Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-26-2011, 10:22 AM   #31
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
Exposure also changes depending on where you focused (if using center weighted or spot).
If you want to experiment with this, try a zebra stripe sofa or fabric or your cat which is a mottled black, white, grey. If you focus and lock on the dark portion of the coat specially using CP, the camera will compensate for the dark shade it sees and overexpose a bit. If you lock focus (locks exposure too) on the lighter shade of the coat, it will compensate for what it sees and underexpose.
Try locking focus and exposure on the white can and the exposure would be different from locking focus and exposure on the carpet.
Anyway, front focus issues and back focus issues only occur with AF lenses.
If you are using MF lens, then whatever back focus or front focus you have is user error since, you focused it yourself.
You can blame the camera if the camera chose the focus automatically.
I found out the differences in the exposure using CP and center weighted metering or spot metering from getting familiar with my camera for a while.
To get the average exposure, use multi-metering.
As stormcloud have pointed out too, focusing and recomposing from a very thin DOF is kinda tricky since one movement askew would have a great offset on your original focus.

06-26-2011, 10:31 AM   #32
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
QuoteOriginally posted by gp1806 Quote
The focus is off by a couple of inches. The carpet right in front of the catnip can is in focus. See the different look of the carpet in this area in both pics. This was a focus test. Camera is set to AFS. I chose a lens that would show focus errors, FA 50mm f/1.4. Is this a bad example to send to Pentax? What sort of pics would be good to send to Pentax?
If you send it to Pentax, they will require you to send in the lens in question too and they will calibrate the camera to the lens you sent. Make sure that this is the lens you will be using most of the time since once the camera gets calibrated to this lens, your other lens might get off focus.
If your other lenses behave this way, then there might be a real issue with the camera but if it is only the FA 50mm 1.4, then you might be able to adjust this in-camera by yourself since as I understand, the K-r is allowed one lens adjustment setting.
06-26-2011, 01:07 PM   #33
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
@GerryL - Good suggestions. I will try different tests. I was not concerned about exposure here, just wanted to try auto focus in dim daylight. I got my FA 50mm way back when I got my DL. That lens has shone good focus with a DL, K100Ds, and a K200D, so I think my 50 must be close to proper calibration, another reason that I chose it. I have been using focus and recompose for many years and the Live View shot is OK, but I understand that I could have blown it, so I guess I'll have to shoot charts with a tripod. Charts don't really 'turn me on', I like real pics for tests, but if that is what Pentax prefers, that is what I'll do.
06-26-2011, 01:19 PM   #34
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
QuoteOriginally posted by GerryL Quote
If you send it to Pentax, they will require you to send in the lens in question too and they will calibrate the camera to the lens you sent. Make sure that this is the lens you will be using most of the time since once the camera gets calibrated to this lens, your other lens might get off focus.
If your other lenses behave this way, then there might be a real issue with the camera but if it is only the FA 50mm 1.4, then you might be able to adjust this in-camera by yourself since as I understand, the K-r is allowed one lens adjustment setting.
If I adjust the K-R to focus properly in dim light, then in broad daylight it will back focus. As far as I can tell, all my lenses act the same way. Calibrating the camera to focus a lens won't help, because it depends on the brightness of the available light. It will properly focus in bright daylight, but not dim daylight.

06-28-2011, 05:58 PM   #35
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
I can't understand why your K-r would focus differently on just a shaded or dim area vs. a well lighted area.
It might produce different results with regards to exposure but I don't think it should produce different result with regard to focusing. I'm stumped.
Your particular copy might have issues if it is really like that.
I'm not an expert on the K-r but with other people experiencing only a FF issue on tungsten light, yours is kind of a whole new world in itself by having a difference in focusing just in the change of light (daylight) situation.
I'm sure there would be others here with a K-r who could do a similar test and see if they come up with the same results..but I doubt it though with so many satisfied K-r users.
06-28-2011, 08:10 PM   #36
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
@ GerryL - This is my 4th Pentax DSLR, so I have an understanding of what to expect from a Pentax DSLR. What I wanted was a camera that acted like my K200D but with better high ISO performance. Was that expectation out of line? I'm very disappointed. My old eyes don't do manual focus well (glasses don't help either). If this thing can't auto focus, I really can't use it.
06-28-2011, 08:23 PM   #37
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
Maybe you really did get a bad copy. It does happen once in a while.
Send it back if you are really not satisfied since, there is no use trying to make it work right if it can't work right in the first place due to malfunctions.
..and if you are not happy now, even if you did make it function a bit right, you would still not be happy since it already started out bad.
Just have it repaired or replaced, in that way, you will have a fresh start.
06-28-2011, 08:35 PM   #38
Pentaxian
twitch's Avatar

Join Date: Nov 2009
Posts: 4,571
QuoteOriginally posted by gp1806 Quote
If I adjust the K-R to focus properly in dim light, then in broad daylight it will back focus. As far as I can tell, all my lenses act the same way. Calibrating the camera to focus a lens won't help, because it depends on the brightness of the available light. It will properly focus in bright daylight, but not dim daylight.
You are speculating and I suspect your are incorrect. Focus shift tendencies occur under different colour temperatures not different light intensities (unless it is very dark). Testing a lens for BF/FF takes very little time, it's worth trying and adjusting it and then seeing if it is consistant in real use.

