My replies in "+++++" below, JCO -----Original Message----- From: Godfrey DiGiorgi [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 22, 2005 1:54 PM To: [email protected] Subject: RE: Manual Focus Pentax Glass on istD
--- "J. C. O'Connell" <[EMAIL PROTECTED]> wrote: > well of course a FF sensor is going to be more sesitive > to lens designs, you are using the whole lens image instead of less > than half of it with APS, That's not really the issue at all. With a FF sensor in an existing lens mount, the corners and edges are farther from the optical axis of the lens which can cause more aberrations, both from CA in the len itself and from the effects of diffraction around the pixel well lens' edges. The telltale signs of this are mosaicing and greatly reduced resolution at corners and edges, along with higher levels of CA and greater than normal corner-edge light falloff. +++++++++++++++++++++++++++++++++++ your above assumptions are based on what I would call mediocre lenses, I was posting in reference to using FF with good qualiy, but not state of the art, extremely exensive lenses like Pentax A* or whatever. +++++++++++++++++++++++++++++++++++ > ... BUT with FF there is more > than twice the detail in the image with the same uniform lens That all depends on the density of pixels on the chip, and has nothing to do with the size of the format. +++++++++++++++++++++++++++++++++++ the image comes from the lens and the amount of detail you get in the lens image DOES depend on the format recording it. Generally larger formats means more details assuming same lp/mm in the lenses. +++++++++++++++++++++++++++++++++++= > vs APS and wides on FF are something APS cant even do! For a larger format chip, of course the same focal length has a larger field of view. This is nothing new to hear. If a larger format sensor has the same pixel density as the current 16x24mm sensor, it will provide the same detailing on a wider field of view with the same focal length lens, with more pixels due to its larger size, PRESUMING that the quality of the lens-sensor optical system is such that corner/edge resolution doesn't fall apart. > ... APS exists because of much lower > costs than FF, not because its technically better. 16x24mm format chips exist because of a practical tradeoff: a combination of being able to get the best results from an existing set of lenses with existing lens mounts and camera chassis as well as the much lower cost of manufacture of the smaller chips. +++++++++++++++++++++++++++++++++ I don't agree. using typical pentax quality lenses, ( not A* or whatever), a full frame 6Mp sensor would yield higher quality results than the current scheme of using APS sensor and shorter lenses with their image cropped and essentially magnified. The sole reason for the scheme is COST SAVINGS in the camera sensor, a FF sensor is just way too expensive for now. +++++++++++++++++++++++++++++++++ A larger sensor format *should* have a larger lens mount *and* recomputed optical designs to maximize telecenticity to the edges and corners of the chip in order to obtain maximum quality. (This fact, BTW, is why the FourThirds cameras from Oly are not that much smaller then the 16x24mm cameras from everyone else even though the format and mount are new.) All the camera manufacturers know this, but they're burdened, as the users are, with a lot of existing lenses in their existing mounts. The cost of the proper redesign of lens mount, bodies and lens lines is astronomical, even in comparison to the cost of the current, somewhat compromised 24x36mm sensor bodies. ++++++++++++++++++++++++++++++++ No one is saying a 24x36mm digital sensor is perfectly optimized for use with good quality 24x36 film camera lenses but it is certainly better optimized than using APS sensors with good quality 24x36 film camera lenses! JCO ++++++++++++++++++++++++++++++++++++++++++++++++ __________________________________ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail
