Reviving this thread to see if anyone has tried this product, in a suitable scope, without NVD. None of the problems described above apply to my use case. What's the image quality like? Any colour changes? Field stop sharp or fuzzy? Things like that.
Thanks!
I've tried the eyepiece in a TV-85, 600mm focal length, f/7. The image is fine, but not as nice as a 40mm XW or 32mm Masuyama, which have the same true field as the TV-67.
Three things are very evident.
First is that the TV-67 needs A LOT of outward focuser travel. I extended the barrel by 2 inches, otherwise it would only come to focus when I held the eyepiece above the diagonal.
Second is that the eye relief is LONG. Even with the eye lens recessed, I have to hover above the eyepiece. An eye guard extender would be beneficial like it is for the 32mm and 40mm TV Plossls.
The apparent field is about 40o. Using the TV-67 visually instead of the 40mm XW has the same feel as using the 40mm Plossl instead of the 32mm Plossl - A brighter image which can be beneficial when using narrow-band nebula filters, but a negative for non-filtered visual use except for the few times one needs the largest exit pupil.
When using the TV-67 in my 85mm, f/7 refractor, the effective aperture drops to about 55mm, so that combined with the brighter background makes some of the stars invisible that are visible in the 40mm XW.
So, for a more fair comparison, this morning I pointed toward Orion and put the 2X Powermate between the eyepiece and diagonal in order to see full aperture for both the TV-67 and 40mm XW. 1200mm focal length, f/14. There was no change in my general impression of the eyepiece, but I did see a little EOFB in the TV-67. Now, the sky was entering morning twilight and some clouds and haze were present, so it might simply have been from the atmosphere interacting with the larger exit pupil. The exit pupil was ~2.9mm for the 40mm and 4.8mm for the 67mm, so a major increase in image brightness.
If you need the 5mm exit pupil, then I wouldn't hesitate to get the 67mm conversion lens, accepting the 40o apparent field as the trade off. It's very simple to install and remove if first I take off the top shroud of the 55mm Plossl.
---and the field stop appeared clear and sharp to me.
Gary
Edited by GGK, 07 September 2024 - 05:56 PM.