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.