Handshake and image size in porro vs. roof (1 Viewer)

I posted this in response to KorHaan's contribution to the Chinese Bins-thread, but think it's better served by a thread of its own.
While comparing roof binoculars to porro binoculars handheld and 'tripoded' KorHaan found the porro's performance better than the roofs, when handheld. His explanation: weight.
I decided to throw in yet another explanation:

It's well known that roof binoculars, because of their objectives being in line with the oculars, give the impression of a larger image (object) size in comparison to porro binoculars, where the objectives are set wider apart than the oculars. Of course this is an illusion - the brain is 'led to believe' that objects are smaller in the porro view - in the way that magnification is not altered (8x is 8x, be it in a porro or a roof) but it is also 'real' in the sense that we 'see' this difference in image size and will be affected by it. My impression is that most people are pleased by the image size effect of roof binoculars in comparison to porro's because the image is more spectacular. However, if the image is perceived as larger, wouldn't displacement of the image be perceived as larger as well? Isn't it logical to assume that the unsharpness caused by our trembling hands is more easily noticed in a roof binocular? And perceived as less troublesome in a porro type binocular?
Just a thought.

Renze

Your eye is pretty fast. I can see the hand shake, and I see the best image for microseconds. I do not see a blur that represents the whole arc. It is a bit of a problem when reading text far away, but with birds you are looking at different kind of detail.

I noticeably hold bigger binoculars more steadily than small ones. I think weight is part of the equation but also balance, which may have a lot to do with the size of my hands.

Renze de Vries said:

I posted this in response to KorHaan's contribution to the Chinese Bins-thread, but think it's better served by a thread of its own.
While comparing roof binoculars to porro binoculars handheld and 'tripoded' KorHaan found the porro's performance better than the roofs, when handheld. His explanation: weight.
I decided to throw in yet another explanation:

It's well known that roof binoculars, because of their objectives being in line with the oculars, give the impression of a larger image (object) size in comparison to porro binoculars, where the objectives are set wider apart than the oculars. Of course this is an illusion - the brain is 'led to believe' that objects are smaller in the porro view - in the way that magnification is not altered (8x is 8x, be it in a porro or a roof) but it is also 'real' in the sense that we 'see' this difference in image size and will be affected by it. My impression is that most people are pleased by the image size effect of roof binoculars in comparison to porro's because the image is more spectacular. However, if the image is perceived as larger, wouldn't displacement of the image be perceived as larger as well? Isn't it logical to assume that the unsharpness caused by our trembling hands is more easily noticed in a roof binocular? And perceived as less troublesome in a porro type binocular?
Just a thought.

Renze

Click to expand...

Hi Renze,

What you're suggesting is valid, but I think it would be of less importance than the weight/balance factor; a pair of binoculars perceived performance is enhanced considerably when they feel right in your hands, which is a very personal thing.
For me, comparing the Swarovski 10x42EL to the 10x32EL, I found the lighter, smaller 10x32EL easier to keep steady than the bigger and heavier 10x42EL; the space of the open bridge in the 10x42 is too small for me, where in the 10x32 I can easily wrap my fingers around the tubes and get a firm grip.
It's different ergonomics that matter here and that make the difference. Even the greater weight didn't help.
Thinking about the porro's and roofs I've owned or looked through over the 4 decades I've been birding, I vividly remember the ones which felt perfect as well as the ones with terrible balance. The Eiffeltower ( Zeiss Dialyt 8x56 ) I was allowed to use during a 1981 fieldwork semester in my biology studies was easier to hold steady than my own trusted 7x50 porro's. Both were big and heavy, 1030 grams vs. 950 grams resp., but the ergonomics of the Dialyt were better for me. Last year on the Dutch Vogelfestival I looked through a 8x56 Classic Dialyt and it still had the perfect feel. I had my 7x42 FL's to compare and the 8x56 was the steadier of the two.
I once owned a cheapish 8x40 porro with the looks of a roof; the eyepieces were in line with the objectives when seen from above, but off-set in the porro fashion when seen from the side ( the objectives elevated above the eyepiece ). Theoretically, in regard of your suggestion, it should have been more vulnerable to handshake than the 8x40 Minolta Classic (normal) porro I had, but the opposite was true. The off-set (roof-like) porro had a better balance which gave me steadier views. Of course it doesn't prove a thing; I should have had them both tripod-mounted as well, to see any real difference, but back then I wasn't even aware of the existence of tripods.

The issue I would like to emphasize, is that you can perceive the amount of handshake you get when you compare your binoculars handheld vs. tripod-mounted; the smaller the difference, the better, I would say. It would give some objective insight on how well the balance of the binoculars is. This was not obvious when I used the 10x42 Bynolyt roofs handheld only, in my perception they provided a wonderfully steady view, the reason I preferred them in the first place. It's difficult to assess any difference in image size between the 10x42 roofs and the Chinese 10x50 porro's I recently purchased, because the FOV in the porro's is considerably wider, and this could be of influence in the perceived image size.

