Search results for 'back focus' - page 663
Pentax 100mm Macro
I don't know where your getting the 3mm tolerance from..... shim I’m asking the question is being able to focus to +-3mm over 450mm i.e. a tolerance of 0.66%, acceptable or not? I take your argument that it's not. The other point I was making is that it's not stated anywhere, that I can find,...
Posted by bforbes on 04/02/2009 - 18:45
Pentax 100mm Macro
If you are having to move the camera back 8mm then there is something wrong with it. My macro shots are dead sharp with my K10D/Sigma 50mm and we have quite a few macro enthusiasts on here posting dead sharp images. If it is still under warranty, send it back. or get it fixed. I am assuming you...
Posted by shim on 04/02/2009 - 19:58
Pentax 100mm Macro
What peeves me about this ridiculous thread is that you waited a year until the camera was out of warranty before noticing there is something wrong and are now not even prepared to send it back to Pentax to see if there is something simple which can be done to fix the problem. We know that the K10D...
Posted by womble on 04/02/2009 - 22:08
Pentax 100mm Macro
Best read up on all the faults Canon have as well before you jump ship, they were selling cameras for £5000 that couldn't focus properly, so don't think jumping ship will solve your problems. Agree with Womble, get it fixed or repaired, and just because it's out of warranty don't think you can't ...
Posted by Unlocker on 05/02/2009 - 10:44
Pentax 100mm Macro
Made a few enquiries this morning and it seems that these focus problems exist right across all manufacturers and to make matters worse the manufacturers won't accept that they exist. Canon and Nikon actually use different set ups/sensors (3x more sensitive Canon) in their Pro Cameras than their Con...
Posted by shim on 05/02/2009 - 14:12
Pentax 100mm Macro
David Kilpatrick (Minolta/Sony)had a problem on one assignment where everything looked OK through the viewfinder when he took the pictures, but later found they were out of focus. I had that problem the other night coming back from the pub.
Posted by Mike-P on 05/02/2009 - 16:22
Pentax 100mm Macro
AF tests with the subject at 45 degrees are unreliable because the camera's focusing point may be slightly off centre - not precisely where it is indicated in the viewfinder. You're better off focusing on a flat subject, making AF adjustments via the Debug/Setup menu, and seeing if they make the ...
Posted by shim on 05/02/2009 - 20:20
Pentax 100mm Macro
But you're doing something with a tape measure at 45 dgrees. Forget that because the centre focus point may not really be *precisely* in the centre, is my suggestion. What AF beam? The camera doesn't have one.
Posted by iceblinker on 05/02/2009 - 20:41
Pentax 100mm Macro
But you're doing something with a tape measure at 45 dgrees. Forget that because the centre focus point may not really be *precisely* in the centre, is my suggestion. I've carried the tests out parallel to the film plane as described above. To make it easier to understand, imagine that you made a si...
Posted by shim on 06/02/2009 - 11:23
Pentax 100mm Macro
When we used film cameras this sort of testing would be done by no-one as the delay in processing meant it never crossed our minds. It was never really needed John, because the manufactures went to great lengths to ensure that the film plane was exactly where it should have been and that the film w...
Posted by shim on 06/02/2009 - 12:20
Pentax 100mm Macro
That Leica one is around £10,000. Bit pricey to put that in a camera I think. And can you imagine the complexity of trying to get that to work with 11 focus points? You'd have to adjust the angle of the laser, the angle being dependent on the distance to the subject... Catch 22? Or you could ...
Posted by Daniel Bridge on 06/02/2009 - 13:21
Pentax 100mm Macro
That Leica one is around £10,000. Bit pricey to put that in a camera I think. Dan Just gives you an idea what would be possible :lol: Most of the Leica instruments have a sort of camera already built in. You just point them roughly where the target is and it goes looking for it. Once it gets it in...
Posted by shim on 06/02/2009 - 14:24
Pentax 100mm Macro
I just wonder if shim is barking uo the wrong tree. If the attached is trustworthy, the whole focus adjustment is based on contrast calculations inside the camera. No beams at all.
Posted by terje-l on 06/02/2009 - 14:55
Pentax 100mm Macro
i suppose if the beam was reflected by anything the camera would use that as the focus distance.
Posted by bforbes on 06/02/2009 - 16:55
Pentax 100mm Macro
I think we've already established that the camera doesn't use beam, just musing about the possibility now. How would a beam system behave in rain or snow, by the way? That's right just pointing out some of the latest methods of measuring distances that haven't yet found their way into cameras yet...
Posted by shim on 06/02/2009 - 20:25
Pentax 100mm Macro
Infra-red autofocus systems have already been used in many compact film cameras. These are "active" AF systems as opposed to the "passive" ones we use these days. Presumably they work on the basis that if nothing comes back they set the lens to infinity :?:
Posted by womble on 07/02/2009 - 10:48
Pentax 100mm Macro
Presumably they work on the basis that if nothing comes back they set the lens to infinity Presumably, and of course focus point is less critical at longer distances. Even so, many cameras had Infinity Lock settings, or Landscape settings, which amounted to the same thing.
Posted by johnriley on 07/02/2009 - 11:00
Pentax 100mm Macro
I was looking around Amazon and just stumbled on this: (Seems to be a current model) Amazon.com Product Description If you are looking for autofocus convenience and flash versatility, find it in the Olympus Trip XB-40 AF QD. In the XB-40, an infrared autofocus system with focus lock and a sharp...
Posted by shim on 07/02/2009 - 20:12
Pentax 100mm Macro
This is rather inconclusive as to how it works. The AF-assist spot beam (SB) works by illuminating the scene with a grid pattern of red light. This gives the camera a sufficiently contrasty area to achieve focus. "The AF spotbeam on the flash unit works accurately only when mounted onto the camer...
Posted by Mannesty on 08/02/2009 - 08:18
Pentax 100mm Macro
"The AF spotbeam on the flash unit works accurately only when mounted onto the camera's hotshoe." The flash has to be mounted to the camera (or connected via cable) to work at all. The SB function does not operate when the flash is electrically disconnected from the body. With a cable connected flas...
Posted by shim on 08/02/2009 - 11:59
