2 replies to this topic

[macleod]

Please can anyone using a Baade MPCC MK3 coma corrector for visual use only, advise me on spacings between top corrector lens and field stop of eyepiece. Especially interested in spacing for ES 24mm 82deg eyepiece. Reading the Baader instructions I find a bit confusing. It says 55mm between ( presumably) top of corrector lens and what I take to be the field stop or focal point of the eyepiece used. As the ES 24mm eyepiece inserts 40mm into the corrector, this means a very long spacer is needed - getting on for 100mm including space for eyepiece barrel ! Any advice or help is greatly appreciated. Thank you, Macleod.

[Pierre Lemay]

I use an MPCC for visual only all the time (f/3,9 mirror).  It is permanently screwed onto the eyepiece barrel of my 20mm ES100, just like a filter would be attached. I use a short spacer to reach the 55mm distance to the field stop which I estimated for that eyepiece. Remember: the field stop in this kind of eyepiece is located inside the eyepiece body, above the top of the focuser draw tube.

 

As far as I know ES does not publish the exact location of the field stop but, then again, the position of the CC does not have to be exact to a fraction of a mm for it to provide a useable benefit to the observer. 

Edited by Pierre Lemay, 17 January 2021 - 09:44 AM.

[macleod]

PIERRE LEMAY - thank you for your reply. I thought the field stop in my ES24mm is 5mm back from inside the barrel of the eyepiece.In this case i thought I needed 55mm spacer between this field stop and top of Baader corrector lens ?  The ES 24mm comes to focus 5mm above the prime focus of the telescope, so it must be different design to your 100degree eyepiece ?  Macleod.