K3 - Manual focusing


Link Posted 22/09/2022 - 23:15
Hello everybody,
I'm using some M lenses on my K3 and my question is: what is the best way to precisely focus manually. Ok, I know using LV and magnification option or viewfinder plus red spots and sound alerts (not every time precise). II'm missing my old K1000's focusing screen system.
Are there any focusing screens for K3 that emulate the old system of matching the upper and lower part of the screen to obtain a perfect focused shot?


Link Posted 22/09/2022 - 23:56
You can use a "focus trap" with manual lenses. You set the shutter to operate only when the suject is in focus, then you hold the shutter button down. The shutter will then operate only as your suject comes into while you turn the focus ring (not too quickly, otherwise the sensor won't have time to lock onto your suject). However, you have to use the AF sensor that is directly on your suject as you take the picture. Using this method, you can't use an AF sensor to focus, then reframe your subject the way you want, it will trigger as soon as the AF sensor you are using "see" the image in focus.
Yves (another one of those crazy Canucks)


Link Posted 23/09/2022 - 01:28
"Catch in focus", as described above does a good job but it can fail just as much as relying on the bleep. There is no split screen option for modern Pentax cameras because the designers assume we will all be using their (mega expensive) AF lenses. Many manual lenses suffer from an ailment known as 'focus breathing' where the In Focus indicator will light and the bleep sounds but both remain active when you turn the focus ring a bit more. (sometimes, a lot more). True focus lies somewhere between the start and the finish of this phenomenon. So keep turning the ring and discover the extent of this event from the lamp lighting and to when it goes off. Now you will at least know its extent and you can make an optical judgement in the viewfinder. This is why waiting for the bleep or using catch in focus can fail because it depends on which end of the focus throw you are coming from. If there is a significant stretch of "in focus" it will be wrong at either end but the shutter will fire regardless as soon as it encounters the boundary.
Not a definitive answer/ solution I fear but at least it explains what is going on.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link


Link Posted 23/09/2022 - 07:55
Have you tried the O-ME53 magnifying eyecap? It's not magic, but it helps when using the viewfinder for manual focus.



Link Posted 23/09/2022 - 11:55
I did try a replacement focusing screen in my K-50. This has a circular diagonal central split screen area which was surounded by a larger microprism circular area. The split screen and microprisms certainly worked just like you had with film SLR cameras. However even when focus looked perfect with the split screen the results were not in focus. I think the problem was probably that the effective optical focusing plane of the replacment screen wasn't the same as the camera's sensor which it needs to be to get focus correct!

Anyhow here's a link to their web site:


I bought mine direct but you can easily find something like them for sale online at Amazon or Ebay.

There used to be a American company called KatzEye that made split screen focusing screens for DSLRs that were highly thought of, unforturnately they went out of business, I have occasionally seen one of these for sale secondhand. I think they came with a selection of adjustment shims to get the focusing screen in exactly the correct plane for correct focus at the sensor's focus plane by trial and error.

Link to their old web site:

Hope this helps!

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