Focal Reduction

[Messier27]

We have a Celestron CPC800 Edge HD...the one with the internal field flattener.  Anyone using one of these and what are you using as focal reduction.  I have seen a Meade f/3.3 used on one with nice reduction but some perimeter coma.  I have an Antares .5 focal reducer...1.25" screw in filter looking 'thingie'.  I have gone to Optec but they suggest what comes out to be about f/6.8 when the T-mount adapter is included.

Anyone got any suggestions?

John

[Slipshoddon]

I also have the C8 Edge HD on an AVX mount.  I am doing some testing with focal reduction combinations of 0.63 and 0.5X reducers. So far I'm have problems with severe vignette get but will let you know after the test of set up is complete.

[Messier27]

We finally got out for our first/initial camera use this past weekend.  We got three nights and used the Antares .5 and the Optec Celestron HD Version for the 8"...it is f/5.2 but about f/5.7 or 8 with the t-mount adapter.  Both worked without coma, though I am probably going to need more reduction someway or get a smaller scope.  The Optec had was very, very nicely and minimal notice between the reduction size.  The Antares worked without coma but I picked up some vertical fine lines in the image.  I was using the Antares (1.25" diameter screw on filter style) mounted to the stock nose piece of the camera and inserted into a 2" diagonal on the back of the scope...we are in Alt/Az mode.  We will stay with the Optec as the results are very nice.  I have glaked with someone that has gone from the Meade f/3.3 to the Optec 3.3 version.  They say they do get some perimeter coma but image is far better than the Meade.  Hmmm, a bit of coma or buy a new scope...will have to think on that for a while.

Ah, still a learning curve but really enjoyed this camera.

Thanks for the reply

[StarMike]

I had the meade 3.3 and had severe vignetting.  It was really designed for a 1/3 inch chip and the Infinity is larger than that.  I sold it and got the Optec 3.3.  It has some minor vignetting but was easily removed using the histogram.  I does have some coma at the edges, but not enough to bother me

[Messier27]

Thanks Mike,

I have talked with Optec and we are waiting to see how things go with the 5.2 to see if we go for the 3.3.  Of course in the wacky way I do things, we ordered a non-HD 8" sct so we will see where this all runs.  (No wonder m head hurts so much 8~))

John