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K10D after 6 months

Discussion in 'Pentax Chat' started by HelenEdith, Dec 16, 2007.

  1. Monobod

    Monobod Phantom of the forum

    Surely the metring is nothing to do with the infra red filter, which is in front of the sensor, is it?

    Have you considered that perhaps your camera is broke? I have never experienced any problems with green, as you describe. I am puzzled by this. AFAIK it has never been mentioned in any test reports. :D

    What do images look like on the rear screen? Are they also over green?
     
  2. HelenEdith

    HelenEdith Well-Known Member

    I'll have a look at some of my older pictures first to see if I think it needs calibrating! It's a long time since I calibrated it, so it might need a recalibration. Thanks for the suggestion.
     
  3. HelenEdith

    HelenEdith Well-Known Member

    I won't get into a discussion on metering right now because I'm not quite sure of my facts. I did some experimentation with infrared photography with the *ist DS and the K10D last summer and I'm almost sure that when I put the Cokin infrared filter on the K10D that the meter calculated quite long exposures compared with the *ist DS set up identically, but that was six months ago and I can't remember for sure.

    If I'm right, the metering must be taking place between the infrared blocking filter and the sensor, but as I said, I'm not sure if I'm right, so I had better not get into it right now.

    As for how the images look on the back screen: I haven't turned on the feature which shows blown highlights, so I don't notice it on the back screen. It's not until I get the images onto the computer and look closely at them that I find the blown highlights.

    Maybe I'm just being too much of a perfectionist, but I've had some very badly blown highlights on the K10D at times, and they mostly seem to be blown in the green channel.

    Here are a couple of images which illustrate my problem.

    Here is a JPEG straight out of the K10D which shows blown highlights on the grass in the upper left of the image and also in the blades of grass in the centre of the image. I've uploaded them 600 pixels wide and I'm not sure that it's enough to really show the problem. The second image a bit further down the page is probably a better example.

    [​IMG]

    Now here's the same image as rescued from the RAW file:

    [​IMG]

    And here it is after I've done a few more adjustments in PhotoShop. I think I need to revisit it, as I've left it too yellow in the course of getting my green highlights under control.

    [​IMG]

    Here's a second image taken on the same day. The JPEG straight out of the camera has completely blown the duckweed along the edge of the lake:

    [​IMG]

    I've rescued it from the RAW file and managed to get some definition back into the duckweed, but now the grass is too yellow:

    [​IMG]

    Then I put it into PhotoShop and made my greens more convincing:

    [​IMG]
     
  4. johnriley1uk

    johnriley1uk Well-Known Member

    Using an R72 IR filter allows only IR light to pass through to the sensor. The IR filtering on the K10D is much more aggressive than on the *istDS and therefore longer exposures will be needed. Frankly I don't think the K10D is the best choice for real IR photography. The *istDS is much better.

    The greens in the first images are over exposed IMO, probably because the dark water has fooled the metering into brightening up the whole image. Once you have this over-exposure there's no going back, so the answer is to use exposure compensation of maybe -0.5 or even -1.0. That should solve the problem and make the colours more realistic too.

    The duckweed is a very, very small part of the overall scene and is quite bright, so again the exposure for most of the image has meant the brightest part is over exposed. Either spot metering on the critical area or exposure compensation as above would be my solution to this.

    Green grass is approximately Zone 5 (18% grey) in the zone system, so it should meter very well. As an experiment, fill the viewfinder with some green grass and take the picture. My guess is that the exposure and colour will be spot on. If not, then there is probably a camera problem.
     
  5. john_g

    john_g Well-Known Member

    I've got a Samsung GX-10 but would be very disappointed with some of those exposures and tend to think you have a camera fault.

    The first JPEG of the lake with duckweed is very flat and washed out and looks just plain wrong... was the lighting really like this? Also, what is the histogram on the camera telling you about the exposure and, finally, have you had a chance to compare the exposure the camera calculates against a separate lightmeter?
     
  6. Dave_Cox

    Dave_Cox Well-Known Member

    From experience I would have expected better from the K10 - I've never had anything like that even using centre-weighted metering. I would either try a few shots using evaluative metering to see if this could be a problem (from the pics above I don't think so) or get a seperate light meter if you don't already have one ( I have two - about £3 from a charity shop or £5 on Ebay) and always carry one in my bag all the time. Check the exposure from the seperate meter against the camera - mine is spot-on. I often take a seperate reading from areas such as grass or foliage as large areas of sky can fool the best metering system! (usually resulting in the ground being underexposed instead of over which I think you have here)
    I also find that for landscapes an exposure compensation of -0.5EV helps the colour saturation, for everything else it's fine on zero.
     
  7. Pogbellies

    Pogbellies Well-Known Member

    Anyone know if this battery (Haehnel HL-PL50) also works with the Samsung GX10?
     
