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If the Pentax XW 30mm & 40mm came back, would you buy?....

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#251 astrophile

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Posted 25 December 2019 - 09:08 PM

...  That he saw FC in both shows his degree of accommodation is well below yours.  ...

...well I'm sure that is less the case now than back then.  My arms still keep getting shorter these days even with readers on!  tongue2.gif   Fixed-focus eyeballs loom near in the future, as with all of us eventually I suppose.



#252 astrophile

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Posted 25 December 2019 - 09:11 PM

Trouble with the Pan is its form factor ergonomics. If TV had copied their 35mm, all would have been fine. But to get available eye relief long enough fir wearing glasses, the screw-on top has to be removed completely leaving a metal volcano top with no buffer. https://stargazerslo...comment-3401806

 

Strewth, even my Rodenstock in its BG Optics housing has a rubbery ring around its eye aperture so a user can go close in comfortably, see photo below.  

Maybe cut a narrow ring out of a rubber jar opener and rubber-cement it to the volcano top?


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#253 Jeff Morgan

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Posted 25 December 2019 - 11:30 PM

I found significant FC with the XW40 in my A-P 130 EDF (f/6).  It was OK with my dob (10" f/6).  But I wanted a widest-field that would work with both... so out the XW40 went (twice--I really wanted to like it!), replaced by a Pan 41 that renders outstanding views in both.  Albeit at a cost in weight which is no issue in a dob, but annoying in the balanced refractor.

 

So no, I will not be buying either new XW--been there and done that.

 

I also had the opportunity to use that eyepiece in 80mm f/6 refractor, same result. Ten years later it still baffles me as to why telescopes with opposite Petzval surfaces showed the same result.

 

Supermonos have a reputation for field curvature. I owned all focal lengths from 5mm to 14mm using them heavily, and never noted it whether the scope was a 2800mm Newtonian or a 1000mm refractor.

 

Indeed, it is rare for me to see field curvature in any eyepiece. That is why I leaned toward the "defective sample" theory on the 40XW, as improbable as that is.

 

The 41 Panoptic is indeed a safe choice in that class. After a long series of eyepiece moves I eventually ended up with a 40 Paragon. Performance is quite good in my f/7 scopes, and seventeen ounces sealed the deal.

 

It would be nice to get a look at another 40XW, but I don't want to go through another return process. Probably the safest course would be to talk one of my observing buddies into buying one wink.gif



#254 Jeff Morgan

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Posted 25 December 2019 - 11:39 PM

...well I'm sure that is less the case now than back then.  My arms still keep getting shorter these days even with readers on!  tongue2.gif   Fixed-focus eyeballs loom near in the future, as with all of us eventually I suppose.

 

lol.gif

 

I know the feeling. Much easier with cheaters, though last December (at age 57) I was able to get my FAA First Class medical certificate renewed without a reading glasses restriction. I think I am going to frame that one!

 

Didn't even try this year though. Can't squint that hard anymore. Surrendered as gracefully as I could manage.



#255 Piero DP

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Posted 07 January 2020 - 03:58 PM

In my 12.5" coma-corrected dob.

I wonder if I got a turkey 30 XW, and you got a turkey 30APM! We will have to compare notes next time I bump into you at Pinos. . .


I never looked through a 30mm Pentax XW, but am very pleased with the views that my 30mm APM UFF delivers in both my 12" dob f6 and Tak 100DF.
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#256 Piero DP

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Posted 07 January 2020 - 04:05 PM

...

In any case I ordered a 30mm APM UFF eyepiece in late October and I was fortunate enough to able to use it for about 5 hours at a very dark sky site (and on a moonless night) and it did perform very well for me. Its true field is 98% as wide as what the 35mm Panoptic provides and I very much like the higher power and darker sky background advantages it provides in comparison to a 35mm eyepiece. And in my F/7 telescope the image sharpness across the entire field is very good (if not excellent) and more than sharp enough to satisfy me.

Also since I was more than satisfied enough with the 30mm APM UFF eyepiece I sold my 35mm Panoptic and now I don't feel like I either want or need to get a 30mm Pentax XW eyepiece.

...

John Finnan


I did exactly the same. Whilst I like the 35mm Pan very much, I prefer the 30mm APM UFF, and the former found a new home.
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#257 areyoukiddingme

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Posted 07 January 2020 - 05:02 PM

I never looked through a 30mm Pentax XW, but am very pleased with the views that my 30mm APM UFF delivers in both my 12" dob f6 and Tak 100DF.

 

The more I use the APM the more I like it. Last night I had my 8" F7 reflector out for a quick peek.

 

The 30 APM is the widest field that scope will do (it has an undersized secondary). Stars were sharp across the field, with only trace amounts of coma from the mirror. It's also very comfortable and easy to use.

 

I'd be surprised if you found the XW bested it in your F6 Dob and Tak.


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#258 Ronofthedead07

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Posted 07 January 2020 - 06:48 PM

The removable metal ring on the 30 and 40 won't seat on the 20 and below. GN

 

Ah, so it's larger than 43mm on the 30mm and 40mm.

This is from some time ago, but to follow up the XW 30 (and 40, I assume) does have the same 43mm threads around the eye lens as the 1.25" models .

 

The removable metal ring does not attach to these threads but rather to a separate set of threads inside of the rotating grip part. They are much wider on the 30 and 40 than the others.

 

The 30 APM UFF has camera adapter threads too but they are a bit larger...I would assume they are the same M44.5 x 0.75 as the APM XWAs.

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Edited by Ronofthedead07, 07 January 2020 - 06:53 PM.


#259 Jeff Morgan

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Posted 07 January 2020 - 10:11 PM

The 30 APM UFF has camera adapter threads too but they are a bit larger...I would assume they are the same M44.5 x 0.75 as the APM XWAs.

 

Some entrepreneurial amateur will come up with a Dioptrx adapter that uses that thread.


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#260 Piero DP

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Posted 08 January 2020 - 03:11 AM

The more I use the APM the more I like it. Last night I had my 8" F7 reflector out for a quick peek.

The 30 APM is the widest field that scope will do (it has an undersized secondary). Stars were sharp across the field, with only trace amounts of coma from the mirror. It's also very comfortable and easy to use.

I'd be surprised if you found the XW bested it in your F6 Dob and Tak.


Same here. The more I use it, the more I like it.

On a side note, I actually prefer the amp 30mm to my Lunt 20mm HDC, although I'm not a great fan of 100 Deg EPs. Both have a very comfortable eyecup.

#261 Ronofthedead07

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Posted 08 January 2020 - 09:07 AM

Same here. The more I use it, the more I like it.

On a side note, I actually prefer the amp 30mm to my Lunt 20mm HDC, although I'm not a great fan of 100 Deg EPs. Both have a very comfortable eyecup.


The Lunt is made by APM and has the same eyecup as the UFF if I am not mistaken. I agree that they are quite comfortable to use and work well at blocking outside light.

I thought the 13mm 100* was a great eyepiece but didn't like the short eye relief. It's the price you pay for that super crazy wide field...


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