Getting soft images?

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dougt
dougt's picture
Getting soft images?

I often see where people complain about their telephoto lens isn't focusing properly or the images are soft.

Well it's not necessarily the lens it can be a number of reasons.

Too far away from the subject.  I have a 600mm lens and it is not used to take a shot of a bird 20 metres away, it is to get up close and personal.

Exposure.

Low light. Shooting action with birds is usually done with spot focus and shutter priority probably 1/000 sec or more which means the aperture will be wide open so you have very little depth of field. The problem is compounded by the low light and and the spot focus uses contrasting areas to determine the correct focus. If there is not enough contrast the focus sensors will have trouble getting an accurate focus.

We are always told to focus on the eye.  I fully agree about 90% of the time.  What about a bird with a black eye and no ring around the eye on a black face?  You may need to focus on the beak or some other contrasting area at the same DOF as the eye.

Over exposure causes the colours to wash our or merge slightly.  Use the Exposure Value to fine tune your exposures.

Noise.

Digital noise from high ISOs.  Contrast Noise, Colour Noise to name a few more.

Movement, Hand shake and vibration.

More or less self explanatory.  Many telephoto lens have some sort of Vibration Reduction (VR).

VR cannot correct your hands shaking like a leaf when trying to focus on a subject. VR does a reasonable job with vibration but not shake.  If you are using a tripod turn the VR OFF because the camera is already on a stable platform and VR can actually introduce vibration nd cause a soft image.

The Bald Eagle below was shot around 4pm in Autumn on an overcast day in Alsaka.  The light was difficult to say the least.  I was using a full frame Nikon D700 camera with a shutter speed of 1/1200s with the ISO at 3200and the EV at +3 with a 500mm lens at a range about 50 metres.

As you can see it is very soft but the flight feathers do seem to have some reasonable detail but I probaly broke every rule in the book to get what I did and I am not complaining.

Devster
Devster's picture

Thanks Doug. While this is very informative and thought provoking. I think it would be best suited to the Photography Tips and Tricks section of the forum.

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