Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-15-2007, 02:30 AM   #16
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
QuoteOriginally posted by frank Quote
I heard that among all the 11 focusing points, only the center one is for F2.8 while the others only at F5.6 level (which means you might be off if a bigger aperture is used when focusing at that point).

I tested my K100D w/ a 77 lens, the center focusing point is spot on even wide open. But the vertical top focusing point is way off, the bottom one is okay, not as good as the center one, but is okay. To get around, I have to rotate the camera the other way around so I can use the vertical bottom (now it's the top) focusing point when I need to. As long as I know the problem, I can still get good enough results.

Maybe some K10D have the same problem?
I shot everything at f 9.0 and above. Most stuff at around f 14.0

Ben

02-15-2007, 02:32 AM   #17
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
Rotate

QuoteOriginally posted by frank Quote
I heard that among all the 11 focusing points, only the center one is for F2.8 while the others only at F5.6 level (which means you might be off if a bigger aperture is used when focusing at that point).

I tested my K100D w/ a 77 lens, the center focusing point is spot on even wide open. But the vertical top focusing point is way off, the bottom one is okay, not as good as the center one, but is okay. To get around, I have to rotate the camera the other way around so I can use the vertical bottom (now it's the top) focusing point when I need to. As long as I know the problem, I can still get good enough results.

Maybe some K10D have the same problem?
Now isn't that funny, I thought to myself last night, "Perhaps if I rotate the camera...that would work" Come on. I have my grip and I would like to shoot it as it was designed. But, why not, I'll give it a try till I get it repaired.
02-15-2007, 03:14 AM   #18
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
Upside Down

QuoteOriginally posted by frank Quote
I heard that among all the 11 focusing points, only the center one is for F2.8 while the others only at F5.6 level (which means you might be off if a bigger aperture is used when focusing at that point).

I tested my K100D w/ a 77 lens, the center focusing point is spot on even wide open. But the vertical top focusing point is way off, the bottom one is okay, not as good as the center one, but is okay. To get around, I have to rotate the camera the other way around so I can use the vertical bottom (now it's the top) focusing point when I need to. As long as I know the problem, I can still get good enough results.

Maybe some K10D have the same problem?
Just shot upside down and it worked. One of the bodies was a little bit sharper. The problem will be when shooting horizontal double page spreads. I don't want to stick the model on the left hand page systematically. Bummer...I'm sure it can be resolved..Gulp!
02-15-2007, 07:22 AM   #19
wll
Veteran Member




Join Date: Nov 2006
Location: Mission Hills, CA
Posts: 773
benjikan, could it be ....

because you are low to the ground and the camera wants to focus on what ever the AF sees first.

If your low to the ground the distance to the feet is less than the distance to the head, so it sees the lower part of the body first and shoots that. If you were high it would see the head first and focus on that.

If you have a long tape measure try it out. Get in your shooting position, put a tape or long string on your lens, stretch it to the models foot, hold your position and have her move the tape or string up to her face, you will see that the measure falls short of your intended focus point..


Just a thought.



wll

02-15-2007, 08:07 AM   #20
Veteran Member
frank's Avatar

Join Date: Nov 2006
Location: Singapore
Photos: Gallery
Posts: 3,202
QuoteOriginally posted by benjikan Quote
Just shot upside down and it worked. One of the bodies was a little bit sharper. The problem will be when shooting horizontal double page spreads. I don't want to stick the model on the left hand page systematically. Bummer...I'm sure it can be resolved..Gulp!
Okay, I guess your K10D has the sampe 'problem' as my K100D, one of the AF sensor is out. Luckily the center AF point is spot on w/ my K100D, and all the other 9 points work fine also. I can live w/ that
02-15-2007, 08:09 AM   #21
Veteran Member
frank's Avatar

Join Date: Nov 2006
Location: Singapore
Photos: Gallery
Posts: 3,202
QuoteOriginally posted by wll Quote
because you are low to the ground and the camera wants to focus on what ever the AF sees first.

If your low to the ground the distance to the feet is less than the distance to the head, so it sees the lower part of the body first and shoots that. If you were high it would see the head first and focus on that.

