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Tak FSQ-85: Will it work well with binoviewer?

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#1 trias702

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Posted 19 May 2020 - 01:20 PM

I am currently considering the purchase of a Tak FSQ-85EDX for purely visual use, for binoviewing only, and eventually, nightvision PVS-7. I have been seduced by all the reports from members like Gavster and Phil regarding how great the FSQ85 is for purely visual use.

 

My question though is, will it come to focus well with a binoviewer, both with and/or without the bino OCS? I currently use a Denkmeier Binotron 27, with the built in power switch. It comes with an OCS as well, which is necessary for reaching focus on every refractor I've tried it with so far. I also use a mirror diagonal with my setup.

 

As I understand it, the FSQ-85 has 200mm of backfocus, and a diagonal eats up about 100mm, so it sounds like there should be plenty left over for a binoviewer? I've also heard some conflicting reports saying the FSQ-85 can sometimes reach focus for binos without the OCS, but some people say it does not, I suppose it depends on your specific binoviewer.

 

My goal is planetary and lunar binoviewing with high mag, around 180x, maybe 200x if I can push it that far. Once I can get some good NV kit, then it will be wide field viewing.

 

Does anyone have any experience with the FSQ for binoviewing, specifically the Denk series of binos? Would greatly appreciate any feedback. Would hate to go to all the trouble of purchasing the scope, only to then find out that it can't come to focus with my bino.


Edited by trias702, 19 May 2020 - 01:21 PM.

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#2 Gavster

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Posted 19 May 2020 - 02:01 PM

I removed the oca and installed a Baader ultrashort clamp as per the link below and this gives a lot of in focus - more than my ap stowaway. I can try my fsq85 with my Baader Mark 5 binoviewers to see if they come to focus without the glass path corrector?

https://www.baader-p...iece-clamp.html


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#3 trias702

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Posted 19 May 2020 - 02:13 PM

Apologies, but I'm not familiar with the FSQ-85 systems so well, so am not sure I understand entirely. What is the "oca" on the FSQ-85? Is that the part which attaches to the focuser and into which you then insert your 2" diagonal?

 

And yes, I would be very keen for any feedback you might give about the ability of the scope to come to focus on the Baader Mk 5, with and without the OCS.



#4 Gavster

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Posted 19 May 2020 - 02:42 PM

Apologies, but I'm not familiar with the FSQ-85 systems so well, so am not sure I understand entirely. What is the "oca" on the FSQ-85? Is that the part which attaches to the focuser and into which you then insert your 2" diagonal?

 

And yes, I would be very keen for any feedback you might give about the ability of the scope to come to focus on the Baader Mk 5, with and without the OCS.

Sorry I mean caa (camera angle adjuster) which isn’t needed for visual use. Here is the system chart so that you can see where it fits (item number 6). So remove it then screw in the Baader Tak adapter and you can then put in the diagonal etc.

Attached Thumbnails

  • 950147C4-256D-4853-9CB2-427C24968DDD.png

Edited by Gavster, 19 May 2020 - 02:44 PM.


#5 trias702

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Posted 19 May 2020 - 02:54 PM

Cheers!

 

So if I understand it correctly, first you screw in the Coupling (item #10) into the focuser, then you screw the Baader part into the coupling (this Baader part takes the place of the CAA, part #6), then you screw the eyepiece holder into the Baader (part # 70S), then your 2" diagonal goes in?

 

Looking at the Baader piece, it seems like the 2" diagonal goes straight into the Baader piece, so if you use the Baader do you no longer need the Tak eyepiece holder (part# 70S) and so the diagonal just goes straight into the Baader?



#6 Gavster

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Posted 19 May 2020 - 02:57 PM

Cheers!

 

So if I understand it correctly, first you screw in the Coupling (item #10) into the focuser, then you screw the Baader part into the coupling (this Baader part takes the place of the CAA, part #6), then you screw the eyepiece holder into the Baader (part # 70S), then your 2" diagonal goes in?

 

Looking at the Baader piece, it seems like the 2" diagonal goes straight into the Baader piece, so if you use the Baader do you no longer need the Tak eyepiece holder (part# 70S) and so the diagonal just goes straight into the Baader?

