4/3rds and movement

[Riley]

well heres the thing, i use wides all the time so its not like i dont have an interest in UWA IQ, its how i make my living. The wider the lens the more acute the problem, but we are, as you point out, speaking of linear dimensions that are quite small.

From the Kodak E1 sensor, which is nearly 20x15 anyway,

whether we use it all or not, to 20x15 is an image circle increase of just 2.5mm on the image size of the old sensor, a radius out of 1.25mm. Jay Turberville tested several lenses and found them to exceed 40mm.

http://forums.dpreview.com/forums/read.asp?forum=1000&message=27090223

so ok, lets get away from vignetting and look at soft edges, assuming that this would be an issue, even without the best of microlenses, there are a number of ways to defeat it. either stop down, or limit the WA.

If you look at the patent information, the image circle specification has a range between 21.2 (less than what we use now) and 25mm. What I am suggesting is actually within the specification, and isnt so darned far from the full size of the Kodak sensor.

http://patft.uspto.gov/netacgi/nph-...50&s1=6910814.PN.&OS=PN/6910814&RS=PN/6910814

 

[jonoslack]

so ok, lets get away from vignetting and look at soft edges, assuming that this would be an issue, even without the best of microlenses, there are a number of ways to defeat it. either stop down, or limit the WA.

this is the crunch - as I say, I do lots of landscape work with thin slivers of land at the bottom - if the corners and edges aren't sharp then it doesn't work.

So I notice.

Most lenses for APSC or Full frame (with one or two noticeable exceptions like the new Nikon 14-24) are not cured by stopping down . . and they aren't cured by zooming out either.

The Olympus 7-14 just makes it at 7mm - it's much better at 8.

But even if stopping down DID work (which it mostly doesn't) then that destroys the whole joy of the mid range olympus lenses, which is that you can shoot them wide open or stopped down at any focal length WITHOUT HAVING TO THINK ABOUT IT.

It simply isn't true of any APSc wide angle lenses that I've tried - and boy I have tried a lot.

but it begs the question - you're assuming that sales hinge on a stop or so of High ISO noise, and I simply don't believe it.

 

[Riley]

on 1.73x the 7mm is 12mm EFL, at 8mm zoomed, its back to 14mm EFL
so you reflash the firmware and have a stop in the body to limit the zoom. You lost nothing. BTW there is some softness and distortion wide open, even in the more heralded 11-22, which doesnt really get sharp until F4.5.

as to marketing
"but it begs the question - you're assuming that sales hinge on a stop or so of High ISO noise, and I simply don't believe it."

once again, there is more to it than that. We are on the threshhold now with high Mp at 10.1Mp that compares to 50D in pixel density. Both have noise at base iso that isnt there in the 40D examples. When you speak about marketing a camera based on Mp (which i recognise is very true) we are on the limits of todays technology now, and we have less Mp by 50%.

Perhaps like you i would prefer bigger wells on a 6Mp sensor, which on 20x15 the wells are the same size as 5D, but they wont ever be going back to that. We cannot offer the same Mp as APSC on a smaller sensor based on the same technology, it will always be a worse position.

Bigger pixels give more DR, less noise, and we get a larger OVF to boot
i better leave it at that, im hogging the thread a bit

 

[jonoslack]

the triumph of numbers over pragmatism!
I agree to disagree, at least it's been civilized.

All the best

 

[asabet]

The strength with Four Thirds lenses is also their weakness. Because of 1) 4:3 aspect ratio, 2) Telecentric lens design, and 3) Large mount compared to sensor, we get the following attributes of the Four Thirds system: A) Excellent edge/corner sharpness, even in budget lenses; B) Low light falloff, even in fast lenses; and C) Larger and heavier lenses than we'd have if willing to give up on wide open corner/edge performance and light falloff.

Since one of the major advantages of the Four Thirds system is size and weight, introducing a lens design requirement that adds significantly to size and weight is a major issue. I'm not saying they did the wrong thing, because the size/weight advantage is preserved (especially vs 35mm full frame) and the quality is very high, even with the kit lenses. However, I think they would have been better off offering more lenses that failed to meet these requirements. For example, the 25mm pancake seems to fail on telecentricity, but it fills a valuable spot in the lineup. Not every lens needs to have sharp corners and insignificant light falloff wide open.

With m43, they are putting tons of emphasis on compact size. I hope they fully exploit this advantage, even if it means having some lenses that make similar compromises to those of the ZD 25/2.8.

 

[jonoslack]

The strength with Four Thirds lenses is also their weakness. Because of 1) 4:3 aspect ratio, 2) Telecentric lens design, and 3) Large mount compared to sensor, we get the following attributes of the Four Thirds system: A) Excellent edge/corner sharpness, even in budget lenses; B) Low light falloff, even in fast lenses; and C) Larger and heavier lenses than we'd have if willing to give up on wide open corner/edge performance and light falloff.

Since one of the major advantages of the Four Thirds system is size and weight, introducing a lens design requirement that adds significantly to size and weight is a major issue. I'm not saying they did the wrong thing, because the size/weight advantage is preserved (especially vs 35mm full frame) and the quality is very high, even with the kit lenses. However, I think they would have been better off offering more lenses that failed to meet these requirements. For example, the 25mm pancake seems to fail on telecentricity, but it fills a valuable spot in the lineup. Not every lens needs to have sharp corners and insignificant light falloff wide open.

HI Amin
Perhaps you're right - but they have managed some very small lenses (the 14-42 springs to mind). I think one of the beauties is that you can use pretty much any lens without considering. Of course, a 50mm pancake is hardly likely to be used for corner to corner sharpness . . . its not bad though.