Whats up with my camera?

melissa6631

ok... i'm not sure if this is where i should even be posting this. But, I've noticed on my 50mm 1.8 ... when I use that lens sometimes my photos are coming out with a mark on them. Like.. almost as if I'm taking it through a screen.

Do you guys see it in these two photos?
It's noticable in the originals. I'm not sure if you can see it well on here or not. It's happened before too and it's just making me bang my head on a wall.. any help and direction is appreciate!

Thanks so much

Andy

melissa6631 wrote:

ok... i'm not sure if this is where i should even be posting this. But, I've noticed on my 50mm 1.8 ... when I use that lens sometimes my photos are coming out with a mark on them. Like.. almost as if I'm taking it through a screen.

Do you guys see it in these two photos?
It's noticable in the originals. I'm not sure if you can see it well on here or not. It's happened before too and it's just making me bang my head on a wall.. any help and direction is appreciate!

Missy, we need the exif, thanks....

melissa6631

andy wrote:

Missy, we need the exif, thanks....

Andy.... this is for the first one (of the baby) Do you see what I'm talking about though?
Size: 3072x2048 Bytes: 2446794 Aperture: f/1.8 ISO: 400 Focal Length: 50mm (guess: 53mm in 35mm) Exposure Time: 0.0333s (1/30)JPEG Quality:3Flash:Flash did not fire, auto modeExposure Bias:0SensingMethod:One-chip color sensorColorSpace:sRGB




and this is of the girl with the dog.

Size: 3072x2048 Bytes: 2107852 Aperture: f/1.8 ISO: 250 Focal Length: 50mm (guess: 53mm in 35mm) Exposure Time: 0.02s (1/50)JPEG Quality:3Flash:Flash did not fire, auto modeExposure Bias:0SensingMethod:One-chip color sensorColorSpace:sRGB

melissa6631

Hey Charlie just suggested it might be a finger print...

hmmmmm i wonder if that could be it.

Andy

melissa6631 wrote:

Hey Charlie just suggested it might be a finger print...

hmmmmm i wonder if that could be it.

Well, g00z-d00d, maybe you could get out some lens tissue and clean that bugger

Andy

Missy, you need to bump the ISO to get your shutter speeds up. 1/60th is the slowest handheld for you with that lens, ideally 1/125th. Shoot at ISO 800 or 1600 to get there.

TOF guy

Honestly I'm not sure about the mark. I see a small smudge in the center of the dog pic, but it is not there in the baby image.

To solve this kind of problems I've found it easier to shoot a uniform surface. That wall behind the girl with the dog would do the trick. Then apply some rather exagerated level correction in Photoshop to exacerbate the problem.

I've always found that a 85 mm lens on a 35 mm camera is still not long enough for a tight portrait of a baby's face, but that's besides the point.

Thierry

52Caddy

Any chance this is dust on the sensor you're seeing?
I've noticed that on some of my shots.

TOF guy

52Caddy wrote:

Any chance this is dust on the sensor you're seeing?
I've noticed that on some of my shots.

Dust on the sensor will affect the image at small apertures, like f16 etc. It will not affect the image in a visible way at larger apertures like f1.8 etc (used by Melissa in the posted pictures). That's probably why Andy asked for the EXIF data, to exclude an issue with dust on sensor.

If you're curious about why the shadow of a piece of dust on the sensor would be much less visible at larger apertures, here is the explanation: at small aperture the light comes very near perpendicular to the sensor, hence the shadow is sharp. But at larger aperture most of the light will come at an angle, lighting the sensor under the dust, which is never right again the sensor (there is the IR filter, AA filter, etc between the pixel surface proper and the sensor surface on which the dust lies).

I still can't see clearly the problem (supposed to be visible on both pics) The most plausible explanation is the surface of the back lens element is dirty (a little smudge on the front lens element would adversely affect contrast quite uniformely all accross the picture).

Thierry

Harrison

I think what you're seeing is slight camera shake. Even the slightest movement can throw an image into the abyss of a mystery diagnosis.
~Harrison

bham

To start I would shoot some images where you can use a f stop higher than the minimum 1.8 and shutter speed much faster than 1/30. Then see if you can still find it.

The only thing I see in these pics is that not much is sharp due to both the extremely shallow depth of field as a result of the f1.8, and possible slight movement during the slow shutter speed.

If it is truely the lens, or something in the lens, try shooting against something flat, one color evenly lit (like a wall) that you can compare to other images of the same thing from various lenses.

Just an idea to start.