Hi - I have a set of 125mm binoculars and would like to replace the narrow AFOV stock eyepieces with something a bit wider. The lenses are at f/5, so I'm thinking I'll need a pair of high-end eyepieces to get decent edge performance. I like the performance of Panoptics in a regular scope - as long as I'm not "panning." The pincushion distortion is so bad in the Pans that I get motion sickness if I do it for very long! I'd like an AFOV of 65 degrees or better. So, I'm looking for suggestions. Thanks! - Chuck
Eyepieces for Binoculars
Started by TheDesertSage, 02/20/2008 01:22AM
Posted 02/20/2008 01:22AM
Opening Post
Posted 02/22/2008 10:39AM
#1
I have no idea if they will work for your proposed use or not...
But, I really enjoy my 21 mm Denkmeir eyepieces in my Binoviewer. From memory, they have 20 mm of eye relief and a 65 degree AFOV. I also have a 24 mm Panoptic (mono) which I adore but I'd place the 21 Denks in the same category with respect to quality. I've found them to be fine eyepieces. For the record, I also have the 14 mm Denks as well and think highly of them as well.
But, I really enjoy my 21 mm Denkmeir eyepieces in my Binoviewer. From memory, they have 20 mm of eye relief and a 65 degree AFOV. I also have a 24 mm Panoptic (mono) which I adore but I'd place the 21 Denks in the same category with respect to quality. I've found them to be fine eyepieces. For the record, I also have the 14 mm Denks as well and think highly of them as well.
Posted 02/22/2008 11:43AM
| Edited 02/22/2008 11:58AM
#2
125mm at f/5? Hmmm, that sounds really quite short. The Oberwerk BT100 is 100mm F=620mm, so it's f/6.2, or F=598 depending on which model you have, straight or angled.
I presume you are looking at 1.25" eyepieces? I've not seen any stock binocular telescopes that use a larger size eyepiece. You might want to start looking at field stop diameters rather than stated Afov. Stated Afov includes pincushion and therefore true fs dia produces a smaller Tfov than the Afov would indicate. Your 65 or better requirement would eliminate the 24Pans, as they actually only have a 27mm fs, which really gives only 64°, not the 68 which includes pincushion. Maximum fs diameters all top out at about 27.5mm. Some eyepiece hav NO field stop, which means inside barrel sleeve diameter of about 28mm controls fov. It gets you a bit wider, but the view is usually an indistict greyed ring in the outer 5%fov.
These will all give nearly identical Tfov, except the Ultimas, would be about 3-4% smaller, negligable really in the grand scheme of things. Probably far more important would be selecting for minimal outer fov aberrations, in which case, I'd eliminate the Meade 5K, which IMO has the most. I have an Oberwerk 24.5mm eyepiece with fs=27.3mm, that gives a similar WF as these, but outer field aberrations ar poor.
24 Panoptic fs=27mm
26mm Meade 5K pl fs=27.4mm
30mm Ultima pl fs=26.2mm
32mm TV pl fs=26.9mm
Once you get a list of eyepiece field stops that max out your fov, select the magnification/exit pupil you want to live with.
edz
I presume you are looking at 1.25" eyepieces? I've not seen any stock binocular telescopes that use a larger size eyepiece. You might want to start looking at field stop diameters rather than stated Afov. Stated Afov includes pincushion and therefore true fs dia produces a smaller Tfov than the Afov would indicate. Your 65 or better requirement would eliminate the 24Pans, as they actually only have a 27mm fs, which really gives only 64°, not the 68 which includes pincushion. Maximum fs diameters all top out at about 27.5mm. Some eyepiece hav NO field stop, which means inside barrel sleeve diameter of about 28mm controls fov. It gets you a bit wider, but the view is usually an indistict greyed ring in the outer 5%fov.
These will all give nearly identical Tfov, except the Ultimas, would be about 3-4% smaller, negligable really in the grand scheme of things. Probably far more important would be selecting for minimal outer fov aberrations, in which case, I'd eliminate the Meade 5K, which IMO has the most. I have an Oberwerk 24.5mm eyepiece with fs=27.3mm, that gives a similar WF as these, but outer field aberrations ar poor.
24 Panoptic fs=27mm
26mm Meade 5K pl fs=27.4mm
30mm Ultima pl fs=26.2mm
32mm TV pl fs=26.9mm
Once you get a list of eyepiece field stops that max out your fov, select the magnification/exit pupil you want to live with.
edz
Funding Member
