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K7 K5 Gross Over Exposure Problem

Mannesty
Posted 03/03/2011 - 16:46 Link
normington4 wrote:

Mannesty - no my K5 firmware is not up to date and from memory is 1.0 - I worry about my position regarding guarantee if I were to update - also I can not find in the literature how to go about it - I am not naturally attuned to electronics !!
Billy

Update your firmware, it will not affect your warranty. Firmware updates are provided by Pentax for a number of reasons, mostly to fix problems that have been identified and reported by users.

It only takes a couple of minutes once you've downloaded the update file from here for Windows, or here for Mac (they are different). Just ensure that your battery is fully charged before doing so.

Instructions can be found here and selecting the options from the menus, starting with cameras. The download also includes a readme file containing the same instructions.

PS: If a fault can be diagnosed by interrogating the EXIF data, Matt will find it. Send him your image and stop worrying.
Peter E Smith - flickr Photostream
Posted 03/03/2011 - 16:54 Link
Chris - Pentax Technical Holland said the new Firmware was not related to my problem.

Chris and John - Thanks for the re-assurance - especially that there is an on-screen idiotsguide to help you through it - however, as I cant find in the manual anything on the subject, I dont know which leads to plug into where, then where to go to get started !!!

In my defence, something as important as this must have written instructions somewhere, rather than be assuming everyone must know how to do it. Some of us did not grow up in the electronic age, and need a little help !!! - thanks in anticipation - Billy
Posted 03/03/2011 - 17:02 Link
Peter - Thanks - will look at everything you have attached to you message when I am wide awake in the morning, and use my new spare fully charged battery.

I sent Matt the full file a while ago - much to my surprise - Virgin must be improving and truly giving me Broadband !! - Billy
Mannesty
Posted 03/03/2011 - 17:08 Link
Billy,

Pentax, and probably other manufacturers, don't always document the fixes that are implemented in any particular firmware update and Pentax Technical Holland may not be aware of all fixes that have been applied by the boffins in Japan.

One of the files included in the download has a file extension .BIN. You copy this file to the root folder of an SD memory card. With power off, insert the card in the camera. Press and hold the Menu button and turn the camera on. You will see a message on the rear screen that tells you what your current firmware version is, and that a newer version exists on the card, and the question "Do you want to update?", or something similar. Perform the update.

There is no guarantee of course that this will cure your problem, but it is senseless to continue trying to diagnose a problem which might already be fixed in the firmware update.
Peter E Smith - flickr Photostream
MattMatic
Posted 03/03/2011 - 17:13 Link
Billy has sent the JPG, and I've run it through PhotoME:

Some initial observations:

* You are on v1.00 K5 firmware. It could do with upgrading, but not critical
* Used a K or M lens.
* Sensitivity Priority
* The exposure values used were:
o f/3.5
o 1/8"
o ISO560
o The effective LV was measured at 4.4 (this pretty much matches the LV for the exposure values above)
* Camera temperature was 17 degrees C - so that's fine

Can you confirm which lens you used?
I'm not too sure about using older lenses on Sensitivity Priority... you should be using stop-down-metering with the camera in "M".

EDIT: The excellent PhotoME package shows a whole heap of data in the EXIF file

Quote:
on a holiday with continuous sun.

If you used 1/8", f/3.5, ISO560 in the sun then you would get a white JPG That's probably 8 to 10 stops overexposed by a rough calculation!

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
Edited by MattMatic: 03/03/2011 - 17:16
MattMatic
Posted 03/03/2011 - 17:26 Link
LV Calculation
If you want to calculate the LV:

LV = log(Av^2 / Tv / (ISO/100) ) / log(2)

Where:
* Av = 3.5
* Tv = 1/8
* ISO = 560

LV = log(17.5)/log(2) = 4.12


Metering on film vs digital
The film cameras had a little mechanical 'finger' that could determine where the lens aperture ring was. This 'finger' was linked into the metering circuit so the camera could work out the light level for a given aperture selection - without the lens being stopped down.

