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Misaligned Pentax 20x60 PCF WP II ?

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#26 BobinKy

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Posted 06 February 2013 - 08:40 PM

Jarrod...

Sorry to hear about the condition of your first pair of Pentax 20x60. B&H should make this right--and I am sure they will. Please keep us posted.

#27 Jarrod

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Posted 19 February 2013 - 10:10 PM

Got the new set in this afternoon. How picky am I (should I) be? I took them out tonight and tested on Jupiter again...this set is much, much better than the first set. But it is not perfect. Still off by probably a tenth of a degree or so. The edge of the fuzzy defocused right eye image of Jupiter is juuust kissing up against the focused left-eye image.

There is quite a bit of CA when looking at Jupiter. A surprising amount, in fact. So far I'm not able to resolve the bands with this bino. The view of the moon was spectacularly sharp, though. Much more crisp than my Zhumell 25x100. My 12YO was particularly impressed by that view.

Bright stars are flaring quite a bit. I think I need a new eyeglasses prescription...it's been a couple of years and the astigmatism in my right eye has become worse than the current correction. So it's hard for me to say how much is the bino vs. my eyes. Faint stars are looking pretty good though.

#28 hallelujah

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Posted 20 February 2013 - 09:21 AM

I think I need a new eyeglasses prescription...it's been a couple of years and the astigmatism in my right eye has become worse than the current correction.
So it's hard for me to say how much is the bino vs. my eyes.
Faint stars are looking pretty good though.


Do yourself a favor and get your eyeglasses updated. :crazyeyes:

Stan

#29 steveyo

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Posted 20 February 2013 - 11:11 AM

Just FYI:

I rcved a pair of the Pentax 20x60s from Adorama a couple days ago, and see no double image whatsoever on Jupiter, or Saturn. Wobbly because no tripod, but tack sharp, perfectly merged images.

My eyes are slightly and differently near-sighted, but no astigmatisms (yet).

#30 Jarrod

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Posted 20 February 2013 - 11:34 AM

Steve - what I was speaking of was testing collimation by defocusing one tube relative to the other and viewing a bright point of light against a dark background with both eyes. This will cause your brain to not merge the two images, exposing even minor collimation issues (the dimmer, out-of focus blob should sit right on top of the sharp point of light if perfectly collimated). With both tubes focused, I don't see double with this replacement set. I did, however see pretty significant chromatic aberration when viewing Jupiter. Do you see any CA on jupiter through your set (and eyes)?

By the way, yesterday I stumbled on this review of the 20x60 PCF WP II by EdZ. I thought I should link to it here since it answers the original question I had about overlapping images at MFD on this binocular quite clearly. I'll quote the most relevant excerpt:

"The barrel images do not overlap at close focus, but almost no binoculars do. This has more to do with close focus than anything else and really has nothing to do with small exit pupil or collimation. Typical 20x binoculars, regardless of what is posted as close focus, have a real closest usable focus of about 75 ft. (20m). They will show the field circles of the barrels will not completely overlap at least out to 200 feet (60m). This is common to most binoculars, and especially prominent in higher powered binocs."

#31 steveyo

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Posted 20 February 2013 - 12:29 PM

Ah, got it. Sorry to have mis-understood. I did not notice much CA but I didn't give them a thorough test yet, either. I viewed the moon and then Jupiter in the daylight (which I was surprised to be able to view). In the dark, I viewed just Saturn, when I had a moment before my running partner arrived at 5:40AM. As I said, I had no tripod, so, even braced on a stump, the image was jumping with every heartbeat and breath.






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