FSQ85 in 2024 or ??? - Forums

Hi everyone,

I'm currently considering purchasing a new optic for astrophotography.

At the moment, I have a Redcat 91 here, but unfortunately, it has a noticeable defect and will be returned to the dealer.
Before this, I had an FRA300, but it showed CA towards the edges with my APSC sensor, which I found very bothersome.

Now, I’d like to invest in an optic that will serve me well for a long time without needing replacement.
Ideally, I’m looking for a flatfield or Petzval optic. However, it seems challenging to find something of very high quality in this category.
The telescope should have a focal length of 400–500mm and weigh no more than 5–5.5kg.

My cameras are an IMX571 mono paired with ToupTek LRGBSHO filters and a 585 color.
The 585 will soon be replaced with a 585 mono.

I’ve been intrigued by the FSQ85 with a flattener for quite some time.
However, I’m unsure if the artifacts on brighter stars might bother me.
At this price point, you'd expect better performance…

What do you think?
Is the FSQ85 still worth buying these days?

There are many alternatives, like the SQA85, but I’m worried I won’t be satisfied with it in the long run either.
On paper, many of the new optics seem to have better performance than the FSQ. I’d greatly appreciate any suggestions!

Best regards,
Brian

Hi Brian,

I read your post on astronomie.de, seems like your Cat 91 has a defect. Why not try a proper copy first?

I have been researching the same thing for some time now and I have the impression that the FSQ85 is not optically better. The main concern I have with the Takahashis is their weak focusers. I'm fighting with tilt with most of my scopes (TS CF APO, Sharpstar 15028 HNT) and I'm intrigued with the WIFD focusers by Williams. I will receive my Cat 91 hopefully next week and will see if it meets my expectations.

However, there is no perfect scope, no matter how much you spend. They all have their problems to deal with. Working around those limitations is part of the hobby.

CS

Stefan

Hi Stefan,

if you like send me a PN on astronomie.de.
Then we can talk about the cat.

Fsq focuser:
I have heard of these problems.
But I think in the future I would replace the original focuser with the PLL one.
Thats not the biggest issue for me.

I know that there is no perfect scope.
But when you look for older post about the Fsq many people love the scope.
But at that time there was no Sqa85 or Redcat 91 around.
Because of that I like to know if there is any reason to still buy the Fsq85.

Its a hard question I know.

Hi Brian,

true, with a traditional scope you can change the focuser, but the WIFD design should be even better than a PLL focuser in terms of cost.
I hope someone is doing a proper 1:1 comparison between the FSQs, the SQA, and the Cat soon.

Cheers

Stefan

I really like the SQA85 so far in regards to its build quality and performance. I haven't had the weather/time to produce an image, but here is a starfield:

Before adjusting tilt:
https://astrob.in/tvsza4/G/

Post Tilt (Baader M68 adjuster):
https://astrob.in/tvsza4/I/
https://astrob.in/tvsza4/J/

I absolutely love my FSQ85. Check out some DPAC tests on Cloudy Nights of it- it's pretty impressive.

I've been using mine with a 533 sensor but literally just got a 571 delivered today, so I can't comment on that yet. However I know that others using the flattener and having the appropriate 56.2mm backspacing are very happy.

My FSQ focuser has not sagged, but again we'll see with my new 571, EFW, and OAG setup. There is slight shift when changing focus direction, but it has not affected my EAF at all.

FSQ85 is a great optics , but you have to consider using it with the 1.01x corrector for its full potential . ( or QB0.73x) . The colors compliance are better with the FSQ85 than the FSQ106 but you have to consider that you will need to change the focuser ( Esatto 3") as the focus is very sensitive to thermal change . But once done , it is maybe one of the best optic you will never use .

The Tak85 remains impressive. Spot chart shows dots half the size of many scopes, such as the FRA500. Huge image circle means less fading in the corners. With a .73 reducer, its aperture becomes a fast f3.85. There aren’t many refractors that can match this combination of features.

My WO GT71 has an identical FOV, but it is not as sharp and, with reducer, opens to a 20% slower f4.8. A Tak85 remains at the top of my wishlist as an ultimate traveler scope.

