Trying to make a decision on selling my WO FLT91 for a WilliamOptics FLT120 - Forums

Topic starter

Aug 24, 2023

I currently own a William Optics FLT 91 and am considering selling it to highpoint scientific in order to purchase a William Optics FLT 120. I am wondering if the change in aperture and focal length is worth it. I am not into SCT’s mostly due to weight and ease of setup, no need to collimate etc, so what I am looking for is a one size fits all refractor, maybe a little planetary imaging, but mostly DSO Objects like Star clusters, possibly some double stars and of course Planetary Nebula and Emission Nebula. The mount I currently use is the ZWO AM5. The AM5 can handle the William Optics FLT 120. The FLT 120 is less expensive than the FLT132, which is why I am looking considering the FLT120 but if the FLT 132 would be a better by I am open to opinions as well. Any help making my decision is greatly appreciated.

Best regards
Joe Matthews

Paul Macklin

Aug 24, 2023 · Edited: Aug 24, 2023

I moved from briefly using a FLT91 to an AT115EDT (f/7), reduced to f/5.6 and a focal length of about 644mm via plate solve. This was actually bigger than I initially wanted, but now I'm super happy with that choice.

With my asi2600mc pro, this gives me 1.2"/pixel and a good field of view. It's been great all around. I do see more detail compared to my 91mm, so I think the jump to 120mm might be even a little nicer, and that 115-120 range is good. Even reduced, you'll get some nice detail with that extra aperture.

(Oh, and do consider the Astro-Tech triplets (EDT). They're at a great price vs quality point. I do see an AT130EDT in stock for $1900, and a dedicated reducer for $200 … )

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Joe Matthews

Topic starter

Aug 24, 2023

Thank you paul for your help.

Eduardo Suárez

Aug 24, 2023

Hey Joe, let me know what you decide in the end and especially if you move to the FLT120. Funny enough I was doing some investigations today on the same topic. :-) I also looked at the Askar 107PHQ and 130PHQ as alternatives as these have a petzval design.

Not sure if you’ve used this tool before http://astronomy.tools/calculators/field_of_view/, it’s great to give you an idea of FOV with different scopes, cameras and reducers. I’ve been playing with it today to give me an idea of fov with different configurations.

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Paul Macklin

Aug 24, 2023

That's a great tip. I also sometimes mock them up in Stellarium and test on different targets of interest.

(and if you're open to mosaics, it makes the FOV issue a lot less critical).

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Eduardo Suárez

Aug 24, 2023

P.S. re: FLT132 I have discarded it because the published imaging circle is only 36mm vs the Askar 130PHQ at 60mm. The FLT132 imaging circle is not large enough if you want to go for a 6200MM in the future (the sensor’s diagonal is over 40mm) or other full frame cameras. Just something to keep in mind.

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Joe Matthews

Topic starter

Aug 25, 2023

hi eduardo and Paul thank you. Eduardo, I agree about the FLT 132, decided it’s out of the running, the FLT 120 is still in the running. However, I have also been considering the Askar 107phq, cost and weight seems to be about right. But to future proof I have been looking at the askar 130phq and even the ZWO 130 ( I think it also an askar design) . the cost is about the same but at 23 lbs a little heavier than I would want. I am pretty sure my AM5 can handle the weight of both the 130’s but portability is also a factor. just really a tough decision

Eduardo Suárez

Aug 25, 2023

Just one more to consider. I’ve also been looking at the Explore Scientific 127ED triplet carbon fibre. As it’s carbon fibre, it’s much lighter than the Askar 130. Perhaps a good compromise.

https://explorescientificusa.com/products/ed127-fcd100-air-spaced-triplet-apo-refractor-telescope-carbon-fiber

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Paul Macklin

Aug 25, 2023

I've heard good things about that ES! I'm intrigued on the Petzval scopes – please do keep posting with your experiences! (A lovely thought to avoid needing a separate flattener/reducer and deal with every extra perturbation to tilt and backfocus …)

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Joe Matthews

Topic starter

Aug 25, 2023

Will do PAUL

Joe Matthews

Topic starter

Aug 25, 2023

Thank you Eduardo, i’ll check it out

Eduardo Suárez

Oct 25, 2023

Hey Joe, I hope you are well.

I'm currently actively looking too and have reconsidered the WO FLT132. The concern I had with the imaging circle being only 36mm seems fine now; their website shows that with the recommended flattener/reducers (68III, 7a, 8) the imaging circle reaches 45mm. The weight is also reported as 9Kg (close to 10Kg with the flattener), so not as heavy as the Askar 130PHQ/ZWO FF130 at 12.5Kg.

I'd be interested to see what conclusion you reached. Did you get a larger refractor in the end?

Clear skies
Eduardo

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Joe Matthews

Topic starter

Oct 25, 2023

Hi Eduardo,

I haven’t purchased a new refractor, I still want the FLT 132, but the cost is a bit much for my wife to agree to, at this time. I have tried to sell my Celestron AVX Mount along with my ZenithStar 61ii and my FLT 91, to help defray some of the cost for the FLT 132, but no takers, not even High Point Scientific. There was a cloudy nights post for a slightly used FLT 120 for $2600, but decided to wait until I can come up with the money for the FLT 132. If I have to settle, it will be for the William Optics FLT120 only because of the lower cost.

Best regards
Joe

Todd Charlson

Nov 29, 2023

Hi Joe,

What are you asking for the FLT 91? I been considering adding it for its FOV. Currently , I'm using the FLT 132 FT scope with the flattener/reducers (68III, 7a, 8). It's hard right now to justify spending 2k for a new one.

CS
Todd

Joe Matthews

Topic starter

Nov 29, 2023

Hi Todd, I know what you mean, I have had to put my plans on hold for the FLT 132, so I am holding onto the FLT 91 for now.

CS
Joe

Paul Macklin

Nov 30, 2023

Todd Charlson:
Hi Joe,

What are you asking for the FLT 91? I been considering adding it for its FOV. Currently , I'm using the FLT 132 FT scope with the flattener/reducers (68III, 7a, 8). It's hard right now to justify spending 2k for a new one.

CS
Todd

I have a FLT91 (plus both flatteners and a good Thousand Oaks full aperture solar filter) packaged and I'd be delighted to cut a deal. Please DM if interested.

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