Alexis: really the Nikon ED50 + 27X eyepiece could get to "compete" (I'm not sure of this word) with the Nikon ED82 + 30X? I ask it from curiosity ..
I would like to ask: if you had to choose a single eyepiece for the Nikon ED50, what would it be? I imagine that it should be the most used for most situations ... and I should have a good balance between brightness and detail resolution, right?
Wachi.
As I tried to explain in my earlier post, when I reach for bins I expect a wide angle ~8x view. That is what I expect bins as a tool to do when I'm birding. Sure, I own 6x, 7x, 8.5x, and 10x bins, but for 99% of my birding etc, I prefer 8/8.5x. For me, when selecting a bin for use, the only real consideration is what size I can carry. I have 8x20, 8x25, 8x30, 8x32, 8x36, and 8x42 bins. In my ideal world, the only differences among them would be those imposed by limitations from the laws of physics, not differences in other design goals, so that I could reach for any of them and get approximately the same view and performance. In the past, small bins weren't designed to perform at their physical limits, but now we have models like the Zeiss 8x25 Victory Pocket, which do quite well as a substitute for full-sized bins under most lighting and other conditions.
When I reach for a scope, I want it to deliver a wide angle ~30x view. Sure, I have eyepieces to cover a wide range of other magnifications from 13x to 150x, but ~30x is what I use most and what I want to see when I first point my scope, rather than my 8x bins, at a bird. The bins give me a view 8x larger (in linear dimensions) than my eyes, and my scope gives me a view ~4x larger than my bins. It's a substantial magnification increase that makes a big difference for my ability to make an ID. Going another 2x larger, to ~60x can also be nice, but it is rarely necessary, is rarely enough make something identifiable as compared to 30x, and it often doesn't work any better than 30x because of atmospheric limitations. I have a 60 mm scope with a 20x eyepiece that I use on a window mount to make quick IDs that are just out of reach of my bins, and I like that scope a lot, but I find it a bit underpowered for general purpose scoping.
In my experience, the Nikon Fieldscope 50ED is optically everything I could hope for in a 50 mm scope. It seems limited only by the laws of physics, not design/manufacturing quality. As noted above, I generally have no interest in lower powers than ~30x, so for me, the perfect eyepiece on it is the 27x. The apparent FOV of the 50x with the 27x is identical to the 82ED with a 30x WF/MC/DS, and the magnification difference is trivial, so I consider these scopes nearly equivalent in capability for most birding. I use the scope on a tripod (Velbon Ultra 455 with small ball head) and I do not find the view dim in normal lighting (It is equivalent in brightness to 32x on a 60 mm scope) or the resolution to be limited at ~30x as compared to the 82ED. Of course the 82ED works better in low light and can support much higher magnifications, but those are not relevant for 95+% of my birding.
After trying many options, nowadays the only eyepiece that I use with the 50ED is the (old) 27x WF, which has the same optical design as the 27x MC and 27x DS but is _much_ less bulky.
--AP