Not quite, you don’t need to screw in part 70s, , looks like this (although here I’ve got the standard Baader clicklock fitted rather than the ultra short).

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Edited by Gavster, 19 May 2020 - 02:59 PM.


#7 trias702

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Posted 19 May 2020 - 03:08 PM

Okay, that's helpful, so it's just part #10 plus the Baader Ultra short? And the diagonal goes into the Baader?

 

What exactly does this accomplish? You mentioned it gives more in-focus, which as I understand it, it means the diagonal will sit closer to the lens, thus allowing more out-focus travel distance?

 

This is helpful for binoviewing?



#8 Gavster

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Posted 19 May 2020 - 03:41 PM

Okay, that's helpful, so it's just part #10 plus the Baader Ultra short? And the diagonal goes into the Baader?

 

What exactly does this accomplish? You mentioned it gives more in-focus, which as I understand it, it means the diagonal will sit closer to the lens, thus allowing more out-focus travel distance?

 

This is helpful for binoviewing?

Yes. It gives more chance that the longer light path of the binoviewer will come into focus.



#9 trias702

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Posted 19 May 2020 - 03:46 PM

Gotcha.

 

May I please ask if you ever had a chance to do some high magnification planetary/lunar viewing with your FSQ85? I read all of your reports on the FSQ when you first got it, but you were doing mainly wide field low mag, NV observing, although you did mention you wanted to compare how the FSQ handles high mag planetary/lunar compared to your AP Stowaway and Baader TC.

 

Am curious if you ever got a chance to do this and what were your results? Is the FSQ85 at least as good at high mag planetary/lunar?



#10 Gavster

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Posted 19 May 2020 - 03:50 PM

Gotcha.

 

May I please ask if you ever had a chance to do some high magnification planetary/lunar viewing with your FSQ85? I read all of your reports on the FSQ when you first got it, but you were doing mainly wide field low mag, NV observing, although you did mention you wanted to compare how the FSQ handles high mag planetary/lunar compared to your AP Stowaway and Baader TC.

 

Am curious if you ever got a chance to do this and what were your results? Is the FSQ85 at least as good at high mag planetary/lunar?

There’s some comments on high mag visual in this link - I have certainly been impressed with it.

https://www.cloudyni...ual-only-scope/



#11 trias702

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Posted 19 May 2020 - 04:00 PM

There’s some comments on high mag visual in this link - I have certainly been impressed with it.

https://www.cloudyni...ual-only-scope/

I've read that entire thread, but I didn't see any impressions regarding high mag planetary/lunar which you did. All I can find in reference is post #5 which says you hope to do some soon, but you never post anything about how it ended up performing.



#12 Gavster

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Posted 19 May 2020 - 07:14 PM

I've read that entire thread, but I didn't see any impressions regarding high mag planetary/lunar which you did. All I can find in reference is post #5 which says you hope to do some soon, but you never post anything about how it ended up performing.

In my first post I stated this: ‘Even at higher mag with a 3.5mm eyepiece (130x) I have some fantastic views of Jupiter with lovely cloud banding and a fantastically clear GRS.’ And another poster made some more detailed comments and a comparison against an AP stowaway towards the end of the thread.


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#13 213Cobra

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Posted 20 May 2020 - 03:54 AM

I've read that entire thread, but I didn't see any impressions regarding high mag planetary/lunar which you did. All I can find in reference is post #5 which says you hope to do some soon, but you never post anything about how it ended up performing.

I don't have a Stowaway or any other AP refractor to compare against high power views through the FSQ-85. I have, however, f/6 & f/7.5 80mm LOMO triplets. Also, for smaller aperture optical perfection, the FOA-60Q.

 

There are occasions where I live in Los Angeles, on the north slope of the Santa Monica mountains, that we get unusually stable air, transparency, and overall good seeing despite the light dome. For high magnification on the FSQ-85ed, I use the Tak 1.5X ED extender, which introduces no deleterious effects optically, with TOE, DeLite and Nagler short FL eyepieces. During an exceptionally clear week, with settled floaters and great seeing last year, using the FSQ85ED + 1.5X ED Extender + TOE 3.3mm eyepiece, I enjoyed detailed views of Jupiter and and flyover vistas of the moon at 204X and a ~0.41mm exit pupil. Now that exit pupil was pretty much at my usual minimum of 0.40mm, and It was fully usable to me. The 4mm DeLite got me into a brighter exit pupil, and the view through the 3.5mm Nagler was engrossing for both Jupiter and moon.

