blurry with 50mm lens

kitkatdubs · Oct 8, 2015

so i am trying to understand where i went wrong. i took some photos of a friend for practice and A LOT of them came out blurry. i can't figure out why all my photos are blurry when i use my 50mm lens. however, it seems when i use my 24mm, my photos turn out much better. HELP!? here is a photo i took with my 50D 50mm lens: ISO 500, f/6.3, 1/125 i feel like i was maybe 10 feet from the subjects....

tirediron · Oct 8, 2015

A 24 mm lens has a much greater depth of field than a 50mm lens, therefore, irrespective of where the lens is focused, much more will be in sharp focus. In the case of the example image, you missed focus, that is, you allowed the camera to focus on the grass in the foreground, rather than on the subject. Notice how sharp the closest blades of grass are? Use single point AF (or the Canon equivalent) and place the focus point where you want the centre of focus.

Overread · Oct 8, 2015

Blurryness comes from four primary sources:

1) Handshake from holding the lens itself. The general rule of thumb for hand holding is 1/focal length of the lens gives you the slowest ideal shutter speed to hand hold at and get a sharp shot. This will vary - typically very short focal length lenses are easier to hold at much slower speeds; whilst much longer lenses amplify the motions so often need faster speeds (they also tend to be heavier so introduce more fatigue into the equation as well). Different people are also going to react differently and fatigue will also play a part.
At 1/125sec you should be fine, in theory, with a 50mm lens (1/50sec min shutter speed according to the theory). So this might not be an issue.

You can normally tell this kind of blur because its global - ergo its even all over the photo.

2) Motion from the subjects themselves. This is easy to tell as it typically shows as blur around areas of motion on the subjects. This can be harder to have general "rules" as to how fast or slow you can get away with - so generally if things are moving faster is better. I would suspect that at 1/125sec it is a risk that if you've got motion with the subjects you will get blur in the shot.

3) High ISO - yes a higher ISO tends to reduce the overall clarity and crispness of detail; in my observations this is also increased if you underexpose the photo and then brighten it up (as this reveals/induces more noise in the shot). "Expose to the right" and "Histograms" are two things you can read up on with regard to this aspect of what under and over exposure are. Remembering that the expose to the right theory is only a theory and thus will not always be practical in real world situations (its an "ideal" you can aim for though).

4) Softness inherent with the lens itself. Stick the camera on a tripod - set the aperture - aim at flatish subject at 45 degrees and take a shot. Use a range of apertures and different shots and get a feel for how the sharpness pans out with your lens. This way of doing it means that you always get a band of infocus sharp within the shot. Note that distance also plays a part in things; but that in general you can tell from a single set of shots how "sharp" your lens is.
This might reveal that the lens+camera combo is underperforming or that its performing well - if its the latter then you know that the softness must be one of the other 3 (or a combination) criteria.

Note that a good sharpening practice and methodology is important as well as part of your workflow - along with noise reduction as well where needed. So these would be other areas to consider to improve the output you get - of course it will not fix any blurryness that you do get; its about polishing what you have got already (so you've still got to get the shot sharp first)

Edit - Tired also shows the other important way blur can be introduced - by missing the focus - and its one I totally forgot to mention!!