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What is the difference between REDUCER/FLATER & LARGE FIELD CORRECTOR

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#1 hongxu chen

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Posted 14 July 2019 - 09:09 AM

What is the difference between REDUCER/FLATER & LARGE FIELD CORRECTOR?
I have a TV NP101, the non-is version, and QHY 16200 CCD. I saw REDUCER/FLATER & LARGE FIELD CORRECTOR on Televue homepage. Is it necessary to buy them?

#2 HydrogenAlpha

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Posted 14 July 2019 - 11:28 AM

The reducer speeds up the system by 0.8x. The NP101 is already flat field, so you shouldn't be getting a reducer/corrector made for doublets or triplets. You need the NPR-1073.

The large field corrector is non-reducing, but corrects for larger sensors. It's use case is advertised for anything larger than APS-C, so your 16200 being APS-H theoretically requires it. However, it is still relatively close to the native well-corrected circle, so you might be able to do without it and crop out the extreme edges (or accept a small distortion).

#3 HydrogenAlpha

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Posted 14 July 2019 - 11:30 AM

Btw, I see that you have asked similar questions in different threads. I recommend just keeping to one thread to consolidate discussion.

#4 hongxu chen

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Posted 14 July 2019 - 12:48 PM

Btw, I see that you have asked similar questions in different threads. I recommend just keeping to one thread to consolidate discussion.


Thank you so much for your answer!
Nobody reply that thread. I just can not wait for the answer. So started another thread. Sorry for any inconvenience.

#5 hongxu chen

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Posted 14 July 2019 - 12:58 PM

The reducer speeds up the system by 0.8x. The NP101 is already flat field, so you shouldn't be getting a reducer/corrector made for doublets or triplets. You need the NPR-1073.

The large field corrector is non-reducing, but corrects for larger sensors. It's use case is advertised for anything larger than APS-C, so your 16200 being APS-H theoretically requires it. However, it is still relatively close to the native well-corrected circle, so you might be able to do without it and crop out the extreme edges (or accept a small distortion).


Thank you for your replay.
I read the introduction of NPR-1073. “It is optimized for imaging with up to APS-size (27mm diagonal) cameras.” Does that mean it will shrink the corrected circle to 27mm and I can not use it for a APS-H CCD?

#6 HydrogenAlpha

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Posted 14 July 2019 - 03:58 PM

Thank you for your replay.
I read the introduction of NPR-1073. “It is optimized for imaging with up to APS-size (27mm diagonal) cameras.” Does that mean it will shrink the corrected circle to 27mm and I can not use it for a APS-H CCD?


Yes that is what it is, or at least on paper. However, there is some subjectivity when it comes to image circles because the level of correction and light fall off is gradual. You may find that the images are still acceptable with a slightly larger chip, but the only way to know is to try it or look for sample images with the combination.

Alternatively, if you don't mind doing a slight crop (which still gives you a wider fov than not using the reducer), then you're definitely good to go.

I have a 16200 as well and I previously considered the NP127IS. If I had gotten it, I would have got the 0.8x reducer as well

#7 hongxu chen

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Posted 14 July 2019 - 10:32 PM

Yes that is what it is, or at least on paper. However, there is some subjectivity when it comes to image circles because the level of correction and light fall off is gradual. You may find that the images are still acceptable with a slightly larger chip, but the only way to know is to try it or look for sample images with the combination.

Alternatively, if you don't mind doing a slight crop (which still gives you a wider fov than not using the reducer), then you're definitely good to go.

I have a 16200 as well and I previously considered the NP127IS. If I had gotten it, I would have got the 0.8x reducer as well


Thank you for your answer!


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