 

Now, normally the sky isn't quite so settled so usually with that scope, I will top out magnification with the extender + 5mm DeLite or 5.7mm Takahashi UW on more average nights, also backing off on the exit pupil .

 

I can do the similar things with my LOMOs. Both scopes are icy sharp natively. The FSQ-85 natively is effectively as sharp, but slightly warmer and more nuanced about revealing color differences. The LOMOs have the edge in sheer contrast. I use the LOMOs with the TSFlat2 1x flattener. The f/7.5 LOMO with a TOE 3.3 yields 182X, 0.44mm exit pupil with the 80mm objective, and it lives up to everything you ever read about an 80mm LOMO. It and its f/6 sister are good reference optics in the aperture category.

 

Making allowances for the smaller aperture and slower optics, the FOA-60Q is perceptibly a more perfect optic than either the LOMO or the FSQ. It's difficult to pinpoint exactly how, given the aperture step-down, but getting your eyeball on a premium eyepiece mounted in an FOA-60Q just elicits a sense of "no improvements needed nor possible" that few other telescopes available to amateurs can elicit. But it's f/15 and highly corrected, so of course it makes a distinct impression. That the FSQ quad with an Extender characteristically puts itself clearly in the family with that perfect FOA-Q is all you need to know. And you're never getting a wide field out of the F-Q f/15 pencil tube.

 

Same experience using the FSQ-106EDX visually, with its 1.6X ED Extender.

 

I keep my 80mm LOMOs because it is interesting to have them, and they are probably the best 80mm triplets made to date (though Stellarvue might dispute that with their current production). But if I had to drop the count, the FSQ stays and the LOMOs will find other homes, with little sense of urgency.

 

Phil


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#14 trias702

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Posted 20 May 2020 - 10:26 AM

Hi Phil, thank you most kindly for that detailed write-up, I very much appreciate it.

 

I'm sort of torn about the Baby-Q now, having read everything here and that massive review by Chris Thomasel over on Astromart. I'm worried that the benefits which the FSQ-85 brings to the table are lost on me. For example, everyone out there praises it for it's flat, wide-field views, which makes sense, as it was designed for that. But I never do lower power, wide-field observing, because I live in a light polluted area where you can't see any DSOs or clusters. Unless I'm at a dark sky sight, all I ever do is high mag lunar and planetary viewing, and while I appreciate everything Phil says about its performance at high mag with the Extender, it seems clear the LOMOs still have the slight edge there, but I suppose that's because they're LOMOs, not necessarily because they're higher F ratios. In another thread, I've seen Eric Bakker (I think that's his name, apologies if that's wrong), who has/had the FSQ-85, state that it's high mag lunar/planetary performance was not great, definitely worse than the Tak FC100s and even the FC76, although am not sure how much worse/better compared to the TV-85.

 

I recently bought a TV-85 and absolutely loved it, for my needs and my light polluted skies, it did everything I needed, and I was happy with it and wasn't planning on getting a new scope at all. However, it was brand new, and had deep scratches in the paint out of the box, so I had to refund it as a defect, and there are currently no more white TV-85s in stock anywhere in the USA, and I have been told that the new ones which will be made once TeleVue re-opens after covid will not be good quality ones, plus I have already been burned by their quality control once already.

 

So my gold standard for comparing the FSQ-85 is the TV-85.

 

The one possible advantage I see with the FSQ-85 is that I could finally take advantage of its flat field, wide viewing ability if I ever manage to find a PVS-7 NV tube which meets my high criteria, but I have been trying to find one for 4 months now, and I still can't find anything. So until I can find one, I would use the FSQ-85 solely for high mag lunar and planetary viewing, and I'm not sure how it compares to the TV-85 in that department. For this kind of viewing, field flatness doesn't matter at all (to me). I know exactly the quality views the TV-85 gave me at 190X in my LP skies, and they were very impressive, and am just not sure if the FSQ-85 would hit the same high watermark. For me, at the moment, I don't care about field flatness or wide field, but I know I would if I ever got the NV kit I so badly want. What I do care about in the immediate term is the high mag lunar/planetary views and how the FSQ-85 compares against the TV-85 in this department. If anyone has any direct experience with both, I would greatly appreciate some feedback.

