Re: [Utah-astronomy] Pupil envy
Chuck sed--
Taken to extremes, the limit with Newtonians anyway, is when the shadow of the secondary mirror gets large enough to completely fill your pupil- then you see nothing at all, on-axis!
That's the problem I have when the exit pupil gets too large for my pupil. The secondary takes a larger and larger portion of the image reaching the eye, and it can be quite difficult to hold an image. For me anyway, long eye-relief makes it even trickier, since you have to keep your head in a perfect position. Even though there might be higher resolution in the image, it's hard for me to deal with that odd blind spot bobbing around out there. Just goes to show you how personal the match may be between observer and equipment. I've often gotten a so-so view with an eyepiece someone else is raving about--even when it's obvious that eyepiece is really showing them a lot. This is why you have to be cautious about recommendations.
Excellent advice, Michael. And not just the personal touch, but the telescope itself matters. Remember that any given eyepiece will perform much differently on an f/4 instrument than it will on an f/15 of the same aperture. Those long FL eyepieces that are a pain in the keyster on a short-focus Newtonian will show a different side of their personality on the Bogdan refractor at SPOC- and no secondary shadow at all. I used to use a homemade 4.25" f/5 Newtonian for low-power sweeping- until I got my ED 80mm refractor. Now I can use those long-FL 2" eyepieces without a secondary shadow. The 4.25" Newt is now decoration on my dresser. And sometimes, mind you, the raver doesn't know a good image from a so-so one. It cost a lot so it must be good, in their mind. List members excluded, of course. We ARE a discriminating bunch! --- Michael Carnes <michaelcarnes@earthlink.net> wrote:
Just goes to show you how personal the match may be between observer and equipment. I've often gotten a so-so view with an eyepiece someone else is raving about--even when it's obvious that eyepiece is really showing them a lot. This is why you have to be cautious about recommendations.
__________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
participants (2)
-
Chuck Hards -
Michael Carnes