I have got mine FSQ85 ED a month ago (second hand, with very reasonable price) . I do have Esprit 120 and LZOS 100/800 and I did some comparisons . I also had Esprit 80 before. I added SestoSenso autofocuser and flattener 1.01.
Positive :
-The sharpness and color correction is better than anything I saw except maybe LZOS where it is comparable . Although LZOS is at 600mm FL .
- So far did not see any problems with focuser.
- With 1.01 flattener , the field is corrected perfectly for APS-C sensor. Did not see any tilt .
Negative
- The corrected field is only 28mm on native FL, with 0.73 reducer and with 1,5x focal extender. Very visible on APS-C sensor size. BXT handles it, but with focal reducer it is at the edge of acceptable.
-Known "spikes" on brighter stars at the edges are there, it seems there is no way to get rid of it as it is embedded in Petzval design
-Benefits of Petzval (no backocus issues) are gone with 1.01 flattener.
- Vignetting is visible (with 1.01 flattener) , although flat frames do correct it perfectly

Overal: If I would have bought it new and paid full price , I would be quite dissapointed. Petzval that is actually not the Petzval with spikes on stars. With the price I paid, I got very sharp, light and flexible telescope , that outperforms anything comparable in that class from the color correction and sharpness point of view. (with 1.01 flattener). Will learn to live with spikes 🙂
CS

I will be fielding an FSQ85 astrograph this spring to complement a narrowband system in the 6' dome, and am posting my design and construction notes. I have a little shop in my garage, machine shop and optical shop where i make and test optical systems.

I'll post 633nm interferograms later, but I can tell you that the FSQ85 I purchased used is very good opticaly. The Field flatner, and the new 0.73 FSQ-85ED-QB reducer are excellent additions. With no degradation of wavefront. The older 0.73x reduced is marginal...

So my suggestion is, Go For IT but plan on replacing the focuser...

I am just about done with the mechanical design, that replaces the focuser, and have the material on hand for the component machining.

link to my notes.

https://cdn.astrobin.com/ckeditor-files/14617/2024/d6682acf-32e6-4cd9-8214-4ddcf09c2f2d.pdf

https://www.astrobin.com/1q3k1m/

I have the Tak FSQ 85-EDX with the 1.01x flattener and it produces wonderful images with an ASI6200mm. I also tried it with the new full frame 0.73x reducer but the results are not as impressive. I've made a couple of posts and images about this on AstroBin. The only issue I have with the Baby-Q is the focuser started to sag with the weight of a 7-position filter wheel and the ASI6200mm after a few months in my permanent observatory setup. As a result, the autofocus motor would not work properly. This has been mentioned by others.

Thanks for your answers guys.

Sounds like a good scope

Bruce Donzanti:
he only issue I have with the Baby-Q is the focuser started to sag with the weight of a 7-position filter wheel and the ASI6200mm after a few months in my permanent observatory setup. As a result, the autofocus motor would not work properly. This has been mentioned by others.

Is there a way to fix that problem or is the focuser damaged forever?

Yes- you need to adjust the 2 set screws on the focuser.

I have a FSQ85-EDX. It is a great refractor in terms of optics. However, forgive my honest opinion but the focuser is simply garbage, not bad, it is worse than bad... Consider ordering an upgrade as soon as you order the scope. I have made a topic about it last year.

Now, my 2 cents is that if you are going to use a fixed permanent setup and if I were you, I would get a Epsilon instead. It is a reflector so colors can’t be any better than this, it is significantly faster and as sharp as the FSQ for a lower price (considering it is a E-130D). Focuser is also garbage but you can upgrade it as well. Downside is it requires collimation and if you never had experience with reflectors before, it might be hard. If you can get the E-160, then you would be very well equipped with one of the sharpest small astrographs available.

However, if you intend to travel with it sometimes, or is not comfortable managing a newtonian, then the FSQ makes more sense, I personally can’t go back to refractors though. You can look in my gallery when I used to use the FSQ and the results I get with the E-130D now, and there’s also the collections separated by equipment.