 

There’s some comments on high mag visual in this link - I have certainly been impressed with it.

https://www.cloudyni...ual-only-scope/

Gavster, quick question, you mentioned in that thread that the FSQ-85 has been giving you more joy than any of your other travel refractors, in fact, more than any of your other telescopes save the C11. But I'm curious, is that because you mostly use it with NV for wide-field viewing? Which, to be fair, is amazing, I have seen your photos, and if I had NV too, I would be using the FSQ-85 all day, everyday for flat, wide-field NV viewing too. But if you remove the NV from the equation, would it still be giving you more joy than all the other refractors? And how would you rate its high mag planetary/lunar performance against the TV-85 specifically?

 

 

Basically, I need the FSQ-85 to be at least as good as the TV-85 for high mag lunar/planetary performance, as that is all I can do right now. All this other talk of wide-field or flatness doesn't matter at all to me, at least not right now. In the future, once I can maybe finally find the NV tube I need, then yes, I think at that point I could finally start harnessing all of the benefits of the FSQ-85. Plus, as a forever scope, I need it to be versatile, even with NV, I would still really enjoy the occasional high mag lunar and planetary views. I can appreciate that the FSQ-85 isn't as good as a FC100 or even an FC76 for high mag lunar, but if it's at least as good as the TV-85, then I'll pull the trigger immediately.


Edited by trias702, 20 May 2020 - 10:40 AM.


#15 213Cobra

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Posted 20 May 2020 - 06:25 PM

Hi Phil, thank you most kindly for that detailed write-up, I very much appreciate it.

 

I'm sort of torn about the Baby-Q now, having read everything here and that massive review by Chris Thomasel over on Astromart. I'm worried that the benefits which the FSQ-85 brings to the table are lost on me. For example, everyone out there praises it for it's flat, wide-field views, which makes sense, as it was designed for that. But I never do lower power, wide-field observing, because I live in a light polluted area where you can't see any DSOs or clusters. Unless I'm at a dark sky sight, all I ever do is high mag lunar and planetary viewing, and while I appreciate everything Phil says about its performance at high mag with the Extender, it seems clear the LOMOs still have the slight edge there, but I suppose that's because they're LOMOs, not necessarily because they're higher F ratios. In another thread, I've seen Eric Bakker (I think that's his name, apologies if that's wrong), who has/had the FSQ-85, state that it's high mag lunar/planetary performance was not great, definitely worse than the Tak FC100s and even the FC76, although am not sure how much worse/better compared to the TV-85....

I don't own a TV-85 but I've looked through one. To my eye, the FSQ85 + 1.5 Extender is sharper and yields more nuanced color differences. This is not criticism of the TV85. It's a great refractor for its design objectives. It's also a different instrument. Doublet. f/7. 600mm FL. The FSQ is a quad, f/5.3, 450mm. If you compare the TV-85 to the standalone FSQ-85 strictly on lunar and planets, and if you then sideline the flat field advantage, the TV-85 is better for you in that specific set of evaluation criteria. No doubt.

 

However, add the 1.5X ED Extender, and things change. The scope becomes all-but f/8, 675mm FL; a full corrected doublet-objective quad. That Extender adds $530 to your cost, from TakAmerica. But now you have a TV-85 beater for lunar and planets, *and* a ready-made wide field refractor. It's the pristine quality of Takahashi's Extenders that makes this possible. Same is true for their Q modules for the FS-60 and FOA-60.

 

I'm puzzled why you can't appreciate DSOs and clusters from your light-polluted location. I am most nights surprised how much can be found under L.A.'s blazing light dome. I'm in a better-than-average spot in Los Angeles for this hobby, but still, my backyard observing is under borderline red-white sky conditions. I start scanning with the RedCat 51; mentally catalog what's cutting through, and then put bigger glass on them.

 

Phil


Edited by 213Cobra, 21 May 2020 - 12:23 PM.

