All Forum Comments
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 10/03/2011 - 10:35
I have the Coolscan IV
Doesn't get used much at all...
My personal recommendation, though, would be to at least try Ed Hamrick's VueScan software first. I had a Minolta Scan Dual before that, and Vuescan did make a massive difference in the quality - the Nikon is quicker, but there wasn't a great deal in the quality difference (from what I remember).
B&W is interesting, because you can't use the IR channel on it.
If you want me to scan a couple of frames for you, I'd be happy to do that. PM me and I'll give you a postal address. If you send a self-addresses envelope
Hope that helps!
Matt
Doesn't get used much at all...
My personal recommendation, though, would be to at least try Ed Hamrick's VueScan software first. I had a Minolta Scan Dual before that, and Vuescan did make a massive difference in the quality - the Nikon is quicker, but there wasn't a great deal in the quality difference (from what I remember).
B&W is interesting, because you can't use the IR channel on it.
If you want me to scan a couple of frames for you, I'd be happy to do that. PM me and I'll give you a postal address. If you send a self-addresses envelope
Hope that helps!
Matt
Comment by MattMatic posted on Coolscan IV help at 10/03/2011 - 08:41
Must be that Monday morning feeling (on Wed afternoon!) - I can't find any EXIF at all! The Flickr page shows a minimal set of info, but I need to see the full Pentax EXIF to have any chance
Adrian - if you can email me the original images to mattmatic at hotmail dot com
...unless you took these in RAW and you have mistakenly adjusted them differently in Lightroom But, I'm happy to look at RAW too! Whatever came out of the camera
Thanks!
Matt
Adrian - if you can email me the original images to mattmatic at hotmail dot com
...unless you took these in RAW and you have mistakenly adjusted them differently in Lightroom But, I'm happy to look at RAW too! Whatever came out of the camera
Thanks!
Matt
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 09/03/2011 - 12:33
Doh! It's been a long night
Thanks got the correction... shutting up now
Thanks got the correction... shutting up now
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 05/03/2011 - 12:18
Just to add a couple of extra points:
* Maybe the exposure doesn't flash when AE-L is activated, but there's huge asterisk/star I. The viewfinder
* In Sv mode the user has to dial in the Av and Tv. Gaining from 1/8 to 1/500, and f/3.5 to f/8 should have raised the slightest alarm bell that something had been set incorrectly.
* Maybe the exposure doesn't flash when AE-L is activated, but there's huge asterisk/star I. The viewfinder
* In Sv mode the user has to dial in the Av and Tv. Gaining from 1/8 to 1/500, and f/3.5 to f/8 should have raised the slightest alarm bell that something had been set incorrectly.
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 05/03/2011 - 11:19
FWIW, my DA17-70 wouldn't focus at the long end - it would hunt around trying to find a lock and not get one. It worked at the wide end though...
...but that was because it had been hit on the end while extended, and crunched the internal zoom mechanism, and de-aligned it all No visible damage - I could have been unscrupulous and auctioned the lens off
The SDM did not fail though - the focus ring moved easily and quickly enough, but still wouldn't focus even though the image looked ok inside the viewfinder. Something in the impact and alignment must have thrown off the AF phase detection.
Once fixed by JP/Pentax - all is good again, and I'm being a little more careful!
Shame about the OP. I have the DA17-70 and DA*50-135 and both have been superb for me in all respects.
Matt
...but that was because it had been hit on the end while extended, and crunched the internal zoom mechanism, and de-aligned it all No visible damage - I could have been unscrupulous and auctioned the lens off
The SDM did not fail though - the focus ring moved easily and quickly enough, but still wouldn't focus even though the image looked ok inside the viewfinder. Something in the impact and alignment must have thrown off the AF phase detection.
Once fixed by JP/Pentax - all is good again, and I'm being a little more careful!
Shame about the OP. I have the DA17-70 and DA*50-135 and both have been superb for me in all respects.
Matt
Comment by MattMatic posted on Getting upset with Pentax at 05/03/2011 - 03:56
Actually, I think I have the solution
But, in Poirot style, let's survey the facts and evidence:
* The shots given were on a K5 with a new 18-55WR lens.
* It happened on a K7 before that. So, I can almost certainly discount a device failure. The OP, perhaps, thinks it may be a 'common' fault with Pentax cameras. I'm not convinced
* The blank shot has the following exposure info: 1/8", f/3.5, ISO560, 19mm
* The subsequent shot has the exposure info: 1/500", f/8, ISO560, 18mm
* If these were seconds apart then there's definitely something wrong with the exposure of the blank shot...
* So, we examine the full EXIF information (exhibits A & B ). Temperature is fine, and other vital signs are good (notwithstanding my error in using PhotoME that can't recognise the lens type! :roll
* However, the EXIF shows LV values that match the Av/Tv/ISO. Blank is 4.4LV, subsequent is 12.6LV - so that's nearly 8 stops of difference. Assuming the light levels didn't change much then an image that is 8 stops overexposed would be white!
* Looking at the subsequent image I realise that there could be some user error - why would an 18mm shot use 1/500" and ISO560? Presumably the ISO range has been set to a minimum of ISO 560 (e.g. ISO 560-1600). Added to the fact that Sv mode has been used is severely limiting the camera's ability to obtain the right exposure. I would have expected the subsequent shot to be at ISO100 or ISO200 and used a slower Tv.
