3 replies to this topic

[HouseBuilder328]

I have the Oberwerk 100XL binocular telescope and they came with their own 70° 14mm (40x) eyepieces.  I was looking to increase this to the maximum 80x zoom with some 7mm eyepieces.  Should I just go with Oberwerk's 70 degree 7mm eyepieces from their website?

https://oberwerk.com...cope-eyepieces/

 

I'm usually used to buying ES eyepieces at 82 degrees.  Any other recommendations like Televue, etc or just get the pair from Oberwerk?

[HouseBuilder328]

https://www.astronom...6.html?___SID=U

How about the above instead of the Oberwerk 7mm pair?

[noisejammer]

Your Oberwerk bino's appear to be very similar to those offered by APM - so I think the objectives are about f/5.6. This is reasonably forgiving for many eyepiece designs. That said, most folk have binocular vision that extends through roughly 70°, so there's no great reason to chase ultrawides, unless you have something that's reasonably close to what you're after.

 

Nevertheless, there are plenty of options. I have a pair of 7mm Nagler Type 6's (that's your second link.) These are great (albeit expensive) eyepieces provided you don't need to use glasses when observing. If you do need glasses - say to correct astigmatism - then you'd be wise to pick something with a little longer eye relief. You could refer to Don's eyepiece buyer's guide which is available here... High end options with a lot of eye relief would be the Pentax or TV Delite 7mm and the Delos 8 mm. Ergonomically, I prefer the Pentax, optically, I think the TV offerings are a little better.

 

Don't lose sight of how critical the collimation will become as you increase magnification. Besides collecting light, telescopes act as optical angle magnifiers and you may pass the threshold where your eyes can compensate for the misalignment.

[HouseBuilder328]

You're right, with the focal length of 560mm, not much benefit over the 70 degree eyepieces.  Most likely, I'll save my money and buy the Oberwerk 7mm.