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  1. #31
    Join Date
    Jul 2005
    You are confusing things. The Canon actually exposed where you focussed on (center shrubs) better than the Nikon.

    A CAMERA CAN NOT KNOW THE CORRECT EXPOSURE. SOmething really important to understand.

    There is only one correct exposure for a subject, and the camera cant know it, simple truth. The camera will meter for a 15% or 12% reflective gray, i forgot which value that actually is (not 18% grey). This is the value of light from a mid tone grey. At least, if you meter with partial or spot metering, the camera will assume your subject to be a mid tone (so 15% or so reflective grey).

    So.. in order to get the CORRECT exposure, you are user will have to make sure things go well and to your taste. Because not everything is a mid tone!
    Histograms say NOTHING about correct or wanted exposure, they just will say if a lot of highlights get clipped or a lot of dark tones get clipped.

    A white subject, correctly exposed, will have the histogram totally to the left. A black subject will have the histogram totally to the right.
    Wrong exposure will give both subjects a grey, with the histogram in the middle (over exposure of the black, under exposure of the white).

    So... your histogram says nothing to what is "correct". Your samples show:
    Your D40 over exposes a bit, your XTi under exposes slightly.
    That is just how they are, and you as user will have to take photos the way YOU prefer them.
    So, if you prefer the over exposed over saturated look, then just set your camera that way, I explained above how to make your XTi over expose in the same way the D40 does.

    The Nikon D70 and D70s underexposed too. The XTi underexposes a bit, the D40/50 over expose a bit, and so on. Just set a camera to your liking, and do not just rely on the camera's exposure, but try to understand how to get a correct exposure.
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  2. #32
    Join Date
    Dec 2007
    I do understand what you are saying and I agree the "correct" exposure may be different for every part of the scene. And yes, in this case perhaps the shrub is better exposed in the Canon shot, but rest of the image is underexposed, and in my opinion this was a poor tradeoff on the part of the camera's meetering algorithm. I understand, and I think this is your point as well, that the camera has no way of knowing exactly what parts of the scene I consider important (unless I choose spot meetering to tell it). In this case both cameras were using their evaluative metering modes. Perhaps the Canon chose to optomise the shrub. If it did, then it made a mistake in my opinion because the rest of the photo looks too dark.

    I understand also that the histograms are for the entire image, and therefore don't prove anything about the "main subject exposure", but they do show a fair amount of dynamic range going unused in the canon's picture for what it's worth.

    Also, you are at a dissadvantage since you never saw the original scene and I did. It was a very bright and sunny day and the Nikon looks more like what my eyes saw.

    As we discuss more it occurs to me there really is no right or wrong to exposure. It's all a matter of preference and artistic intent as well. When it comes to *automatic* metering, some will like the Canon and some will like the Nikon. I agree with you that the only way to "get it right" is to adjust it yourself manually based on what *you want to see*. Either camera will do this competently.


  3. #33
    Join Date
    Jul 2005
    My point is, Rich, that it is up to YOU to set the camera to YOUR liking.

    So.. if you prefer the over exposed look, then just set your XTi like that, it will make both cameras equal in that respect. And that is what you were after in the first place!

    So.. set your camera to Av, then add some exposure compensation by holding the Av+/- button, and add +1/3 or +2/3 or whatever gives you what you need.
    So.. this setting will stick to your Av, Tv and P metering. The camera will meter WITH your chosen exposure compensation, giving you what you are after.
    Same with saturation, contrast and sharpening, set them to your liking.

    YOU are the one that says you prefer the XTi over the D40, I am just trying to help you to get the results you are after.

    And do get a different lens... now you will always pixel peep and be not happy with the 18-55 you have now. The 18-55 IS may be a good starting point.
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  4. #34
    Join Date
    Dec 2007
    You are missing my point from earlier in the thread. The XTi overexposure is not consistant. So I can not simply dial in say +2/3 and expect it to more or less match the D40. I never can tell which scenes it will overexpose on. I wish it were that simple, but it's not.

