Search results for 'back focus' - page 1688
Focusing Screens
There's been some mention of focusing screens for thye 50mm f1.2 lens, but rather than divert other threads I've opened this one instead. It has been suggested that it's difficult to focus the 50mm f1.2 lens accurately, but unfortunately (or fortunately) I can't judge this as I don't have any dif...
Posted by Smeggypants on 28/05/2012 - 18:00
Focusing Screens
The only suitable screen I know of is made by Canon :lol: It's FF and has to be cut down for Pentax. There is an online retailer who sells them cut down. This is just the details of the screen: http://www.digitalrev.com/product/canon-ee-s-focusing-screen/MzI1NQ_A_A Some reviews: 31 p...
Posted by Smeggypants on 28/05/2012 - 18:12
Focusing Screens
No need to get excited about it, we are just trying to be helpful. The information about Pentax screens is accurate, and if we think for a moment it would be bizarre indeed if Pentax (or anyone else) made a lens but not a screen to assist in its use. However, the screens are from the manual fo...
Posted by johnriley on 28/05/2012 - 18:23
Focusing Screens
Actually Smeggy I've never had to adjust the AF for any of my lenses either:D, my 16-50 back focuses slightly on my K10D but not to the extent that it's ever been a problem.
Posted by fatspider on 28/05/2012 - 18:44
Focusing Screens
Actually Smeggy I've never had to adjust the AF for any of my lenses either:D, my 16-50 back focuses slightly on my K10D but not to the extent that it's ever been a problem. But at least you've checked your lenses and found that they didn't need adjustment :)
Posted by Smeggypants on 28/05/2012 - 19:36
Focusing Screens
As soon as I get the chance I'll see how the Pentax f/1.2 focuses using Live View at 25X focal length. Just had a quick look. LV seems to show DOF for all apertures from f/1.2 The small 3" LCD isn't good enough for focusing even at 10X plus a 5X magnifier :| When I'm in focus at 1.25M at f/1...
Posted by Algernon on 28/05/2012 - 19:51
Focusing Screens
As soon as I get the chance I'll see how the Pentax f/1.2 focuses using Live View at 25X focal length. Just had a quick look. LV seems to show DOF for all apertures from f/1.2 The small 3" LCD isn't good enough for focusing even at 10X plus a 5X magnifier :| When I'm in focus at 1.25M at f/1...
Posted by Smeggypants on 28/05/2012 - 20:39
Focusing Screens
There's been some mention of focusing screens for thye 50mm f1.2 lens, but rather than divert other threads I've opened this one instead. It has been suggested that it's difficult to focus the 50mm f1.2 lens accurately, but unfortunately (or fortunately) I can't judge this as I don't have any dif...
Posted by gartmore on 28/05/2012 - 21:29
Focusing Screens
I resized the Canon Ees screen and wacked on a Tenpa magnifier. My K50/1.2 is now easy to focus accurately wide open. Pete
Posted by Transit on 28/05/2012 - 21:41
Focusing Screens
[quote:3496ace15f="johnriley"]There's been some mention of focusing screens for thye 50mm f1.2 lens, but rather than divert other threads I've opened this one instead. It has been suggested that it's difficult to focus the 50mm f1.2 lens accurately, but unfortunately (or fortunately) I can't judg...
Posted by Smeggypants on 28/05/2012 - 22:53
Focusing Screens
The lack of microprism/split image actually dates back a very, very long way, as far as the introduction of AF cameras. Perhaps it was deemed superfluous or perhaps it interfered with the accuracy of AF. It depends on how you work, but personally I always used the general ground glass area to foc...
Posted by johnriley on 29/05/2012 - 10:29
Focusing Screens
If you look through the throat of the camera with lens removed, you will see the mirror. Now look upwards and you will see the focusing screen. When you look through the viewfinder, you are seeeing the image projected onto that screen, reflected upwards by the mirror. When you take the picture, t...
Posted by johnriley on 29/05/2012 - 13:18
Focusing Screens
If you look through the throat of the camera with lens removed, you will see the mirror. Now look upwards and you will see the focusing screen. When you look through the viewfinder, you are seeeing the image projected onto that screen, reflected upwards by the mirror. When you take the picture, t...
Posted by annieogg on 29/05/2012 - 13:46
Focusing Screens
The only f1.2 lens I ever had was a Cannon 50mm f1.2 with the Leica tread. I used it on my Leica M3 and never had any problems focusing, The performance of this lens was supposed to be not quite up to scratch, but I never noticed it.I thought it was a superb lens. The interesting thing is, though, ...
Posted by womble on 03/06/2012 - 22:43
Focusing Screens
They always said that a rangefinder has a longer base than an SLR split-image focusing aid and therefore is more accurate, however it relies on absolute accuracy in the way everything is aligned/positioned. The only AF camera I have with a split-image screen is my MEF, seeing it drive the focus t...
Posted by johnha on 03/06/2012 - 23:23
Focusing Screens
A rangefinder is only more accurate than an SLR with wide angle lenses. That's why there was always a limit of 135mm for rangefinder lenses. Beyond 135mm, rangefinders are little use. SLRs are more accurate to focus when longer lenses are used.
Posted by johnriley on 03/06/2012 - 23:38
Focusing Screens
Anyone with excellent eyesight will know if a screen works with a lens or not. Most don't work :shock: Unfortunately not many people open their eyes when using cameras and for years we have had a lot of total nonsense about DOF preview levers etc. and whether cameras should have them or not....
Posted by Algernon on 04/06/2012 - 09:02
Focusing Screens
But this has nothing to do with focusing screens right Algi? If you can't focus accurately at 1.2 with the OEM screen, it's because your eyesight isn't as good as you claim. Or maybe your dioptre isn't set right. Have you tried getting the framing lines perfectly sharp in the viewfinder? LOL j...
Posted by Pentaxophile on 04/06/2012 - 10:29
Focusing Screens
The problem is that with an f/1.2 lens you see through the viewfinder the DOF of an f/2.6 (approx) lens, so because you can only focus within the DOF of f/2.6 it might be outside of the DOF of the f/1.2. Some bits that look in focus through the camera won't be in the actual shot :shock:
Posted by Algernon on 04/06/2012 - 10:40
Focusing Screens
I think the confusion here may be one of nomenclature, or how it's being described. Clearly we can't see more or less DOF than actually exists, but there is a limit to what the eye can differentiate. Even a 35mm viewfinder is too small to accurately assess DOF in a shot. What looks sharp at 36x24...
Posted by johnriley on 04/06/2012 - 13:27
