I bought this on Ebay a couple weeks ago. I have never owned a Vernonscope/Brandon telescope before, but I have enjoyed the Brandon eyepieces for several decades. So, without much research, I put a bid in an actually won the auction. Then, I started to research the telescope
There is limited information on these 80mm scopes. But, what I could find was in the range of not good to bad. There seems to be several versions of this scope. I think I have one of the early ones. But, if I am wrong, please let me know. I know for sure it is not one of the 1990's version that were considered very good.
So, the story I found online was the Vernonscope got a proto-type from Japan and was very impressed. They ordered about 1000 of these lenses and the Japanese lens manufacturer did a bait and switch and sent lenses that in no way matched the quality of the proto-type. Any verification of this?
So, here is what I found. The telescope arrived Friday and I was excited to take it out and try it. I mounted it on my also newly acquired Pentax MS-3 mount (shown below on Kenko Alt/Az mount) and gave it a whirl. I was impressed! But, I was only using the eyepieces that came with the kit I purchased and the highest power I could get was 48x.
These past two nights I have been out with the scope utilizing 4/5/6/7mm orthos, a 7mm Nagler, a 4.8mm Nagler, and my favorite high power eyepiece, a 2.5mm Vixen LV. So, with these I could clearly see the issue, CA is bad, but not horrible in my old eyes.
The reason for my post is this....The 4.8mm Nagler was the best of the bunch to evaluate the scope. Using Vega and Altair as my targets, inside focus was yielded a violet halo. Outside focus was a green halo. Why? But, on this third night of observing with the scope I noticed something. There is a very small area of focus between the in focus violet and the out focus green where there appears to be no CA. Not a little. None. But, then again I am only at 100x. Is this typical for these scopes? Why does this happen? We are talking about the finest touch of the focuser to get this area between the two.
Thank you for any thoughts you might have on the above questions
Edited by Steve_M_M, 06 December 2020 - 09:08 PM.