questions for 100mm users (1 Viewer)

i have some questions for folks who currently use, or did in the past, a 100mm prismatic spotting scope.
which one?
which eyepieces?
your comments on its performance?
did you ever use it for astronomy, and if so, how was its performance?
If you no longer use it, why not?

thanks

Im not owner but i can asnwer some of those questions:

The performance is better always if we talk about the same series, more apperture means more resolution and more bright exit pupil at same mags, but if you compare diferent brands then to me its not surprise if some 85 mm are brighter and offer better views than another 100 scope.

For the experts astronomers only the alpha scopes can do some decent to good performance on planetary, i guess for stargazing at low powers could be a good option.

If they not using no more probably is because they move to a lighter scope, read this recent thread:

http://www.birdforum.net/showthread.php?t=284438

To resume: mainly a big scope takes advantadge when the sun comes down and you need a bigger exit pupil or your preference is the need of that extra mags for long range targets. To me make no sense pick a no APO/ED 100 scope, they are designed to hold high mags and at high mags is when chromatic aberration is more present, unless you want make the most the daylight at low powers i dont see the reason to buy one no APO/ED 100 scope.

its not so much the objective being the problem for astro -its the prisms which show unwanted features at higher power. do you want the scope for both birding & astro?

dannat said:

its not so much the objective being the problem for astro -its the prisms which show unwanted features at higher power. do you want the scope for both birding & astro?

Click to expand...

Just curious. A waterproof dual use would be cool.

for astro use you'll need to go with one of the name brand expensive options -the celestron regal 100ed was hoped to be good, esp that it fits standard 1.25" astro epos -but doesn't review well for astro use -if you kep the magnification to 100x you may be ok -dont try pushing past this, most prisms start showing effects astro wise above about 50-60x, but swaro, nikon generally hold up better with the higher mag's

i just went out & checked my fieldscope (its 700pm here)
the optics it has are remarkably good -the CA on the moon at 75x is virtually non-existent, you can only detect a tiny line on one half of the limb on the moon if you are either just off focus, or you tilt your eye to induce it.
the view of saturn was also good (you needed perfect focus to remove the spikes from the prisms)-the ring was clearly visible & separated form the planets disc. jupiter's moon were clearly visible, i could just make out one of the salmon bands of the eq belts{its low & setting here}
mars was hopeless -as it is in less than a really good scope (i have a 10' hand crafted dob. reflector)
overall i was quite impressed with what the 82ED could throw up -i may have my friend with a lathe make an adapter to use either a 5mm or 4.5mm eyepiece with the scope -the WP is great for our frosty/dewey nights {i live 1700ft elevation}

In my experience the best specimens of prismatic birding scopes have been just as well corrected as high quality astronomical refractors, even reaching 1/8 wave, but those have been cherry examples of high end Swarovski, Nikon and Kowa scopes.

By the way dannat, the roof edge of the Schmidt prism in the Nikon 82ED doesn't cause a diffraction spike, so I think you must be seeing something else. One of the nicest things about the design of that scope is that the prism is oversized and offset so that the roof edge is kept out of the light cone.

jaymoynihan,
You might be interested on having a look at http://www.pt-ducks.com/cr-telescopes.htm#Test%20of%20100mm%20telescopes
I still use the Optolyth but prefer the TMB92+barlow+FSA-L2+Ethos17 http://www.pt-ducks.com/cr-telescopes.htm#Test%20of%2082%C2%BA,%20100%C2%BA%20and%20102%C2%BA%20AFOV%20zooms since allow me to reach higher magnifications without loosing TFOV.
I'm not a astro observer but the colours of the TMB are better. However I used the Optolyth on astro observation nights at the secondary school where my wife is teaching and no one complained...