Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-01-2010, 05:38 AM   #1
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Tamron 10-24mm could not focus with ISO100 F22 10mm under day light

I've bought the Tamron 10-24mm and observed that it could not focus with F22, 10mm, ISO100 with my Pentax K7 during day light. Is this normal or something that I should worry about it? Thanks.

04-01-2010, 05:46 AM   #2
Senior Member




Join Date: Jan 2010
Location: Manistee, MI
Posts: 295
my tammy 10-24 is 'fussy' about focusing from time to time, but generally it gets it right. Why F/22? Your IQ is fairly diminished at that point. Do you have the same trouble at f/8-f/11?

Another interesting quirk I've noticed, the camera doesn't seem to honor the far end focus stop, if the lens starts hunting for focus the camera will run up against the far stop and sit there ticking, even though the far stop is well past infinity.
04-01-2010, 06:22 AM   #3
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Original Poster
I've just got the new lens so I wanted to test it out to make sure it is not defect. From my test, I have to open up till F11 to get it focus to infinity (landscape shoot). What would be the point of design if the lens allow us to stop down to F22 but the camera cannot focus? Is it the limitation from the camera internal focus or I should not even go to that extreme with ultra wide angle lens?
04-01-2010, 06:38 AM   #4
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
there should be no difference iwth aperture setting since all focusing is done wide open.

How are you changing aperture, on the lens (don't know the lens to know if this is possible or not) or using the camera body dials.

How bright is the viewfinder image?

To be honest, unless there is something wrong with your lens and it is stopping down when you change aperture, The aperture setting and focusing should be wholly independant.

WIth respect to focusing wide angle lenses, the very high DOF makes focusing difficult, and high contrast images (like those on sunny days) can cause focusing problems because the camera cannot distinguish the contrast from the scene to the contrast of sharp focus.

I have a Sigma 10-20 and have not noticed any issues focusing on my K7 but I am not sure the focal length, other than the inherent DOF at 10mm has any impact.

We need a few more details of what you are doing and how you are shooting

04-01-2010, 06:43 AM   #5
Forum Member




Join Date: Nov 2008
Posts: 84
That's pretty simple actually. At 10mm, F22, your depth of field is so huge your whole picture is going to be in focus. It doesn't really matter what you focus on, your pictures will come out ok. The diffraction from F22 will be something else though and it will cause a degradation of image quality.
04-01-2010, 06:56 AM   #6
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
QuoteOriginally posted by vandamro Quote
That's pretty simple actually. At 10mm, F22, your depth of field is so huge your whole picture is going to be in focus. It doesn't really matter what you focus on, your pictures will come out ok. The diffraction from F22 will be something else though and it will cause a degradation of image quality.
Your first comment is not really addressing the issue. While it is true that at F22 the DOF is huge, this should not impact the ability to achieve focus. (assuming I have read the OP's question correctly. Uless there is a defect in the lens, all focusing is performed with maximum aperture on any autofocus SLR.


Your second point is quite true that with a 10mm lens, the aperture is so small that defraction will be an issue.

Additionally, at 10mm, the field of view is so large the OP may be confusing focus with resolution primairly that of the sensor.

A few photos would be a big help otherwise we are speculating on the problem
04-01-2010, 06:58 AM   #7
Veteran Member




Join Date: Jun 2007
Location: Owego, NY
Posts: 976
It sounds like you have a serious problem (or are just not mounting the lens properly) if aperture is affecting focus.

AF will break when lens aperture is stopped down beyond f/6.3 or so (sometimes you can push it to f/8). However, as stated above - unless the lens is improperly mounted, it will focus with the lens wide open and then stop down for the shot.
04-01-2010, 07:13 AM   #8
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Original Poster
Here is my captured image with f14 where I can archive focus. I've tried to focus on the stop light with f22 without success.
https://www.pentaxforums.com/forums/members/vietnam74-albums-test-images-pict...-imgp1447.html

04-01-2010, 07:33 AM   #9
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
QuoteOriginally posted by vietnam74 Quote
Here is my captured image with f14 where I can archive focus. I've tried to focus on the stop light with f22 without success.
PentaxForums.com - vietnam74's Album: Test Images - Picture
no offence intended but a 150 x 100 pixel image is completely useless to assess anything. Even the link at 1024 x 640 is not really good.

can you explain exactly how you are setting aperture, and post the exif data from the image as well so we can see what the camera is doing?

ALso you are shooting it appears directly into the sun. This is not good, and the stop light in the image is badly backlit. I think you have a problem with respect more to the way you are shooting than the lens itself
04-01-2010, 07:46 AM   #10
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Original Poster
I could not upload picture higher resolution. I've shot that picture in a cloudy day though. I've tried everything I could even try focus on the buildings themselves too but could not archive focus.
04-01-2010, 09:29 AM   #11
Veteran Member




Join Date: Jul 2009
Location: Berlin, Germany
Posts: 344
I'm not saying you should just accept that it doesn't properly focus but at f/22 focus doesn't matter especially not on a lens that wide. f/8 or f/11 will already allow for infinite DOF so stopping down any further won't improve anything.

