Originally posted by Univer Hi All,
I've searched for relevant discussions and haven't found any, so I thought I'd impose on your collective wisdom.
I've been using a K20D for a little over a year, exclusively with manual focus lenses - mostly screwmount, some k-mount, and a few other odd mounts, via various adapters, bellows, etc.. It's not at all unusual for me to changes lenses several times in a day. I mention that because I'm wondering if it might be relevant to an issue that has manifested itself recently.
Up until a few weeks ago, I had good success using the focus confirmation system as a focusing aid. It wasn't always 100% accurate, of course, but it was usually very helpful. But recently, I've found that it seems to be almost invariably wrong - just "off" the proper focus distance. I've tried a bunch of different lenses, a bunch of different subjects and lighting conditions - indoors, outdoors, on and off a tripod. The result is always the same. I'm in the process of trying to figure out whether the confirmation signal is always front focusing or back focusing; if that's the case, I can at least use it as a rough indicator.
I've used the sensor cleaning routine several times, and I've updated to the latest firmware version.
Maybe I've become a little too dependent on the focus confirmation feature, but I'm having trouble doing without it. I wish my old internal biological focus-confirm system were as good as it used to be (or that the viewfinder image were as bright as that of my old Spotmatic!). I'm using the stock screen, so I may need to invest in a Katzeye or something similar.
Any thoughts on what might be responsible for this issue? Any recommendations by way of diagnosing the problem? (For example, should I attach the kit lens and verify that AF is working properly? I know the K20D allows focus adjustment for AF lenses - would that be useful here?) Do you reckon that the frequent lens changing might have something to do with this? Grasping at straws here, I guess, but I know that my personal shooting habits aren't necessarily typical, so I wonder whether they have something to do with the problem.
Thanks so much for your help!
Cheers,
Jon
I have the K20 also. I don't think changing the lenses has much to do with it, except that one or more of your lenses may have a severe front focus or back focus problem.
You might check your adjustment menu, and confirm that you haven't entered "all" changes that may be affecting your camera.
AF is not perfect, it can be fooled by things like windows or grass that is between you and the subject you are photographing. In addition, the AF search area is nowhere as small as the focus indicator spot on your optical viewfinder. You may think you are telling the camera exactly where to focus, but the camera is actually picking up a contrast difference somewhere nearby to your subject.
I don't use the focus indicator light that much, because i'm never quite sure if i stopped in time when i saw it, etc. If you are going to use it, i would think your success rate would go up if you used a smaller apertuer, i.e. larger DOF with the indicator light. perhaps whats changed for you is a current tendency to use larger apertures than what you did formerly. I'm just brainstorming here, you need to be the judge of it.
I would be somewhat lost without my Katzeye screen. my optician says i have the start of some cataracts, so i got the Katzeye with the "brite" treatment as a help. But to get back to your question - the Katzeye helps me monitor AF performance. And i have done AF lens adjustments in the field, based on what i've seen from the Katzeye. From what some experts have said, lenses can change their focusing performance from a close focus to a distant focus. Also, tungsten light indoors, because of its frequency, can cause the camera focus point to move towards a front focus condition. Now K7 was supposed to have a feature that would help conpensate for that - not sure how successful that effort was because i haven't seen any posts on it.
What i'm trying to say is there could be many reasons for this issue, and the Katzeye screen, i have found, is a great tool for helping to monitor the situation except in extreme low light. I first had this screen on my K10, then shifted it to my K20 when i upgraded. it will cause errors with your spot focus metering, but i have found that to be a small loss compared to the flexibility it gives to my focusing. I normally use AF where i can, but there are situations, such as some of my MF lenses, etc, where the focusing screen is invaluable. Also, not all focusing screens are the same. my brother had an inexpensive ebay screen, and now is very happy with the katzeye. I can't speak to all the different varieties in that market.
hope this helps,