Image Sharpness and Flash

[albertdong]

Hi...I was looking for some advice.

I've owned a d7000 for about 12 months now.

It's my first dslr and I recently had it repaired for an autofocus problem ( significant back focus issues ). If I'm being honest the battle with reliable focus with the camera has dented my confidence in it a bit...to the point it sat on the shelf for 6 months.

However, over christmas I took a number of pictures using the inbuilt flash and the sharpness and focus was excellent.

Then I went for a walk yesterday and took a few pictures and once again I'm not happy with the sharpness or level of focus.

So, I'm beginning to think it's bad technique, or maybe me expecting far too much.

I'm assuming that photos taken using flash allow for far faster shutter speed and therefore less chance of camera shake / blurring?

For me taking handheld, non-flash pictures, are there any rules of thumb to improve sharpness / focus ( e.g. minimum realistic shutter speed, optimal aperture etc )

Sorry for the very basic question....I guess I'm still a bit suspicious of the camera and now just hoping it's me needing to learn more and improve technique.

Thanks.....

 

[TCR4x4]

The rule is your shutter speed should be 1x faster than your focal length, although with crop cameras, this changes to 1.5x your focal length.


So if you are shooting at 200mm ideally you want 1/250th or faster.

Is isn't hard fast, different people can handhold much slower, it depends on you and how steady you are, but its a good starting point.

As for aperture, most lenses are sharper stopped down a bit, so try somewhere like f/5.6 if the light allows.

More expensive lenses don't suffer so badly from this, I tend to shoot wide open most of the time, so either f/1.4 or f/2.8, unless I'm doing landscapes,in which case Ill be around f/11.

 

[dejongj]

As Tom has said...For nikon d7000 it is about 1.5x which for 200mm should make it 1/300 But yet it depends on the person holding the camera, however it also depends on how the subject is moving.

If you have a fast moving subject and are shooting using a 50mm lens, then 1/75 might not be enough to get them still (and sharp...).

Most lenses seem to be good around f8, but again it all depends on the lens and what it is that you want to shoot...

 

[Phil V]

If your flash shots are nice and sharp, your problems are almost certainly related to shutter speed.

The 'rule of thumb' is that the shutter speed should be 1/ the focal length (35mm equivalent).

So if you're using a crop camera with a 55mm lens, you should keep to 1/100 or above. But this is a rule of thumb. you really need to do your own tests. It's very much down to technique, stance, breathing, keeping the weight in your left hand (cradling the lens).

 

[gad-westy]

As above really. The D7000 is capable of very clean results at high iso so don't be afraid to increase the iso a bit to get your shutter speeds up if need be.

As Jean Paul says, if your subject is moving, to an extent the 1/focal length guidance goes out of the window anyway as you're likely going to need to be faster than that to avoid blur for most subjects. My daughter is a toddler and I can't really get away with less than 1/250 if she's moving. 1/125 if she's fairly still. A racing car might need 1/500 or faster still.

 

[HoppyUK]

Just reading between the lines, if your shutter speed is sufficiently high, and your focus accurate, then I'll hazard a guess that maybe what your seeing is just a trick of the light.

With flash, the light source is small, hard, contrasty, and emphasises sharpness. If your outdoor shots were taken on a dull, overcast day, the light will be ultra-soft, shadowless, very dull. Colours will be muted and if there's any distance invloved then atmospheric haze/mist will make things look even more flat and lifeless.