mm triplet scopes they get heavy.

Consider your motivations, if your looking for a scope in that size range you have many choices that can do the job but is it important for you to be able to brag about LZOS, or Tak, etc . I'm a cheapskate, I want the best possible specs for imaging for the least amount of money, and that eliminates all the high end "name premium" scopes.

[gregbradley]

Hi Glen,

I was just looking at Sharpstar and TS and yes they are the same. But Sharpstar prices are much the same as TS once you pay shipping and GST.


I agree about keeping the size under control. I have other larger scopes so this would be more about portability ease of mounting and use.

107 6.5 looks good as an allrounder.

Greg.

[Retrograde]

Throw the Skywatcher Espirit 120 into the mix?

[casstony]

The Esprits are very nice but heavy for their size.

[Profiler]

Skywatcher have a new 150 APO Doublet refractor which is due for release any day now. It is currently advertised on various Oz astro stores as being approximately AUD$2,800. It is F8 and has a FPL51 lens.

[el_draco]

Whats a "high end" refractor... :question:
Any thing that makes you whistle loudly whilst thinking "holy momma" :eyepop:
... applies to other things as well :rolleyes:

[LewisM]

A couple come to mind:

AP's reintroduced Traveller

TEC 110, but I think you had one and didn't like it?

TSA 102 or 120 (simply perfect)

Not sure I'd recommend Sharpstar...seen more than too many horror stories, and NOT worth the extra for SV or TS to check them for good ones

Any of the old TMB or Made for TMB (W.O) series

Anything with a LOMO or LZOS objective up front (APM, older SV)

[roughy]

There is an FSQ106 EDXIII on the second page of the IceinSpace classifieds at the moment for 4.5K including accessories. Originally posted 6/2/18. Seller states pick up only in the Sydney area.

[Slawomir]

I believe there is only one 4" refractor that can well handle KAF-16803...FSQ 106.

[glend]

The Agema 120mm looks to have the best specs of comparable Doublets of this size range, and a pretty amazing Strehl ratio comparison at all wavelengths.

http://www.agemaoptics.com/telescopes/

[Slawomir]

Agema 120 is surely a fine visual and photographic instrument, but f/8.7 and 42mm imaging circle might not be the best match for Greg’s KAF 16803.

[LewisM]

I believe it is sold actually

[roughy]

Not surprised at that price.

[gregbradley]

Thanks for the replies so far.

The Agema scopes sound nice, like the Tak FS scopes but probably better correction.

The TEC110 I had I loved but sold it to fund an AP scope which I love more!
Yuri does not make those TEC110's anymore and tried to do them at F6.5 or so instead of F5.6. No way.
The focuser is light weight really and suits a lighter to medium imaging train.
In hindsight I think it would have been good to remove the focuser completely and replace it with a Feathertouch or even a fixed adapter tube and attach an Atlas electronic focuser. The original focuser could be reattached if you wanted to use it visually.

The FSQ106EDX is definitely an interesting and well proven scope. The scope doesn't have to be able to handle a 16803 camera as I could also use the Microline 16 which is the KAF16200 APSh sized sensor.

Greg.

[Peter Ward]

Soo...can I interest you in an AP130 with FFC and FFR? ....just kidding :)

[troypiggo]

Seen the AP 130 Starfire in classifieds?

[FlashDrive]

I have ....droool :help:

[SkyWatch]

There must be a lot of drool around this morning (and even on my pillow last night...)! ;)

- unfortunately that's all it will ever be: the Finance Dept is not even remotely interested; in fact incredulous laughter was the only sound from that direction...

Regarding Greg's query: I am not sure what you are looking for Greg: visual or photographic? You don't need a big scope for photographic though.
You say the FS 102 was way too dim for a visual scope, and the FSQ106 not satisfying visually. I have the TSA 102 and love it (although the 120 would be nice...)- so I would think you should be looking for at least 130-150mm. The new Skywatcher 150ED should be a very nice visual scope, but I am guessing not so hot as an imager.