* So, this gets me thinking, and the answer was there in the EXIF - AE Lock: On! Actually, it looks like the camera is doing what it has been asked to do (whether intentionally or not). I would guess that the lens has been pointed at something quite, quite dark (lens caps, coat insides etc), and the AE-L button pressed - capturing the metering of 4.4LV. When the shot is taken it is 8 stops overexposed and the image is white.
It's not that difficult to do by mistake, but the viewfinder display would certainly have been flashing - indicating that the camera is seeing a massive overexposure.
Again, I cannot find any evidence to support a view that the camera is somehow defective, nor that this is a wide-spread problem and a conspiracy type issue that "Pentax Japan are aware of"
To be honest, I use the camera in Av mode, rather than Sv mode. Using Sv with a severely limiting ISO range means you will always have to check the viewfinder for over/under exposure (flashing in both cases). With the K7/K5 you can map the ISO setting to a wheel (I use the front E-dial) and have the Av on the rear E-dial. That way you have instant access to the main settings - can see Av/Tv/ISO in the viewfinder, and the camera has the flexibility with the shutter speed to select a value over a massive range.
But, it's all personal preference
...it might also be a good idea to learn an instinctive feel for exposure values - it's quite possible to view a scene and guess the camera settings within 1 or 2 stops.
Hope that helps!
Matt
But, in Poirot style, let's survey the facts and evidence:
* The shots given were on a K5 with a new 18-55WR lens.
* It happened on a K7 before that. So, I can almost certainly discount a device failure. The OP, perhaps, thinks it may be a 'common' fault with Pentax cameras. I'm not convinced
* The blank shot has the following exposure info: 1/8", f/3.5, ISO560, 19mm
* The subsequent shot has the exposure info: 1/500", f/8, ISO560, 18mm
* If these were seconds apart then there's definitely something wrong with the exposure of the blank shot...
* So, we examine the full EXIF information (exhibits A & B ). Temperature is fine, and other vital signs are good (notwithstanding my error in using PhotoME that can't recognise the lens type! :roll
* However, the EXIF shows LV values that match the Av/Tv/ISO. Blank is 4.4LV, subsequent is 12.6LV - so that's nearly 8 stops of difference. Assuming the light levels didn't change much then an image that is 8 stops overexposed would be white!
* Looking at the subsequent image I realise that there could be some user error - why would an 18mm shot use 1/500" and ISO560? Presumably the ISO range has been set to a minimum of ISO 560 (e.g. ISO 560-1600). Added to the fact that Sv mode has been used is severely limiting the camera's ability to obtain the right exposure. I would have expected the subsequent shot to be at ISO100 or ISO200 and used a slower Tv.
* So, this gets me thinking, and the answer was there in the EXIF - AE Lock: On! Actually, it looks like the camera is doing what it has been asked to do (whether intentionally or not). I would guess that the lens has been pointed at something quite, quite dark (lens caps, coat insides etc), and the AE-L button pressed - capturing the metering of 4.4LV. When the shot is taken it is 8 stops overexposed and the image is white.
It's not that difficult to do by mistake, but the viewfinder display would certainly have been flashing - indicating that the camera is seeing a massive overexposure.
Again, I cannot find any evidence to support a view that the camera is somehow defective, nor that this is a wide-spread problem and a conspiracy type issue that "Pentax Japan are aware of"
To be honest, I use the camera in Av mode, rather than Sv mode. Using Sv with a severely limiting ISO range means you will always have to check the viewfinder for over/under exposure (flashing in both cases). With the K7/K5 you can map the ISO setting to a wheel (I use the front E-dial) and have the Av on the rear E-dial. That way you have instant access to the main settings - can see Av/Tv/ISO in the viewfinder, and the camera has the flexibility with the shutter speed to select a value over a massive range.
But, it's all personal preference
...it might also be a good idea to learn an instinctive feel for exposure values - it's quite possible to view a scene and guess the camera settings within 1 or 2 stops.
Hope that helps!
Matt
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 05/03/2011 - 03:48
LOL@George. Going just a little way off topic now...
It all seems a little strange then if it's the 18-55WR. Billy emailed me the next shot - and this shows up as K/M. So it's probably down to PhotoME not recognising the lens type
Definitely upgrade the firmware in the camera - that's a start.
Certainly check the contacts on the lens and body again.
I'm a bit puzzled - especially as you had it happen on the K7 as well?
The exposure of the next good shot was 1/500", f/8, ISO560.
So that makes the blank shot some 8 stops overexposed (LV4 vs LV12)
I have put the EXIF data on two links:
The blank shot
The next shot
Matt
It all seems a little strange then if it's the 18-55WR. Billy emailed me the next shot - and this shows up as K/M. So it's probably down to PhotoME not recognising the lens type
Definitely upgrade the firmware in the camera - that's a start.
Certainly check the contacts on the lens and body again.
I'm a bit puzzled - especially as you had it happen on the K7 as well?
The exposure of the next good shot was 1/500", f/8, ISO560.
So that makes the blank shot some 8 stops overexposed (LV4 vs LV12)
I have put the EXIF data on two links:
The blank shot
The next shot
Matt
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 04/03/2011 - 10:43
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
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
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 03/03/2011 - 17:26
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
Matt
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!on a holiday with continuous sun.
Matt
Comment by MattMatic posted on K7 K5 Gross Over Exposure Problem at 03/03/2011 - 17:13
Any news from Mattmatic?
Matt