If you have a long tape measure try it out. Get in your shooting position, put a tape or long string on your lens, stretch it to the models foot, hold your position and have her move the tape or string up to her face, you will see that the measure falls short of your intended focus point..
Just a thought.

wll
You might be right if you rely on the camera to select the AF point. But if you select the focusing point yourself, it shouldn't be like what you said above...
02-15-2007, 08:23 AM   #22
Veteran Member
Ivan Glisin's Avatar

Join Date: Nov 2006
Location: Belgrade
Posts: 656
I suspect the problem is...

QuoteOriginally posted by benjikan Quote
Just shot upside down and it worked. One of the bodies was a little bit sharper.
...in the AF plate not being parallel to the sensor plane, causing the error. The error should appear with all lenses, but wide angle lenses or zooms at wide angle settings used at short distances should exhibit the error more clearly (similar to "focus-recompose" errors).

The solution: Pentax should be able to easily adjust the AF plate for you. FYI, there are three screws that are used to position the AF plate. You can take a look at this post here with the illustration (*istDS is depicted, K10D should be similar):

Re: Pentax DSLR AF accuracy: Pentax SLR Talk Forum: Digital Photography Review

I would recommend you to EXPLICITLY ASK them to adjust the AF plate position, not to simply give you a new body hoping the problem will go away. It may not, since there are variances between samples as you have already seen.

And the final note: the image quality, ergonomics, electronics, software and hardware in Pentax cameras are all excellent. But Pentax should really find out why simple final calibration and quality control are allowing for such a large tolerances in products hitting the market.

-= IVAN =-
02-15-2007, 11:36 AM   #23
wll
Veteran Member




Join Date: Nov 2006
Location: Mission Hills, CA
Posts: 773
QuoteOriginally posted by frank Quote
You might be right if you rely on the camera to select the AF point. But if you select the focusing point yourself, it shouldn't be like what you said above...
You are 100% correct if that is the case.


wll

02-15-2007, 01:43 PM   #24
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
No Offence

QuoteOriginally posted by wll Quote
because you are low to the ground and the camera wants to focus on what ever the AF sees first.

If your low to the ground the distance to the feet is less than the distance to the head, so it sees the lower part of the body first and shoots that. If you were high it would see the head first and focus on that.

If you have a long tape measure try it out. Get in your shooting position, put a tape or long string on your lens, stretch it to the models foot, hold your position and have her move the tape or string up to her face, you will see that the measure falls short of your intended focus point..


Just a thought.


wll
Thanks for your input. However, I have been shooting this way for years and never had a problem with that other brand..I would use the 17-40 lens sometimes literally placing the camera on the floor and the model towering sometimes up to six feet about eight feet from me, focus on the eyes and the eyes were in focus. That is all I really want. I think there is an issue with the camera and will probably just have to have a minor adjustment to remedy it.

The 40 and 70 aren't a problem. There is a problem with the 21 and somewhat less with the 16-45. They are both incredibly sharp lenses if focussed manually. In fact I would dare to say that the 16-45 is as sharp as the 21mm, which might make the 21mm redundant..and no I am not giving it away! I am reading your thoughts!

...and thank you so much for your input. I am as perplexed as you are. I'm am not a tech person, just a "Dumb" Fashion Photographer...

Last edited by benjikan; 02-15-2007 at 01:50 PM.
02-15-2007, 01:49 PM   #25
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
Focus Point

QuoteOriginally posted by frank Quote
You might be right if you rely on the camera to select the AF point. But if you select the focusing point yourself, it shouldn't be like what you said above...
Thanks for the input. I always manually choose the focus point, using the four pivot selector.

Thanks
Ben
02-15-2007, 02:23 PM   #26
Veteran Member
Denis's Avatar

Join Date: Jan 2007
Location: St-Albert, Alberta, Canada
Posts: 333
QuoteOriginally posted by benjikan Quote
Thanks for your input. However, I have been shooting this way for years and never had a problem with that other brand..I would use the 17-40 lens sometimes literally placing the camera on the floor and the model towering sometimes up to six feet about eight feet from me, focus on the eyes and the eyes were in focus. That is all I really want. I think there is an issue with the camera and will probably just have to have a minor adjustment to remedy it.

