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Old Sunday 3rd May 2015, 15:46   #1
AlanFrench
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Recent Papilio Experiences

I first saw the Papilio binoculars soon after they were introduced, back when Pentax came to the Northeast Astronomy Forum (NEAF). I was never quite convinced to buy a pair, but have been reconsidering the idea. This year I found a dealer at NEAF who had them.

The "floor" model was awful, with two fields that overlapped only by about 50% on close objects - in other words, exhibiting exactly the problem the moving objectives were designed to prevent. A fresh pair was removed from the box, and it had the same issue, but to a lesser degree.

Does anyone have a recent pair and what are your experiences with them? Is my memory wrong about how well the Papilio nicely eliminate the overlapping fields on close objects?

Thanks, and clear skies, Alan
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Old Sunday 3rd May 2015, 17:48   #2
Binastro
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. Hi Alan,
I posted a test of the 6.521 Papilio II on the recent thread started by klar, second page.

One minute ago I tested them again looking at the laptop screen which is at a distance of about 70 cm or 28 inches about.
Although I did not notice this when I was testing it earlier I can report the following.

There is an overlap of about 78% i.e. 22% is not shown in both barrels at 70 cm.
With both eyes I see an oval, which is not unpleasant and where there is very good resolution in the centre field and quite a way out. This does not really bother me.

I did notice in the test that I did earlier that the IPD does not change with distance, even close-up.

I may not be the best person to comment on the overlap, as I need a prism prescription for reading glasses.
However, I have special computer screen glasses set up for about 70 cm, and these do not have prism correction.

I don't know if this sort of overlap would bother you. Also it would be interesting to see how much overlap other people see close-up. I am longsighted, so I found that I could only close focus to about 57 cm.

Hope this helps.
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Old Sunday 3rd May 2015, 17:56   #3
Binastro
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I just did a further test, by counting letters on the computer screen.
The part missing is almost exactly 5 letters out of 36 letters. Although I know that all letters don't have exactly the same wdith, this is about 14%. I.e. the overlap is 86%.

My earlier estimate was just by eye without reference to anything and I underestimated the overlap.

I will check this further.

Addition.
By actual measurement rather than estimating.
Using a tape measure.
The distance from my eyes to the screen is 63 cm.
Measuring the overlap on the screen using a tape measure, the overlap is 84.5%. This is for my eyes, another person may find a different overlap.

I have not made any correction for the length of the 6.521 Papilio II binocular, which is 12 cm long physically and maybe 10.5 cm from the front of the objectives to the exit pupil approximately. So the distance from the screen to the front of the objectives is about 52.5 cm.
I will leave it to somebody else to say what is the actual distance one should use.

Last edited by Binastro : Sunday 3rd May 2015 at 18:15. Reason: Addition
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Old Monday 4th May 2015, 15:28   #4
Binastro
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. Using a tape measure I tried to measure the real field size when viewing the computer screen at a distance of 63 cm from my eyes and about 52.5 cm from the objectives of the 6.521 Papilio II.

There is quite a bit of scatter in my measurements, but the average is 6.0 in each barrel, and viewing normally using both barrels the vertical field averages at 6.0 and the horizontal field at 6.9.
This is using the distance of 52.5 cm from the computer screen to the objectives.

As viewed from my eye position the field is quite a bit less, say about 5.0 high by 5.8 wide.

I don't know which field size would be the correct one.

Using the stars, I made the field size of the Papilio II, 7.52.

Last edited by Binastro : Monday 4th May 2015 at 15:31.
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Old Tuesday 5th May 2015, 00:57   #5
AlanFrench
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Thank you. I'll have to see if I can look at another pair somewhere and spend a bit more time with them.

