-
Welcome to the new forums! Please read this first. For known issues we are working to resolve, click here.
is my new da21 limited back focusing ?
- Thread starter jz466
- Start date
at close distances. Mine can do it but sometimes, not always. odd.
If it is under warranty see what Pentax will do for you but do not hold your breath.
--
***********************************************
Please visit my gallery at http://www.pbase.com/alfisti
Pentax Lens examples at http://www.pbase.com/alfisti/images_by_lens
Updated November 2007
If it is under warranty see what Pentax will do for you but do not hold your breath.
--
***********************************************
Please visit my gallery at http://www.pbase.com/alfisti
Pentax Lens examples at http://www.pbase.com/alfisti/images_by_lens
Updated November 2007
chris gunn
Veteran Member
You lucky sod! I didn't know the 21 could have so little BF!
I adjust about -80.
--
cheers!
Gunn
-- Get a big lens and get closer™.
http://www.dpreview.pentaxistDS.photoshare.co.nz
http://www.y3m.net/penwik/pmwiki.php/Main/PentaxLensWiki
FAQ: http://www.pentaxuser.org/tiki-index.php
--You lucky sod! I didn't know the 21 could have so little BF!
I adjust about -80.
--
cheers!
Gunn
-- Get a big lens and get closer™.
http://www.dpreview.pentaxistDS.photoshare.co.nz
http://www.y3m.net/penwik/pmwiki.php/Main/PentaxLensWiki
FAQ: http://www.pentaxuser.org/tiki-index.php
Really, So I should be happy with it ? I'm new at this and not sure what to expect. Just was reassurance I guess.
John
chris gunn
Veteran Member
I expect this is within factory tolerance.
If you want better, the 20D will have AF adjustment, and their may be a FW upgrade later for the 10D.
--
cheers!
Gunn
-- Get a big lens and get closer™.
http://www.dpreview.pentaxistDS.photoshare.co.nz
http://www.y3m.net/penwik/pmwiki.php/Main/PentaxLensWiki
FAQ: http://www.pentaxuser.org/tiki-index.php
--I expect this is within factory tolerance.
If you want better, the 20D will have AF adjustment, and their may be
a FW upgrade later for the 10D.
--
cheers!
Gunn
-- Get a big lens and get closer™.
http://www.dpreview.pentaxistDS.photoshare.co.nz
http://www.y3m.net/penwik/pmwiki.php/Main/PentaxLensWiki
FAQ: http://www.pentaxuser.org/tiki-index.php
Thanks so much for the input. I will await the k10D FW update, or better yet a 20D !
John
theshadowes
Forum Enthusiast
check your DOF chart for this lens though. the rule of tumb is 1/3 - 2/3rds.
4 mm is in front focus so anything around the 8 -10 mm back focus is acceptable.
--
shadow
4 mm is in front focus so anything around the 8 -10 mm back focus is acceptable.
--
shadow
--check your DOF chart for this lens though. the rule of tumb is 1/3 -
2/3rds.
4 mm is in front focus so anything around the 8 -10 mm back focus is
acceptable.
--
shadow
DOF chart. This is something new I am going to have to study. Where do I find this chart you speak of ? Is it in the instruction booklet that came with the lens ?
John
Backfocus tends to get worse at longer distances. On a wide lens, chart tests can be difficult to interpret. the cereal box test (search this forum) is also a bit difficult, since it is hard to know what the af sensor actually locks on to.
Try in real life situations, and see if the images seem softer than you would expect. If the focus throw on the lens is long enough, there is another, crude but effective test. Put the camera on a tripod and aim at a big flat target 3-4 meters away. Let the camera focus, take a picture. Turn of the af and move the focus ring in tiny, tiny increments while snapping. Repeat several times. If one of the mf shots always turn out sharper than the af one, you have a problem.
Try in real life situations, and see if the images seem softer than you would expect. If the focus throw on the lens is long enough, there is another, crude but effective test. Put the camera on a tripod and aim at a big flat target 3-4 meters away. Let the camera focus, take a picture. Turn of the af and move the focus ring in tiny, tiny increments while snapping. Repeat several times. If one of the mf shots always turn out sharper than the af one, you have a problem.
theshadowes
Forum Enthusiast
you can down load it here
http://www.pentax.se/upload/files/SMC%20DA%2021mm.pdf
try not to strip you exif data out of your photos when you up load them as it makes very hard to interped the data.
in your case your lens looks fine its about 1/4 3/4 focusing about ideal for a wide lens.
BTW when you do a focusing test make sure you measure from the sensor in your camera to the paper not from the end of your lens.
--
shadow
http://www.pentax.se/upload/files/SMC%20DA%2021mm.pdf
try not to strip you exif data out of your photos when you up load them as it makes very hard to interped the data.
in your case your lens looks fine its about 1/4 3/4 focusing about ideal for a wide lens.
BTW when you do a focusing test make sure you measure from the sensor in your camera to the paper not from the end of your lens.
--
shadow
Laurens
Senior Member
Your lens is fine (much better than mine) - no manuf. specifies AF as "exactly in the middle of DOF"
--you can down load it here
http://www.pentax.se/upload/files/SMC%20DA%2021mm.pdf
try not to strip you exif data out of your photos when you up load
them as it makes very hard to interped the data.
in your case your lens looks fine its about 1/4 3/4 focusing about
ideal for a wide lens.
BTW when you do a focusing test make sure you measure from the sensor
in your camera to the paper not from the end of your lens.
--
shadow
Thanks for the link. I'm not sure why my exif data is being stripped. I use the flickr uploader. Possibly that is stripping it during the uploading process. I'll try uploading using a different method in the future.
John
Keyboard shortcuts
- f
- Forum