  8. Monobod

    Monobod Phantom of the forum

    Have you checked all of your settings, ISO, Compensation etc. I find these images to be nothing like that which I would expect from a K10D. Here is a typical example from a RAW file:

    [​IMG]

    I still wonder if your camera is faulty?? :D
     
  9. HelenEdith

    HelenEdith Well-Known Member

    It's not listed as an "essential accessory" on the Warehouse Express website, so I suspect not. (It is listed for the K10D and if it worked for the GX-10 I think they would have said so.)
     
  10. HelenEdith

    HelenEdith Well-Known Member

    The day I took those pictures was a grey day threatening rain, and the shutter speeds were getting down into the shake reduction area, so the lighting could well have been rather flat. I don't routinely check all my histograms on the camera back, but would expect the histograms for those example pics (particularly the first one) to be bunched up in the middle. Jacking up the contrast in conjunction with some exposure correction may have helped.

    The sample pic posted by Mobobod appears to have been taken in good conditions, and I would expect my K10D to take a similarly good picture in similar conditions.

    However, the K10D does throw in the occasional horribly wrong exposure. I've got one example of a cerise David Brown tractor where the auto white balance was totally fooled when I zoomed in close, although it did a good job when I was zoomed out a bit and correctly rendered the tractor as red; and I've got a number of pictures of heavy horses where the "feathers" above their hooves are totally blown. When I took another look at them, the horses themselves were correctly exposed, so they may have been better shot with lower contrast.

    It was after the day when I took the cerise David Brown and the horses with blown "feathers" that I switched to RAW+JPEG. I wouldn't like to say what percentage of my shots I go back to the RAW, but when I do, it's usually for blown highlights. As centre weighted metering takes less account of the sky, I would expect evaluative metering to expose for a bit less. I've just never had much luck with it, and keep returning to what I'm familiar with, although I go into spot-metering occasionally. I must give evaluative metering another try.

    Both the example pictures were taken centre-weighted. The first was 1/20 second and the second was 1/60 second. I had a tripod, but left it in the car, as the National Trust can be a bit touchy about tripods. Apparently Fountains Abbey aren't, so I could have used it, but I didn't know that, so the first picture was taken at ISO 400 and the second one at ISO 800, which might also have had a bearing on the results.
     
  11. john_g

    john_g Well-Known Member

    The Hähnel website lists the Hähnel HL-S1674 as being their replacement battery for the Samsung GX-10. Warehouse Express have it priced at £19.99 rather than the £49.99 they want for the Samsung original.

    If you are going to order one, please verify this information as I've no personal experience of using one.
     
  12. Zou

    Zou Well-Known Member

    Do you have a colour channel histogram with the K10D? It would be interesting to see what the recorded levels are for green, to see if the camera 'knows' that greens are overdone or not, if that makes sense.
     
  13. HelenEdith

    HelenEdith Well-Known Member

    I've just referred to the manual, and yes, colour histograms are available. When on the histogram display, you press the four-way controller and you can switch between the brightness histogram and brightness + R, G & B histograms.

    Also, on the playback menu, you can turn on Bright/Dark area and blown highlights (and areas that are too dark) will be highlighted.

    I will try using these options. They should warn me when taking another shot at something is advisable - provided that I look at them! Sometimes I refer to the histogram, and sometimes I just use the K10D like a film SLR and shoot away without reference to the back panel. A bit more attention to the histograms won't hurt.
     
  14. Vormulac

    Vormulac Active Member

    Apologies for resurrecting an old thread, but I was wondering whether HelenEdith had sorted out those wayward green issues?
    Also, it was suggested that there may be a problem with her camera, how would you check this? I have just bought a K10D and have had all manner of issues with the exposure and so-on (I'm quite prepared to accept that this is down to me being a total beginner and I'm using wholy inappropriate settings for shots), but it did make me wonder - is there a test you can run?

    Thanks.
     
  15. spinno

    spinno Well-Known Member

    do something simple.
    Take a pic in Program Mode...check the settings...then go to Aperture priority and use the appropriate setting (f number), similarly in Shutter mode use the appropraite shutter speed, and finally in Manual mode use the settings for both Aperture and shutter speed.
    You should end up with four fairly similar exposures...
     
  16. Vormulac

    Vormulac Active Member

    Program mode is effectively 'auto' if you press the green button, yes? I shall try this later and see what happens. Thanks Spinno.
     
  17. Monobod

    Monobod Phantom of the forum

    Or sell it and but a K20D! ;) ;) :D
     
  18. spinno

    spinno Well-Known Member

    better using the P setting on the dial, then A, T and then M
     
  19. Vormulac

    Vormulac Active Member

    Right, I shall steer clear of the green button. If I see a green button I will turn and walk briskly in the opposite direction. :)

    Nice idea, not sure I'd get the extra £1000 on top of what I paid for the K10D to make that happen! Still, you never know... :D
     
  20. spinno

    spinno Well-Known Member

    That's the spirit...... :D
     

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