Split screen focus aid - a few questions

There is the cheaper split screens being discussed on the Pentax forum in the US they have found this one, just as good as the Kateye.
The AF points still show up, AF still works etc. exposure works fine except in spot which is the same for the Kateye costs just over £20

That one is different from the Katz Eye in that the microprism collar is much larger in relation to the split circle. Also it looks like the one in the picture has an alignment fault along the left side of the split.

Altogether it looks like the even cheaper screen I got off eBay that was NOT as good as a Katz Eye. There are many similar products from various Chinese and HK eBay sellers.

Try this site I purchased the nikon (F6) style focusing screen for my K10 and loved it, and cheaper than Katzeye

I was going to get another for my K20 but just recently decided on the Katzeye.

I don't know if it was me, the Katzeye, the camera or lens but I had my DA*300 on for my first shots with the Katzeye installed and found them terribly over exposed, camera set on AV, I had to punch in -1.5 EV comp at 100iso, spot metering.
I haven't had time to investigate it fully, but could it be the screen affecting exposure :

Spot metering is affected. The answer is to use Centre-weighted instead. This has been mentioned on the forum before. This will be the case with all split-image screens, not just katz Eye's.

From www.katzeyeoptics.com/item--Pentax-K10D-K20D-Focusing-Screen--prod_K10D.html :

"Spot Metering Mode: Our testing showed spot metering mode to be within factory tolerance for all AF lenses having a maximum aperture of f2.0 or larger (lower f number). Lenses having a maximum aperture smaller than f2.0 (lager f number) will show a significant shift toward increased exposure, with the shift increasing for lenses with smaller maximum apertures. Spot metering mode is NOT RECOMMENDED when using a split prism focusing screen with lenses slower than f2.0. However, if spot mode must be used, it is strongly advised to first take a test shot, check the histogram, and adjust exposure compensation as required."

Thanks Pete I suspected as much. must learn to read the manual in future.

I've just learnt about 'capture focusing' where the camera is set to AF with a manual lense, shutter release pressed and gently brought into focus until the camera fires. It seems to work really well for me.
Does anyone else use it with manual lenses?

Yes, I have used this to good effect with my old Sigma 35-200 zoom lens.