But still I suspect there is either something wrong in your lens-camera pairing or with your usage of it (whatever that should be).

Here's a site that will easily take your full sized picture: http://www.pic-upload.de/ Upload limit are 16mb - the page is german but it should explain itself.
04-01-2010, 09:41 AM   #12
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
QuoteOriginally posted by vietnam74 Quote
I could not upload picture higher resolution. I've shot that picture in a cloudy day though. I've tried everything I could even try focus on the buildings themselves too but could not archive focus.
just crop the center and perhaps one edge to about 1/10 the frame and upload at full resolution, and also do the same with one shot where the focus is deemed unacceptable,

but again, also give us the exif data so we can see that the camera is doing.

You also have not said how you are selecting F22, is it with an aperture ring or the camera controls

and when you say you can't get focus, does this mean you can't have the camera tell you that you are in focus or just that image is not as sharp as at F11?
04-01-2010, 11:49 AM   #13
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Original Poster
Please see this link: IMGP1446: vietnam74: Galleries: Digital Photography Review

I did use the camera control since the lens do not have aperture ring.

Basically the camera tried to focus to infinity and then the lens' motor whining and either stop or keep whining while the camera would not allow me to take the picture with the green hexagon blinking inside the viewfinder. I've just test it again outside my home also with even f9 but I can archive focus and be able to take picture ~5-10% of the time for distance of 10-20 feet tree/fence/windows.
04-01-2010, 05:36 PM   #14
Senior Member




Join Date: Jan 2010
Location: Manistee, MI
Posts: 295
QuoteOriginally posted by vietnam74 Quote
Please see this link: IMGP1446: vietnam74: Galleries: Digital Photography Review

I did use the camera control since the lens do not have aperture ring.

Basically the camera tried to focus to infinity and then the lens' motor whining and either stop or keep whining while the camera would not allow me to take the picture with the green hexagon blinking inside the viewfinder. I've just test it again outside my home also with even f9 but I can archive focus and be able to take picture ~5-10% of the time for distance of 10-20 feet tree/fence/windows.
Are you sure you're using a Pentax? AFAIK the Pentax version of the 10-24 is screw drive focus, there is no lens motor. The canon and nikon versions do us a lens motor. Your shot is badly over exposed, something my tammy likes to do as well, I usually shoot -1 to -1.3 ev when it is very bright.

Looking at the full size image, it doesn't look that bad - mostly it looks soft, not out of focus. according to the exif your was exposed at f/3.5 that is WIDE OPEN and it takes a gem of a lens to be sharp wide open.

take a look at this one:
http://projects.dimension-x.net/pictures/misc/IMGP5777.JPG
14mm, f/5.6, iso 200.

if you pixel peep, you'll see it is soft around some of the details. I guess this is why people don't like the tammy, claiming it's dull.

this one is re-sized using a bicubic filter to 50%:
http://projects.dimension-x.net/pictures/K-x/church2-lg.jpg
10mm, f/8, iso 100

I have no complaints with my copy. remember, your computer screen is very low resolution compared to print media.
04-01-2010, 06:34 PM   #15
Junior Member




Join Date: Apr 2010
Photos: Albums
Posts: 31
Original Poster
Thank you very much for the information and pictures. I'm sure that I'm using Pentax version. I guess the noise is from the screw drive.

I could not do focus or taking picture at f22 so I have to open up so the camera can take picture. I also have another one at f14 as well. I'm used to the DA* 16-50mm or Tamron 17-50mm lens combination that works well with my K7: set aperture, point, and shoot.

I think the problem is the lens auto focus or lens/camera combo since I can manage to take picture now with f3.5 to f22 but with several attempts per picture to find the right spot where the lens/camera can auto focus. I do not have this issue with manual focus at all.
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!
10-24mm, 10mm, day, focus, iso100, k-mount, light, pentax lens, slr lens, tamron 10-24mm
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for input Tamron 10-24mm vs DA 12-24mm ManhattanProject Pentax SLR Lens Discussion 8 12-17-2010 01:22 PM
Difference between Pentax fish eye @ 10mm and Sigma @ 10mm? Big G Pentax SLR Lens Discussion 15 10-07-2010 12:12 PM
For Sale - Sold: Sigma 24-60mm F2.8 (K mount) and Tamron Adaptall 24mm F2.5 with Tamron P/K ada pxpaulx Sold Items 4 08-27-2010 08:47 PM
Landscape photo using F22? raider Photographic Technique 39 11-26-2008 02:27 AM
Pictures taken at f8 vs. f22 landscape shots weaponx525 Photographic Technique 10 08-26-2008 03:02 AM



All times are GMT -7. The time now is 08:39 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