Focusing Screen for K-r. Any recommendations?

My K-r is great but I find that I'm missing the large bright viewfinder of my SLR, and most especially the split focussing ring in the centre. Yes, the autofocus is a handy feature that I do use a lot now, but it occasionally struggles so I do like to check and I do make fine adjustments with the quick shift (superb feature!) Also, and like many here, I have a couple of older manual lenses. A split focus ring would be a real help, and it surprises me greatly that Pentax don't offer one! (there's a suggestion for them) I mean, the K-5 accessories include a good range of focus screens for under £40 that just show differing focus area markings - why no split ring when it'd be SO much more useful? And the K-r has a user changeable screen mount that Pentax don't even want you to know about!

Looking at the OEM market I see that KatzEye offer a high priced solution (£120 plus by the time it arrives) but my quibble is that I prefer a 45 degree split - it just makes a great deal more sense practically. I see some Chinese cheapies on eBay with said 45 degree feature and costing all of twenty quid. Has anyone tried installing one of these in their K-r? Heard any reports / horror stories?

If I was a K-5 owner already I'd (reluctantly) invest in a KatzEye job, but my whole K-r kit was only £339 new so premium extras that I can't later migrate to a K-5 just aren't worth it for me.

Thoughts? Suggestions?

I love to see one. And I want it to be standard. Problem with that is that Pentax has to spend extra time during the manufacturing process to get it correctly shimmed (calibrated) resulting in additional costs.

The fact that it will influence metering can be circumvented in the camera software and is no excuse not to provide it.

I use Katzeyes in my K100D and K10D so can't advise on 3rd party screens. But plenty of people use them in different Pentax cameras including models for which it's not mentioned in the manual; I think I've read one horror story one day which boiled down to 'brute force and ignorance'.

There hasn't been a split image focusing screen since AF arrived. It upsets AF so what would be the point?

Admittedly it will depend very much on individuals' eyesight, but I can easily focus using the ground glass screens. In fact, I always did, even when microprisms and split images were available. They are far too slow and fiddly.

Practice more, make sure the dioptre adjustment has been done correctly, but in the end these are all AF cameras with manual focusing available as a backup.

For dioptre adjustment, defocus the lens, point it at a white or even background and adjust until the etched lines on the focuing screen are sharpest.

I've had split screens fitted in both my K10D and my K20D without any impact on the AF whatsoever. I managed to get a katzeye split screen second hand and have never looked back. Best thing I ever bought to go with the camera. Much more useful than, say, the grip which I never use.

K.

Hi,

I have A Kr too and it's the cheap Pentamirror that gives less light than a prism as well as the smaller sensor format.

I've had screen out for cleaning on a KX and now my KR when dust gets above the screen. Don't know why they classify them as not changeable as they clearly are, albeit with great care needed to not scratch them.

I'm intrigued, why has the focus screen to the viewfinder got anything to do with autofocus? Indeed where are the sensors located?

I did not realise they affected the AF. I thought it was just the metering. In particular spot metering.

As I use centre point focusing only, it's bound to affect things if we put slanted prisms in the way. Exactly how much I don't know.

I'm not getting this John. I thought the Af system resided in the base of the body and not in line with the focus screen or prism. Am I wrong?

You're probably right, we're dealing with a bit of a crisis here today, so I'll think about that one later. Too much stress in one day I'm afraid.

[IMG]http://i679.photobucket.com/albums/vv154/bforbes/201be06_fig4-w700.jpg[/IMG]Figure 3. A phase detection AF system uses a series of mirrors, a small sensor at the bottom of the camera and a processor to calculate precise focus.

AF system

Photographers are used to trusting auto-focus — even on action shots where the shooter is following a moving subject. When a DSLR's mirror is in the 45-degree-position in order for the shooter to see the subject, AF is possible. (See Figure 3.) A portion of the image passes through a semitransparent area of the mirror, reflects off a small mirror mounted on the back of the mirror and is cast onto a small sensor at the bottom of the camera. The sensor, in conjunction with a processor, sends commands to the lens' AF motor to move to a position calculated to be correct for precise focus. This system is called phase detection AF.

DSLRs employ a different AF system when shooting video because the mirror must be continuously up. The processor, therefore, obtains information from the CMOS image sensor, which is why it is called contrast detection AF.

Mirrorless cameras such as the Panasonic GH2 and Sony NEX-5N must use contrast detection AF. (Strictly speaking, digital cameras without a mirror do not have a reflex system and, therefore, are not DSLRs.)

Contrast detection AF systems work by having a microprocessor rapidly command the lens servomotor to step forward and backward by a tiny amount. The processor notes whether contrast increases or decreases. If contrast increases, then current focus is not perfect. Therefore, stepping forward and backward continues. When there is no change in contrast, the current focus is the best possible.

Contrast detection tends to be slower than phase detection and becomes slower at low light levels. And, unless the lens is designed to be quiet, AF noise may be recorded.

Aperture system


Read more: http://broadcastengineering.com/hdtv/4k2k_part2/#ixzz1n7NOfcyO

You need to get out more!

No, that was helpful. Apologies for the errant post, my Mum had just fallen downstairs and had to be rushed to hospital and I wasn't concentrating....she's on the mend hopefully.

Sorry to hear that John. Hope she's OK.

I'm only allowed out for 2 x 20min walks per day at the moment, hence time to spare.

I do hope she is ok with no lasting damage.

Thanks both, hopefully she got away with it but at 81 it's always tricky.