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The Pentax PR Spotting Scope Meets The ULF APM 24MM Eyepiece (1 Viewer)


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The Pentax PR 65 Spotting Scope Meets The UfL APM 24MM Eyepiece

After waiting month's for the APM Ultra Flat Field 24mm 65 Degree Eyepiece to be shipped to me from AgenaAstro.com, it finally arrived today. It could not have come at a better time, with me having on hand another Pentax ED spotting scope. I first read about this eyepiece months back on some of the well known Astronomy web sites, where it got pretty much great reviews across the board. I originally had second thoughts, would it focus correctly ? Would it provide the full AFOV(65) with its very large FieldStop of 30.2mm ?, because this is the first low power(15.4x) fixed 1.25" eyepiece I have ever tested having a FieldStop that big on any of the Pentax 65 ED spotting scopes ...... I was quite relieved not only when it focused correctly but also showing no signs of cut off issues with the little Pentax 65 prisms. As you can see from the pictures this eyepiece is huge. It fits the Pentax PR 65 like a glove, with the base of the APM eyepiece diameter fitting on the Pentax eyepiece locking collar having pretty much the same diameter. The eyepiece itself slides easily into the 1.25" locking collar on the Pentax. As you can see in the 2nd picture with its rubber eyecup folded down, its ocular lens is huge. I could not find any reviews on any of the Astronomy web sites regarding its use for terrestrial daytime viewing. The daylight here in this part of the world(3:30 PM EST) with snow flurys/freezing rain is not the best viewing hours for even this low power(15.4) fixed eyepiece but what I am seeing is a very impressive clear/sharp view. With its huge ocular eye lens, combined with the large amount of eye relief it provides, makes this a very easy/comfortable eyepiece to use. I will post back later when I get a better day with some daylight, my opinion of just how well the Pentax PR 65 spotting scope/APM UFL 24mm eyepiece combination performs durring daytime terrestrial viewing.


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Thanks for the post. :t:
I'm interested to know your opinion on how it compares to the ES62 26 and the XW20, in terms of comfort, image quality and AFOVs - in terms of TFOV I think I know the difference...;)
If you could make photos to show AFOVs, as I did at http://www.pt-ducks.com/cr-telescopes.htm#Test_of_my_present_preferred_cr-telescopes it would be great

Hi David ...
This is my opinion based on using these three eyepieces on either the Pentax 65 PF-ED or PR ED Angled Spotting scopes.
Ranking the three With Number 1. At The Top : From one to three on my perception of the image quality thru my eyes
1. The Pentax XW20
2. The APM UFL 24mm
3. The ES 26mm 62 Degree

Comfort :
1. Pentax XW20 Being Equal To The APM UFL 24mm.
2. With The ES 26mm 62 Degree
My comfort rating of the Pentax and the APM being so close to the same is because of them both having at least 20mm of eye relief with both having large ocular lens. Some, even many here might have a different opinion because of ones eyes/facial characteristics not always being the same as mine. This also goes for the way I have ranked the three's image quality, we all do not see things the same due to age, facial characteristics. One last thing I would like to say that relates to the Pentax and the APM eyepiece with regards to comfort : the APM has a folding down rubber eyecup, with the Pentax having a rotating twist up/down eyecup which in my opinion is one of the nicest eyepiece eyecups I have ever used on any 1.25" eyepiece.
I have ranked the ES 26mm 62 last not because I did not like the eyepiece, I did. Optically it was a gem. With its ocular lens meeting my minimum lens diameter size while providing just enough eye relief for use with my glasses.
As far as the apparent field of view(AFOV). With the Pentax XW20 on paper spec's saying 70 degrees and the APM having 65 degrees, to my eyes the APM field of view looks considerably larger. I do not know if this is due to the different focal lengths of the two, one being 20mm and the other 24mm or because the Eyepiece ocular lens/Field Stop of the APM eyepiece is larger than Pentax XW20 eyepiece or if it is just the way my brain is perceiving the image. Maybe someone more qualified here on this forum can more explain just how the size of the scopes objective lens/focal length, combined with the focal length of the eyepiece and field stop size/lens ocular size come to formulate the size of the view we see. David I can not post any pictures of the AFOVs of the eyepieces because I do not have the right camera equipment.
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