f. problem.

[Jeremy]

Hi guys, i'm new to this forum and this is my first post. Sorry if it's in the wrong location

I've recently jumped up to a D90 from my lovely little Nikon p5000. Everything is fine so, managing to keep my head above water while learning all the new stuff....However....

....Ok, so while in 'P' mode, where the best f. is supposed to chosen by the camera, it's obviously not. I can manually change the f. while in 'P' and this fixes the dark image. However, what's the point in doing that if the camera is supposed to be able to do it for you?

I think it has something to do with my f. getting ramped up, but i have a couple of examples where it's the same shot, same f. same zoom. one turns out nice and normal and the other is really dark.

Shots at 70mm turn out normal but then anything after that up to and including 24mm, are dark.

MY ISO is on auto, the only thing i change is the WB depending on what i'm taking a picture of. i've checked the info and the ones that are dark (although not all the time) are the ones with high f. numbers. (8 to 10 usually)

The shots were taken during the day, bright sunlight. After about ooh, 5pmish, the shots turn out fine. likewise indoors, no problems. I'm using a D90 and the lens is a sigma 24mm 70mm 2.8 ex dg macro. With this in mind, is it then a camera or lens error? or...both!?

Of course it could be just me being an idiot and it's supposed to do that, if so...be nice

Thanks.

[OsmosisStudios]

Examples would be great

a higher f/ number means a small opening, and thus less light. Showing examples of what your encountering is gonna be key.

As for your P mode problems: Nikons allow you to select which program the camera uses for a shot. If you press the shutter half way and see that it's giving you 1/100 @ f/4, you can turn the rear wheel (your thumb) and get different options. Turn it left and itll likely give you 1/200 @ f/2.8, turn it right and it should give you something like 1/50 @ f/5.6. The camera is choosing an exposure that works, but it allows you to choose an equivalent depending on what you need from the camera.

[Jeremy]

DSC_1280.jpg

DSC_1281.jpg

I hope these attach themselves!

the one you can see is at 70mm f.7.1 iso 200 the one that's dark was taken with the same settings and the same location but at about 50mm...f.10

does this help?

[wulf]

P (program) mode is meant to give you more control - that is the point of it. If you want to leave everything to the camera, Auto mode is your friend... but then, if you are are going to leave everything to the camera, you might as well use a point and shoot and get the portability too!

Personally, I use manual mode almost all of the time. Try turning off Auto-ISO and taking control ISO, aperture and shutter speed. It isn't that hard and will give you a much richer understanding of what options you (or the camera) has to get a good exposure.

Wulf

ps. Can you tell us ISO and shutter speed for the above shots as well as the aperture?

[OsmosisStudios]

That looks like alot more than just a stop (roughly).

I'd be tempted to ask for FULL exif data.

[dcclark]

Those are pretty extreme. I'd like to see full EXIF data for each, including exposure compensation.

[whiggy]

Could it be that D90 requires the aperture ring to be locked on your sigma lens?