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Pentax XW dimensions

Eyepieces
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#1 GGK

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Posted 03 March 2021 - 09:34 PM

Will someone who owns a Pentax XW 7 though 20 mm eyepiece please measure the eyecup opening diameter for me - the opening in the screw-on adjustable eyecup where you put your eye to view.  I cannot find that dimension online anywhere, don't know anyone who owns one, and there are no telescope shops in my area.

 

I have a C8 SCT and use Delos and Pentax XL eyepieces for 20mm and lower. Reasons are optics quality and 20mm eye relief with the adjustable eyecup positioning. I find the Pentax XLs to be excellent eyepieces, but with one big negative -- the eyecup opening at the lens is quite small (only about 28mm / 1-1/8") compared to the much larger diameter opening of the Delos. I prefer the Delos in this respect, and it's strictly a comfort thing for my personal viewing -- the older Pentax XL eyepieces have great optics and function.

 

I want to know if the newer 1-1/4 Pentax XW eyepieces have a larger opening in the eyecup than the older XLs since they changed from 65 degrees to 70 degrees AFOV.  I plan to replace the XLs and would prefer to keep a mix of Pentax and Delos if the XWs have a larger eyecup opening.

 

Thanks and I wish you all clear dark skies these last weeks before Daylight Savings Time makes us stay out an hour later.

 

.

 

 



#2 Lentini

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Posted 03 March 2021 - 09:54 PM

Looks like 33mm for the 10mm XW.

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#3 Stellar1

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Posted 03 March 2021 - 11:18 PM

My 3.5, 5, and 14mm XW’s all measure exactly 3.4cm inside edge to inside edge of extendable eyecup as shown in image above, I’m guessing they’re all the same.


Edited by Stellar1, 03 March 2021 - 11:24 PM.


#4 Gastrol

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Posted 04 March 2021 - 12:38 AM

My 7, 10, 14, & 20 XW’s all measure 34mm.



#5 GGK

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Posted 04 March 2021 - 09:34 AM

Perfect, Thank you all very much. 

 

Added information that might be useful to anyone looking for this type of detail when comparing the different eyepieces:

 

These pics are 1-1/4 barrel Delos vs. Pentax XL (not XW):

Delos Pentax XL Eyecup.jpg

Delos Pentax XL.jpg

The pictures show both eyepieces with the eyecups fully extended.  The eyecup opening in the Delos is 3.8cm vs. the Pentax XL at 2.8cm.  Delos APOV is 72 degrees vs. the 65 degrees of the Pentax XL.  As noted in replies to my opening post, the newer Pentax XW has a 3.4 cm opening and the APOV is 70 degrees.

 

All of these eyepieces have 20mm eye relief, adjustable (in-out) eyecups and outstanding optics.  The Pentax eyecups adjust by screwing them in or out; the Delos by twisting to unlock, pulling in or out then twisting to lock. Both are good, the Delos is faster.

 

I also use 30mm and 40mm Pentax XW and 22mm Nagler T4 eyepieces.  The eyecup openings in the 2 inch Pentax XW (30 & 40mm) are 3.4cm, and the Nagler T4 is 38 to 39cm.  XWs have 70 degree APOV, 82 for the Nagler.  The Nagler eyecup adjustment is different than Delos.  It simply pulls in and out with click depressions to keep it in place.  Simple and fast, but some guest users will push it in by mistake.  Note that the eye relief of the 22mm Nagler is 19mm. vs. the Pentax XW 20mm eye relief, but I cannot tell the difference between 19 and 20 when viewing.

 

My current eyepiece set: 6 /10 /17.3mm Delos, 7 / 10 / 14mm Pentax XL, 22mm Nagler T4, 30 / 40mm Pentax XW.  I use all of these in a 25 year old C8 SCT on a EQ6-R mount, visual only.

 

I view without glasses, eyecup fully extended and my eye is just about against the eyecup, which is why I prefer the larger eyecup opening - the eyecups with the smaller openings tend to hit my eyelashes, which is sometimes annoying.  In no way does the XL eyecup interfere with the field of view. It's a great eyepiece, just less comfortable for me. Light pollution isn't too bad here, but ground level ambient light can be, so the eyecups are pretty good shields.  I also wear a hood to block ground level light

 

Thanks again to those who replied.

 



#6 rkelley8493

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Posted 04 March 2021 - 11:03 AM

Here's a size comparison of XW vs Delos vs Morpheus

XW looks smaller because of the eye cup, but the difference is only marginal [negligible]. They're roughly the same size. 

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Edited by rkelley8493, 04 March 2021 - 11:13 AM.


#7 rkelley8493

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Posted 04 March 2021 - 11:04 AM

Here's a size comparison of XW vs Delos vs Morpheus

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#8 GGK

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Posted 04 March 2021 - 12:11 PM

RKelley, thanks for the pic.

 

I've not used a Baader Morpheus.  I've read positive reviews, but not a direct comparison for visual use.  How does it compare in image quality to Delos?  The style looks similar.  Is the eyecup adjustable in/out?  I like the winged eyecup option shown on the flyer to shield side light (neighbor's lights).  The 12.5mm Morpheus could be a good replacement for my 14mm Pentax XL.  Dropping from 17.3mm Delos to 14mm XL is too small of a step, but dropping from 17.3mm to 10mm, which is my next eyepiece is sometimes too much in bad seeing conditions.  I try to keep eye relief at the 20mm mark and the 12.5mm Morpheus is right on target.  The 12.5 Morpheus might be a good option.  

 

Thanks also for including the Delite in the one pic. I had not seen a direct comparison before. I briefly considered the Delite series, but instead moved right to the Delos for the extra 10 degrees AFOV.  Many times I see something of interest next to my original target because of a larger field of view.  


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#9 Starman1

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Posted 04 March 2021 - 03:33 PM

RKelley, thanks for the pic.

 

I've not used a Baader Morpheus.  I've read positive reviews, but not a direct comparison for visual use. 

1) How does it compare in image quality to Delos?  The style looks similar. 

2) Is the eyecup adjustable in/out?  I like the winged eyecup option shown on the flyer to shield side light (neighbor's lights).  The 12.5mm Morpheus could be a good replacement for my 14mm Pentax XL.  Dropping from 17.3mm Delos to 14mm XL is too small of a step, but dropping from 17.3mm to 10mm, which is my next eyepiece is sometimes too much in bad seeing conditions.  I try to keep eye relief at the 20mm mark and the 12.5mm Morpheus is right on target.  The 12.5 Morpheus might be a good option.  

 

Thanks also for including the Delite in the one pic. I had not seen a direct comparison before. I briefly considered the Delite series, but instead moved right to the Delos for the extra 10 degrees AFOV.  Many times I see something of interest next to my original target because of a larger field of view.  

1) Morpheus is wider (76° and measured at 78°) and at the 72° point is about the same as the Delos.  TeleVue has a more elaborate eyeguard and a better finish.

2) Morpheus eyeguard has 4 possible heights (using the supplied extender).  The Wing eyecup fits the eyepiece or the extender, so 2 possible heights there, too.

It's a LOT wider than an XL.



#10 GGK

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Posted 05 March 2021 - 03:28 PM

Starman1, thank you. Very helpful to have this information as I look to upgrade.


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