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View Full Version : What do I do wrong with Nikon D40?



CNC
09-03-2007, 06:38 AM
Hy everybody.

I am new in DCRP forum and new in the dslr photography. My Previous camera was PS A610, so I am comfortable with some fotographic terms.

Hier is my question: in M-mode I choose every parameter to expose a picture properly myself: ISO, shutter, aperture. I pont the camera to a sunny bright sky (but still "very" blue) and fokus but do not schoot, I then point the camera down to a tree with the prefocused camera and make a shot of the tree. The tree is underexposed. OK. I understand, the with the settings I made I produce an underexposed tree. second shot and this is the place whre I do not understand what happens: same settings as before, with no changes from the previous shot I aim at the same tree, focus and shoot. The Tree is now prperly exposed. Why ist that?Same settings, differnet results...

thank you in advance!

Rooz
09-03-2007, 06:52 AM
can you post some examples pls. at first glance it sounds like metering. the first time it metered off the sky and the second it metered off the tree. actually re-reading your post...you said you were shooting in M mode and didnt change anything...so maybe it isn;t metering after all. (you dont have to focus to meter btw).

try moving into a constant light source that won;t change and try again. maybe the light just got better at the time you were shooting ?

tcadwall
09-03-2007, 11:34 AM
So you think you set everything Manual... But did you really?:eek:

Tip: double-check. Look at the EXIF information for the photos. I bet you the ISO setting is different

Now - I have shot only a few photos with a friend's D40, but I still would bet that (similarly to my D70s) you have auto-ISO set to "ON" (which I do not do because of this). Yes, this affects the settings even if you are in M mode. I am not sure how the D40 handles the warning, because it doesn't have a top display. On my D70s, there is a little flashing indicator on the top lcd which signifies that the auto iso is taking over.

Effectively, the menu-based auto-ISO setting enables you to adjust the aperture and shutterspeed and allow / disallow the camera to help you get exposure correct by adjusting the ISO.

fionndruinne
09-03-2007, 01:59 PM
Like others have said, I think auto-ISO is your problem here.

All in all, I'd suggest... just point your camera at the tree when you want to take a photo of the tree, and at the sky when you want a photo of the sky. So much easier.:p

SpecialK
09-03-2007, 10:31 PM
He's in bright daylight for both shots. I doubt Auto-ISO is going to change on him. I'm surprised a) he can focus on the sky, and b) the tree is in focus after that.

I suspect the "same settings" weren't the same, but the proof is in the EXIF pudding :-)

tcadwall
09-04-2007, 08:13 AM
SpecialK...

Thanks for your theory. Hopefully the OP will come back and inform us as to what was found in the EXIF. But I find it amusing that you don't think Auto ISO would affect this shot. I will give the OP the benefit of the doubt that he didn't change settings. I can provide a very sensible theory based on that. To basically suggest that the most probably cause is the OP changing his settings is maybe a bit abrasive. Especially when it was stated to the contrary. Well, sure, he may have inadvertently slid a wheel and changed a setting, but he'll figure that out on his own when he looks at the EXIF. If, however, it WAS / IS the autoISO that is screwing with the exposure, then we were able to help.

K1W1
09-04-2007, 04:29 PM
Where have people got the idea that auto ISO is involved?
If you read the first post it says, "I choose every parameter to expose a picture properly myself: ISO, shutter, aperture.".

SpecialK
09-04-2007, 05:21 PM
SpecialK...

Thanks for your theory. Hopefully the OP will come back and inform us as to what was found in the EXIF. But I find it amusing that you don't think Auto ISO would affect this shot. I will give the OP the benefit of the doubt that he didn't change settings. I can provide a very sensible theory based on that. To basically suggest that the most probably cause is the OP changing his settings is maybe a bit abrasive. Especially when it was stated to the contrary. Well, sure, he may have inadvertently slid a wheel and changed a setting, but he'll figure that out on his own when he looks at the EXIF. If, however, it WAS / IS the autoISO that is screwing with the exposure, then we were able to help.

Ah, yes, but I question how sensitive the "auto" part would have to be if the exposure - in daylight - was off the sky, then simple lowered to a tree - also in daylight.

No offense intended to the OP.

tcadwall
09-05-2007, 08:34 AM
K1W1

The idea stems from the fact that Auto - ISO may be enabled. In which case, the ISO might be "CHOSEN" but then over-ridden the next time the shutter release is pressed.

I believe that the default setting for Auto-ISO is "on". Not sure what the default limits are for that particular camera, etc. but since he states that he is new to the camera.... Also, knowing that Auto-ISO DOES kick in when you are in "M" mode, and also, since this happened to me when I first started shooting in "M" mode, it rang a bell.

Depending on the settings for focus and ae lock, if he does a half press on the sky, and then lowers the camera to a shady tree, it will be underexposed. Even the OP understands why that would happen. But when he DOESN'T set the focus and exposure on the sky first, the exposure is corrected. This makes sense to me that AutoISO would bump up to correct the exposure. A shady day this might not be as pronounced. Think about how easy it is to blow out the exposure on the sky when you have a subject that you are metering off of that even though the subject is in the bright sun, the subject is not reflecting nearly as much light as the sun....

Of course, it appears that the OP might not even be around anymore to confirm / deny, etc.

Edit---

Just realized, SpecialK you are listed with a Pentax... Maybe you *have* shot with a Nikon, but since you are into assuming things, I will just assume that you really wouldn't understand how quickly the NIKON camera can adjust and under what circumstances the camera would adjust the AutoISO.