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#16 trias702

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Posted 20 May 2020 - 07:14 PM

I don't own a TV-85 but I've looked through one. To my eye, the FSQ85 + 1.5 Extender is sharper and yields more nuanced color differences. This is not criticism of the TV85. It's a great refractor for its design objectives. It's also a different instrument. Doublet. f/7. 600mm FL. The FSQ is f/5.3, 450mm. If you compare the TV-85 to the standalone FSQ-85 strictly on lunar and planets, and if you then sideline the flat field advantage, the TV-85 is better for you in that specific set of evaluation criteria. No doubt.

 

However, add the 1.5X ED Extender, and things change. The scope becomes all-but f/8, 675mm FL; a full corrected doublet-objective quad. That Extender adds $530 to your cost, from TakAmerica. But now you have a TV-85 beater for lunar and planets, *and* a ready-made wide field refractor. It's the pristine quality of Takahashi's Extenders that makes this possible. Same is true for their Q modules for the FS-60 and FOA-60.

 

I'm puzzled why you can't appreciate DSOs and clusters from your light-polluted location. I am most nights surprised how much can be found under L.A.'s blazing light dome. I'm in a better-than-average spot in Los Angeles for this hobby, but still, my backyard observing is under borderline red-white sky conditions. I start scanning with the RedCat 51; mentally catalog what's cutting through, and then put bigger glass on them.

 

Phil

Interesting, thanks for the write-up. Would you say the FSQ-85 is better colour corrected than the TV-85, with or without the 1.5 Extender? I note that with my TV-85, as sharp as the views are on bright planets (Venus), I can still see quite a bit of colour. For example on Venus, with good seeing, I can come to really good focus, but one edge of Venus will have a noticeable red/warm hue, and the opposite side will have a blue hue. This is textbook CA right? Does the FSQ-85 remove all that excess colour because of its quad element?

 

One thing is that, even despite the red/blue hue, the focus on Venus is super sharp with the TV-85, really impressive. I'm worried if I will lose some of that razor sharpness by adding as much extra glass as the FSQ-85 has, plus the 1.5X Extender?

 

One question about that 1.5X Extender: do I really need it if I'm only ever using a binoviewer which requires a 2X OCS corrector? My Denk 27 won't reach focus unless I have the Denk-supplied OCS installed, which is either a 1.5X or 2X OCS. So if I have that OCS threaded on, then am I not already viewing at f/10, which makes the Tak 1.5X Extender redundant? I understand that the Tak 1.5X Extender is custom made for the FSQ and has better glass/elements than my OCS, but assuming I HAVE to use the Denk OCS, am I not then viewing at f/10? So in that case, my Binoviewer + OCS should make the FSQ-85 a TV-85 killer even without the Extender?

 

I'm happy to buy the FSQ-85 so long as it at least equals the TV-85 for high mag planetary views (using whatever combo of Extender and/or OCS), as that is my current focus. The flat, wide field views is a great option to have, but I won't be touching that until I get NV. I'm sure once I do get into it, I'll enjoy it immensely.

 

I can't enjoy any wide-field views here because I don't see anything, just a few stars. There's no structure whatsoever, you don't see any spiral arms or nebulae emission.



#17 213Cobra

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Posted 20 May 2020 - 08:50 PM

Interesting, thanks for the write-up. Would you say the FSQ-85 is better colour corrected than the TV-85, with or without the 1.5 Extender? I note that with my TV-85, as sharp as the views are on bright planets (Venus), I can still see quite a bit of colour. For example on Venus, with good seeing, I can come to really good focus, but one edge of Venus will have a noticeable red/warm hue, and the opposite side will have a blue hue. This is textbook CA right? Does the FSQ-85 remove all that excess colour because of its quad element?

 

One thing is that, even despite the red/blue hue, the focus on Venus is super sharp with the TV-85, really impressive. I'm worried if I will lose some of that razor sharpness by adding as much extra glass as the FSQ-85 has, plus the 1.5X Extender?

 

One question about that 1.5X Extender: do I really need it if I'm only ever using a binoviewer which requires a 2X OCS corrector? My Denk 27 won't reach focus unless I have the Denk-supplied OCS installed, which is either a 1.5X or 2X OCS....

