Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-26-2011, 09:33 PM   #16
Veteran Member
Smeggypants's Avatar

Join Date: Sep 2010
Posts: 1,536
QuoteOriginally posted by _phil_ Quote
I dimmed the lights until the focus assist light came on and then covered it with my hand, forced a refocus and took some shots. I assume this was dark enough to show any FF problem. There was none. I had previously calibrated the lens focus in sunlight. There was no discernable change with incandescant.

Build: 02/17/2011
Version: 1.03
What lens and what aperture did you test this at?

06-27-2011, 06:14 AM   #17
Site Supporter




Join Date: Feb 2008
Location: Boston MA
Photos: Gallery | Albums
Posts: 279
Original Poster
I didn't have time to test last night, but hopefully tonight I can show some results here.

In every other way I do really like the K-5. I just cannot imagine that the new camera I bought just coincidentally also has the FF problem.

I am shooting a dance coming Friday, and will try out my "repaired" K-5 to see if there has been any improvement.

Eric
06-27-2011, 07:24 AM   #18
Junior Member




Join Date: Aug 2009
Location: Melbourne
Posts: 25
QuoteOriginally posted by smeggypants Quote
what lens and what aperture did you test this at?
DA50-135 @135 f2.8
EDIT:
Ok, just had another go (in dull incandescant) with different lens (DA17-70)... F4, 1/4, 3200 and I can barely see what I'm taking (manual focus impossible). Perfect focus and if I'm not mistaken, about 1EV.

I'm not gloating... just the result for one camera.

Last edited by _phil_; 06-27-2011 at 07:55 AM.
06-27-2011, 07:37 AM   #19
Junior Member
magnosantos's Avatar

Join Date: May 2011
Location: Lisboa
Photos: Gallery
Posts: 46
It seems i'm lucky. Yes i had FF issues but they seem consistent with all light conditions.

06-27-2011, 02:29 PM   #20
Inactive Account




Join Date: Feb 2010
Photos: Gallery
Posts: 488
I have the same results that Eric Seavey has. Exactly!! Having only Pentax and never another brand. I am going to buy a canon 328 with the 7D I think, and check it against the Pentax K-5 and Sigma 328 lens. I am kinda curious about the differences if any. When i get the canon equipment and test I will post my thoughts.
06-28-2011, 03:40 AM   #21
Forum Member




Join Date: Dec 2010
Location: Silkeborg, Denmark
Posts: 82
QuoteOriginally posted by Eric Seavey Quote
The bad news is that they both are exhibiting the front focus problem. It doesn’t even have to seem to be that dim for this problem to occur. Also, it occurs when there is still too much light to trigger the focus assist light. It seems that the AF (without AF assist light) starts getting unreliable under 2 EV.
I seem to have the same problem with FF on my K-5, posted some threads about it as well, though at the time I thought it was a lens quality thing, but that seems less likely the more I think about it. Tried 3 different lenses and they all seemed to give me FF.

So now my K-5 is in for repairs/calibrating, depending on what they find wrong with it, if anything at all... Therefor I am a bit interested in how you handle this.
06-29-2011, 08:01 AM   #22
Site Supporter




Join Date: Feb 2008
Location: Boston MA
Photos: Gallery | Albums
Posts: 279
Original Poster
Update:
I have done some hypothesis testing last night and found a difference between dimming a light with a dimmer (resulting in a shift towards red) and having a little light coming from another room.
My preliminary tests are showing severe FF with the dimmed light, and acceptable focus from a bright light leaking in from another room.
I also looked into adding an IR cut filter vs no IR cut filter when focusing in dimmed lit conditions. Preliminary results are showing a difference in focus behavior. Where the camera was able to focus without the IR filter, there was no ability to focus with the IR-cut filter on the lens.
My question is now related to the camera using IR to help the AF, and why it affects the AF on the K-5 and not the K10D? I do know that AF can be used with a number of lenses for IR photography, despite the focus shift in IR.

More to come....

Eric
06-29-2011, 10:01 AM   #23
Inactive Account




Join Date: Feb 2010
Photos: Gallery
Posts: 488
I just purchased a new Canon 7D which is suppose to be the K-5 equivalent. Also I purchased a Canon 300mm f2.8 lens. When my K-5 gets back from Japan service. I will put the Sigma 300mm 328 on it and do a comparison.
That said I will defiantly keep the Pentax even if the Canon blows it away ( or not ). But as a wildlife photographer I want to know if the Canon is a better system. I am very unhappy with the K-5 so far. It just cannot handle my 328 lens and AF. I am at a dead end with Pentax I do not know what else to do but to try another system to see if it is better. If not I will post the findings.

06-29-2011, 03:47 PM   #24
Pentaxian




Join Date: Jun 2009
Location: GMT +10
Photos: Albums
Posts: 10,828
QuoteOriginally posted by garyk Quote
try another system to see if it is better.
An expensive experiment!

The two systems are hard to compare on the basis of their simple AF specs - eg:

7D
• 19 cross-type AF points (f/2.8 at centre)
• Center point additionally sensitive with lenses of F2.8 or faster
• AF working range: -0.5 - 18 EV (at 23°C, ISO 100)

K-5
• 11-point TTL Phase Difference detection sensor (SAFOX IX+)*
• Center 9-points are sensitive to both horiz and vert. detail
• AF working range: -1 to 18 EV (at ISO 100, F1.4 lens)

On the basis of these specs a K-5's AF should work in slightly lower light than the 7D's. The K-5's EV sensitivity even looks a lot like the current camera AF king, the Nikon D3s:

• 51 focus points (15 cross-type sensors)
• Multi-CAM 3500FX
• AF working range: -1 to +19 EV (ISO 100, normal temperature)

Even the old faithful K-x's AF (on paper) looks more sensitive than the 7D in low-light:
• 11-point wide autofocus system (SAFOX VIII)*
• TTL Phase matching
• AF working range: -1 to 18 EV (at ISO 100, F1.4 lens)

Be keen to see how you go.
06-29-2011, 06:09 PM   #25
Inactive Account




Join Date: Feb 2010
Photos: Gallery
Posts: 488
If the Canon does not meet my expectations I will sell it. And move on and quit griping.. I think out very little for peace of mind. Who knows maybe the K-5 will kick ass... Then I can put it to the canon folks... LOL
Either way I have to know.
06-29-2011, 07:28 PM   #26
Pentaxian




Join Date: Jun 2009
Location: GMT +10
Photos: Albums
Posts: 10,828
QuoteOriginally posted by garyk Quote
Either way I have to know
Yeah, ultimately the only real way to test something out is to use it for a while and put it to work. Hands on sure beats reading brochures or looking at websites. You may find the AF is ordinary on the 7D, but it might have other virtues that make it better than the K-5 for your kind of work that you can't anticipate until you've used it for a while. Horses for courses.
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, dslr, evaluation, ff, focus, k-5, k-5 ii, k-5 iis, k5, light, month, pentax k-5
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low Light? How about Zodiacal Light? KansasHorizons.com Pentax K-5 31 03-03-2011 03:23 PM
People Low light with DA* 16-50 barbosas Post Your Photos! 2 11-24-2010 08:10 AM
Video problem! interference waves in low light. dedmozaj Video and Pentax HDSLRs 10 09-06-2010 09:18 AM
Low light versus Poor light d.bradley Pentax DSLR Discussion 4 07-11-2007 07:53 AM
Low Light - Low Experience - Fix $$$ ? daacon Pentax SLR Lens Discussion 35 04-26-2007 07:52 PM



All times are GMT -7. The time now is 06:42 AM. | 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