Sharpest aperture of Canon EF 75-300

10 Gauge · Jan 11, 2011

I have this lens, and it's cheap, real cheap. I find that most of my images from this lens are very soft. Where does the sharpness for this particular lens peak @ 300mm, does anyone know? I seem to get about the best results from about f/8, but they still aren't "stunning" by any means.

Robin Usagani · Jan 11, 2011

f8 is about right. But shutter speed is more important than the sweet spot of your lens. You could have the sharpest aperture but your shutter speed may be too slow and you may have camera shake blur.

Dao · Jan 11, 2011

In general (not always true) lenses are best when set at 2 stops from wide open. At 300mm, max aperture is f/5.6, so I will try to use it at f/11 or maybe f/8. Use a tripod for better result.

As for the soft image, it could be the lens (limitation of the lens) as well as how you take the photos.

10 Gauge · Jan 11, 2011

Thanks for the input. I'll try bumping up the ISO a notch to get my shutter speeds a little quicker and see if that makes a difference.

FranDaMan · Jan 11, 2011

I have it to and at 300mm it is just very soft.
It tends to get better at f8/f11, but at 300mm your shutterspeed is quite slow, unless you jack up the ISO to 6400.

It's just not the greatest lens around unfortunately

Big Mike · Jan 11, 2011

Yes, the first thing is to make sure that you eliminate movement blur. So putting the camera/lens on a tripod and using a remote, can mostly stop camera movement, but you'll need a faster shutter speed if you're shooting hand held or if your subject is moving.

The rule of thumb for shooting hand held, is that you want 1/focal length. So shoot for a shutter speed of 1/300. Some say that you should take the crop factor into account, which makes it 1/480 (1/500).

As you will see, you need a lot of light to get shutter speeds like that, with a lens like that. You will likely need to crank up the ISO.

Once you are sure that you can control motion blur, then look at which apertures will give you the best image quality. As mentioned, it's probably around F8 to F11.

Also, lenses like this tend to be worse at the ends of their zoom range. So shooting at 200-250mm will probably get you a sharper photo than shooting at 300mm.