Use of Tak 645 QE 0.72x reducer with non-FSQ refractors - Forums

Topic starter

Feb 20, 2023

Hello

Anyone using the (new) 645 reducer with non-Tak refractors or a model that is not the FSQ-106ED? I would be interested to know if this reducer can be optimised to work with a TOA-150 for example. Considering it for use with a medium format camera (Moravian C5). I'm interested in experiences with the REDUCER not the FLATTENER.
Thank you

Roberto

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Bob Lockwood

Feb 20, 2023 · Edited: Feb 20, 2023

Roberto,

Most highend reducers and flatteners are designed around the focal lengh of the scope. The 645 reducefor the FSQ-106 is designed for a scope with 530mm F/L
The TOA-150 has a focul lengh of 1100mm, you should see if the 645 reducer for the CCA 250 would work, as it's F/L is 1120mm. But do your homework first, as you want to be sure it will work with the price tag of the 645 reducers.

If your thinking of putting this on an EDF-152, I'd get with AP first, they will tell you if it will work, and or tell you what will work.

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Roberto Botero

Topic starter

Feb 20, 2023

Hi Bob

Thank you. Yes, that's why I was asking for users who might have used the 645 with another scope. I have a 4" Astro-Physics flattener for my EDF but the 4" reducer (with 53mm image circle) is unobtainable.

I have asked AP but they are non-committal for the medium camera, even with their own reducers. It's too large a chip! I think the 645 is the only reducer in the market that could cover it.

I could buy and test but it's an expensive exercise! The TOA-150 has a similar focal length to my EDF (1100 vs 1140mm) so as you say I should check for users of that reducer: https://takahashiamerica.com/products/takahashi-645-reducer-ca-0-72x

Maybe I should change the title of this thread!

Roberto

Lynn K

Feb 20, 2023

My understanding is that most Takahashi reducers are scope specific. The 645 Fsq106 is for that scope and that scope only.

LYNN K.

Bob Lockwood

Feb 20, 2023

I think if you use the C5 IMX461 chip, you may find options?? as the chip is the same size as the 455.
If you use the C5 IMX411 chip, I think you'll have issues finding anything that can flatten or reduce that chip with a 66.7mm dignonal.

Roberto Botero

Topic starter

Feb 20, 2023

Bob

I have the IMX461 but it is 44x33mm and the IMX455 is "only" 36x24mm…so still substantially bigger.

Roberto

Roberto Botero

Topic starter

Feb 20, 2023

Lynn K:
My understanding is that most Takahashi reducers are scope specific. The 645 Fsq106 is for that scope and that scope only.

LYNN K.

Yes all reducers are scope specific....but they can be used with some adjustments to backfocus if the focal length is not too different. I have done this with Astro-Physics flatteners. It can be done. It will not be perfect but with a 60mm image circle, I can afford a reduced fully corrected area if my diagonal is "only" 54mm.
Thank you.

Bob Lockwood

Feb 20, 2023 · Edited: Feb 20, 2023

Yep, my mistake, I was thinking the dignonal of the 455, and compairing to the dimention of 44 x 33.
I think you should look into that Tak CA-250 reducer, it may be your best option.

Tyrel Smith

Feb 22, 2023

Roberto Botero:
Lynn K:
My understanding is that most Takahashi reducers are scope specific. The 645 Fsq106 is for that scope and that scope only.

LYNN K.

Yes all reducers are scope specific....but they can be used with some adjustments to backfocus if the focal length is not too different. I have done this with Astro-Physics flatteners. It can be done. It will not be perfect but with a 60mm image circle, I can afford a reduced fully corrected area if my diagonal is "only" 54mm.
Thank you.

Not all reducers are scope-specific.

Those reducers you linked to are not flattening reducers, so they would not produce a corrected (flat) field at all on a scope that does not already have a corrected (flat) field. It would not work with the TOA150 for imaging. Those are designed for scopes that already have a natively flat field, like the CCA (the CA reducer), FSQ (the QE reducer), and Mewlon (CR reducer) scopes.

What could possibly work is the new 645 Flattener .99x that is designed for the TOA130 and TOA150 scopes. Although only testing would tell if it would still perform to the specs stated when paired with the two scopes it was designed for. You could end up with round stars on the frame, but ones that are bloated in the middle and corners, or some other combination of weirdness.

https://takahashiamerica.com/products/tak-toa-645-flattener-0-99x-for-toa-130?_pos=3&_psq=645&_ss=e&_v=1.0

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Yuxuan

Feb 22, 2023

The 645 reducer for FSQ-106 is designed for a scope that already has a flat field, which the TOA-130 does not. So it won't work. You can expect the FSQ-106 reducer work well for other flat field scopes that is not too fast, such as EdgeHD, CDK, iDK, and CCA-250…

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Roberto Botero

Topic starter

Feb 22, 2023

Thank you all for your input. A theoretical discussion still.
Back to my original question, has anyone used the reducer (not interested in flattener as I have one that covers the medium format camera) with a non-FSQ or non-CCR scope?

Roberto

bergerjp

Jul 2, 2023

Hi Roberto, I used the 645 reducer with the FSQ-106EDX4 with an ASI6200 and the stars were not round in the corners to my liking. I only used the telescope at F/5 and sold the reducer. I tried the Astro-Physics reducer (QUADTCC;0.72x) on my TOA-150 and the result was not satisfactory in the corners with an ASI6200. So, forget those two reducers for the 461 sensor!
I asked Astro-Physics if the new reducer for the AP110GTX (0.83x) would work with a telescope with a longer focal length (e.g. 900-1000mm), but it hasn't been tested yet. I read on CN that Astro-Physics is working on a new reducer (0.8x) for 900-1000mm focal lengths. But it hasn't been corroborated by them.

For now, the best option for the 461 sensor is the Tak 645 flattener or the AP flattener.

Best regards.

Jean-Pierre

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