If you want guaranteed high end for visual and have a heavy wallet, I would be looking at the AP130 in the classies, a TEK 140, a Stellarvue 130T or 150T (although that is a BIG jump in price from the 130), or a Tak TOA 130 or 150. All the big boys will need appropriate big and heavy mounts of course!

Stellarvue have a "refurbished" carbon fibre 130T for sale at the moment for a nice price: http://www.stellarvue.com/stellarvue-cpo-svr130t-130-mm-f-7-apo-triplet-refractor-telescope/

Happy hunting!

- Dean

[gregbradley]

Teaser!




A beautiful scope that would last a lifetime.





Thanks for the suggestions. Idon't "need" another scope but sometimes it would be nice to do some visual and maybe even some full frame DSLR type imaging on a nice little 4 inch widefield APO astrograph that could also do double duty as a nice widefield visual. A C11 is lovely but galaxies even at 11 inch aperture are still mostly a white patch and not particularly entertaining. A lovely widefield starry vista though can be mesmerising.

Greg.

[FlashDrive]

Sounds like you need a nice 4"inch ( 110mm ) WO ZenithStar with TMB Optics ...;)

LZOS were Zeiss subcontractors, and are renown for the TMB lens line. Nothing wrong with them.

[SkyWatch]

I suspect none of us "need" another scope... ;)

[SkyWatch]

Speaking of Williams, what about: https://williamoptics.com/products/all-new-2018-gt153
:thumbsup:

[casstony]

You're describing an NP101is pretty well there - more of an all rounder and less of an imaging specialist than the FSQ. Also much lighter in weight.

[gregbradley]

Do they still make those? I don't see them for sale on their site.



True.



Looks like a nice scope. Too large for my intended use though.

Greg.

[Slawomir]

I agree with Tony, TV101is looks like a nice choice.

I would also look at APM 107mm http://apm-telescopes-englisch.shopgate.com/item/33333037 and CFF 105mm or 92mm.

[gregbradley]

The APM 105 sounds good but appears overpriced. APO 102-107mm air spaced triplets are plentiful on the market these days and Stellarvue has them >.95 strehl for a lot less.

APO triplets used to be a rare thing now they seem plentiful. I imagine quality could possibly vary so getting one of these from a reputable telescope maker that provides an interferometric test report would ease that concern.

The other weak spot would be focusers. Stellarvue probably has a good focuser and they also offer a 3 inch Feathertouch upgrade which probably would be a smart move. In my experience you need at least a 3 inch focuser to use a full frame or larger sensor.

Has anyone any experience with carbon fibre APO scopes? I know Roland Christen of AP is against them due to internal air currents but I see a few makers using them - Stellarvue and Officina Stellare.

I think I would stick to an aluminium tube unless there are some nice advantages to carbon fibre. The main advantage appears to be its lighter and looks good.

The more you look into this area of telescopes the more the FSQ106 seems the standout for imaging at least. Most seem to have a smallish corrected circle.

Greg

[glend]

Greg i believe carbon tubes for refractors is just a design fad and not justified. It also makes heating an objective, to prevent condensation, more difficult.
I agree there are many excellent choices in your size range and going for the best published specs, rather than buying for a name, makes sense. Most APOs in that size range have pretty good imaging circles with flattened or reducer/corrector. I consider corrector mandatory as they increase speed. If your worries about lost of some focal length with a corrector, just buy the next size up imho.

[gregbradley]

Thanks Glen.

I agree it seems more of a marketing thing. Stellarvue to be honest though are quite clear on their site that aluminium tubes have several advantages over carbon fibre.

Having a good flattener or reducer is another important consideration although these days you can get a nice Riccardi reducer for about $550.

Looking at the Stellarvue site this seems pretty hard to beat in an aluminium tube (nice pearl type paint job as well):

http://www.stellarvue.com/stellarvue-svr102t-102-mm-f-7-apo-triplet-carbon-fiber-refractor-telescope/

Guaranteed better than .95 strehl. Boy scopes have come a long way over the years. That was only Takahashi, AP, TEC and some APMs before.