By the way, there is absolutely nothing wrong with the exposure settings in your test pics, 1/60, f1.8, ISO1600 makes perfect sense to me in an indoors situation, the test pics show it's a clear case of FF. What's causing it is likely the K-r body and the fix is easy. Try it, what's it going to cost ya?

06-29-2011, 08:32 AM   #39
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
QuoteOriginally posted by twitch Quote
You are speculating and I suspect your are incorrect. Focus shift tendencies occur under different colour temperatures not different light intensities (unless it is very dark). Testing a lens for BF/FF takes very little time, it's worth trying and adjusting it and then seeing if it is consistant in real use.

By the way, there is absolutely nothing wrong with the exposure settings in your test pics, 1/60, f1.8, ISO1600 makes perfect sense to me in an indoors situation, the test pics show it's a clear case of FF. What's causing it is likely the K-r body and the fix is easy. Try it, what's it going to cost ya?
Does sunlight color temp change as sun goes down?
I never said exposure was wrong, just that I wasn't concerned about exposure.
What is easy fix? Send to Pentax?
Cost? Probably $50 or so if I send with all my lenses (insured). I have many lenses. and loss of use of lenses while they are at service.
06-29-2011, 08:54 AM   #40
Veteran Member
Philoslothical's Avatar

Join Date: May 2011
Posts: 1,723
QuoteOriginally posted by gp1806 Quote
Does sunlight color temp change as sun goes down?
Yes, it does. Late afternoon sun is much warmer than midday, and closer to tungsten.

You don't need to send all your lenses. One or two is sufficient, and they should probably be the ones that you use most frequently.
06-29-2011, 04:20 PM   #41
Pentaxian
twitch's Avatar

Join Date: Nov 2009
Posts: 4,571
QuoteOriginally posted by gp1806 Quote
What is easy fix? Send to Pentax?
Cost? Probably $50 or so if I send with all my lenses (insured). I have many lenses. and loss of use of lenses while they are at service.
The "easy fix" to at least try is to use AF micro adjust on the K-r body. If that doesn't work then send it in, but you have a free remedy in your hands which may work, why not try it.
06-30-2011, 03:20 AM   #42
Senior Member
Elva's Avatar

Join Date: Sep 2009
Location: Grahamstown in the Eastern Cape province of South Africa
Photos: Gallery
Posts: 126
I sometimes fine that the best AF setting is spot and not any of those multi section settings, gives me spot on AF in all conditions. I am using a Kx. Try it on set on of the select zones for AF depending on the subject.
06-30-2011, 07:33 AM   #43
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
QuoteOriginally posted by twitch Quote
The "easy fix" to at least try is to use AF micro adjust on the K-r body. If that doesn't work then send it in, but you have a free remedy in your hands which may work, why not try it.
I thought that I mentioned that, sorry if I didn't. I need something like -15 (a guess, could need more) for tungsten, and -10 to -6 for dim light (varies with condition). But when I go to bright daylight I need to set back to zero, and I sometimes forget and get BF.
06-30-2011, 07:34 AM   #44
Veteran Member




Join Date: Mar 2009
Location: Chicago suburbs
Photos: Albums
Posts: 848
QuoteOriginally posted by Elva Quote
I sometimes fine that the best AF setting is spot and not any of those multi section settings, gives me spot on AF in all conditions. I am using a Kx. Try it on set on of the select zones for AF depending on the subject.
I use center spot and recompose.
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!
auto, camera, k-r, kr, p30, pentax k-r, time, waste
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Night Nightmare jaieger Post Your Photos! 3 09-04-2010 06:09 PM
ist DL firmware update nightmare jax1960 Troubleshooting and Beginner Help 4 02-18-2010 03:53 AM
ebay nightmare - what to do SteveM General Talk 52 10-29-2009 11:53 AM
The nightmare pingflood Post Your Photos! 7 09-30-2008 09:55 AM
Retail Nightmare ronsworks Photographic Technique 9 02-06-2007 01:06 PM



All times are GMT -7. The time now is 01:43 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