.... If you have used one of the KatzEye screens on a D7100 or otherwise, I would love to hear about your experience. Also curious if the KatzEye screen is/was noticeably dimmer than the Nikon one?
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On a D300.
Still have it, will never let the D300 go simply due to the screen!
Fitting was easy peasy. In saying that tho, I have removed and cleaned and refitted the screens on both D300 and D70s prior to fitting the Katzeye.
With the helpful tools they supply in the box, it made it less worrying using a pair of pliers and whatever I had to hand prior to the Katzeye tools!
Adjusting focus was easy too.
I worried a bit over this myself but again a little prior experience with focus adjustment probably helped.
Prior to getting the Katzeye, I used liveview to fine tune the manual focus adjuster screw in the mirror box.
Seemed hard to get too, but having read instructions on how too, I thought to have a go anyhow.
Prior to the katzeye, I had a hard time focusing the 50/1.2 at close-ish distances with any certainty. So using live view, I set the lens up to be in focus, and using the green dot method, finely tuned the manual focus screw stop for the mirror.
What I'd done was to ensure that the green dot would light up when focus was near achieved or as accurately as possible when focusing from near(to far).
The green dot is no way near accurate enough for the DOF at close range.
So now, my manual focus system is 'out of whack' by Nikon standards, but working fine for my purposes.
Enter the Katzeye!
Live view focus confirms that the 50/1.4 is in focus, but Katzeye is not in focus(split prism is not lined up correctly).
Obviously my manual focus(for green dot) fix for the 50/1.2 was not ideal for the Katzeye screen.
Fix was to readjust the manual focus stop to make it ideal again.
Once again easy fix, took about 15mins with abotu 5 shots taken to confirm everything works fine .. all that was done years ago(maybe back in '09-'10)_ and have never had an issue since.
Point to note. I got the mosre costly optibright option at the time.
Vf brightness is incomparable to any current Nikon Vf I've tried, since and before.
I haven't tried D4 and D5s(no interest) but I have tried D3s at about that same time.
Katzeye is much brighter. (remember tho, I have the optibright treatment).
Split screen blackout is for all intents and purposes not an issue.
I can invoke it at f/22 on my old manual Tamron 300/2.8 with both 1.4 and 2x converters hooked up.
At f/22 with just the bare lens, I still only just get a glimpse of it(but not blackout).
500/8 with a 2x converter did cause blackout .. I think. It was a long time ago that I had that opportunity, so can't recall with full clarity.
Bare 500/8 is not a problem tho.
And just to refresh my ailing memory . I just hooked up the 180/2.8 Ais. Set it to f/32 and hit DOFP. Only just barely noticeable split prism blackout, and to describe it is a very slight BMW badge pattern .. not really a blackout as such.
If Nikon were smart, they should have bought the rights to Katzeye's replacement viewfinders and marketed them as their own.
It seems that many Nikon users crave good manual focus ability and these things are close to ideal.
Haven't noted any weird exposure issues(which you may get warnings about), and AF seems totally unaffected(as would be expected).
Hope that helps.