Kind regards, Ronald

Renze de Vries said:

I posted this in response to KorHaan's contribution to the Chinese Bins-thread, but think it's better served by a thread of its own.
While comparing roof binoculars to porro binoculars handheld and 'tripoded' KorHaan found the porro's performance better than the roofs, when handheld. His explanation: weight.
I decided to throw in yet another explanation:

It's well known that roof binoculars, because of their objectives being in line with the oculars, give the impression of a larger image (object) size in comparison to porro binoculars, where the objectives are set wider apart than the oculars. Of course this is an illusion - the brain is 'led to believe' that objects are smaller in the porro view - in the way that magnification is not altered (8x is 8x, be it in a porro or a roof) but it is also 'real' in the sense that we 'see' this difference in image size and will be affected by it. My impression is that most people are pleased by the image size effect of roof binoculars in comparison to porro's because the image is more spectacular. However, if the image is perceived as larger, wouldn't displacement of the image be perceived as larger as well? Isn't it logical to assume that the unsharpness caused by our trembling hands is more easily noticed in a roof binocular? And perceived as less troublesome in a porro type binocular?
Just a thought.

Renze

Click to expand...

Hi Renze,

What you're suggesting is valid, but I think it would be of less importance than the weight/balance factor; a pair of binoculars perceived performance is enhanced considerably when they feel right in your hands, which is a very personal thing.
For me, comparing the Swarovski 10x42EL to the 10x32EL, I found the lighter, smaller 10x32EL easier to keep steady than the bigger and heavier 10x42EL; the space of the open bridge in the 10x42 is too small for me, where in the 10x32 I can easily wrap my fingers around the tubes and get a firm grip.
It's different ergonomics that matter here and that make the difference. Even the greater weight didn't help.
Thinking about the porro's and roofs I've owned or looked through over the 4 decades I've been birding, I vividly remember the ones which felt perfect as well as the ones with terrible balance. The Eiffeltower ( Zeiss Dialyt 8x56 ) I was allowed to use during a 1981 fieldwork semester in my biology studies was easier to hold steady than my own trusted 7x50 porro's. Both were big and heavy, 1030 grams vs. 950 grams resp., but the ergonomics of the Dialyt were better for me. Last year on the Dutch Vogelfestival I looked through a 8x56 Classic Dialyt and it still had the perfect feel. I had my 7x42 FL's to compare and the 8x56 was the steadier of the two.
I once owned a cheapish 8x40 porro with the looks of a roof; the eyepieces were in line with the objectives when seen from above, but off-set in the porro fashion when seen from the side ( the objectives elevated above the eyepiece ). Theoretically, in regard of your suggestion, it should have been more vulnerable to handshake than the 8x40 Minolta Classic (normal) porro I had, but the opposite was true. The off-set (roof-like) porro had a better balance which gave me steadier views. Of course it doesn't prove a thing; I should have had them both tripod-mounted as well, to see any real difference, but back then I wasn't even aware of the existence of tripods.

The issue I would like to emphasize, is that you can perceive the amount of handshake you get when you compare your binoculars handheld vs. tripod-mounted; the smaller the difference, the better, I would say. It would give some objective insight on how well the balance of the binoculars is. This was not obvious when I used the 10x42 Bynolyt roofs handheld only, in my perception they provided a wonderfully steady view, the reason I preferred them in the first place. It's difficult to assess any difference in image size between the 10x42 roofs and the Chinese 10x50 porro's I recently purchased, because the FOV in the porro's is considerably wider, and this could be of influence in the perceived image size.

Kind regards, Ronald

Sorry, managed to post the same thing twice.
My fault,

Ronald

...However, if the image is perceived as larger, wouldn't displacement of the image be perceived as larger as well? Isn't it logical to assume that the unsharpness caused by our trembling hands is more easily noticed in a roof binocular? And perceived as less troublesome in a porro type binocular?

Click to expand...

Hi Renze,

Interesting conjecture, but somewhat difficult to get a handle on.

An underlying implication, which would be quite important, if true, is that if one were to tripod mount optically equivalent roof and porro prism binoculars, the observer's performance under vibration would be better with the porro than the roof. This could be put to the test by vibrating the platform (or the target) during reading, target detection/identification, or acuity tasks.

The "...unsharpness caused by our trembling hands..." being "...more easily noticed in a roof binocular..," suggests that if one gradually changed platform or target vibration (in frequency or amplitude), that viewing with the roof would facilitate earlier detection of the change.

Which if any such experiments do you think would support the conjecture?

Ed