View Full Version : Optical bottleneck?
01-05-2009, 08:46 AM
Let me start off by say that I am in no way an expert.
I almost fell off my chair when I re(a)d about that monstro 28k sensor. But after I put a bag of ice on my head, I started to see thing a bit more clearly.
I occasionally read photo magazines. In one there was a test of a high end canon SLR (1Ds mark III) which have a 21 megapixel sensor. In the review the editor pointed out that to gain full adavantage of the pixelcount, one must have a lens with very good(!) optics.
So, when I read about the monstro 28k, I started to ask myself; Is there lenses, on this side of NASAs telescopes, that can match that sensor???
Even the 9K sensor seem like overkill in terms of pixels if it is the optics that is the bottleneck!?
Please enlight me!
01-05-2009, 08:53 AM
If the sensor had stayed the same size, then yes, you'd have an optical issue. But the sensor is much, much bigger, and hence when used with lenses designed for large format photography, you will get a benefit from the large resolution.
01-05-2009, 09:16 AM
Bear with me for a follow up question...
But does it really matter of you scale up the sensor. I mean, the optical flaws from the lens is still there and should reasonably affect even more pixels due to the higher pixel count. I.e same same but different. Am I totally lost now?!
Is there a theoretical maximum resolution for lenses that are produced with techniques that are known today?!
But when I say "flaw" I mean foucs issues too. It there really lenses that can utilize a 28K sensor from the center to the edges without losing details?
01-05-2009, 09:23 AM
It's all about line pairs per mm resolution. If you increase the number of mm on the sensor, you can fit in more lines, hence higher resolution. It's the size of the pixels that matter, not so much how many you have...
01-05-2009, 09:41 AM
I know I am stubborn... :)
Yes, I understand that, and I can very well understand that bigger sensors means better pictures in terms of light gathering and S/N.
But. In terms of details for instance, is it even theoretical possible to gain full advantage of a +100MP resolution sensor due to the fact that the lenses are not 100,00% perfect or have 100% perfect foucs?! Or is it just a matter of sizing up the sensor?!
(I think I already know what the answer will be :) )
Thanks for your patience!
01-05-2009, 09:44 AM
Sure, there's a limit to the resolving power of lenses. But if you use bigger pixels, (or avoid using too small pixels) you move that limit.
David Mullen ASC
01-05-2009, 09:46 AM
Actually when the sensor gets large enough, the lens itself can be less good -- it's when you have a tiny sensor that the lens has to be of higher optical quality. I know that sounds backwards, but when you have a really large sensor or film format, then capturing small / fine detail is relatively easy even with a lens of moderate or mediocre resolution, partially because you'll be enlarging the image less than you would with a tiny format.
Graeme can explain in it more mathematical terms like MTF, etc.
Maybe it would easier to imagine if you think in really big terms, like a lens projecting an image onto a wall-sized sensor where the photosites are bricks in the wall. It's easier -- the lens has to work less hard -- to fit fine detail into a larger wall with more bricks than a smaller wall with tinier bricks, when both images will end up being the same size when viewed later.
Or to think of it another way, your lens can resolve fewer lines per millimeter IF detail is going to get more lines and more millimeters assigned to it in the first place.
I'm probably not explaining this accurately though...
01-05-2009, 09:47 AM
I think I should leave more detailed explanations up to lens gurus....
But the simple answer is that large format photography "wouldn't work" if the lenses were not up to it :-)
01-05-2009, 10:06 AM
You are both right.
I found some good explations here (maybe I should have googled before I asked my very intelligent questions ;) ):
01-09-2009, 08:34 AM
The bigger the format the bigger the circel of diffusion can be.
when you take a picture with an 8 by 10" camera you will always have more detail even with an old lens.
that is why Cooke put on the market an old design tripel convertible lens an few years ago. The same type that was used by the great American landscape photgrapher Ansel Adams.