    Of course I am in charge of making the camera do what I like. This is not the issue. Each camera can do whatever the operator tells it to do manually, and this is great. My point is that if you leave the light meetering up to the camera (for example in P S A M modes) the camera needs to make choices as to how to adjust whatever parameters the user did not, and these choices are based on the camera evaluating the scene and comparing some metric of measured brightness to a programed target value. The exposure compensation setting changes this target to influence the metered result. My point is that (in general) the Nikon algorithm seems to this task better. Better in the sense that the pictures more frequently appear closer to what I see with my own eyes (except in fairly dark rooms where it significantly overexposes;-)).

    Do you believe that the Canon metering algorithm is better overall? I am just curious. Which of the three images I posted do you believe is overall more appealing?

  5. #35
    Join Date
    Dec 2006
    God's Country - Australia
    i think nikons metering has always been a bit better.

    in the first pic with the d40, yes, it has tried to expose with more dynamic range by bringing out more shadow detail but this is at the expense of the highlights of the trees which is really the main part of the photo, to me that is not desirable but this is exactly what the d40 was designed to do. take pics out of the box that requires minimal PP and appears better to the amateur photographer.

    why dont you just use a spot meter and expose the focal point of the scene the exact way you want it ? thats really the beauty of any good slr and the point of it actually when you improe your technique...YOU can pick the way a scene is exposed quite accurately. as coldy mentioned...the camera is limited in its ability to expose cos its trying to meter everything in the scene without any guidance from the user.

    or, you can always point the camera at the shadows, use AE lock and then recompose to get more shadow detail. remember that all slr's have a lmimitation with regards to the amount of dynamic range they can produce.

    besides which...if you are taking better pics with the d40 then whats the issue...just keep the d40 ? this is about your choice, not mine or coldy's. the reason that this thread has gone on so long is becasue you asked the question in the xti CAPABLE of doing what the d40 does. the answer is of course it can.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75

  6. #36
    Join Date
    Dec 2007

    Thumbs up Thanks

    Thanks guys,
    I really value you taking your time to share your insights and especially your experience as I figure out this stuff. It has been very helpful.

    Signing off now,

  7. #37
    Join Date
    Feb 2005
    Derbyshire, UK

    Thumbs up Thanks guys

    Just caught up with this thread & would just like to add that it was a very good read & very useful to me too. I still don't have a dslr yet & that day is probably still a way off but the insight given here will be very useful when doing the actual back to back comparisons myself when the time comes. Don't underestimate the help that threads like these give to those of us who don't have anything to add to help out but just enjoy the read. Rich I sympathise with many of your views also being an engineer of sorts myself. I have been recently comparing the test images of the D40X with the 400D on imaging resource's comparometer where you can get side by side images for comparison & they bear out much of what has been said by the guys here. You might want to have a go yourself to add to the body of evidence that you are building up to make your decision which camera to send back. Final note when you do decide please tell us what you decided & why. It would kind of add a happy ending to the thread.
    Around every picture there's a corner & round every corner there's a picture
    - the fun's in finding them

  8. #38
    Join Date
    Jun 2005
    Sydney, Australia

    Comparing Cameras

    Ahhhh...takes me back about 18 months when I was tossing up between Nikon D50 and Canon 400D. The salesman was kind enough to let me take both cameras for a test drive in the carpark outside his shop whereby I started snapping away in full auto mode with the kit lenses attached.

    Once I got home and looked at the results on my PC, the Nikon won hands down. So which camera did I buy ?

    The Canon of course
    (not sure what the moral of the story is )

    I think that all cameras in this market range will provide the ability for nice results (especially with approriate lenses attached). Sometimes you have to look at other things like functionality, how it feels, accessory availability etc....and forget about quick sample images...they'll all take a good shot you'll be proud to display to others
    Canon 5D MKlll & Canon 50D
    Canon 70-200mm f/2.8L USM | Canon EF-S 17-55mm f/2.8 IS USM | Canon EF-S 10-22mm f/3.5-4.5 USM | Canon 100mm f/2.8 USM Macro | Canon 70-300mm f/4-5.6 IS USM | Canon 50mm f/1.8 | Sigma 17-70mm f/2.8-4.5 | Canon 430EX Flash | Lowepro Mini Trekker AW | Lowepro Toploader 65 AW | Lowepro Slingshot 200AW | Kata 3n1-10

    Panasonic Lumix FZ200
    Panasonic Lumix TZ7 (aka ZS3)
    Panasonic Lumix FT3 (aka TS3)

    Ali Baba.....the Thief of Bad Gags

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