I have a Tak85 and the focuser has been absolutely reliable even with a few pounds of photography gear on it. Perhaps some models, like newer ones, have improved focusers. It's evident from forums that there are about as many posts saying the focuser are awful as there are saying the focuser is just fine, so this is certainly a topic to explore.

Mine was sufficiently reliable to send to a remote facility and I've been pleased at its performance and the Tak's extremely sharp images.

You could consider the SVX101T with the 0.75x field flattener / reducer: https://www.stellarvue.com/svx102t/

Sorry I haven't read through all the discussion but considering your requirements, the first 2 things that come to mind are Askar SQA series, or (if money is no issue) WO Pleiades

Gleb Polyakov:
You could consider the SVX101T with the 0.75x field flattener / reducer: https://www.stellarvue.com/svx102t/

I would absolutely love one of these personally, but not availabe anywhere in the U.K. ☹️

P.S, I am not the OP..

There's always https://www.stackry.com/, i used them when I lived in the EU and needed to get US things.

Hi Brian

I have the SQA85 and think it is a great scope. It is well made and stars look great. I measured tilt using ASTAP and it was at 2% when I got it so I didn’t have to adjust anything. I like its light gathering ability and ease of setup - no backspace requirement. I had to add a spacer to get focus since there wasn’t enough travel. The focuser is smooth when extending and not quite as smooth when retracting. It has no problem supporting the weight of my camera and EFW. The scope isn’t very big so it’s a bit crowded with my equipment. The two finder shoes are nice, but I can’t use them for my finder scope because of its length with the guide camera sticking out. They are too close to the back of the scope and my EFW gets in the way. If you don’t use a filter wheel they will work fine. Nothing you can’t work around but just know there isn’t a lot of room on the scope. Very easy to install an EAF and the EAF has no problems moving the focuser. I am using a full frame camera and stars are good to the edges (looked at using AberationInspector in PI). The level of detail I get with the faster optics is noticeable and worth the cost of the scope.

Hi,

thanks for all your replys.
I tought about the FSQ85 a lot the last days.

I will not buy it.
The mixed feedback gave me the feeling to not buy the scope.

The price is to high for a focuser that is maybe bad and a optic that maybe cant handle my IMX571.

I like to buy a scope wich give me 100% good feelings when I look at it and at the moment its not the FSQ85.

Maybe it will be the SQA85, but I dont know.
Its hard to decide…

Brian:
Hi,

thanks for all your replys.
I tought about the FSQ85 a lot the last days.

I will not buy it.
The mixed feedback gave me the feeling to not buy the scope.

The price is to high for a focuser that is maybe bad and a optic that maybe cant handle my IMX571.

I like to buy a scope wich give me 100% good feelings when I look at it and at the moment its not the FSQ85.

Maybe it will be the SQA85, but I dont know.
Its hard to decide...

It is a hard choice with so many options. For what it is worth, I am one (and have posted here) that I am very disappointed in my Baby-Q. I just replaced it with the new William Optics RedCat 91 WIFD. Take a look at my first light with it... https://astrob.in/bczxui/0/.

It is a much cheaper option with excellent optics.

Brian:
The price is to high for a focuser that is maybe bad and a optic that maybe cant handle my IMX571.

The scope most-definitely can handle an IMX571 - 5 mins searching this very site will confirm this.....

I just got my 2600MM for my Baby Q and so far I have zero issues. I'm using a 7x36mm EFW and OAG-L with M54 tilt plate. With the 1.01x flattener I'm getting excellent stars right to the corners, and the focuser has no issues holding the equipment.

Christopher Schementi:
I just got my 2600MM for my Baby Q and so far I have zero issues. I'm using a 7x36mm EFW and OAG-L with M54 tilt plate. With the 1.01x flattener I'm getting excellent stars right to the corners, and the focuser has no issues holding the equipment.

Same for me for the first two years….. until now. And my scope was well cared for in my observatory and kept in focus for minimal movement. Hopefully, you won’t have any problems but too many people complaining about this same draw tube issue.

I probably expressed myself poorly.

What I actually mean is that with the Fsq85, you need a reducer or flattener to use a modern chip.
The image field produced without a flattener or reducer simply cannot handle it. I find that unfortunate because it takes away one of the major advantages of the optics.