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04/21/2006 04:16:18 PM · #26 |
Originally posted by kirbic:
Canon's yield on 24x36mm sensors was 10% as recently as a couple years ago; it's above 25% now, and will likely improve dramatically in the near future, |
There's no real justification for assuming that though.
Yield improvements come from maturing technology but also size shrinks/ new/ smaller process geometries and so on. E.g., typically any time we fab a chip, we'll make a 10% optical shrink on the same masks to get a speed/ yield improvement without needing a redesign/ new tape-out.
But for camera sensors, the physical size is fixed by the need to cover the image area so the traditional scaling efficienies don't come in to play. There is a certainly amount of maturation of the fab process that can improve the yield and I'm sure they are working on it, but the fundamental relationship is that yield is proportional to area and that doesn't change. |
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04/22/2006 01:44:42 AM · #27 |
So can you polish older hazzy foggy looking glass? any sites or anything i can read about this?
I have an older converter that looks kinda smokey. Ive cleaned it with rubbing alcohol and it doesnt seem to clear up.
Its just a cheap lens i got for almost nothing so its just a learning tool more then anything. I want to try to see if it can be done, i dont care if it get ruined its no good anyway. |
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04/22/2006 11:11:42 PM · #28 |
Originally posted by Bear_Music:
Originally posted by hankk:
What I wonder is why aren't DSLR sensors a 36mm x 36mm square? That way, you can use your existing lenses, and you could crop horizontal, vertical or a larger square image. (Of course, you'd need some new hoods.) |
Speaking in terms of full-frame sensors like the 5D has, if you wanted a square image you'd have to decrease the long dimension. Draw a circle and place in it a rectangle that's both centered and tangent on all 4 corners; the longer you make the long dimension, the shorter you must make the short dimension for the whole to remainw ithin the image circle. At the extreme, the longest dimension you could fit in would be equal to the diameter of the circle, but the other dimension would have to be "0" if the whole were not to vignette.
Of course, you could theoretically float a square APS-C size sensor within the image circle of a full-frame lens...
R. |
Well, the square APS-C sensor is interesting. The problem would be that the EF-S lenses may vignette, but the EF wouldn't. This may cause an incredible support burden for Canon :-) -- I think the 5D has a focusing screen with a square frame, which (sort of) gives you the APS-C sized square within the image circle (but then you have to crop later).
But I was thinking FF.
I was thinking of croping in post-processing. When I shot sports, sometimes I didn't have time to rotate the camera. And when I cropped, I usually arbitrarilly cropped around the action, not a 4x6 or 5x4 area. (that is, sometimes I'd get a square photo, sometimes a long, thin one, sometimes a thin, tall one.)
Sometimes, you want a little more height (or width on vertical shots) and don't mind a little vignetting. This sometimes happens when you're cropping to 5x7 or 8x10.
Some people like vignetting--you may be able to use it as an effect.
And thinking out of the box, there's no reason a photo has to be rectangular or square. Some framed photographs have oval or round holes in the mats. Other shapes are used--octagons, triangles, etc. Even complex shapes made up of the others can be occasionally used.
Until the price of sensors comes down, I don't think we'll see a 36mm x 36 mm sensor. On the other hand, the 3:2 ratio we use is a relic of film; 4:5 reflects monitor standards. And we commonly crop to 5x7 and 8x10. 35mm sensors are approaching the quality of Medium Format, which (I think) has a different ratio also.
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04/22/2006 11:18:16 PM · #29 |
| Another thought on sensor cost--Canon's pricing has been coming down. They have to do something to bring it back up! :-) |
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04/28/2006 11:27:32 PM · #30 |
| Everyone is hung up on the E18 errors and the CCD problems. People are scared to buy canons now? maybe? |
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04/28/2006 11:48:16 PM · #31 |
Originally posted by kirbic:
No, 1 is not as large as they can go. Thef-stop is a ratio. It's the focal length divided by the aperture size, so if the aperture is bigger than the focal length, the result can be less than one. It cannot, however, be negative.
There have been lenses as fast as f/0.95, and Canon used to produce a 50/1.0L, but the DoF is incredibly thin for these uber-fast lenses and the optical performance leaves something to be desired. Don't look for sub-f/1.0 lenses to appear with any regularity in the future. |
Right on, Kirbic. I own an f/0.95 lens that I use with a video camera, and an f/0.80 that is the catadioptric lens for my night vision scope. Both exhibit spherical abberration at the periphery of the image plane, but they are fast! |
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04/29/2006 12:03:58 AM · #32 |
Originally posted by kenskid:
You can't have square lenses. If you did have square lenses and you dropped your camera bag, no one could laugh at you as you chased all of your rolling lenses into the street :-)
Originally posted by BowerR64:
Can the appature be larger then the sensor? or is it already?
Why cant you have a square lense? or why isnt the sensor round?
Sorry if these are dumb, just thing ive always wondered. Why lenses are round but the pictures are developed square. |
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Square lenses have been used for most of a century in the viewfinders of older cameras, usually a negative meniscus. But these are actually truncations of round lenses and their figure is still spherical. |
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