shooting at certain aperture values to get crisp pictures..?

[skimmilk68]

um i know that my 50mm f1.8 lens takes pictures most sharpest when shot with f5.6 or something like that

i always tried to shoot with the lowest aperture value possible whenever i used that lens.

How do i find out the maximum potential aperture value for all my other lenses? Is there an explanation why lenses are sharpest at a specific aperture value?

[Eric DeCastro]

i usually shoot around 4 to 8. you just have to know your lense. just keep practicing.

[tim]

Try it and make up your own mind. I did it for my lenses and the results are here.

[Wavy C]

Of course it depends on your subject, but sometimes a little lens softness can work to your advantage. I shot the picture below using my 50mm 1.8 wide open, handheld at just 1/6 sec and ISO 200:



It's only a snapshot really, but I hope shows that using a lens wide open creates a nice soft effect that I imagine could be quite difficult to recreate in an image editor.

I mentioned in another thread here about the 50mm 1.8 versus 1.4 that I like the 1.8's slight softness so much that I would keep this lens just for that 'feature' alone - even if I sometime got a 1.4 as well.

-

[pierrot]

Excellent, Tim, I'll do the same with my gear.
And btw, I'm less impressed by the 50@f/1.8... lokks blurry and disappointing. I'll think twice again before placing any order.
Thx to Wavy C, too.

[aam1234]

Heard it many times, to get the sharpest results you need to stop the lens down 2-3 from the max.

[BDM]

Originally Posted by skimmilk68

um i know that my 50mm f1.8 lens takes pictures most sharpest when shot with f5.6 or something like that

i always tried to shoot with the lowest aperture value possible whenever i used that lens.

How do i find out the maximum potential aperture value for all my other lenses? Is there an explanation why lenses are sharpest at a specific aperture value?

As a general rule of thumb, lenses are usually sharpest at about three stops down from their maximum aperture. Generally speaking, the faster a lens, the higher percentage of rays from the element edges are used to form the image. And that brings greater problems with abberations such as chromatic aberation, comma, etc.. There are a very few high speed lenses specifically designed to give their highest performance with a wide open aperture. The Leica F:1.0 Noctilux comes to mind. When stopped down to F:5.6 or so, it is no better and perhaps a bit worse than the Leitz F:2.0 Summicron. But that is a speciality lens and costs $$$$$!.

The other end of the scale is that stopping down past F:8.0 or so causes increasing sharpness loss through diffraction. This tends to be worse the faster the lens is to start with. So an F:1.4 lens will tend to exhibit diffraction effects sooner than say an F:2.0 lens.

Finally, necessary depth of field is also a factor. Shooting at the "optimum" aperture may give the best theoretical sharpness at the point focused on but if the necessary picture elements are not rendered sharp enough, you really haven't accomplished much. A good example might be using a high speed telephoto for a portrait with the subject relatively close to the lens for a frame filling image. You focus on the eyes which are quite sharp. Unfortunately, the nose and ears are not and so . . . You should try to shoot at the "best" aperture when possible, consistant with depth of field and other needs (such as action stopping, etc.).

Bruce

[kb244]

With the 50mm f/1.8 I noticed the best range seems to be at 5.6 to 8 , I noticed this quite well when shooting macro and had to go upto f/22 and such and was very soft.

[Olegis]

At such small apertures as f/22 the quality decreases due to diffraction.

[skimmilk68]

so im guessing you guys all shoot in M manual mode?

i dont understand how to have my aperture set 3 stops below my widest point while trying to compensate with the lighting and shutter speed...

[Jon]

You have some control over the aperture used in any of the Creative zones. In Program mode, the "Main" dial will let you change the shutter speed/aperture combination. In Av, you'd just set the aperture you want. In Tv, you'd change the shutter speed until you get the aperture you want. If those would take you out of "safe" shooting conditions, you can then change ISO settings. But if you're using a "Basic" setting, there's not a lot you can do.

[Jay J]

Hi Skimmilk,

A general rule of thumb to determine the sharpest aperature of a lens is to go up two full stops from the most wide open aperature. For example if you have a 4.0 lens then by going up two full stops you'll arrive at F8.0. This is typically the sharpest aperature settings.

Jay J

[skimmilk68]

Originally Posted by Jay J

Hi Skimmilk,

A general rule of thumb to determine the sharpest aperature of a lens is to go up two full stops from the most wide open aperature. For example if you have a 4.0 lens then by going up two full stops you'll arrive at F8.0. This is typically the sharpest aperature settings.

Jay J

i know i know, but are you guys letting the camera set the shutter speed when you bump up the fstops (obviuosly in Av mode) ??

If I bumped up the aperture value, the shutter speed would decrease and i cant capture any movement or hold it steady enough... unless i was in M manual mode

[Mitch]

Bottom line, if you want sharp photos indoors, use 1/60 shutter speeds for 17 to 85mm focal lengths and f5.6 for everything. Adjust your flash power and how close you are to the subject. At night, indoors, use manual mode with flash. Bounce the flash off the ceiling if you can or use FEL pre-flash and get close to your subject (5 to 20 ft), use the 17-40 or 24-70, or 28-135 and you will get consistantly sharp pics. Practice steadiness while holding your camera and taking pictures. Oh yeah, don't be afraid to use ISO settings from 200 to 400 with these suggested shutter speed and fstop settings.

[Scott J]

Stopping down a couple of stops from max aperture is good advice with a lens of poor quality. You can often get acceptable results from doing so.

With canon L series and some prime lenses this should not be an issue. Any softness in the lens will be within the tolerance of either the camera -- all digital images are slightly soft if you don't apply any sharpening to them -- or the output medium. Inkjets for example no matter how good are not going to show anything in the lens.

Where most beginner to intermediate shooters will have problems is in not using a tripod / using too slow a shutter speed hand held as in the image above which does not come near showing the sharpness capabilities of the lens used. Other typical problems are not stopping down to achieve the right depth of field for the shot and / or allowing the autofocus to focus on the wrong part of the image.

Also be aware that with all digital there is an issue using apertures below f16 that causes unsharpness.

Here is a good article on sharpness:

http://www.luminous-landscape.com/tu...harpness.shtml