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Quark and focal reducer (plus dark band)

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I used my 100ed a few times with a Quark and quite enjoyed the views. This morning the views with my TV40mm plossl were amazing.

I'm tried to get my head around the use of focal reducer but I am still confused.

If I would like to turn my f9 scope into a let's say f7.5 with not only the lower magnification but also wider views a 40mm plossl would give in a generic f7.5 refractor, how would I go about it. Focal reducer in front of the quark or eyepiece, or doesn't it matter.

I also read a fr will increase the bandwidth of the quark.

Lastly, I used the quark a few times and only noticed today that on side of the fob was darker then the rest. Is this what people called banding ?

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Some say that having the reducer on the EP is a better way to go as it won't change your (optimum) f9 x 4.3= f38.7 that feeds the etalon.

Figuring out the reduction can be a challenge, espc before the Quark ie on the diag nose piece. My own reducer, on the EP side gives .5x @ 1.87" from the field stop ( focal plane) and I normally use less reduction than this- mostly about .8x. Individual EP's vary in the amount of reduction they like... The limiting fov with the Quark is it's own 22-23mm internal diameter, the reducer will not give any wider views than is constrained by this (using EP reducer).

If you fed the Quark f7.5 using the reducer, this should (maybe) ok, but what will the actual reduction be in this config when the reducer is so far away from the focal plane? I don't know to a certainty.

Your 100ED is a perfect scope for the Quark as is and I would personally reduce it on the EP side, just my opinion. :smiley:

Edited by jetstream
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Thanks, I had a look and found for the Antares 0.7 2" reducer measurements how the magnification will work out. The reducer needs 78mm and I think I have 90 between the fr and the shiny bit inside the quark nose piece. This would give me 0.75x reduction, perfect :)

The only problem is that the Antares fr doesn't seem to have a filter thread for the uv ir cut filter.

How does the fr affect the in/ out travel need ? Do I have to rack out further with the fr in place.

(The orange card board is an attempt to deal with the excessive er of the 40mm TV plossl ;) )


Edited by Bender

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I'll check the relative focus positions next time out, the nice thing about the EP reducer is that it "pulls in" the ER so that my 32mm TV plossl is useable. The shiny thing is the ITF surface and after this is the telecentric I think- I have no idea what the effective FR would be, but if its .75x perfect. I read that about the Antares 2" , no filter threads. Maybe put the UV/IR on first and then the reducer? I make sure my solar UV/IR "rattles" it's cell- room for expansion- the Antares retaining ring can be loosened if needed. I don't know for sure this would work.... maybe ask some more experienced solar members about it.

Very nice set up BTW!

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