Pentax PF-64EDII-Straight: Reality Check (1 Viewer)

Hello,
I am totally unfamiliar with Pentax spotting scopes. 4 questions about the Pentax PF-64EDII-Straight-through.

1. ED, therefore color aberration is low, how is the chromatic aberration?
2. Do i understand correctly, i could use 1.25" eyepieces (astronomy ones) with this scope?
3. Is there a thread or site covering what 1.25" ones work/don't work etc.
4. Has anyone used this scope with a University Optics eyepiece?

Thank you

Jay,

Both the original Pentax 65 ED and the ED II are practically identical scopes. They changed some internal element reportedly to even further reduce chromatic aberration in the image.

1. I am confused. ED/FL glass is utilized in optics to help reduce chromatic aberration (color fringing). I am not sure what you mean by color aberration. Chromatic aberration is fairly well controlled in both the original and the ED II. How pronounced it appears is going to be dependent on the eypiece and magnification you utilize. If you use an ED glass eyepiece in conjunction with the ED glass objective then CA is very controlled. If you don't then the scope is still better than average in this regard but is not living up to its full potential.

2. Yes, any 1.25 inch astro eyepiece will fit into this scope. Not all of them will achieve infinity focus though.

3. Though comments about one eyepiece or another are scattered throughout this Pentax spotting scope forum there was an excellent thread started by Can Popper, I believed, called the "Eyepiece Roundup" or something similar several years ago. There were several pages of discussion on the subject.

4. Not that I remember but there were alot of posts on the subject.

jaymoynihan said:

Hello,
I am totally unfamiliar with Pentax spotting scopes. 4 questions about the Pentax PF-64EDII-Straight-through.

1. ED, therefore color aberration is low, how is the chromatic aberration?
2. Do i understand correctly, i could use 1.25" eyepieces (astronomy ones) with this scope?
3. Is there a thread or site covering what 1.25" ones work/don't work etc.
4. Has anyone used this scope with a University Optics eyepiece?

Thank you

Click to expand...

1. Higher than other ED scopes. I've owned two (which says I like 'em enough) but the first series (prior to II) had noticeable CA in some conditions (high contrast). The II series claims to correct that some but I don't know for sure. You are asking about the II so this may be less of an issue. I wouldn't consider any of it objectionable.

2. Yep, almost any 1.25" ep.

3. I heard about some zooms that won't come to focus without an adapter or modification. As I recall, I think the William Optic zoom and one of the "super wide" eps (I think Night Owl?) but you might search on the specific EP. Sorry, can't be more specific. I used the 8-24mm Lanthanum and it was fine, but too narrow.

4. Negatory. I think the best bets are fixed 14-17mm, Hyperion for low budg and Pentax XW for best.

5. You didn't ask but I sold mine after viewing through various Nikon, Swaro and Kowa ED scopes. Even with a top of the line ep, the alphas were better. By a very small margin, but nonetheless. Again, that was the I series, not II.

FrankD said:

1. I am confused. ED/FL glass is utilized in optics to help reduce chromatic aberration (color fringing). I am not sure what you mean by color aberration....

Click to expand...

Yes. Still wanted to ask, as in the astro world (where most of my scope experience is), not all "ED" is created equal

And thank you to both you and Matt for your responses.

For what it is worth I pretty much agree with Matt on the CA issue. I have seen other optics control CA better. I am still pleased with the overall optical performance of the XW fixed eyepieces with the original ED A 65 though even in that combination there is noticeable CA around the outer edge of the image.