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10x32 v 10x42 image size (1 Viewer)

Example of magnification shift.

VisionKing 5x25 binocular.

Observer. Me.

No glasses 5.0x
Approximate magnifications.

Astro glasses 5.1x
Distance glasses 5.2x
T.V. glasses 5.3x
Computer glasses 5.4x
Reading glasses 5.5x.

The field of 15 degrees is seen with all glasses.
The AFOV increases steadily as stronger glasses are used.

Regards,
B.
 
Further to the above.

Using low priced non prescription glasses.
If they are held 20cm in front of my eyes while out I get a 2x magnification with increased stereo effect at say 50 metres, which is spectacular.

In addition, when using a 2,200mm focal length observatory refractor at about age 30 my friends and I got considerable magnification just using our eyes with no eyepiece.

So the magnification is very much to do with the observer and positioning of lens elements.

Regards,
B.
 
Hi Binastro,

Designs are different, but neither has a focusing element. Both focus by moving the objective lens group, so the effect on magnification should be the same as moving the eyepieces.

Henry
 
Thank you, Henry.

I suppose I should look in the front of the 10x42 and see the movement.
I have done this in the past with Canon IS binoculars to see the IS working and the focus arrangement.
It is surprising to see how steady objects are looking through the binoculars backwards when the IS is engaged.
The 10x42 has optical windows, but I don't have a 10x32 to compare.

I suppose, though, that the change of magnification is still because of the observer rather than the binoculars.

If the 10x42 has an objective of 150mm fl then the eyepiece is 15mm fl.
If the 10x32 has an objective of 120mm fl the eyepiece is 12mm fl.

Regards,
B.
 
Example of magnification shift.

VisionKing 5x25 binocular.

Observer. Me.

No glasses 5.0x
Approximate magnifications.

Astro glasses 5.1x
Distance glasses 5.2x
T.V. glasses 5.3x
Computer glasses 5.4x
Reading glasses 5.5x.

The field of 15 degrees is seen with all glasses.
The AFOV increases steadily as stronger glasses are used.

Regards,
B.
Hi B.,

Interesting observations. I would like to interpret them in light of what (I think) I know: let's say that I am near-sighted and my prescription is -5d for both eyes (to simplify); then imo the objects that I view thru binos should look smaller when I don't use my distance/-5d glasses than when I use them---if I am not mistaken this fact is confirmed by your observations. However, reading glasses will then typically be only -2..5d (that is, -5d+2.5d)---then why should they make the objects look bigger than distance glasses? The only explanation I can see is that you are far-sighted, and the more near-sighted you become (by using glasses) the larger the objects seem to be----this would be the opposite of what I expected.

Best regards,
Peter
 
Hi Peter,

Correct, I am far sighted.

I don't know what near sighted folks experience.

It may have been Dawes who was so near sighted he didn't recognise his friends if they walked by.

Regards,
B.
 
In two binoculars of equal magnification but with different fields of view, won't your brain insist that the image (of the moon) in the wider field of view is smaller?
 
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I find that estimating apparent fields of view accurately is very difficult.

However, comparing magnifications is easier if one has both binoculars to compare.

Regards,
B.
 
Thank you Arthur!!! In this case, the Canon specifications are way off the mark. At least in my two units.
In my youth, we would say, "If you want something done right, do it yourself."
Today it's, "If you want something done right ... forget it!"

Nikon West once had world-class customer service. When I called, I could speak to a KNOWLEDGEABLE repair tech. Since about 1995, you can speak to a ... well, I better say no more.
Bill
 
Hi Peter! No, it's not on account of the IPD, because the real (?) difference is most obvious when I hold only one barrel of each binocular to each eye, and 'merge' the images of the moon into one (which makes one moon-image fit comfortably inside the other, instead of both being the same '10x' size). As Binastro says, this could well be my eyeballs and frazzled brain, rather than the glass involved.
Hi Sancho,
Can you produce the same effect reversing which binocular is viewed through the left and right eye?
Ed
 
Yes Elkcub, the image size difference is obvious no matter which barrel of which bino I put to which eye;). But I've given up wondering about the reason; the binos, my eyes, me brain, whatever. Recent events stateside take up more of my attention (as does the horrible fact that I'm back to 'online teaching' as classroom work is suspended for at least a month).
 
In two binoculars of equal magnification but with different fields of view, won't your brain insist that the image (of the moon) in the wider field of view is smaller?
Hi Maljunulo, you mention a very interesting effect. In the German Wikipedia there is a website about the so-called moon illusion. Because of your contribution I have searched once, the effect was in my memory. However, it does not quite fit the topic of perception of objects with different fields of view, I link some German websites with nice pictures, if interested, the reader can search in his native language. Furthermore, there are many nice books (gift idea also for childrens and teenagers, shared fun viewing and explaining) and websites on optical illusions. Best wishes. Jessie

At least pictures work worlwide, I think the 1st link halfway fits to topic of thread:
https://de.wikipedia.org/wiki/Optische_Täuschung#/media/Datei:Mond-vergleich.svg
moon illusion with pictures:
some optical illusions, more pictures:
Have fun when thinking about what our brain reports to us incorrectly due to older experiences in special cases that do not correspond to the "memory content".
 
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Hi Binastro,

I know that we should do the measures focusing at the infinite (due to the fact that some binoculars/scopes can have lower mags and/or aperture at close focus), but Sancho can always verify if what he sees at close distance is the same he sees when focusing at the infinite...
 
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