Advantages with 7x binos (1 Viewer)

[scampo]

I think you perhaps meant $5000 rather than $500 then, Art?

 

[Swissboy]

I think you perhaps meant $5000 rather than $500 then, Art?

900 Canadian Dollars are about 366 British Pounds.(According to FXConverter)

 

[Art Thorn]

900 Canadian Dollars are about 366 British Pounds.(According to FXConverter)

Thanks. Anyway, before we get too mired in details, my point still is that if binoculars were expected to be really great, on the level of APO astro scopes, they would have to cost far more than they do. And it isn't directly related to high power either. In fact the eyepieces with the longest focal lengths (hence lowest power) are the most expensive. The bottom line, for me, is that I get to see, clearly, the birds that I want to see. And for that, I have three binoculars, all Nikon, each suited to a particular situation. Waterproof 10 power at the shore, wide field 8 power in the woods, and the best, brightest image 10 power for general birding. And all for the price of a Swaro 8.5x42 (on eBay anyway). I'm happy!

 

[CDK]

I'm with Jonathan. There is really not that much you can do with a 30 mm porro-objective in terms of fov. The eyepiece of SE is the optical masterpiece.
Ilkka

Ilkka. What difference does the objective lens make to fov? Is it not the case that the fov is something to do with the eyepiece design (as mentioned in your post regarding the SE), and nothing to do with the objective lens, which gathers the light.
I thought that a good Porro prism binocular will give a wider fov than a roof prism binocular.

I heard that some cheaper Porro prisms, might not actually give the magnification, as stated, I certainly am not saying that about the Nikon, but someone purchasing a cheaper Porro might not be getting the magnification that they are expecting. Is this correct?

 

[scampo]

I have found that with cheaper binos, it's almost always the field of view that is most obviously lacking.

 

[iporali]

CDK: I may not be the best person to answer but I think Art Thorn put it very well: "Field of view is a complex function of the objective lens, focal length and the eyepiece... A particular scope, without eyepieces, will have a maximum field of view."

The focal length and the objective lens diameter determine the "window" size, through which you look at the world (or a bird ) and which is magnified by the eyepiece. You can increase the field of view by shortening both the focal lengths of objective and eyepiece, and keeping the front lens diameter constant - this is why some "wide angle" binoculars are so short. When I said that you can't do very much with the 30mm objective in terms of fov, I meant that the physical dimensions of the binocular and the prism system determine approximately the useful focal length of the objective. And this determines the f of the eyepiece - and then the eyepiece designers decide how much of the maximal fov they are willing to show. The more fov they "open", the more difficult it is to maintain a good image quality. Nikon EII has a very wide field but you can see the decrease of the edge-to-edge sharpness. SE has quite a wide field, but still it is very sharp and well corrected at the edges. Some manufacturers (as Steve said) eg. Olympus (I have heard - take it with a grain of salt) prefer sharp edges over the fov.

All I know about porro vs. roof prism is - as you mentioned - that porros usually do have a slightly larger fov, maybe their objective focal length is shorter?

Re differences in magnification - I believe the observations, but I have absolutely no idea why this is the case.

Ilkka

Steve: We Finns have no ear for (the?) definite articles, sorry