What am I doing wrong?

[Mudgey]

Hey guys,

I have had my new camera a few months now and have been playing around with it, however I cannot get my pictures any sharper than these:



This was shot with a Canon 550D with a 17-70mm Sigma Lens 1:2.8-4.5

The camera was in auto mode with flash turned off.

Can anybody give me any tips?

[steve2]

what ISP are you using, try in aperture mode and repost

[Simpo Two]

Dim light, seemingly good depth of field - I wonder if high ISO is causing the look. But it's not basically unsharp. What ISO?

[jaik]

Can you post up the following (it'll be in the EXIF metadata in the original image):

• Aperture
• Shutter speed
• ISO

I've got the same lens and have a bunch of shots on Flickr (newer ones with 7D, older with 30D) if you want to see how sharp the lens can be:
http://www.flickr.com/photos/jaikdean/tags/sigma17...

Edited by jaik on Thursday 2nd August 21:56

[LongQ]

Which bits did you want in focus and which bits not in focus?

Looks ike you are using a wide angle setting quite close to the subject that would mean that the distance from the lens to, say, the back wall is probably no more than and likely a bit less than the distance from the lens to the furthest part of the tyres. In fact very few parts of the bike will be a consistent distance from the lens. This means that apparent sharpness can, if the lens is wide open to allow in as much light as possible, vary across the subject in odd ways. There may also be ather factors realted to the expected performance of the lens if wide open. (If it was not wide open then other factors may be involved.)

Frankly, at the size presented by Thumbsnap, it doesn;t look noticeably bad to me. Where do you see the problem(s)?

[Xerstead]

Mudgey said:

The camera was in auto mode with flash turned off.

Thats what did it

Check what settings the camera used, (ISO, aperture, focal length and shutter speed).
Some parts look sharp so my guess is that the camera picked which bits to focus on and used an aperture too large (low f. number) to get the rest of the bike in focus. The end of the handle bar and pedal look fine but gets blurry for the rest of the bike. The lower the f. number the bigger the hole through the lens so you can use a faster shutter speed but the depth of field (the bits in focus) gets smaller which is great when you want it, but not here.

Try setting the camera to AV (aperture priority) set the lens to f.10 and turn the flash on (or ISO up). You will get a sharp image.
Play around with all the settings (AV and TV) and see how it affects the picture, once you grasp those your camera will never be back in auto.

ETA I had a similar problem with my Sigma 50mm 1.4 lens on my 500D, I'd turned it back to auto for a friend to get a few shots of me and it went for something around f.2 without flash, almost everything apart from my nose was blurry

Edited by Xerstead on Thursday 2nd August 22:09

[Mudgey]

Hey guys, thanks for the advice, I have been playing around with the camera and this is where I have got to so far.

This shot is from last week with the first time taking it out n about, I have to admit I didnt know where to start so just left it on Auto mode!!



F/7.1
1/250s
ISO-100
0 Step
Focal 70mm

This is in my light tent on a project I am working on and this time it was in manual mode so I played with the settings until I was happy:



F/10
1.3s
ISO-100
0 Step
Focal 48mm

Really happy with the camera so far but I am sure these shots can get better!

[Otispunkmeyer]

Try f8 or f5.6

Lots of lenses tend to sharpest around those points.

Have a look on dpreview or photozone.de for a review of your lenses...they should tell you where the sweet spots are.