Clear skies, Alan
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Old Wednesday 6th May 2015, 01:29   #6
henry link
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I don't see how different samples of the Papillios could have different field overlap characteristics since they all should have the same magnification, AFOV and the same baseline distance between objective centers. Given equal magnification and AFOV it's easy enough to determine how field overlap at close distances compares in different binoculars based on simple geometry. Just measure the baseline between the objective centers and compare the distances at which the baselines of different binoculars form the same angles with an observed object. I imagine the Papillios have a baseline of about 24mm, so they would have the same field overlap at 24" that a typical inline roof prism binocular with the same magnification and AFOV would have at 65" provided the viewer's IPD is 65mm and the same overlap as a typical Porro with a baseline of 120mm at about 120".

Last edited by henry link : Wednesday 6th May 2015 at 01:32.
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Old Wednesday 6th May 2015, 16:25   #7
Binastro
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. Dear Henry,
At the distance I was viewing, 630 mm from my eyes and about 525 mm from the objectives of the 6.521 Papilio II. Assuming the distance between the objectives was 24 mm, which I will check, then this gives an angle of about 2.5. The field size seems to be 6.0 about. This gives an overlap quite different to the 85% that I found.
What am I missing here? Is it my eyes? The binocular? Or perhaps the size of the objectives?

P. S.
Is the fact that my eyes can swivel inwards by about 15, presumably about half that with each eye, part of the equation of how much overlap I see with the Papilio II binocular.

If so, I expect that there is quite a big variation seen by different observers.

Last edited by Binastro : Wednesday 6th May 2015 at 17:41. Reason: Addition
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Old Wednesday 6th May 2015, 21:51   #8
henry link
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Binastro,

Try this technique. Put the Papillio on a tripod and set up a ruler 525mm from the binocular objectives so that it passes horizontally through the middle of both binocular fields. Focus on the ruler and set the IPD for best comfort at that distance. Place the ruler's 0mm mark at the left field edge of the left barrel. Now you can simply read the field widths in millimeters and the amount of offset between the two.

Just as an example, if the field widths read 100mm then the left field will read 0-100mm and the right field might read something like 20-120mm. The area of overlap would fall between 20mm and 100mm or 80mm total, 67% of the total 120mm width of the combined fields.

Henry
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Old Thursday 7th May 2015, 15:15   #9
Binastro
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. Thank you Henry,
. That is in fact what I was doing, using a ruler on the computer screen with a fixed text.
What I was doing wrong I suppose is that I was describing the overlap as 85%, when it is actually 74% I think.
I.e. there is a 15% space on the left with the computer screen only seen with one eye, and there is a 15% space on the right only seen with the other eye.
That is, 85 units overlap with a total horizontal dimension of 115 units. So dividing 85 by 115 I think is 74% in my head.

Yesterday, I measured the size of the objectives of the 6.521 Papilio II. This was without removing the optical window so I couldn't get close to the objectives.
The objectives seem to have a clear aperture of 21 mm. The separation between the edges of the objectives at the closest focusing position is 7 mm. The closest separation of the objectives is 28 mm centre to centre.

At my comfortable focusing distance of 630 mm from my eyes and 525 mm from the objectives the separation of the objectives is I think 29 mm centre to centre.

The 74% overlap, seems to be more reasonable with regard to what I'm seeing. Although I'm still not sure whether the natural ability of one's eyes to angle inwards contributes or not.

Thanks again.

Last edited by Binastro : Thursday 7th May 2015 at 15:23.
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Old Thursday 4th June 2015, 12:45   #10
klar
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I've had overlapping views a few times and couldn't figure it out at first. Thought it was something wrong with the binos but looking at the objective moving normally and the fact it didn't happen every time made me think it was my eyes.

When close focusing sometimes one eye gets 'persuaded' to go off the bino axis and then I see overlap focusing near or far during that view session. When I pull away and shake my head, blink a few times it usually resets my eye muscles and all is ok again.

Sometimes it will persist a bit longer but I always end up snapping out of it so it has to be my eye muscles as opposed to the bino. Doesn't happen every time I close focus. Years ago I was told about strengthening eye muscles by doing pencil pushups - maybe that'll help.

That's been my experience, anyways.
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