[matt_lin18]

I noticed some issues with the shutter on my K5 yesterday.

About 50k shutter camera. Set at JPEG 2MP, no lens correction, no highlight/shadow correction, using Sandisk 45mb/s class 10 card.

Metering mode is set to multi-segment, aperture priority, hi speed burst, af-s.

When I aim at a dark object like my black backpack (it can still focus on it): burst drops noticeably slower about 4-5fps. I'm in Av and compensating my aperture and ISO to get a shutter speed of 1/250s.

Now when I am at a stack of white papers (again it can still focus on it): burst speed picks up to normal about 7fps. Still in Av and compensating aperture and ISO to get 1/250s.

Now if I go into manual mode and set shutter speed to 1/250s, there is no difference in burst speed between the black backpack and the stack of papers. Same thing happens if I use AE-L at 1/250s, burst rate stays the same.

Any reasoning for this? I haven't had this issue in the past and I normally always shoot in aperture priority with fast moving subjects.

[dms]

As a test to rule out the matrix/multi-segment metering algorithm (and possible processing time--which should be very short!) what happens in spot or center weighted exposure mode?

[Adam]

I noticed some issues with the shutter on my K5 yesterday.

About 50k shutter camera. Set at JPEG 2MP, no lens correction, no highlight/shadow correction, using Sandisk 45mb/s class 10 card.

Metering mode is set to multi-segment, aperture priority, hi speed burst, af-s.

When I aim at a dark object like my black backpack (it can still focus on it): burst drops noticeably slower about 4-5fps. I'm in Av and compensating my aperture and ISO to get a shutter speed of 1/250s.

Now when I am at a stack of white papers (again it can still focus on it): burst speed picks up to normal about 7fps. Still in Av and compensating aperture and ISO to get 1/250s.

Now if I go into manual mode and set shutter speed to 1/250s, there is no difference in burst speed between the black backpack and the stack of papers. Same thing happens if I use AE-L at 1/250s, burst rate stays the same.

Any reasoning for this? I haven't had this issue in the past and I normally always shoot in aperture priority with fast moving subjects.

Do you have AF on? You won't get the max brust rate when the system has to re-acquire in between shots.

[Fogel70]

Do you have AF set to focus priority or release priority?

Try both and see if you notice any difference.
I believe if in focus priority the camera try to confirm that each shot is in focus before capturing the shot, which might take longer time on a dark low contrast subject. Not sure if it works the same in both AF-S and AF-C.

---

Last edited by Fogel70; 08-01-2015 at 01:12 AM.

[matt_lin18]

As a test to rule out the matrix/multi-segment metering algorithm (and possible processing time--which should be very short!) what happens in spot or center weighted exposure mode?

Tried same test with spot metering and center weighted, same results.

Do you have AF on? You won't get the max brust rate when the system has to re-acquire in between shots.

Yes, I am shooting with AF-S. Even if I turn it into manual focus, the results are the same. Slower burst rate on darker objects.

Do you have AF set to focus priority or release priority?

Try both and see if you notice any difference.
I believe if in focus priority the camera try to confirm that each shot is in focus before capturing the shot, which might take longer time on a dark low contrast subject. Not sure if it works the same in both AF-S and AF-C.

I default have it to focus priority. I set it to release priority as well, no difference. And yes, the shot is in focus before I start the burst.

Even 1/8000s on a dark subject burst is slower than 1/250s on a bright subject. Also tried 2 lenses, same result. Have also tried 3 different memory cards, and made sure battery was fully charged. This issue might not be an issue but just was designed that way, but if it was, I never noticed it before. Anyone else able to test if their camera does the same?

[Adam]

Yes, I am shooting with AF-S. Even if I turn it into manual focus, the results are the same. Slower burst rate on darker objects.

I would test it on MF until you get the full burst rate in that case. Make sure you've disabled lens corrections and shadow/highlight corrections.

[matt_lin18]

I would test it on MF until you get the full burst rate in that case. Make sure you've disabled lens corrections and shadow/highlight corrections.

MF doesn't change anything. Shooting JPEG, low quality, 2 megapixels. No corrections for distortion, abberation, shadow or highlight correction.

[Adam]

MF doesn't change anything. Shooting JPEG, low quality, 2 megapixels. No corrections for distortion, abberation, shadow or highlight correction.

How high of an ISO are you using for the dark subject? That could be causing the issue, since the camera will always apply some noise reduction to high-ISO JPEGs even when NR is disabled in the menu. Internally, the camera could potentially be dealing with more data since high-ISO files are harder to compress (though that really depends on how the processing is implemented).

In any case, it doesn't sound like there's anything wrong with the camera.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers: