celestron corrector/ flattener

[lhuchison]

Does anyone have any experience of using the celestron .63 corrector/ flattener on their SCT? Ive had one for about 3 months now and cant decide whether it helps with the visual image.

i tried it with it on and off and both visual images seem to blur stars to the outer edges. I know it dosnt compare to the HD but apart from a wider FOV i cant

detect a improvement in outer edge pinpoint stars or am i expecting too much? I only use it visually , can it have a negative impact on the image?

i,ve looked at the collimation using a overhead star at 200x and it seems ok.

[michael.h.f.wilkinson]

I have the 0.63x but used it for visual with a 1.25" visual back and diagonal. In those conditions (and in imaging with the right distance to the chip/film) it works well. In my WO 2" diagonal it is not such a success (distance to image plane too large), and it does not work with 2" EPs (it is designed for 1.25" EPs, with a max image circle of 28mm). Since I got my 2" EPs I have not used my reducer for visual. I have used in photographically, and then it is fine.

[lhuchison]

i,m using it with a WO 2in diagonal, plus one 2in lens (32mm ) but mainly 1.25mm lens, 25, 18 and 7mm is the 2in diagonal the problem?

[michael.h.f.wilkinson]

I think so. Any corrector is designed for a particular distance to the image plane. The optical path through a 2" diagonal is too long.

[earth titan]

Good to know chaps. Gonna invest in one of these sooner or later so I'm glad I know what to expect.

If you changed the spacings, would it work with a 2"?

[earth titan]

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Good to know chaps. Gonna invest in one of these sooner or later so I'm glad I know what to expect.

If you changed the spacings, would it work with a 2"?

Come to think of it, nope, as you need to reduce the distance rather than increase it. Doh!

[michael.h.f.wilkinson]

Don't forget, the reducer only produces a 28 mm image circle, which is matched to the largest field stop of a 1.25" EP. Not that useful for a real 2".

[lhuchison]

Thanks for the info. I'll try it with the standard diagonal that my SCT was shipped with.

[Chris Rowland]

Some say it works with 2" diagonals but it depends on the diagonal because as the distance between the FR and the EP increases the reduction increases, the image circle reduces and the aberrations increase.

My feeling is that it's either FR and 1.25" diagonal and EPs or 2" diagonal and EPs with no FR.

IMO the FR is almost essential for deep sky imaging to get the focal length down.

Chris