Andreas, that is so of course. But, as for myself I was thinking of actual use "in the field": where the person may move about from place to place, the hands are less steady than usual on stopping and raising the binocular to the eyes to immediately take in some detail, near or distant; the birds being viewed may be positioned across, and may move across, the person's "y and x axes"...
Initial very quick answers to you both, as am currently worked off my feet (but I choose to do so so & like it, so that's OK!)...
I am more or less building up this comparison already. All I can say so far is that after however short a spell using the 8x I do notice a difference with the 7x. Mentioning the first things that come into my head:
1. The view through the 7x feels more relaxed and I don't think about binocular shake (would that be the phrase, like camera shake?); I just think how 'enabling' the binoculars are. No doubt that is part of the classic appeal of the Dialyt; it seems to have quite a status! So it might be the particular binocular as much as the actual magnification.
2. While the detail rendering of my 7x42 is very fine I notice that certain things stand out much better with the greater pulling power of the 8x42. For instance, there is a small label of about 3" x 1" on my fence at the end of my approx. 20 yd long back garden and if I view the label from my back window the name QUINNEYS is that noticeably easier in poorer light to read with the 8x though I can make it out well enough of course with the 7x. Under the name is a phone number 01227 xxxxxx in much fainter writing; again I can make that out OK with the 7x but it really stands out with the 8x. That all sounds pretty obvious but I am just saying that the difference is noticeable. Bear in mind I have done these comparisons first thing in the morning while the kettle is boiling and I am not properly awake, so the test is under laughable conditions as far as my eyes are concerned.
3. Even though the overall impression of the view out in the fields with trees in a line at the far end - say 200 yards away - feels almost wide-angle with the 7x I haven't felt that the details are inaccessible. I am wide awake and very alert, I hasten to say, while outdoors.
4. It's too early quite to make a confident pronouncement. This is all quite tentative but if more occurs to me -- perhaps a blinding flash of revelatory light through the barrels of 7x or 8x -- I'll let you know! It might be easier if both bins were from the same manufacturer and product line, with the same design philosophy. One suggestion if you are unsure about the magnification to choose would be to try the Zeiss Victory SF 8x42 if you want an alpha product. Maybe the wide FOV with 8x gives the best of both worlds. I have wondered that myself as I was lucky enough to have these on loan for a fortnight. (Wish I could have had access to the 8x42 HT also, but that's another matter.)
Feel free to ask anything else; I will answer as soon as I can but be aware I'm not a scientific type so my response will be very dependent on the day. Like the photographer who said his choice of lens for a journalistic assignment was like deciding which tie to wear in the morning!
Hope this helps.
Tom