I can't comment on the optical quality of the 2X OCS but let's assume it's good. No, you would not need the 1.5ED Extender if you are forced to have the 2X corrector in the optical train anyway. Yes, you'd be at equivalent of f/10.5 in that case. I have never seen any color on Venus nor anything else through any of my Takahashi scopes, including the FSQs. That's with or without the 1.5X ED Extender. So no color @ f/5.3. Yes, the flattener also furthers the intrinsic correction of the doublet objective.

 

Phil



#18 The Ardent

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Posted 20 May 2020 - 09:24 PM

It's not from the scope 

 

http://www.astropix....dispersion.html

 

https://en.wikipedia...eric_refraction

 

 

 For example on Venus, with good seeing, I can come to really good focus, but one edge of Venus will have a noticeable red/warm hue, and the opposite side will have a blue hue. This is textbook CA right? Does the FSQ-85 remove all that excess colour because of its quad element?

 

 

Rather than binoviewing a small aperture scope for deep sky, my experience that binoculars are better suited for two eye viewing.  (larger mounted binoculars with angled prism.)  Even in my TSA 120 , doing deep sky BV at native focal length, is was barely ok in a dark sky. Not enough aperture. A nice view but dim compared to monoview. 

 

Deep Sky observing is all about capturing light. A small scope BV is one aperture divided for two eyes. A binocular is 2 apertures for 2 eyes. Much better efficiency for conserving light. 

 

What works well In a small scope is BV the bright planets and moon. These have "excess" light, so there is no concern for conserving light. My old FS78 was "blah" on Jupiter mono, but exciting with BV. In this case the new FC 76 would be a more practical choice than the FSQ 85. 

 

I agree with 213Cobra about " flat field astrographs for visual use" Im interested in the FSQ85 for this very reason. 


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#19 trias702

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Posted 20 May 2020 - 10:21 PM

It's not from the scope 

 

http://www.astropix....dispersion.html

 

https://en.wikipedia...eric_refraction

 

 

Rather than binoviewing a small aperture scope for deep sky, my experience that binoculars are better suited for two eye viewing.  (larger mounted binoculars with angled prism.)  Even in my TSA 120 , doing deep sky BV at native focal length, is was barely ok in a dark sky. Not enough aperture. A nice view but dim compared to monoview. 

 

Deep Sky observing is all about capturing light. A small scope BV is one aperture divided for two eyes. A binocular is 2 apertures for 2 eyes. Much better efficiency for conserving light. 

 

What works well In a small scope is BV the bright planets and moon. These have "excess" light, so there is no concern for conserving light. My old FS78 was "blah" on Jupiter mono, but exciting with BV. In this case the new FC 76 would be a more practical choice than the FSQ 85. 

 

I agree with 213Cobra about " flat field astrographs for visual use" Im interested in the FSQ85 for this very reason. 

Ah, good point, I forgot all about atmospheric refraction.

 

You are entirely correct about the bino viewing for deep sky, which is why I never do it. As I stated before, I don't ever observe DSO nor do I want to, not with my light polluted skies, bino viewer, or low 85mm aperture. The only way I would ever do any DSO viewing is with NV. Hence am wondering if the FSQ-85 is wasted on me, with its flat, wide field which I would never use. Plus even with NV, I would be using a PVS-7, which has a very narrow AFOV, so I would never be seeing more than 1-2 degrees of sky at any time. I don't own any Ethos and don't plan on getting any.

 

But, it may be that the FSQ-85 is still an objectively better telescope than the TV-85, for wide, flat field observing, AND also for super high magnification planetary/lunar as well. It may well be an all around better scope overall, with just plain better optics for every occasion and role.

 

Ultimately, as I learned with my recent foray into telescopes with the TV-85 versus FC100, you just need to order both scopes and look through them yourself, there's really no other way to do it. Talking about it online only goes so far.



#20 25585

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Posted 21 May 2020 - 05:57 AM

But with the 1.5x Extender, would a GPC be needed at all?



#21 trias702

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Posted 21 May 2020 - 10:29 AM

But with the 1.5x Extender, would a GPC be needed at all?

I'm not sure to be honest. Binoviewing is a strange and arcane matter, the only way to know what will work is to actually get the scope and extender and test out a bunch of combinations and see what comes to focus and what doesn't.



