Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-06-2009, 05:52 PM   #1
Junior Member




Join Date: Jan 2009
Location: SE Connecticut
Posts: 38
Focus Issues

Camera is *ist DS, purchased new (dealer demo) a month ago, and sent back for service today.
Been using the camera for macro, specifically digitizing old 35mm slides. Setup includes a 105mm Takumar lens, a bellows, a short extension tube (so the bellows clears the flash snoot), and a light box for the slide (strobe & opal glass). Distance from camera to slide is adjusted and fixed to give desired magnification. Focus is accomplished by moving the bellows and lens.
Anyway, focus using viewfinder (diopter adjusted) with lens at f2.8. Stop down to F5.6 or so and expose (Vivitar 283 with 10K resistor). Initial results not really sharp. Added a dial indicator to track lens position, and started bracketing the viewfinder zero position. Found sharpest images with the lens .080" closer to the camera than the 'best' viewfinder position. Tested repeatability of viewfinder 'best' focus - +/- .010" on lens position. Repeated sharpest image test 3 times - consistent at about -.080". Hmmm... What about autofocus??
Mounted the kit lens, set to Av f5.6, and mounted on a tripod about 6 ft from the garage wall. Zoom at 55mm. Taped a resolution chart to the garage, used AF, and made exposure #1. Shifted to MF and moved the lens about 1/8" towards infinity and made exposure #2. Refocused in AF, shifted to MF, moved the lens 1/8" away from infinity and made exposure #3. Results? Exposure #2 is way out. Exposure #3 is far superior to exposure #1.
Conclusion? Camera is FUBAR. If lens mount to view screen is 46mm, then the distance to the CCD is 47mm+. Don't know how the AF works, so can't really comment on what's out of whack there.
Moral? Check your camera. Don't assume that since it's new out of the box, things are in A1 shape. Comments by thread reply or to: aeschober@snet.net

Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
af, camera, dslr, exposure, focus, garage, infinity, lens, mf, photography, position, viewfinder
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
KX and Focus Issues dmfw Troubleshooting and Beginner Help 7 07-29-2011 02:26 AM
Focus Issues JohnKSA Troubleshooting and Beginner Help 4 06-11-2010 04:39 AM
Focus issues bethtphotos Troubleshooting and Beginner Help 27 03-02-2010 09:01 AM
Focus issues with K-7 jslifoaw Pentax DSLR Discussion 8 08-21-2009 07:24 AM
Focus issues? benplaut Photographic Technique 23 10-04-2008 02:28 PM



All times are GMT -7. The time now is 12:38 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top