Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-28-2008, 12:22 AM   #1
Senior Member




Join Date: Apr 2008
Location: Barcelona, Spain
Posts: 264
About focus issues on new lenses

Hello.

I am quite new on the DSLR world, but one thing that seems quite important lately is new cameras and lenses having focus issues (back or front). I dont know what would you think about that but for me it is becoming some kind of psico, and to tell you the truth that was the main reason to stop my LBA

So my question is: do you really check all your new lenses with the Focus Chart or do you just test it on the real world and then if noticing something strange you do the chart?

For people like me doing this lab test requires some experience and having the correct light and owning a tripod, etc.. so probably the results would be a bit dissapointing and even depressing, we never know for sure if the test was correct, or maybe the problem was on the lens or what.

Thanks.

07-28-2008, 02:41 AM   #2
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,342
In my opinion, and I am sure there will be lots who will disagree after reading this, in most cases the focusing charts are a complete waste of time.

I have not seen a single posting where they have been used correctly and interpreted correctly.

Additionally, I am not sure every one understands the physics of focus and the range of acceptable focus.

Just to let you know, when you use a focusing chart, the range of acceptable focus should be 1/3 in front to 2/3 behind the line.

If you want to test with a focusing chart, you need to be on a tripod, with the camera perfectly square with the front edge of the chart. Some companies recommend a different angle than 45 degrees, I have seen that posted here,

you should also check how your camera achieves focus by both coming from minimum focus and maximum focus.

but in the end all of that is irrelevant, what matters is how the images look, and nothing more. take real pictures. I have never seen a focusing chart hanging in a gallery
07-28-2008, 07:02 AM   #3
Pentaxian
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 10,054
QuoteOriginally posted by cooldude14es Quote
Hello.

I am quite new on the DSLR world, but one thing that seems quite important lately is new cameras and lenses having focus issues (back or front). I dont know what would you think about that but for me it is becoming some kind of psico, and to tell you the truth that was the main reason to stop my LBA

So my question is: do you really check all your new lenses with the Focus Chart or do you just test it on the real world and then if noticing something strange you do the chart?

For people like me doing this lab test requires some experience and having the correct light and owning a tripod, etc.. so probably the results would be a bit dissapointing and even depressing, we never know for sure if the test was correct, or maybe the problem was on the lens or what.

Thanks.
I noticed some serious focusing issues with my K20 right off the get go. I ended up testing all my AF lenses with the D-70 focus chart and dialed then in as best as was possible. My particular K20 is very sloppily built, and the adjustment range on a few lenses wasn't long enough to manage proper AF. Setting up a focus chart is fairly easy, but a certain amount of accuracy is required..
07-28-2008, 08:45 AM   #4
Veteran Member
troyz's Avatar

Join Date: May 2008
Posts: 389
QuoteOriginally posted by cooldude14es Quote
Hello.

So my question is: do you really check all your new lenses with the Focus Chart or do you just test it on the real world and then if noticing something strange you do the chart?

I've tested enough of my lenses with the 45 degree ("D70") focus chart to conclude that I get inconclusive results with a 45 degree focus chart.

The D70 chart is a good torture test for the camera's AF system; however, for my purposes it has many drawbacks as a calibration tool:

-- The target is smaller than the AF sensor area

-- I don't take wide-open pictures of flat objects at a 45 degree angle. Ever.

-- I'm not certain that an AF adjustment that is optimal for a very close target will be optimal for a distant target

Every new lens gets a pretty careful check for sharpness wide open, at the range of its intended use. If I'm disappointed by the results, then I start tinkering with the AF adjustments using relatively large focus targets parallel to the plane of focus.

07-28-2008, 09:31 AM   #5
Veteran Member




Join Date: May 2007
Location: York Region Canada
Posts: 642
Go and shoot some pictures. If they look good, keep shooting.

Dave
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!
chart, focus, focus issues, issues, k-mount, lenses, pentax lens, slr lens, test, world
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
New K-5- I need help with focus issues Kini62 Pentax K-5 27 10-25-2010 10:12 PM
Focus issues VincenTC Troubleshooting and Beginner Help 5 02-09-2010 01:49 PM
Focus Issues aesch Pentax DSLR Discussion 0 03-06-2009 05:52 PM
help FA 50 1.4 Focus issues qksilver Pentax SLR Lens Discussion 7 06-23-2008 06:21 PM



All times are GMT -7. The time now is 06:03 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