#22 The Ardent

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Posted 21 May 2020 - 04:19 PM

BV ready refractor has been done before, I think you may be interested in these :

 

https://astromart.co...-bizarro-211374

 

https://astromart.co...ified_id=848945



#23 trias702

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Posted 21 May 2020 - 04:30 PM

BV ready refractor has been done before, I think you may be interested in these :

 

https://astromart.co...-bizarro-211374

 

https://astromart.co...ified_id=848945

Cheers. Yeah, I'm familiar with those, I current have a SV Nighthawk NG (bought in 2007), which is bino-ready by removing a section of the tube.

 

I've decided I'm going to go back to the TV-85 for now, try and find a white one which is brand new and doesn't have scratches in the paint fresh out of the box. TV's quality control is really lacking these days.

 

I'll also monitor the classifieds for a used FSQ-85, and if one comes up will buy it to use a guinea pig and see how it compares. Will then sell whichever one I don't end up keeping. It's too hard to make decisions for visual by just reading the forums. You just need to get the scope in your hands, no other way about it unfortunately. Especially with binoviewers and OCS in the equation, reaching focus becomes a nightmare of various intersecting variables.



#24 The Ardent

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Posted 21 May 2020 - 04:39 PM

Here is a sketch I did with my 32x82 angled binoculars the other night. Corona Australis scrapes the horizon from my latitude. Normally invisible, I can see it on a good dark transparent night. The spot in the center is a bright nebula, and the globular is just north in Sagittarius. I try to make the best of small aperture in light-polluted skies. 

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  • 2F02E3E0-43B9-4DA7-AECC-07708E651B75.jpeg

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#25 Max Lattanzi

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Posted 22 May 2020 - 05:36 AM

I am currently considering the purchase of a Tak FSQ-85EDX for purely visual use, for binoviewing only (...)
 

My question though is, will it come to focus well with a binoviewer, both with and/or without the bino OCS? (...)

I've also heard some conflicting reports saying the FSQ-85 can sometimes reach focus for binos without the OCS, but some people say it does not, I suppose it depends on your specific binoviewer.

 

My goal is planetary and lunar binoviewing with high mag, around 180x, maybe 200x if I can push it that far. (...)

Hi there,

I may pass you my experience with a Sky90-II; not the same OTA, but same issue.

Once I upgraded the 2.5" original focuser to the FSQ-85 3", basically giving birth to a novel Sky90-III, I was also faced with a short backfocus concern, despite having a SV version. This because, obviously, the FSQ-85 focuser is larger/longer than the original Sky-90 one (see pix). 

post-28298-0-47429500-1508175230.CN.jpg

No problem, of course, with mono-view, or with a bino using the Ext-Q 1.6x or any OCS. But, using the bare (no-OCS) Mark-V, with the short Baader/Zeiss T-2 prism, for lowest possible magnification, I was just a tiny hair short of focus (we are talking less than a millimiter... but no focus is no focus...).  Since this is the SV version, I didn't want to cut the OTA, which is perfectly tailored for the 95mm Tak clamshell (again see pix) and, after having tried the shortest adaptors on the market, decided to simply contact a machinist and have a tailor-made adapter ring which, after the removal of the original TKP37001 coupling, would screw into the focuser drawtube and, on the other side, has a mere T2 male so as to screw into the Baader/Zeiss prism. This gave plenty of focus to use, without any focus issue whatsoever and w/o OCS, TV Plossls 40, Zeiss Abbe 34, TV Panoptic 19, etc.  Given that the FSQ-85 OTA is already obviously sized for its focuser size, such a tailor-made adapter should address any of your concern. You may see it in a separated slot in the middle left of the carrying case.

photo_2020-05-22_11-27-16.CN.jpg
 

 

This being said -- and given that we are talking *your* telescope, with *your* money and, therefore, you are of course master of doing whatever you like --, and with all due respect to the excellent FSQ-85 optics, if your aim is planetary and lunar high mag observation AND you are not a frequent flyer with your equipment (...and you do not want to dismantle your equipment into parts/components...), ANY of the FC100 series (just to remain in the Takahashi realm) would give you *visibly* higher performances and satisfaction. Mainly the DZ, of course, but even simply the DF.

 

A "Flatfield Petzval Quadruplet" is clearly designed with astrophotopgraphy in mind. Telescopes tailored to your interests are usually called "superplanetary".

Hope this helps.

 

Cheers,
-- Max


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