Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Olympus dSLR

Reply
 
Thread Tools Search this Thread
Old Jan 14, 2009, 3:37 PM   #11
Senior Member
 
HarjTT's Avatar
 
Join Date: Aug 2004
Posts: 4,534
Default

Hi Mark

Thanks for your comments - all to the point and well put. With the new FF form Sony's A900, Canon's 5DMKII and Nikons D3x all at 20MP+ I think the marketing pressure for really high MP is going to remain across all sensor sizes. I was hoping that Nikon;s D3 @12MP and amazing IQ (its still a big beast of a cam and not for me) was a wonderfully bold move and that it would have slowed down or changed the race - IQ/DR/High ISo over MP but it looks as if that won't be the case.

Riley, my own thoughts are that they just might have designed the lenses for the max sensor size - although I think i do remember seeing the images of the 4/3 lenses on a Pentax body some time ago. You would have thought that they would have designed the lenses for the max. possible sensor size from the start and thus have the knowledge and foresight to be able to upgrade the sensor without any impact on lens quality or have to start a new format/mount.

Cheers

Harj

:? :O
HarjTT is offline   Reply With Quote
Old Jan 15, 2009, 1:45 PM   #12
Senior Member
 
Join Date: Aug 2006
Posts: 1,066
Default

HarjTT wrote:
Quote:
Riley, my own thoughts are that they just might have designed the lenses for the max sensor size - although I think i do remember seeing the images of the 4/3 lenses on a Pentax body some time ago. You would have thought that they would have designed the lenses for the max. possible sensor size from the start and thus have the knowledge and foresight to be able to upgrade the sensor without any impact on lens quality or have to start a new format/mount
the biggest problem would be with the UWA lenses, these would be lenses were you would expect the corners to be weak. But both the 7-14 and the 9-18, are aperture limited to F4. Since stopping down a lens will fix its ills, you can be pretty sure they would be ok.

Also since the lenses are near telecentric, the light path varies to around 6 degrees, not a terribly crucial angle, as opposed to RF lenses like those ultra wide Voigtlanders that reach angles of 60 degrees. So that isnt going to be a causal factor either.

That leaves the actual image circle, and there is some evidence for this too. Jay Turberville tested a number of lenses and found that the image circle on some is around 40mm.

http://forums.dpreview.com/forums/re...ssage=27090223

> 4/3 glass already has an image circle optimized for the sensor, so
> bringing the lens closer might cause some edge problems.

"The idea isn't to bring a 4/3's ZD lens closer. The idea is to design a new ZD/EVIL lens that would be closer. You'd use and extension tube of some kind to also so that you could mount regular 4/3's lenses if you wanted to."
>There is a
> bit of leeway for sensor shift IS, but not much.

"Actually, with the lenses I've looked at there is a ton of leeway. The ZD50, for instance has a nearly 40mm image circle.
Here's my little survey. The box is 40mm to a side. "

image and quote attributed to Jay Turberville


Rriley is offline   Reply With Quote
Old Feb 11, 2009, 5:56 PM   #13
Senior Member
 
Join Date: Jun 2004
Posts: 477
Default

Well, I suppose it depends how the cameras capture the image in LOWER resolution modes.

e.g.

Canon 50D is 15M pixel, but has a lower Res mode (medium) that captures 8M pixel.

So how does that work? Does it image at 15M pixel then downsize, or does it scan all of the sites, and arrive at composite values for each of the "8M" pixels.

For example, the 50D has a "small" mode, which is 3.7M pixel, and is pretty much half the resolution along each side. (2352 x 1568, versus 4752 x 3168 for the full 15M pixel) so that means that each "saved pixel"should actually be 4 pixels, reducing the pixel density from 45,180, down to around 12,000 !!!! This means the noise performance SHOULD be perhaps 4 times better at "small" or 3.7M pixel, than at 15M pixel.

So what I'm trying to say, is that provided the capture at lower resolutions uses all of the sites to produce"composite pixels", and not just down sizing 15M pixel, then any camera you buy in the future, just set it to a lower resolution for better noise performance!!!

I suppose we could actually test this ourselves: Shoot full resolution, then at the smallest resolution on the camera,in low light, then compare the noise.






dnas is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 8:33 AM.