The 40 and 70 aren't a problem. There is a problem with the 21 and somewhat less with the 16-45. They are both incredibly sharp lenses if focussed manually. In fact I would dare to say that the 16-45 is as sharp as the 21mm, which might make the 21mm redundant..and no I am not giving it away! I am reading your thoughts!

...and thank you so much for your input. I am as perplexed as you are. I'm am not a tech person, just a "Dumb" Fashion Photographer...
I have quickly tested K10D and 16-45mm to see if focus had a problem. On the floor 9 feet away from base, at 23mm, with object 6 feet up and book on floor the camera showed sharp focus on the object. Focus was slightly out at floor level just the way it should be. I reverse the camera, moved focus point to other edge and tested. Same results were shown in latter images. I dimmed the lights to see if focus would still act proper. A few images did not focused as good but the difference between ground level and upper object remained as per initial test. Focus with 16-45mm does appear to work fine on my camera. It was not a very scientific test put results showed selected focusing point as it should be.
02-15-2007, 02:27 PM   #27
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,312
Original Poster
Mail

QuoteOriginally posted by Denis Quote
I have quickly tested K10D and 16-45mm to see if focus had a problem. On the floor 9 feet away from base, at 23mm, with object 6 feet up and book on floor the camera showed sharp focus on the object. Focus was slightly out at floor level just the way it should be. I reverse the camera, moved focus point to other edge and tested. Same results were shown in latter images. I dimmed the lights to see if focus would still act proper. A few images did not focused as good but the difference between ground level and upper object remained as per initial test. Focus with 16-45mm does appear to work fine on my camera. It was not a very scientific test put results showed selected focusing point as it should be.
Just go to your post office and put the K10D in it's original packaging and ask what it costs to send it to Paris, France. That is the least you could do...
02-15-2007, 03:21 PM   #28
Inactive Account




Join Date: Oct 2006
Location: Boise, Idaho
Photos: Gallery | Albums
Posts: 1,414
QuoteOriginally posted by benjikan Quote
Just go to your post office and put the K10D in it's original packaging and ask what it costs to send it to Paris, France. That is the least you could do...
Hee hee, for a fashion photographer you're kinda funny. (Joke.) I think you are quite right, that a slight adjustment will have your K10s running perfectly. Let us know how it turns out.
02-15-2007, 03:50 PM   #29
Veteran Member
Alvin's Avatar

Join Date: Dec 2006
Location: Mississauga, Ontario, Canada
Photos: Gallery
Posts: 2,530
QuoteOriginally posted by benjikan Quote
In fact I would dare to say that the 16-45 is as sharp as the 21mm, which might make the 21mm redundant..and no I am not giving it away!
Drat! LOL.

Sorry to hijack Ben, but doesn't the K100 use the same AF sensor as the K10D, and if so, would that problem potentially exist as well? I've been reading through this and just had to ask.
02-15-2007, 04:06 PM   #30
Veteran Member
Denis's Avatar

Join Date: Jan 2007
Location: St-Albert, Alberta, Canada
Posts: 333
QuoteOriginally posted by benjikan Quote
Just go to your post office and put the K10D in it's original packaging and ask what it costs to send it to Paris, France. That is the least you could do...

SURE...!

I asked my son to quickly pose for me as a test. It was quick(teenage kids, no patience). Took images at 23mm F7.1 100 iso with focus offset to max on either side. Crop eye and foot to show difference. First set is with focus to right follow by left. Don't look at the image but the focus difference. AS I said this was very quick.

Last edited by Denis; 03-01-2007 at 09:08 AM.
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!
21mm, bodies, camera, dslr, lenses, pentax, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is this a front focusing camera problem or lens problem? Lens tests Metalwizards Pentax K-r 15 03-06-2011 01:24 AM
K-5 battery problem? camera problem? user problem? imtheguy Pentax K-5 39 11-03-2010 06:02 PM
Problem with my LX Art Vandelay II Pentax Film SLR Discussion 27 12-18-2009 04:50 PM
Anyone have this problem? dankuno Pentax DSLR Discussion 9 12-10-2009 08:00 AM
Card read problem K20d. Have you had this problem? rsi1986 Pentax DSLR Discussion 8 12-27-2008 05:25 AM



All times are GMT -7. The time now is 07:44 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