Search results for 'back focus' - page 662
Pentax 100mm Macro
I've managed to acquire a nearly new lens at a cracking price - low enough to steer me away from the Tamron or Sigma alternatives. Can anyone give guidance (or point at some) on how and when to use the focus locking device? Many thanks.
Posted by paul.graber on 13/02/2007 - 15:42
Pentax 100mm Macro
Focus lock is intended to avoid the lens "creeping" if it is pointed downwards or upwards. So, for example, if you were copying documents you could lock the focus point and know that the lens would not gradually creep out of focus due to gravity. All this implies that the camera is on a...
Posted by johnriley on 13/02/2007 - 15:56
Pentax 100mm Macro
in this review's verdict they talk about the lack of a "focus limiter" how is that different to a focus lock. http://www.ephotozine.com/article/Pentax-SMC-100mm-f28-D-FA-Macro
Posted by bforbes on 02/02/2009 - 20:41
Pentax 100mm Macro
I've got the F 100/2.8 Macro version, its Limiter Switch can be set to Full so the AF searches the Full range of the Focus ring or Limit in which case it restricts it's search to the Macro range max 0.6m. See shim
Posted by shim on 02/02/2009 - 21:46
Pentax 100mm Macro
...or Limit, in which case it restricts it's search to the Macro range max 0.6m. ...or 0.6m to infinity, depending where the focus is before you switch the limiter in. Dan
Posted by Daniel Bridge on 02/02/2009 - 23:28
Pentax 100mm Macro
...or Limit, in which case it restricts it's search to the Macro range max 0.6m. ...or 0.6m to infinity, depending where the focus is before you switch the limiter in. Dan ok got that. so what is the disadvantage of the Pentax 100mm f/2.8 Macro SMC P-D FA not having it.
Posted by bforbes on 02/02/2009 - 23:35
Pentax 100mm Macro
[quote:3496ace15f="shim"]...or Limit, in which case it restricts it's search to the Macro range max 0.6m. ...or 0.6m to infinity, depending where the focus is before you switch the limiter in. Dan ok got that. so what is the disadvantage of the Pentax 100mm f/2.8 Macro SMC P-D FA not having it.[/...
Posted by shim on 03/02/2009 - 08:57
Pentax 100mm Macro
The only trouble is the viewfinder of my K10D is a bit off for manual focusing with this lens. Can you expand on that a bit? A viewfinder can't be a bit off for manual focusing with one particular lens - it would be a bit off for all lenses and your images would be blurred. If you are finding i...
Posted by johnriley on 03/02/2009 - 10:04
Pentax 100mm Macro
would the 100mm macro lens also double as a 100mm telephoto or does the construction to suit short distance focus mean this is not practical
Posted by bforbes on 03/02/2009 - 10:22
Pentax 100mm Macro
would the 100mm macro lens also double as a 100mm telephoto or does the construction to suit shot distance focus mean this is not practical The D-FA100 makes a sublime portrait / short telephoto lens. Here's a couple of examples: Of course it's pretty damn good at close range too... :...
Posted by hefty1 on 03/02/2009 - 10:29
Pentax 100mm Macro
would the 100mm macro lens also double as a 100mm telephoto or does the construction to suit short distance focus mean this is not practical One from my Vivitar 100mm f2.8 macro.
Posted by Mike-P on 03/02/2009 - 11:26
Pentax 100mm Macro
The only trouble is the viewfinder of my K10D is a bit off for manual focusing with this lens. Can you expand on that a bit? A viewfinder can't be a bit off for manual focusing with one particular lens - it would be a bit off for all lenses and your images would be blurred. If you are finding i...
Posted by shim on 03/02/2009 - 12:27
Pentax 100mm Macro
Just carried out a fairly quick test at about 450mm so that I could also check against the Standard 50mm f/1.4 FA lens. Set a tape up at 45deg. Cut the back corner off an asprin box and trimmed it to fit the tape so that I could focus at 100mm take a pic then move the box to one side and take ano...
Posted by shim on 03/02/2009 - 15:08
Pentax 100mm Macro
Don't forget that the human eye has a variable amount of accuracy. Tests done in the 1970s showed that the point of focus varied quite a lot each time a photoapher manually focused a camera. This might be as accurate as you can hope to get.
Posted by johnriley on 03/02/2009 - 15:31
Pentax 100mm Macro
Don't forget that the human eye has a variable amount of accuracy. Tests done in the 1970s showed that the point of focus varied quite a lot each time a photoapher manually focused a camera. This might be as accurate as you can hope to get. Looking through the viewfinder at the tape you can actua...
Posted by shim on 03/02/2009 - 16:02
Pentax 100mm Macro
Just had a look at this and the depth of field for a 50mm lens at f/2.8 and 1.5ft (450mm) distance is only +-3mm. I've repeated the test with the 100mm Macro at double the distance and the results are the same..... Back focusing on manual and AF by 5-10mm which means the K10D is about as much use ...
Posted by shim on 03/02/2009 - 19:02
Pentax 100mm Macro
You can't back focus on manual. But the eye isn't accurate enough to judge. The focusing screen has to be in the right position if any of your pictures hope to be sharp - the amount of depth of focus is very small indeed. The mirror also has to be in the right place. The AF system could back f...
Posted by johnriley on 03/02/2009 - 19:05
Pentax 100mm Macro
in relation to front/back focus has anyone ever asked the manufactures what tolerance they work to when assembling the cameras? Just had a look at this and the depth of field for a 50mm lens at f/2.8 and 1.5ft (450mm) distance is only +-3mm. I've repeated the test with the 100mm Macro at double th...
Posted by bforbes on 03/02/2009 - 19:34
Pentax 100mm Macro
in relation to front/back focus has anyone ever asked the manufactures what tolerance they work to when assembling the cameras? 3mm over 450mm is a tolerance of 0.66% would seem very good to me I don't know where your getting the 3mm tolerance from..... that's the depth of field that you have t...
Posted by shim on 03/02/2009 - 20:06
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 womble on 03/02/2009 - 20:23
