The science of light: is there a 'perfect' lens length

[ricktas]

Thinking about all the posts on the site about 'which lens' and the replies, got me to wondering if the science of light and how it interacts with lens elements etc, if there is a specific lens length that generally produces sharper results, not withstanding any differences in lens design/element composition etc.

We know that some lenses are generally sharper than others, often because the manufacturers have gone a long way to produce a brilliant lens, using technology. But I was wondering if just due the nature of light, if a specific lens length was more suited to being sharper etc, just cause of the way light works.

I am not after a discussion about brands here. I don't want to know that your Nikon this or your Pentax that is the sharpest straight out of camera. I want to know which of your lenses is sharpest, without the brand discussion. We may just find a trend (though we may not).

For me, my 24-70 is the sharpest.

[ZedEx]

That's a tough call. At present, all of my lenses out resolve the 12.8mp sensor on my 5D. Will be interesting to see how they fare when I get the 21mp version sometime next year. Once you start getting epic amounts of pixels, however, I'd hazard a guess that high end 50mm and 85mm primes, stopped down to f8 would probably offer the sharpest optics. They really have come a long way with zoom lens designs over the last 30 years and are now capable of making some that are just as sharp on the the dSLR bodies we currenty have available, as are primes.

[ricktas]

That's a tough call. At present, all of my lenses out resolve the 12.8mp sensor on my 5D. Will be interesting to see how they fare when I get the 21mp version sometime next year. Once you start getting epic amounts of pixels, however, I'd hazard a guess that high end 50mm and 85mm primes, stopped down to f8 would probably offer the sharpest optics. They really have come a long way with zoom lens designs over the last 30 years and are now capable of making some that are just as sharp on the the dSLR bodies we currenty have available, as are primes.

That was not the question. Which of YOUR lenses is the sharpest straight out of camera, now! All I want is a simple : my xxx is my sharpest lens.

[LJG]

Sharpest. OK, don't laugh. My sharpest SOOC believe it or not is my Canon 55-250 kit lens. I must have got lucky and got a really really good one, because it delivers consistently sharp images. It does not matter if it is my 450D or my 50D. I would probably never sell it, no matter what other lenses I have. I wish all my lenses were as good, but sadly I can say they aren't.

[milesy]

definately my Pentax 50-135 F2.8 lens

[Tannin]

It is easiest to make a mid-length prime lens - normal to moderate telephoto - so ZedEx is right on the money when he talks about his high quality 50 and 85mm primes.

Simply, it is a lot easier to make a really sharp 85mm prime than it is to make an equally sharp 10-24mm zoom. In fact, if your 85ish mm prime is even half competent, the 10-24 won't be able to go close to it no matter how hard the manufacturer tries.

So, by rights, the sharpest lenses out to be all in (roughly) the 50-150mm focal length range. (I'm assuming here that we are talking about 35mm format - different rules if you are talking medium format, of course.)

But in practice, the manufacturers tend to try very hard with the longer lenses too. So a 600/4 or a top-notch 70-200/4 will go pretty close in overall sharpness to a first class 85/1.2 or 135/2.

Nevertheless, actual measurements (I'm not going to hunt up links for this, google will soon find some) show that the theory is correct: the top-quality mild telephoto primes are the sharpest lenses made.

PS: Now Rick is going to be grumpy because I didn't answer the way he wanted us to. Rick wants to see us all cite a single lens ..... hmmm .... not sure that that is a valid or useful way of doing this, but why not? I guess either my 60mm macro or the 500/4.

[William]

OK, On my 30D It has to be the 24-105 , Just to see if we get a trend going

[jjphoto]

Almost all 50's are sharp. But sharpness is not everything.

Anything in the 28-200mm range seems easy enough for lens designers to work with. Outside that range, especially wider than say 28-35mm, and lenses have more issues. The speed of a lens is a huge factor. A slow lens is easy to make/design compared to a fast lens. Any 35/2.8 will be sharp but a 35/1.4 is another story altogether.

Virtually any 135mm lens is sharp, and cheap. That's probably the sweet spot for cost/quality, aside from the 50mm lenses.

The sharpest lenses I've EVER used are the Leica M 28/2.8 ASPH and Leica R 28/2.8 V2. Really amazing stuff, but an old Contax 28/2.8 or Olympus 28/2.8 is not really that far off either, and only 1/10th-1/20th of the price too!

JJ

[wmphoto]

50mm at the moment.

[kiwi]

My 400mm F/2.8 VR Magic Baby

[unistudent1962]

My 70-200 f4L IS.

The sharpest I have EVER used, but not been fortunate (or rich) enough to own: - a Canon 200mm f2L IS USM a news photographer was generous enough to let me have a play with one day!!!

[JM Tran]

100 F2 and 135 F2 for me

just edging out the 70-200 F4 IS - which does beat a lot of other primes for pure sharpness

[Jules]

The sharpest lens I've owned so far was my 60mm f2.8 macro. That little baby was dangerously sharp.

[Rattus79]

OK, I'll bite.

my m42 screw mount 100mm f/2 prime is so sharp you could cut yourself on it.

Suprisingly my 28mm /f2.8 Super Tak is also suprisingly sharp. (and renders beautiful bokeh)

[swifty]

My 14-24mm is pretty darn sharp but so is my 50mm and 85mm. Havn't really made measurements.
I'd think the less gymnastics the lens has to bend the light, the sharper it would be. Or am I thinking of distortions, CA etc.??
A 50mm 1.8 is a pretty simple design but then again the 14-24mm is the opposite and yet they're both damn sharp so maybe the correlation isn't that simple.
Anyways.. you closet optical physicists out there... speak up and enlighten us

[Kym]

Pentax 50/1.7 and then the Tamron 28-75/2.8; but the Sigma 50-500 is very good at the long end; given the super zoom range of it I'm very happy.

Sharpest at what aperture? I'm assuming f/8

[etherial]

The 70-200 F4L was the sharpest I have had, that lens was amazing. Wish I hadn't sold it.

[farmer_rob]

...
Sharpest at what aperture? I'm assuming f/8

No, that would be cheating - you'd be using the aperture to increase the sharpness, not the glass. (smiley not withstanding!)

my 35mm f1.8 I think gives me my sharpest photos - and much wider than f8 .

[ZedEx]

That was not the question. Which of YOUR lenses is the sharpest straight out of camera, now! All I want is a simple : my xxx is my sharpest lens.

As I said, ALL of lenses are my sharpest lenses, SOOC, on my 5D. Neither one outresolves any other. Though I will give the edge to the 50mm f1.4

[Mat]

My 18 - 125mm