William Optics FLT 91 - imaging

[Jonny_H]

Hi all,

Curious to see if anyone has any reviews/thoughts on the WO FLT 91 scope.

As some know - I am currently looking for a nice refractor (now to sit beside my 150PDS as opposed to replacing it) and will be used primarily for imaging like the 150.

I have therefore been looking at shorter wider field fracs such as the Esprit 80, GT-81 and similar.

However the FLT 91 has also caught my eye. It seems that with the dedicated 0.8x reducer/flattener it puts it into a very similar fov as the others.

My main imaging camera is the 533MC Pro.

Any thoughts?

Clear skies.

Jonny

[Adam J]

Have you considered the Stellamira 85mm with 0.8x reducer?

Its what I would go with in that 80mm-90mm aperture range. 

Adam

 

 

Edited March 15, 2021 by Adam J

[scotty38]

I have the GT81 and adjustable 6AIII but I'm a beginner so would love to know your thoughts on why the Stellamira is the one to choose vs the GT81 or FLT91?

I have a Stellamira 80 by the way so no axe to grind there 🙂

[Jonny_H]

8 minutes ago, Adam J said:

Have you considered the Stellamira 85mm with 0.8x reducer?

Its what I would go with in that 80mm-90mm aperture range. 

Adam

 

 

Don't give me any more to choose from....! 😩

Just kidding. Thank you I will take a look at that also! 🙂

[Moodtastic]

I have the Stellamira 104. Its a nice scope and if the 85 is of the same quality it would be a good option.

I have a gt-81 on order for that wider field and for a more grab and go set up.

I would have considered the flt 91 over the 81 if I didn't have the SM 104.

Edited March 15, 2021 by Moodtastic

[Jonny_H]

The 91 does look like a lovely scope....to be honest they all do and im sure will fill that widefield hole that I have. 

Back to the decision  making again to look at all of my collated thoughts and options! 

[Iced Tiger]

Not managed to use my new FLT 91 yet, still waiting to source a Skywatcher EQ6 R Pro mount. When I looked at the fov it matched the Esprit 100ED I was also looking into buying for imaging. FLO had the FLT 91 in stock in red so I took the plunge, my guide scope is the William Optics 50mm with a ZWO 290MM and the main camera is a ZWO 294MC. 

[Jonny_H]

12 minutes ago, Iced Tiger said:

Not managed to use my new FLT 91 yet, still waiting to source a Skywatcher EQ6 R Pro mount. When I looked at the fov it matched the Esprit 100ED I was also looking into buying for imaging. FLO had the FLT 91 in stock in red so I took the plunge, my guide scope is the William Optics 50mm with a ZWO 290MM and the main camera is a ZWO 294MC. 

Nice.  If i decide to get the 91 the next tough decision will be the colour! 😆

Out of interest did you also get the flat6iii flattener with your scope?  Interested to see the colour of that if so.  On Flo's website it shows the gold version but there is a bit of text that says that the colours in the image may differ for the FLT91 version.

[Iced Tiger]

37 minutes ago, Jonny_H said:

Nice.  If i decide to get the 91 the next tough decision will be the colour! 😆

Out of interest did you also get the flat6iii flattener with your scope?  Interested to see the colour of that if so.  On Flo's website it shows the gold version but there is a bit of text that says that the colours in the image may differ for the FLT91 version.

I did not get the flattener, I went for a red 91 to match my guide scope and camera’s. I looked at the flattener on the William Optics website and it looks all black. Might invest in one, FLO only have one in stock, I have emailed them asking what colour it is.

Edited March 15, 2021 by Iced Tiger

[Jonny_H]

18 minutes ago, Iced Tiger said:

I did not get the flattener, I went for a red 91 to match my guide scope and camera’s. I looked at the flattener on the William Optics website and it looks all black. Might invest in one, FLO only have one in stock, I have emailed them asking what colour it is.

Yes that's what I would probably go for tbh for the same reasons (cameras, EAF & asiair pro all in red).

Edited March 15, 2021 by Jonny_H

[newbie alert]

For that kind of price I'd go esprit 100 over the W/O 

[Whirlwind]

1 hour ago, Jonny_H said:

Nice.  If i decide to get the 91 the next tough decision will be the colour! 😆

Out of interest did you also get the flat6iii flattener with your scope?  Interested to see the colour of that if so.  On Flo's website it shows the gold version but there is a bit of text that says that the colours in the image may differ for the FLT91 version.

The FLT91 is only just out so there are unlikely to be many real world users out there just yet.  Nevertheless in theory it does guarantee a certain quality of lens (and you can ask for a report at an extra cost - which might incentivise to be given a better one, especially as an earlier adopter).  

In terms of practical use I always found their more integrated flattener/telescopes more easier to use - especially the variable adapters which gives a bit more scope to play with back focus.  I also think a lot of the earlier mechanical issues are now resolved (poor focusers etc).

They probably are going to be much of a muchness with many similar triplets which are either from the countries of China (Skywatcher) or Taiwan (WO). I tend to steer towards the latter (or Vixen/Tak being Japan based) but that's more of my own personal political sensitivities.  

