Originally posted by barondla Have all the DSLR manufacturers crippled their viewfinder focusing?
For the factory-installed focusing screens they did, as far as I have read / seen / tried. The difference is, that other manufacturers offer manual-focus optimized options, whereas Pentax's ML/MF/MI/ME-60 (for APS-C Kameras) just differ in the lines, despite their claims in the catalog: "These interchangeable focusing screens provide easy detection of the in-focus area, and allow for extra fine focus adjustment in manual-focus operation." Obviously, Pentax
does talk about focus screens and using them for manual focus.
Just did an informal experiment: With the Pentax standard focusing screen, my KP is A LOT brighter than my EF-S equipped K-5 when using the DFA 50mm Macro, without significant advantages in determining focus, maybe a tad narrower range but not a night-and-day difference (which it is for brightness). Using the FA77, the viewfinder brightness has somewhat caught up, but it still muted. The DoF of the viewfinder image is a little narrower on the EF-S-Type screen. If I had to quantify, it's maybe about 1.5cm (+/- 0.7cm, EF-S) instead of 2cm (+/- 1cm, Pentax) range at an 80cm ruler as target, at a ~30 degree angle, outside of which things blur visibly
for me. For the FA 50mm 1.4 (my only f/1.4 lens), things improve in favor of the EF-S again. Only slight difference in brightness left, and a lot narrower DoF in the viewfinder than on the Pentax screen, especially with a lot "steeper' fall-off and overall more pronounced blur in the unsharp regions.
The DFA 100mm WR and FA 31mm behave similar to the above - very little difference other than a darker viewfinder for the 100mm f/2.8, and some improvement for the 31mm LTD, still at the price of a somewhat darker viewfinder. The EF-S created a moireé out of the 1mm marks on the ruler when vieed at 60cm distance, so things where somewhat difficult to judge.
As a third data point, the brightness of the screen in my Pentax program-A is in between the other two, and it looks fairly grainy outside the focusing aids. It has a microprism ring and a horizontal split image circle. The microprism ring showed the slightest deviations of the focusing point on my relatively contrasty and regular target. I remember this is different with less contrasty subjects. For both the Fa50mm/1.4 and the DFA50mm/2.8 macro, it definitely gave the most distinct indication of focus.
So if manual focus with really fast lenses is your concern, the EF-S definitely is much more usable. Around f/2.8, I don't see an improvement anymore and would recommend one of the other types. Note that at around f/5.6, those focusing aids tend to go (partially) dark unless your pupil is in the dead center. Even then, the microprism is almost unusable, the split screen still works well though.