Greg.

[Geoff45]

I believe that the 101is can handle a 16803 as long as a field flattener is used. I bought all the requisite gear from Bintel a while back, but haven't had a chance to set it up. I did use the 101is with my qsi 540 for a while before getting my PlaneWave. It gave pretty good images.
https://www.astrobin.com/full/54280/0/
I also used a William Optics ZS110 for a long while, but even with the 15mm x 15mm QSI chip, there was still noticiable field curvature.
Geoff

[Slawomir]

From what Ive read some manufacturers provide Strehl for 95% of the lens omitting the outer part as it usually has more significant irregularities. Including the outer 5% (by diameter) would lower the quoted Strehl.

[Wavytone]

The triplet APO's 100-130 mm seems to be a sweet spot for sure, and at a stretch to 140, maybe 150mm great... but... beyond that they're impossible in terms of size, weight, the mounting required and sheer cost.

OTOH no such thing as a 9" refractor that is reasonably portable in a small car. But a 9" mak does (or dob or SCT), and this one is 0.965 strehl, for a fraction of the price of an equivalent refractor.

[gregbradley]

What about the Teleskop Services Photoline 115 F6.96. They also have a range of flatteners and reducers. Not sure if the backfocus of the flattener is enough though at about 55mm.

https://www.teleskop-express.de/shop/product_info.php/info/p3041_TS-Optics-PHOTOLINE-115-mm-f-6-96-Triplet-APO-with-2-5--RP-focuser-1-11.html

Astrotech from Astronomics sells the same scope with their brand on it. It seems a lot of scope for the money.

Greg.

[glend]

I have that scope Greg, and it is great, even at the old price, and a steal at the current price. I run the Photoline 3" 0,79x reducer corrector, which also works on my TS80. With the reducer it's an f5.53. Backspacing with that 3" Photoline Reducer Corrector varies slightly depending on the focal length of the scope yourbputying it on, but yes on the115mm it is 55mm (+-2mm). My Nikon D5300 suits that Photoline Reducer perfectly on the 115mm but I have to add a little spacing to the 80MM. I mainly use my ASI1600MM-C on that 115mm and it does need some spacing, about 32mm behind the reducer. I also run the 2.5" flattened at f6,96 on that scope but I prefer it at f5.53 for the speed.
No vignetting, easily handles the APS-C sensor of the D5300. You need a M68 to M63 adaptor to put the 3" Photoline on the 2.5" focuser but it all fits just fine (and that adaptor does not affect spacing). That 2.5" R&P focuser is strong, it holds my heavy cooled Canon 450D with no problems, it also rotates.
Best buy right now I think. I might have to look at what else they have reduced.

[clive milne]

Greg,
If it were me, I would default to an FSQ (is there anything better for imaging?) and spring for a dedicated visual instrument to go with it.

What about a pair of TS photoline 125mm FPL53/Lanthanum OTA's turned in to a pair of binoculars, using something like these:
http://binotechno.com/product_en.html
I'd mount these on an Alt Az mount for simplicity.


The photolines run at around $2k AUS per OTA.

Or, if you wanted to DIY, These might be interesting:
https://www.teleskop-express.de/shop/product_info.php/info/p9191_APM-ED-Doublet-Lens-152-1200-optics-FPL51-La-D--in-cell.html

A pair of 6" ED bino's would be one hell of an instrument.

~2c

[gregbradley]

Thanks Glen. That is good to hear. It does seem like a standout bargain.


Greg.



A huge APO bino would be amazing. All imaging roads seem to lead to an FSQ but I have had 2 already. My last wide scope was the TEC110 F5.6 which I would rate as slightly better than an FSQ106ED as fluorite tops FPL53 in my opinion. But its focuser was a bit on the weak side whereas FSQ focuser is usually good (but not always, lots of posts complaining about it). Have they finally handled it with FSQ106EDiv? Who knows.
They said it was handled with FSQ 2, and 3 as well.


