Ahh mate, chill out, married a Kiwi so I understand your need for the #8 baling wire.
Maybe if you took the time to actually read my post you'd have found my answer helpful, but perhaps that's why I feel compelled to repeat it. If you did bother to do a search you'd probably come across more than a few posts where I got deep into it, and my clear advice in the post that by removing the acrylic screen from the F3 and mating that to the F4 condenser you'd have something that might get you close. Maybe not to what Nikon intended but maybe close enough for a Kiwi. My snippy snip was because this Internet Legend has been going on since before the internet was a twinkle in Al Gore's eye, and every time this topic comes up somebody chimes in that just because the F4 screens and F3 screens are close they are interchangeable, and the legend rolls on.
But, I know being a Kiwi you'll try it, I just thought that by giving a bit of hard earned advice I could save you a bit of angst and soft images. So go for it! Go get a DW-4 for the F3 or a DW-21 for the F4 or even a DG-2, swap the screens, do some film and see for yourself.
I've rebuilt both F4 and F3 screens by taking apart the condenser from the acrylic screen for cleaning, but there is a very small gap between them created by a small lip on the screen. I don't have the precision tools to measure the difference between the lip of the screens F4 vs F3 but I've long suspected this is the difference that causes the error, which is why when the F4 came out Nikon was very clear that the screens were not interchangeable. The original F and the F2 had identical screens and thus were completely and totally interchangeable. Even the F3 screens could be used in the F2 as long as you installed them in a different orientation, the frame fits in opposite, its a bit tight but correct and true in focus. I think this past cross usage perhaps gave some the idea that they could swap them and thus the mis-information begins. I have seen and adjusted an F3 that had a F4 screen installed, it gave focussing errors and a previous repairman had adjusted the mirror as a way to compensate but it only worked at certain distances and when the original F3 screen was put back in the focus was off again, this time due to the mirror not being set true. Easy fix: setting the mirror back in alignment using the Original and proper screen.
So, if you do find what I have to say helpful, go have a Tui or two and relax a bit mate. Its all good.
