Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
11-23-2010, 08:47 AM   #1
New Member




Join Date: Nov 2010
Location: Washington DC
Posts: 4
Is my *istDS wearing out? Lenses? Brain?

So, I'm finding my camera when on autofocus and autoexpose mode just doesn't work as well as it used to . . .

I'm using a Pentax *istDS with a Tamron 18-300 most of the time. My first instinct was that it's the lens. I purchased this lens in 2006 for a long trip through China where weight was an issue and it served me really well as my only lens (there were points climbing holy mountains in July heat where I considered chucking my toiletries to get more weight off my back so I'm glad I wasn't carrying an extra lens). However, the camera hit a concrete church floor in 2009 lens down and I thought I might have done some real damage, but it performed ok for the rest of the trip. Since then though, I find it gets stuck finding the focus or stops focusing at an out-of-focus point, especially in low lighting.

My only other AF lens is a 28-70 Quandary that I got for some ridiculously discounted price at a going out of business sale for when I want the camera and lens combo to be super light and I don't need much zoom. After some fairly light use, it doesn't AF all that well either. I've been running on the assumption that this lens wasn't all that great to start with.

However, overall, I'm noticing also a heighten tendency of my *istDS to underexpose the images when in the auto settings and find myself lightening all lot more images than I think I used to. But I also have a couple bright sun shots that are ridiculously over exposed for the first time ever. (I've confirmed the exposure compensation settings are at 0.)

Thoughts on what is going on here? Is the camera, the lens, or maybe my brain? As the parent of a toddler, I haven't had been as focused on photography in the last couple of years and am more likely to be shooting in less-than-ideal lighting, but I still find myself dissatisfied by the exposure more than I feel I should be . . .

Thanks.

11-23-2010, 08:55 AM   #2
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
I guess either the camera is wearing out (on the mechanical problems) or your batteries are or both. I've had AF zooms far more than 4 years old and didn't notice any slow action on the AF. WRT to the hunting and giving up on some random focus point, that's been the case with all of my cameras---- in a low light low contrast situation.

11-23-2010, 10:15 AM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
with respect to under exposure, have you gone back and looked at the histogram of your old shots against that of newer shots. On average, they should be similar.

You have not, by accident, set the EV comp, have you?

Also, i note you dropped the camera. It may be possible that you have misaligned the AF mechanism in the lens, have you been able to test other lenses?
11-23-2010, 10:20 AM   #4
Senior Member




Join Date: Jul 2008
Location: Arizona
Posts: 283
If damaged - replace

It's probably not worth fixing if it really is damaged or malfunctioning, but there are some little-used second hand ones available at crazy prices - I've seen an almost unused one sell for $150!

Of course, if you are like the rest of us, you could use this as an excuse to upgrade!

Mike

11-23-2010, 05:53 PM   #5
New Member




Join Date: Nov 2010
Location: Washington DC
Posts: 4
Original Poster
Thanks. I haven't been able to test with other lenses, but I'm planning to. The camera has 18189 shutter releases, it turns out.

I did compare the histograms of recent shots with older ones and they are definitely skewed way to the left. However, I started shooting raw last summer and that seems to be when the problem began. (It's not the EV compensation settings). My jpegs from before that are more better exposed. No idea if that ends up being relevant, but I'll shoot some jpegs and see.

Any suggestions for helping me work with this camera for at least a few more months would be appreciated. I updated the firmware (was at 1.0) and have only taken a few shots since then.

How low is low light when imagining I should start having AF problems? This evening, I was shooting a fairly flat subject (a row of shirts in a closet) 6 ft away with a zoom lens at the wide end, on Auto ISO (a new feature with the firmware update that I'm just messing with), with the room lit by three compact fluorescent bulbs and the AF just went back and forth and didn't settle on a focus point.
11-23-2010, 06:55 PM   #6
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
QuoteOriginally posted by studiojmm Quote
Thanks. I haven't been able to test with other lenses, but I'm planning to. The camera has 18189 shutter releases, it turns out.

I did compare the histograms of recent shots with older ones and they are definitely skewed way to the left. However, I started shooting raw last summer and that seems to be when the problem began. (It's not the EV compensation settings). My jpegs from before that are more better exposed. No idea if that ends up being relevant, but I'll shoot some jpegs and see.

Any suggestions for helping me work with this camera for at least a few more months would be appreciated. I updated the firmware (was at 1.0) and have only taken a few shots since then.

How low is low light when imagining I should start having AF problems? This evening, I was shooting a fairly flat subject (a row of shirts in a closet) 6 ft away with a zoom lens at the wide end, on Auto ISO (a new feature with the firmware update that I'm just messing with), with the room lit by three compact fluorescent bulbs and the AF just went back and forth and didn't settle on a focus point.
You answered my first question (un-asked) about EV Compensation. You say you just updated the firmware. Did this change come WITH the firmware?

When I answer the how dark is too dark question, it's usually black on black in a dark room. Actually Any flat contrast dimly lit object will cause most of my camera/lenses to hunt. I haven't really had a problem with it lately though because both the K7 and the K5 have AF assist lamps (a huge improvement in these situations).

11-24-2010, 03:10 AM   #7
New Member




Join Date: Nov 2010
Location: Washington DC
Posts: 4
Original Poster
JeffJS - No, I updated the firmware a couple days ago to see if it would help.
11-24-2010, 03:52 AM   #8
Veteran Member
jolepp's Avatar

Join Date: Oct 2010
Location: Finland
Photos: Albums
Posts: 3,196
A new set of lithium batteries might be worth a try: if these help with AF speed, then its the batteries?

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!
camera, couple, dslr, exposure, images, lens, photography, settings, time, trip, weight
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Complete istDS kit (Camera, 3 lenses, bag, SD card, batteries) (CONUS) palmor Sold Items 4 08-11-2010 04:26 PM
Brain Disease? Rupert General Talk 5 08-12-2009 12:17 PM
Wearing of the Green :) rmtagg Post Your Photos! 16 05-21-2008 10:57 PM
*istDS and manual lenses kuuan Pentax DSLR Discussion 3 04-27-2008 12:07 PM
Just got an *istDS, looking for manual focus lenses capinbuck Pentax SLR Lens Discussion 8 02-15-2007 06:11 PM



All times are GMT -7. The time now is 05:56 AM. | See also: NikonForums.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