is it my lens?

[Nix]

Swap that 6 for an 8, and that's what I've always heard.

Each lens design is different, some lenses are actually designed to be very sharp when at their max (wide open)...while most lenses tend to get much better when stopped down a stop or two. A safe bet for the sweet spot on most lenses would be F8.

f8!? then why get a lens thats f2.8?

 

[Don Simon]

You'll notice Mike actually said that many tend to get noticeably better when stopped down one or two f-stops, and that f/8 is just a "safe bet". So if you have a cheap "kit lens" chances are it will perform best stopped down to f/8. It doesn't mean that an f/2.8 lens needs to be stopped down to f/8 for good performance. An f/2.8 lens may be excellent at f/2.8 and reach the "sweet spot" as early as f/4, depending on the individual lens design. As for why you would buy an f/2.8 lens... well, even if it doesn't perform at its best until f/4 or even f/8, the reason to buy it is because it is has f/2.8! The larger maximum aperture lets in more light. An aperture of f/2/8 enables you to capture an image with a shorter exposure time than f/4 or f/8. Which enables you to freeze movement or shoot handheld in situations a slower lens would not allow. It also allows for shallower depth of field than a lens of the same focal length with smaller max aperture.

 

[divided]

^^ To add to that isnt it generally true that lens with higher max aperatures also use better glass?

 

[sabbath999]

It may "generally" be true, but "generally" doesn't feed the bulldog.

I have a Sigma f/2.8 24-60 that isn't as sharp wide open at 55mm as either my 18-55 kit lens or my el-cheapo 55-200 VR.

Set them all at f/8 and it is a pick-em for sharpness, they are all about the same.

The vaunted Nikon 70-200 VR f/2.8 is not significantly sharper wide open at either 70mm or at 200mm than my 55-200mm VR... the big difference is that wide open, it is 2.8 as opposed to the 4-5.6 of the 55-200. At f/11, they are virtually identical in sharpness.

Obviously, the f/2.8 is vastly superior for shooting things like sports and other events where light is limited, there is absolutely no comparison in build quality, the VR on the 70-200 is MUCH better, it focuses more quickly and accurately, yadda yadda yadda... it also his better when it comes to things like CA, etc... but... for simple sharpness at f/11? There is virtually no difference.

Lets take it one step further... you really have to know what you are doing to shoot an f/2.8 wide open with group shots... You do get different (and much smaller) depth of field with fast glass wide open than you do with slow glass. When I first got my 70-200 (my first f/2.8 lens) I thought there was something wrong with it, because it wasn't very sharp... turns out it was operator error (not surprisingly, Nikon does actually check to make sure $1700 lenses can actually focus before they ship them out), I was taking picture of subjects where the depth of field was causing problems... Completely different shooting technique is required, and I am learning that. Shot CORRECTLY, focused CORRECTLY, the 70-200 is quite sharp wide open... but then again, so is my lowly little el-cheapo 55-200 VR.

 

[Sideburns]

f8!? then why get a lens thats f2.8?

Because when it's dark, you can't use f8



Just an aside.
In overcast weather, you shouldn't need to use flash, unless it's rain clouds and about to pour...
overcast is like a photographers favourite type of weather...

 

[sabbath999]

Because when it's dark, you can't use f8



Just an aside.
In overcast weather, you shouldn't need to use flash, unless it's rain clouds and about to pour...
overcast is like a photographers favourite type of weather...

Exactly... plus sometimes you want an extremely shallow depth of field.

 

[Sideburns]

Exactly... plus sometimes you want an extremely shallow depth of field.

ahh yes. that too. How silly of me..that's the biggest reason for a lot of photographers.

 

[Ls3D]

Informative post! Thanks everyone. :thumbup:

-Shea :mrgreen:

 

[bellavita64]

Understanding Exposure - Bryan Peterson. That is the book with the "who-cares aperture" and it is f/8 or f/11. Get the book and read it, as he explains why different apertures are important for different applications and different results. It is very easy to read and understand and was probably the most helpful book I have read on photography.

 

[dipstick]

f8!? then why get a lens thats f2.8?

Cause like others already said, a lens is normally at its sharpest 2-3 stops down from max aperture. So if you have a 2.8 lens it will have max sharpness at 5.6, while a lens that is 5.6 to begin with, will have max sharpness at 11. So the faster the lens, the better of course. But you can make perfectly fine images with a lens wide open as well. You would typically get less sharpness in the corners wide open, while center would normally perform ok.

A 2.8 would also give you a narrower depth of field, so thats why you would choose to shoot with it wide open, unless light conditions force you too. When a narrow depth of field is what you want, you can normally live with less sharpness in the corners, as it would probably be blurred anyway.

 

[Bevel Heaven]

Morning shot, complete cloud layer [no sun]. This is straight out of the camera only cropped the edges and reduced it smaller to show here.

Taken using my D80 and Nikkor 17-55 f2.8 lens, settings below;
f2.8, ISO100, 1/250 sec, exp comp -0.7, no flash, focal length 40mm

You really should see the high resolution original photo, the individual hairs stand out against the green bushes[which are only about 3 feet back], the light is soft and well, I could just be completely biased but I really love this shot. I printed it out rather large - it is at a framer - for a small gift to my wife - she hasn;t see this photo yet.

I think the original poster has focused on the bushes, there is a slight over exposure [maybe just from youir flash?]. I am a big fan of slightly under exposing to saturate colors a bit. I really like the composition on this photo, how you have your wife/kids sitting, they are all smiling and look like they are enjoying themselves etc etc etc.... Now it is time to figure out what went wrong with this photo, or, just use your other lens that you say does such a better job for you...... I would also just try it again next cloudy day and this time don't use a flash... or at least drop the flash value to maybe 1/3 just to add a bit of light to the party

 

[cherylmuhr]

that is a beautiful sooc image.

 

[confucious]

I am not so sure it is a problem with the lens or the focus. I have a feeling the shot would have been better had you ditched the flash. The light was enough for this portrait had you used a slightly longer exposure (which yes, may have necessitated a tri-pod or a lower aperture, in which case you lose the definition in the porch/plants).

I have a feeling the flash washed out your subjects while giving you perfect lighting for the plants behind (which came through quite nicely, by the way . In this case it is not so much a focus issue as an inability to see sharp and defined features because they are somewhat washed out.

When I look at the white in the two females shirts I see no detail and little colour...the little girls shirt has colour splotches all over and even what looks like a pink sash, and yet it is literally pale in comparison to the colour in the plants behind.

Take a look at the almost blinding glare of thier white shirts, and you'll see what I mean. The fact they are pale English stock like me, and you get a good bounce and little defining shadow from the flash.

Just my two cents - It could be a combo of a lot of things. Good luck!