Digital SLRs do not have this mechanical linkage and cannot tell what aperture is being used when the lens is wide open. You must use stop down metering.

It is also possible that if you take quick-fire images, and the aperture blades are a bit sticky the camera may mistakenly meter less light - and consequently overexpose.

What time stamp was the previous image?

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
Edited by MattMatic: 04/03/2011 - 10:46
Posted 03/03/2011 - 17:29 Link
Matt - the holiday with continuous sun was in September with the K7, which went back - as I told you in the Email the lens for teh white out was the Pentax waterproof 18-55m which came with the camera - I look forward to your comparisons with the shot taken several seconds later and now have - Billy
johnriley
Posted 03/03/2011 - 17:31 Link
The OP states above that he checked and cleaned both the camera and lens electronic contacts, which doesn't tie up with using a K or M lens. There seem to be a number of inexplicable contradictions in what is going on here.

Can you confirm what lens was actually used when this problem was experienced?

Afterthought: was it taken in a blizzard or on a sunny day? Both have been mentioned.
Best regards, John
Edited by johnriley: 03/03/2011 - 17:34
fatspider
Posted 03/03/2011 - 17:39 Link
Surely if a K lens was used the EXIF would be unable to record aperture?
My Names Alan, and I'm a lensaholic.
My PPG link
My Flckr link
Posted 03/03/2011 - 17:41 Link
Matt - The times were

Image 19 10.38 - Image 20 12.25 the white out - Image 21 12.26

The difference between 20 and 21 was certainly not a minute, and immediately I knew I had a white out immediately retook the shot, hence my suggesting "several seconds". - Billy
Mannesty
Posted 03/03/2011 - 17:48 Link
@Matt - I know that it is possible to take an exposure before the SR has stabilised. Is it also possible to 'stab' the shutter button such that an image is exposed before the metering system has done it's bit, thus resulting in an issue similar to this?

The fact that the lens has not been identified by PhotoMe (unless the lens is not in the PhotoMe database) leads me to think that the exposure was made at full aperture, when it should have been smaller. According to Billy, the lens used was a kit smc DA 18-55mm f/3.5-5.6 AL WR.

I think this is definitely an electrical contact or lens mounting issue. I would (almost, but not quite) bet money that the correctly exposed shot shows the correct lens and a different aperture.
Peter E Smith - flickr Photostream
Edited by Mannesty: 03/03/2011 - 17:52
Posted 03/03/2011 - 17:52 Link
John - It was definitely a blizzard for the white out - the other points were covered at 17.29 - Billy
johnriley
Posted 03/03/2011 - 18:22 Link
We await tomorrow's image, which may clear up the issues involved.

Peter, the shot can be taken before the SR has stabilised, but the metering is fast enough to measure flash output, so I doubt that can be beaten by the speed of a fingertip.
Best regards, John
Mannesty
Posted 03/03/2011 - 19:39 Link
johnriley wrote:
... the metering is fast enough to measure flash output, so I doubt that can be beaten by the speed of a fingertip.

Yes, you are probably right.

Re. the two images, Matt has them both by now. I think he's just teasing us . . .
Peter E Smith - flickr Photostream
golfdiesel
Posted 03/03/2011 - 21:00 Link
In regards to dirty contacts, I have cleaned my K20D when it was 6 months old and I was amazed on how much dirt came of them.
I cleaned them with a cotton tip and some 96% alcohol.
Camera:K20D|Ist*DS|Spotmatic II|MZ-10
Pentax Lenses: DA16-45|DA50-200|50A 1.7
Tamron Lenses: 28-200
Takumar Lenses: SMC 55 1.8
Sigma Lenses: EX DG 50-500 'Bigma'|EX 50mm Macro
Flashes: Metz 58 AF-1|Samsung SEF-36PZF|Pentax AF-220T

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