Edited March 15, 2021 by Whirlwind

[The Lazy Astronomer]

10 hours ago, Jonny_H said:

Don't give me any more to choose from....! 😩

Just kidding. Thank you I will take a look at that also! 🙂

I think the Stellamira 85 is what FLO use for the IKI observatory, if you wanted to check out some data (granted those images are from an excellent location, but still...)

[Jonny_H]

On 15/03/2021 at 23:45, The Lazy Astronomer said:

I think the Stellamira 85 is what FLO use for the IKI observatory, if you wanted to check out some data (granted those images are from an excellent location, but still...)

Thanks TLA,

I might be wrong but I think FLO uses the 104 in the IKI?

So.....I think I have narrowed it down to 3 contenders: Stellamira 85, WO GT81 iv or the TS-Optics CF-APO 90.

The Stellamira and TS-Optics seem similar in terms of focal length and speed so I guess it will be down to personal choice. The WO will give me a slightly wider fov....All will be used for AP so will be getting a FF/reducer.

[Jonny_H]

21 minutes ago, Jonny_H said:

Thanks TLA,

I might be wrong but I think FLO uses the 104 in the IKI?

So.....I think I have narrowed it down to 3 contenders: Stellamira 85, WO GT81 iv or the TS-Optics CF-APO 90. This after discounting the FLT91 (for reasons I can't explain it doesn't give me 'the feeling').

The Stellamira and TS-Optics seem similar in terms of focal length and speed so I guess it will be down to personal choice. The WO will give me a slightly wider fov....All will be used for AP so will be getting a FF/reducer.

 

[The Lazy Astronomer]

23 minutes ago, Jonny_H said:

Thanks TLA,

I might be wrong but I think FLO uses the 104 in the IKI?

So.....I think I have narrowed it down to 3 contenders: Stellamira 85, WO GT81 iv or the TS-Optics CF-APO 90.

The Stellamira and TS-Optics seem similar in terms of focal length and speed so I guess it will be down to personal choice. The WO will give me a slightly wider fov....All will be used for AP so will be getting a FF/reducer.

Yep, you're right, no idea why l thought it was the 85!

[Jonny_H]

1 minute ago, The Lazy Astronomer said:

Yep, you're right, no idea why l thought it was the 85!

If the 85 is of similar quality to the 104 then it is a great piece of kit!

[Jonny_H]

On 15/03/2021 at 22:09, newbie alert said:

For that kind of price I'd go esprit 100 over the W/O 

I was originally looking at the 100 and for reasons i can't explain I keep getting drawn in to it.

The only gripe I have is that it is reasonably similar to my 150pds in the sense that it doesn't give me a hugely different fov (Albeit still noticeable).

Granted the 91 has a similar fov but with the dedicated reducer it takes the fov a step wider.

Unless of course there is a reducer that works with the 100?

[KP82]

1 hour ago, Jonny_H said:

I was originally looking at the 100 and for reasons i can't explain I keep getting drawn in to it.

The only gripe I have is that it is reasonably similar to my 150pds in the sense that it doesn't give me a hugely different fov (Albeit still noticeable).

Granted the 91 has a similar fov but with the dedicated reducer it takes the fov a step wider.

Unless of course there is a reducer that works with the 100?

There are a few universal reducers that work with the Esprit 100 such as the Riccardi and TS APO reducer 0.75x. You can find user feedbacks about these combos on CN.

[Jonny_H]

4 minutes ago, KP82 said:

There are a few universal reducers that work with the Esprit 100 such as the Riccardi and TS APO reducer 0.75x. You can find user feedbacks about these combos on CN.

Thanks for the info. I will take a look.

Edited March 18, 2021 by Jonny_H

[kbrown]

Can any of you give me an idea what sort of weight the focuser on the WO FLT91 can handle? I think this is my current favourite to get.

[Ken999]

I just received my WO FLT91 last week. Got the 6AIII Flattener as well. First images showed severe collimation/lens alignment issues. I would prefer not to think it is a quality control issue on the first run of what appear to be very fine instruments. Could also be damage in transit.

M51-RGB-session_1-St.tif

[KP82]

7 hours ago, Ken999 said:

I just received my WO FLT91 last week. Got the 6AIII Flattener as well. First images showed severe collimation/lens alignment issues. I would prefer not to think it is a quality control issue on the first run of what appear to be very fine instruments. Could also be damage in transit.

M51-RGB-session_1-St.tif 66.84 MB · 6 downloads

Oh no... coma all over the place.

Have you tried to test the scope on its own? Maybe it's the flattener that's the culprit.

[Ken999]

Hmmm, that’s a thought. I’ll try it next time.

[Adam J]

7 hours ago, Ken999 said:

I just received my WO FLT91 last week. Got the 6AIII Flattener as well. First images showed severe collimation/lens alignment issues. I would prefer not to think it is a quality control issue on the first run of what appear to be very fine instruments. Could also be damage in transit.

M51-RGB-session_1-St.tif 66.84 MB · 9 downloads

Yeah that not just a little bit out is it. I think you are correct and that is colimation.