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Old Feb 5, 2007, 9:34 PM   #1
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Hey everyone, I almost hate to type this email up here because I have read about it so many times on other forums. However, from reading around here, everyone seems to be a lot more civil to one another and a lot more helpful when questions are asked. I have been reading about this a lot on dpreview.com and all those people do is argue against each other and never really help the original poster.

Here is my situation. I have only shot P&S in the past. I am used to having a camera in full auto mode to take snap shots and have them turn out great. This is my first dSLR and also my first SLR for that matter. I have an XTi. I know that the reason for an SLR is much different than for a P&S, which is why I bought the camera. I admit I'm a newbie to this (SLR)and I want to learn as I love photography and would one day enjoy doing it as a profession.

When taking pics with the XTi in full auto mode and using the Kit 18-55 EFS lens, my pictures often times come out under exposed. (Visually and also according to the histogram) I began researching online and found out that many people are having this same complaint. It seems like in the beginning the respones were (You just don't know how to use the camera, change the settings to this and then try again) . Now from very recent postings, people have been sending their camera into Canon to have the problem corrected. When their cameras come back, theirimages aremuch better exposed.

My experience is that my camera only seems to underexpose when using the kit lens. It could happen other times, and that is whyI want some suggestions on different things that I can try to "prove" if the cam does have a problem, or if its OK. The only other lens that I have to use is a Canon EF 28-80/3.5-5.6 II . When shooting the same subject with that lens, the images come out better exposed.

(Sorry this is so long) . What I want to know, is, what kind of tests can I do myself (Changing lenses, etc.) to actually find out if my camera does indeed have an exposure problem. People have been waiting for up to 3 weeks to receive the camera back from Canon service.I am only talking about FULL AUTO mode. I do not seem to have these problems when using P/Av/Tv/M modes. I wouldfind that obvious since you change the settings yourself, it appears to me at least that full auto mode either a)maybe has some settings incorrect, or B) the kit lens is bad.I have not tried any of the other auto modes, so it very well could be the lens and nothing to do with the mode. I would assume and expect that full auto mode takes properly exposed pictures w/out having to go into manual modes. I DO understand that this is NOT the reason for an SLR, I don't plan on using it in full auto all that often, however there are times that either myself, or a significant other will be using the camera and will want to use it in full auto mode. Please don't give me the response that I should be using a P&S. I would expect that this quality of a camera provide just as good images; and yes I am aware that there is less post processing on this cam than there is on a P&S and I'm ok with that as far as sharpness, etc. but not as far as the exposure goes.

Any advice, thoughts, comments, etc. are appreciated. Again sorry for this being so long.

Gary
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Old Feb 6, 2007, 2:09 AM   #2
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The camera is probably functioning as intended, to prevent novices from blowing highlights in JPG files. It is essentially working on the principle that it is better to underexpose a bit and save highlights than expose correctly and risk the displeasure of the masses at blown out highlights. There has been criticism of Canon for over-exposing on previous Rebel models, my guess is that they have listened to that criticism - and of course may now be regretting it.

I don't know how much control you have in full-auto mode, but I presume you can still dial in exposure compensation. If you feel it is under-exposing then why not just dial in +1/2 EV or something?

At any rate there is little difference between Auto and P mode with JPG, so why not start there and get that extra bit of control. P mode is still usually suitable for P&S operation by aunty Mabel.

It seems very unlikely to me (verging on impossible) that the lens could have anything to do with the exposure settings being wrong.

The one variable that seems fairly constant in such complaints is that the user is inexperienced, and of course there's nothing wrong with this - everyone has to start out somewhere. Just keep working at your craft and you will be surprised how muchbetter the camera will get over time. The novices of today have been "spoilt" by the remarkably good results that P&S cameras can seem to give, but you really do have to take the time to learn how your camera's metering system works, where it will perform well, where it's weaknesses are. Learning how to expose correctly under a range of different conditions does take a while and is one of the foundation stones of mastering your camera. And of course metering varies (a little) between different models from the same manufacturer and (more widely) between manufacturers.

You know all this though, you obviously have a sensible head on your shoulders.

I'm surethat Canon will adjust your camera to dial in some extra EC in firmware if you send it back to them, but I don't really see how that will be of sufficient benefit to compensate for the loss of 3 weeks' photography. That trade-off is a decision only you can make.
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Old Feb 6, 2007, 5:48 AM   #3
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I tend to agree with peripatetic but IMO there's might be another reason as to why you're seeing underexposure with one lens and not another:

The kit lens has a wider angle of view than the 28-80 hence depending on the images captured an 18mm lens could include more bright background (sky or water for example) than a narrower 28mm lens - The camera 'evaluates' the whole scene and compensate for this brighter image with a lower exposure...

