Can't get really sharp images on EOS 40D

[dylj]

17mm, ISO 800, 0.8/sec @ f/2.8

Image showing which points i'll be showing 1:1 crops of:

Try these with ISO 100. They look plenty sharp for me, though.

 

[Sw1tchFX]

Could be a few things, field curvature, depth of field, front or back focusing, camera shake..

they look ok to me for a shot at f/2.8.

 

[Garbz]

I'm sorry but did you just really compare L glass to a cheap Tamron? Also when was the last time you printed an photo that big? If it's a bit blurry apply an unsharp mask.

 

[Mav]

17mm, ISO 800, 0.8/sec @ f/2.8

Image showing which points i'll be showing 1:1 crops of:
http://img149.imageshack.us/img149/8660/zoompointsqn3.jpg

http://img149.imageshack.us/img149/7152/zoom1tf1.jpg

http://img341.imageshack.us/img341/9568/zoom2vh9.jpg

These look fine to me.

They don't look completely sharp because ISO 800 isn't completely sharp, and because only one of those points is really in focus. The lens only focuses at one point so either one of those points or the other is in an area that's falling out of focus.

Drop your ISO down to 100, and stop the lens down to at least f/4 and you should get much better results. It'll also give you an exposure time of about 12-13 seconds. This is how most night photography like this is done. And then make sure you're using either a remote shutter release, or the time delay feature on the 40D so that any vibration from hitting the shutter itself dampens out before it starts taking the photo. Otherwise you'll get blurry photos from the camera setup vibrating.

 

[BoblyBill]

I'm sorry but did you just really compare L glass to a cheap Tamron? Also when was the last time you printed an photo that big? If it's a bit blurry apply an unsharp mask.

I wasn't comparing the two. I was giving an example of how blurry the LCD is on the back of the camera. That was one of the shots that I still had on my camera last night so I used it so that I could blur the sharp crop to look similar to what the LCD looked like. I don't really want to print a picture that big... yet... but sadly I'm a pixel pusher and I like to have see pictures sharp even at 100%.

 

[BoblyBill]

To the OP... Mav is completely right. throw that down to 100 ISO with an aperature of f/4, and I bet you'll get better performance of that lens.

 

[MDesigner]

To the OP... Mav is completely right. throw that down to 100 ISO with an aperature of f/4, and I bet you'll get better performance of that lens.

Very curious why the adjustment to f/4 instead of f/2.8.

 

[Mav]

Very curious why the adjustment to f/4 instead of f/2.8.

Because lenses usually don't perform their best at their maximum aperture. If you stop down 1 or 2 stops to f/4 or f/5.6 you're likely to get sharper results. This is true of most lenses, although different lenses tend to have very different starting points as to how sharp they are wide open.

 

[MDesigner]

Great, thanks for all the tips..very helpful!

 

[Dao]

Very curious why the adjustment to f/4 instead of f/2.8.

FYI, according to photozone:

At 17mm, your lens perform the best at F4
From 24mm to 50mm, it perform the best at F5.6

But F4 or even f2.8 should still pretty sharp. I would agree with others try it with iso100 with longer exposure. And for the type of photo you take, a smaller aperture may look sharper (more DOF). Please correct me if I am wrong.

 

[MDesigner]

Because lenses usually don't perform their best at their maximum aperture.

Does that rule apply to prime lenses?

 

[reg]

Is a prime lens a lens?

BTW quit staring at 1:1 crops. You'll drive yourself crazy.

 

[Dao]

I do not think that is a rule. However, when I look at lenses review sites, it appear that way. Lens usually performs better few stops down from the max aperture size.

 

[MDesigner]

Is a prime lens a lens?

Hey, just asking. May I remind you the forum we're in:

"The Beginners Place Brand new to photography, or brushing up on some of the basics?"

I know that prime lenses tend to be sharper than zoom lenses. Just wondering if a prime lens at its max aperture will yield better (sharper) results than a zoom lens at its max aperture.

 

[Mav]

Does that rule apply to prime lenses?

Yes, although generally speaking prime lenses are going to be sharper than consumer grade zooms, so they may be as sharp as you'd ever need them to be even wide-open at their maximum apertures. My Nikon 50mm f/1.8 lens was crazy sharp even wide open at f/1.8, and got ridiculously sharp stopped down to f/2.8 or f/4. It depends on the lens though. Pro level zooms that cost $1000+ are usually going to be as sharp as you need them to be at maximum aperture and can shoot them there all day if you want. This is also why it's impossible to shop for lenses just based on specs alone.