Pentax 85 degree eyepieces: Feedback from owners ?

[John]

The 23mm and 16.5mm Pentax XW 85 degree eyepieces have been out for around 10 months now. From time to time I have thought about moving to an all-Pentax eyepiece line up for the sake of simplicity and because I am very fond of my current XW's in the 10, 7, 5, and 3.5mm focal lengths in both performance and ergonomic terms. Adding the 23mm and 16.5mm 85's to those XW 70's would seem to create a pretty comprehensive and versatile set of quality eyepieces even feeding my "ultra wide" tastes when required 🙄 

I wonder if folks who own either (or both !) of these 85 degree eyepieces have any comments on how they have found them in the real world of practical observing ? 🙂

Many thanks in advance for any feedback 

[Don Pensack]

I reviewed both of them:

https://www.cloudynights.com/topic/849945-new-85°-pentax-eyepieces/?p=12369694

https://www.cloudynights.com/topic/849945-new-85°-pentax-eyepieces/?p=12369699

Bottom line: The 16.5mm is better than the 23mm, 85-90% of glasses wearers will not be able to see the entire field when wearing glasses (you need a very very close eyeglass-to-eye "vertex" distance to use only 12mm of effective eye relief from the rubber up.  The 70° XWs have about 3mm more effective eye relief than the 85s.).

They are heavier than the 22mm TeleVue Nagler, and I'm not sure about the transmission %--they seemed darker than other eyepieces at/near the same focal lengths.

I use a Paracorr in my dob, and the 23mm was noticeably vignetted.  Is that inherent in the 23mm, or an interaction with the Paracorr?  I don't know.  The 22mm Nagler does not, but that does not prove the 23mm eyepiece is at fault.

I liked the 16.5mm enough it might be in my collection right now had the eye relief been sufficient for glasses.  It is compatible with a DioptRx, however, though eye relief would be VERY tight with DioptRx added.

[John]

Thanks Don 

I'm not a glasses wearer when observing so ER , as long as it's reasonably comfortable, is not a critical issue.

Other feedback very welcome 😃

 

 

[Don Pensack]

1 hour ago, John said:

Thanks Don 

I'm not a glasses wearer when observing so ER , as long as it's reasonably comfortable, is not a critical issue.

Other feedback very welcome 😃

 

 

Then you will find them both comfortable.  Enjoy.

[Stu]

On 15/06/2023 at 18:59, Don Pensack said:

I reviewed both of them:

https://www.cloudynights.com/topic/849945-new-85°-pentax-eyepieces/?p=12369694

https://www.cloudynights.com/topic/849945-new-85°-pentax-eyepieces/?p=12369699

Bottom line: The 16.5mm is better than the 23mm, 85-90% of glasses wearers will not be able to see the entire field when wearing glasses (you need a very very close eyeglass-to-eye "vertex" distance to use only 12mm of effective eye relief from the rubber up.  The 70° XWs have about 3mm more effective eye relief than the 85s.).

They are heavier than the 22mm TeleVue Nagler, and I'm not sure about the transmission %--they seemed darker than other eyepieces at/near the same focal lengths.

I use a Paracorr in my dob, and the 23mm was noticeably vignetted.  Is that inherent in the 23mm, or an interaction with the Paracorr?  I don't know.  The 22mm Nagler does not, but that does not prove the 23mm eyepiece is at fault.

I liked the 16.5mm enough it might be in my collection right now had the eye relief been sufficient for glasses.  It is compatible with a DioptRx, however, though eye relief would be VERY tight with DioptRx added.

Thanks for the reviews Don. Have you tried them in a refractor? I’ve tended to steer clear of the longer focal length XWs for fear of them not playing nicely with refractors in terms of field curvature. Is that likely to be an issue?

[Don Pensack]

I can't say.  I did use them briefly in my 102mm f/7 triplet refractor and didn't notice field curvature.

The 16.5mm, in specific, had a very flat field.  I used them in the daylight.  I wanted to determine if I could use glasses.

But, that was only a few seconds to see if I could use glasses with them, and most of their usage was in my 12.5" reflector with Paracorr.

I could use glasses with them if I pushed my glasses hard against the eyecup and my eyelashes were brushing the back of the eyeglass lens.

Not comfortable for more than a few seconds.  With a comfortable pressure against the eyecup, I could only see maybe 70° of field or a hair more.

I think one would say they are glasses compatible only for those glasses wearers who have a near-zero distance from eye to glasses lens and thin lenses in the glasses, which probably rules out at least 80% or more of glasses wearers.

The eyepieces have 20mm of eye relief from the glass, but only 12mm of eye relief from the rubber eyecup.

[Stu]

3 hours ago, Don Pensack said:

I can't say.  I did use them briefly in my 102mm f/7 triplet refractor and didn't notice field curvature.

The 16.5mm, in specific, had a very flat field.  I used them in the daylight.  I wanted to determine if I could use glasses.

But, that was only a few seconds to see if I could use glasses with them, and most of their usage was in my 12.5" reflector with Paracorr.

I could use glasses with them if I pushed my glasses hard against the eyecup and my eyelashes were brushing the back of the eyeglass lens.

Not comfortable for more than a few seconds.  With a comfortable pressure against the eyecup, I could only see maybe 70° of field or a hair more.

I think one would say they are glasses compatible only for those glasses wearers who have a near-zero distance from eye to glasses lens and thin lenses in the glasses, which probably rules out at least 80% or more of glasses wearers.

The eyepieces have 20mm of eye relief from the glass, but only 12mm of eye relief from the rubber eyecup.

Thanks Don. I don’t (yet) wear glasses to observe so eye relief should be ok.

I currently have a 17.5mm Morpheus, 17mm Nagler and 22mm Nagler. I need to spend some more time comparing but do find eye placement quite sensitive on the Naglers compared with the Morpheus.