Re: eyepiece projection setup recommendations?


"Chris L Peterson" <clp@xxxxxxxxxxxxxxxxxx> wrote in message
news:v4c8r1loeta27c9aarnvlgalgd4pq9siva@xxxxxxxxxx
> On Thu, 29 Dec 2005 18:44:22 GMT, "George"
> <george@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
>>I have two digital cameras; one is an SAC IVD, and the other is a DSLR
>>Cannon 300D. I have two 1.25" adapters with the T-ring threads on one
>>end
>>that would let me mate either camera to a barlow and then to my newtonian
>>telescope. So would this work?
>
> It sure will. You might be better off using a 2" adapter with the 300D,
> however. The smaller barrel may vignette the large sensor.
>
> _________________________________________________
>
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com

Hmm. That might be a problem, since my focuser comes with a 2" adapter
(and T-threads on the focuser itself for mounting cameras with a T-thread
adapter) for 2" eyepieces, but I'd have to buy a 2" adapter with T-threads
on it in order to mount the camera to a 2" barlow. Then, of course, I'd
also have to buy a 2" barlow, and since I only have one 2" eyepiece, it
wouldn't be very useful for visual use. On the other hand, a good 2"
barlow for photographic use might just provide better results, and I can
always buy a 1.25" one for visual use.

A couple of questions though that have bothered me for a while. I have a
Konus 200MM Newtonian scope. I bought a 2" 50 mm meade MH50 eyepiece a
while back for doing wide field visual observation, and was rather
disappointed to find that when using the 2" eyepiece adapter for the scope,
I have to rack the focuser all the way in to focus using this eyepiece, and
even then it still doesn't come completely into focus. I've thought about
shaving perhaps 1/8" off the adapter so the eyepiece will come into better
focus, but I don't like to perform that kind of surgery if I don't have to.
So my question is is this normal for a scope manufacturer to provide a 2"
eyepiece adapter and then have a factory 2" eyepiece not focus properly
using the adapter? Is it something specific with this eyepiece so that if
I bought another one (say, a 32 mm, which I'd love to do), and had already
modified the adapter, would I have another focusing problem? Since a lower
power eyepiece normally focuses further away from the secondary mirror than
a higher powered eyepiece, would shaving 1/8" be enough, or would I have to
rack the focuser further in than it is able to travel? And how would this
problem affect my trying to use a 2" Barlow? I guess by now you might see
why I've been leary of spending money on the Barlow. I don't have a
problem when the scope is configured for 1.25" lenses, or when I set the
scope up for digital photography at the focal plane of the scope (although
I do have to rack the focuser almost all the way in for any image to come
into focus using the Cannon camera). I realize that you might not be
familiar with this scope, but I thought I would ask anyway. TIA.

George


.

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