FSQ106ED is a fabulous instrument in many ways but I think its weakness is its colour transmission. Its seemed to lose the vibrancy of the FSQ106N but improved the optical performance in other ways.


Greg.

[LewisM]

Re the 106ED (and the 85ED), I found that the colour DOES need more bosting than the N fluorites, but in PI it's a simple job.

Optically, the blue halation endemic in the N is practically gone, and I also feel the red/orange vibrancy is better. Sharpness of the ED's seems quite a lot better, as is the ability to use the reducer etc, making it an f/3 beast (you cannot use the reducer on the N).

Only thing I really dislike of the ED over the N is the weight/heft and the OTA size - they should have kept it at 114, but I am sure they had some specific reason (baffling, throttling/vignette or somesuch)

[gregbradley]

There is a slight green bias in the FSQ106ED. It comes from the paint Tak uses on the inside of the tube. I thought it was the mustard coloured objective coatings but its not.

When I first took an image with the TEC110 fluorite the increase in colour was immediate and easy to see.

FSQ106ED probably is sharper than the 106N and no vignetting like the 106N can do on bright stars near the edges of the image.

I'd love to see more FSQ130 images but I guess at a $20,000 landed cost you won't see too many.

Greg.

[LewisM]

I only know of ONE user of a 130 here. No posts with pictures from him at all.

I might have a look on astrobin.

[gregbradley]

I am not sure how much of a jump 106 to 130mm aperture is.
106 will be wider but the 130 has a reducer available which I suppose takes it back to closer to the 106 FOV.

The cost of the 130 is of course very high and puts it up against much larger instruments for the same price. But then you are starting to lose the widefield strength of the FSQ design.

So perhaps 106 is the ideal aperture and 130 is getting too long focal length and competes with 140-155mm instruments or larger compound scopes.

Hard to say without seeing a lot of example images. I have seen a couple but surprisingly they were done with modded DSLRs. It seems strange to spend that much on the scope and then use a modded DSLR but whatever people are used to using I suppose but despite that they were impressive images.

Greg.

[clive milne]

fwiw) There's a TOA 130 on Astromart for $4k US.

[Slawomir]

130 mm should have smaller spot size comparing to a 106mm scope. IMHO a high quality 130mm with a high quality reducer would be a more capable instrument, especially when working with KAF16200 or similarly sized sensor. One of the best reducers would have to be 0.72x Quad Telecompressor from AP that fits a 3.5" FTF. I know that CFF is testing prototypes of 0.75x reducers dedicated for their refractors. Then there are 'mass produced' Riccardi reducers, but their quality apparently varies from model to model.

[RickS]

Drs Jim & Linda Powell at DSW who kindly take my requests for targets and share data with me have a TEC-160FL with a SXTL-16200 camera and the combination produces some stunning results. Just sayin' Greg. Maybe 110-115 is not thinking big enough :lol:

[gregbradley]

A TOA 130 would be a nice instrument.



Yes I agree but its narrower field of view. I did not know that about the Riccardi reducers.



Hehe. I had a TEC180FL for many years and yes they are a nice scope for sure.

Greg.

[Slawomir]

Greg - a relatively fast good quality f6.3-6.5 130mm refractor combined with a nice 0.72x or 0.75x reducer will give a similar FOV to a f5-f6 4” refractor.

[gregbradley]

Right. Not many 130mm scopes are F6-6.5 though. Most seem to start at F7,
AP has an F6.

Greg.

[glend]

Teleskop Express has one, if you feel the need for speed, the Imaging Start 130, in fact is f5 (FPL-53 triplet with a 3 element corrector built in) but setup for imaging only if that's ok:

https://www.teleskop-express.de/shop/product_info.php/info/p8373_TS-Optics-Imaging-Star-130-mm-f-5---6-element-Flatfield-APO-Telescope.html

Very tempting.

[Atmos]

The Sky Rover I have is optically the same but has different decals.