A question of sharpness

BobBCN

BobBCN

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Bob
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Hello,

I have looked around but not found as I imagine this question has been raised before, but here goes anyway ......

Is sharpness (and general image quality for that matter) directly related to lens size? In other words, would a short lens, say 50mm, produce a sharper image than a long 300mm lens? Like it's a question of physics rather than 'photographer'? And of course assuming that the focusing is spot on, there's no camera shake, no shutter speed issues etc etc.

I have seen some photos of garden birds on the forum which seem to be incredibly sharp and must have been taken from a fair distance - I mean they do tend to fly away if you get anywhere near!

Or is it that these shots have been taken with superior equipment?

I must add that I am a newbie with a beginner's Canon 1100D

Thanks and sorry for perhaps digging up a pretty basic question.

Bob
 
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Just seen in the tutorial section that high ISO affects image quality.

At the moment most of my shots are at indoor sports events often in poorly lit places and more often than not on a long lens. I'm fixed on 6400 and maybe that's why I'm getting the 'not so sharp' final result.

I don't know the physics of the thing, but I'm guessing that the combination of:

high ISO (because I'm indoors), long lens (as I'm far away from the action) and fast shutter speed 1/250 (I don't want blurred movement and so I'm in Tv mode and this means the aperture is wide open and often flashing - perhaps warning me?

- is not the best if I'm looking to get pin sharp results?
 
No, its down to lens quality, the length has no bearing really. You can get super sharp 14mm lenses and super sharp 800 mm lenses.

The better quality the glass, the sharper the image, and usually the more expensive it becomes.

There are many 300mm zoom lenses aimed at the beginner market. Whislt these provide a cheap intoduction to long zooms, the quality is often sacrificed and the results wont be very sharp. Once you spend on a pro quality 300mm zoom or prime, you will see significant results in the sharpness.
 
BobBCN said:
Just seen in the tutorial section that high ISO affects image quality.

At the moment most of my shots are at indoor sports events often in poorly lit places and more often than not on a long lens. I'm fixed on 6400 and maybe that's why I'm getting the 'not so sharp' final result.

I don't know the physics of the thing, but I'm guessing that the combination of:

high ISO (because I'm indoors), long lens (as I'm far away from the action) and fast shutter speed 1/250 (I don't want blurred movement and so I'm in Tv mode and this means the aperture is wide open and often flashing - perhaps warning me?

- is not the best if I'm looking to get pin sharp results?
Click to expand...

High ISO is a killer for sharpness, in fact your camera is also probably performing noise reduction too, which further decreases sharpness.

Your aperture is flashing as the camera wants it to go lower, but the lens isnt capable. This is where you need to spend out on a fast lens with a aperure of f/2.8 or faster. This will allow you to keep your shutter speed up, but with a lower ISO.
 
Also answered my worries too. For the past few months i have noticed an increasingly poor performance on terms of "sharpness". Shooting sports outdoors i have the ISO more or less maxed out at 3200 to keep shutter speed somewhere reasonable. Hopefully you have given me the reason why. Fingers crossed
 
Can say for certain thats why. The higher the ISO the less sharp images appear. Even more so if you shoot JPG with high ISO NR turned on. To get the best possible sharpness from high ISO, turn off all noise reduction in the camera and do it in PP.
Of course the best way is not you use high ISO, but thats not always possible.

Most high ISO shots will look fine web sized, its only when you pixel peep you notice the effects of the noise.
 
If you wish to get the best out of your high iso images, shoot raw. Straight out of the camera the images won't look particularly good but the detail will still be there and careful noise reduction will preserve more of it than the in-camera jpegs.
 
More iso means worse photos! Pixel peepers wont like this but lightroom is good or helping to get this sorted....... Try and shoot no highter that 1000 iso if possible......
 
If you have a longer lens, you are more susceptible to camera shake if hand held (or possibly on a tripod), so a shorter length lens does assist with sharper images in a way.
 
And always use a shutter speed equal or more than the focal length of the lens?
 
Gregory Hicks said:
More iso means worse photos! Pixel peepers wont like this but lightroom is good or helping to get this sorted....... Try and shoot no highter that 1000 iso if possible......
Click to expand...

Sometimes but not always.......

For example, I'm shooting a rugby match and need to maintain a shutter speed of at least 1/500 (usually a little more). It's getting dark ISO1600 f6.5 (max f-stop at full zoom) is no longer cutting it so the images are now starting to get under exposed which will exacerbate the noise situation.

I could slow the shutter speed but then I'll get blurry images and no amount of PP will cure blurry photos.

My only option is to up the ISO, yes there could be an increase in noise BUT I will (hopefully) be getting non-blurry, properly exposed images.

IMHO a slightly noisier image is better than a dark & blurry image or no image at all ;)
 
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