-> 1. You should compare the two lenses at the same focal lenght and see if the underexposure follows the lens

-> 2. Change the metering to partial so the camera only looks at specific object (rather than the whole scene), and use the back of your hand (or a grey card) to test the exposure - This is what the camera is calibrated for (neutral gray) and the exposure should be spotted on regardless of the lens... For example if you meter off a white wall instead which is not neutral gray the camera will also underexposed

-> 3. The camera's exposure varies with the scene content: shooting a bride wearing bright white will usually underespose, vs shooting a black tux groom which would overexpose - which way should the manufacturer calibrate the camera for?
The camera also meter through-the-lens (TTL), which lens would you have Canon calibrate against? Fixing it for the kit lens would make the 28-80 overexpose - Correct?
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Old Feb 6, 2007, 8:51 AM   #4
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I enjoy more to control the XTI in M mode than let the robot does everything for me.
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Old Feb 8, 2007, 2:31 PM   #5
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hopkinsg wrote:
Quote:
Here is my situation. (...) When taking pics with the XTi in full auto mode and using the Kit 18-55 EFS lens, my pictures often times come out under exposed. (Visually and also according to the histogram) I began researching online and found out that many people are having this same complaint.
(...)
My experience is that my camera only seems to underexpose when using the kit lens. It could happen other times, and that is why*I want some suggestions on different things that I can try to "prove" if the cam does have a problem, or if its OK. The only other lens that I have to use is a Canon EF 28-80/3.5-5.6 II . When shooting the same subject with that lens, the images come out better exposed.
Hello, it is exactly the same experience I had. I too have a 400D and when I use the EFs 18-55 kit I obtain only underexposed pictures in P, AV and TV (I do not use full auto). If I use EF lenses as 50 1.8 or 28-70 3.5-4.5 with the same settings and same focal lenghth 50mm I have better pictures, well exposed.
The kit lens underexpose around -2/3 to -1 stop. These are some examples:

http://www.diegocuoghi.it/test400d/400d_lens_test1.jpg
http://www.diegocuoghi.it/test400d/400d_lens_test2.jpg
http://www.diegocuoghi.it/test400d/400d_lens_test3.jpg
http://www.diegocuoghi.it/test400d/400d_lens_test4.jpg

http://www.diegocuoghi.it/test400d/esp-diversa/

If I set manually shutter and aperture I have the same exposure:
http://www.diegocuoghi.it/test400d/esp-uguale/

Ten days ago I sent the camera+lens to the Canon Assistance. I am waiting...
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Old Feb 8, 2007, 9:24 PM   #6
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Diego Cuoghi wrote:
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Ten days ago I sent the camera+lens to the Canon Assistance. I am waiting...
Thanks for the info. I'm very curious to find out what the end result is going to be. Please post an update when/if you have one, that would be great!

I would send mine in (maybe I'm just paranoid) but I'm hoping they don't just increase the exposure across the board just to make people happyand then having the camera blow out the highlights. It is annoying that it does underexpose, but if that is truly how it should work, then I'd rather keep it that way and just use post processing on more of my photos.

-Gary
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Old Feb 8, 2007, 9:27 PM   #7
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peripatetic wrote:
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I don't know how much control you have in full-auto mode, but I presume you can still dial in exposure compensation. If you feel it is under-exposing then why not just dial in +1/2 EV or something?
As far as I know, you don't have EV control when in full-auto. It really doens't let you set anything at all. I could be wrong.This is why people feel that full-auto should produce great results because it doesn't give you any control over anything and one would assume that in full-auto the cameara would choose good/acceptable settings.

-Gary
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Old Feb 9, 2007, 6:59 AM   #8
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hopkinsg wrote:
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peripatetic wrote:
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I don't know how much control you have in full-auto mode, but I presume you can still dial in exposure compensation. If you feel it is under-exposing then why not just dial in +1/2 EV or something?
As far as I know, you don't have EV control when in full-auto. It really doens't let you set anything at all. I could be wrong.This is why people feel that full-auto should produce great results because it doesn't give you any control over anything and one would assume that in full-auto the cameara would choose good/acceptable settings.

-Gary
That's why program mode exists. It does everything full auto does but allows you to dial in EC.

As to expecting a camera to do well in auto mode - the camera's algorithms are no match for your brain. They just aren't. Sure they do well in many circumstances but they're not perfect. When lighting is uneven and their are shadows and highlights, decisions often need to be made as to which you want to be properly exposed - the shadows or the highlights? If you try to expose for both then you end up with a picture that has NEITHER exposed correctly. If you try to expose for shadows you may clip highlights - if you expose for the highlights, you lose your shadows and your midtones are often underexposed. How would you like a camera to read your mind and determine which it should do? Most will try to preserve highlights, I believe. But that may not be the affect the photographer wants.

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Old Feb 9, 2007, 8:35 AM   #9
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and in full auto mode the camera is going to pick its own focus points. the metering is obviously done on these points.

it picks the most distinguishable points and in doing so will def try to find a match where there is difference in dynamics. It never picks a point thats either too bright or too dark. it picks that difference.

thats why they have the P mode where u can specify the focus points as either centre or anyh of the five focus points or all the five. Mostly keep it in centre focus points and focus on those areas where u want more details to come out.
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Old Feb 9, 2007, 2:31 PM   #10
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Eh, since when does the camera meter off the focus points?????


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