The (expensive) Carl Zeiss 16-80 for the Sony Alpha DSLRs is only good
from F5.6 onwards. With wider apertures at wide angle the corners become
soft to very soft, depending on aperture and distance from the image
centre. According to photozone the same holds for several other DLSR
zooms (the Sigma 17-70 being an example).
However the lens of the Sony R1 is good wide open at F2.8, even in the
corners. Could this be because in the R1 the lens is very close to the
sensor (just 2mm distance vs. 2cm in an APS-C DSLR)?
Also the Zuiko 14-54 is good wide open, which could be a consequence of
the 4/3 design.
--
In message news:MPG.22e7406e37be776c98bd63@news.supernews.com , Alfred Molon
<alfred_molon@yahoo.com> done wrote:
> However the lens of the Sony R1 is good wide open at F2.8, even in the
> corners. Could this be because in the R1 the lens is very close to the
> sensor (just 2mm distance vs. 2cm in an APS-C DSLR)?
"That80sGuy" <clark@griswold.com> wrote:
> In message news:MPG.22e7406e37be776c98bd63@news.supernews.com , Alfred
> Molon
> <alfred_molon@yahoo.com> done wrote:
>
>> However the lens of the Sony R1 is good wide open at F2.8, even in the
>> corners. Could this be because in the R1 the lens is very close to the
>> sensor (just 2mm distance vs. 2cm in an APS-C DSLR)?
>
> Yeah, the light gets lost trying to travel 2cm.
Finally we've got someone here who understands quantum mechanics!
Somewhat seriously, is the above really true? That is, has anyone actually
compared the R1 at f/2.8 at 24mm equiv. with the Canon 24-70/2.8 at 24mm (or
24/2.8) on a 5D? (Also note that for the same DOF and the same shot noise,
you'd shoot the 5D at f/4.0, not f/2.8 (assuming the same ISO and shutter
speed settings), so the comparison with both at f/2.8 is bogus on two
counts.)
Alfred Molon <alfred_molon@yahoo.com> wrote in
news:MPG.22e7406e37be776c98bd63@news.supernews.com :
> The (expensive) Carl Zeiss 16-80 for the Sony Alpha DSLRs is only good
> from F5.6 onwards. With wider apertures at wide angle the corners become
> soft to very soft, depending on aperture and distance from the image
> centre. According to photozone the same holds for several other DLSR
> zooms (the Sigma 17-70 being an example).
>
> However the lens of the Sony R1 is good wide open at F2.8, even in the
> corners. Could this be because in the R1 the lens is very close to the
> sensor (just 2mm distance vs. 2cm in an APS-C DSLR)?
>
> Also the Zuiko 14-54 is good wide open, which could be a consequence of
> the 4/3 design.
All the books on photography I have ever read say you should not use any
lense at its largest aperature setting or smallest due to light difraction.
In article <8cgfk.74718$kx.60067@pd7urf3no>, Dauphin de Viennois says...
> All the books on photography I have ever read say you should not use any
> lense at its largest aperature setting or smallest due to light difraction.
Diffraction only occurs at small apertures and there are lenses which
perform well even wide open.
--
"Alfred Molon" <alfred_molon@yahoo.com> wrote:
> In article <8cgfk.74718$kx.60067@pd7urf3no>, Dauphin de Viennois says...
>
>> All the books on photography I have ever read say you should not use any
>> lense at its largest aperature setting or smallest due to light
>> difraction.
>
> Diffraction only occurs at small apertures
Right.
> and there are lenses which perform well even wide open.
But they tend to be slow primes, not fast 5x zooms.
> "Alfred Molon" <alfred_molon@yahoo.com> wrote:
>> In article <8cgfk.74718$kx.60067@pd7urf3no>, Dauphin de Viennois says...
>>
>>> All the books on photography I have ever read say you should not use any
>>> lense at its largest aperature setting or smallest due to light
>>> difraction.
>>
>> Diffraction only occurs at small apertures
> Right.
>> and there are lenses which perform well even wide open.
> But they tend to be slow primes, not fast 5x zooms.
There are two different approaches to designing a zoom. The first
approach is to design it to a minimum standard of performance
throughout the zoom range. The second approach is to design it to a
maximum performance standard at an important part of its range, and
simply do the best you can, without disturbing the best performance, at
more distant focal lengths than the best one.
I get the impression that some of the latest best quality zooms have
adopted the latter approach, so that what you get is reasonably good
performance for a zoom at the extremes, allied with a part of the zoom
range which approaches the quality of a prime. Of course in a lens
with more glass elements (as zooms typically have) it will be very
hard to avoid a concomitant drop in contrast.
On Jul 15, 6:18 pm, Alfred Molon <alfred_mo...@yahoo.com> wrote:
> The (expensive) Carl Zeiss 16-80 for the Sony Alpha DSLRs is only good
> from F5.6 onwards. With wider apertures at wide angle the corners become
> soft to very soft, depending on aperture and distance from the image
> centre. According to photozone the same holds for several other DLSR
> zooms (the Sigma 17-70 being an example).
>
> However the lens of the Sony R1 is good wide open at F2.8, even in the
> corners. Could this be because in the R1 the lens is very close to the
> sensor (just 2mm distance vs. 2cm in an APS-C DSLR)?
>
> Also the Zuiko 14-54 is good wide open, which could be a consequence of
> the 4/3 design.
> --
>
> Alfred Molon
> ------------------------------
> Olympus 50X0, 8080, E3X0, E4X0, E5X0 and E3 forum athttp://tech.groups.yahoo.com/group/MyOlympus/http://myolympus.org/photo sharing site
I'd send the lens back or at least in for calibration, there is
manufacturing slop in making lenses, the expensive ones can be
recalibrated the cheap ones tossed or at least replaced by your
vendor. It is quite possible you received a very good sample of your
Olympus lens and a poor sample of the Zeiss. Sample variation has gone
on for years, only a few companies test every lens, Leitz and
Hassleblad for roll film and Schneider and Rodenstock for large
format. You pay for that service. This has been going on for years, in
the 70's my photo profs used to say buy 3 copies of a lens and return
the the 2 lesser performers. Fine advice when a good WA lens cost $200
not so much with today's expensive zooms. Try to return the lens or
get it recalibrated. Everyone who said the widest aperture of the lens
is one of its worst testing performance points is right too. But we
often buy fast lenses for manual focusing and or bokeh, it is a trade
off.
In article <6e62fdF5gmv8U1@mid.individual.net>,
Chris Malcolm <cam@holyrood.ed.ac.uk> wrote:
> There are two different approaches to designing a zoom. The first
> approach is to design it to a minimum standard of performance
> throughout the zoom range. The second approach is to design it to a
> maximum performance standard at an important part of its range, and
> simply do the best you can, without disturbing the best performance, at
> more distant focal lengths than the best one.
This is true of designing anything, not just lenses.
A device has some operating envelope. It will perform better in some parts
of the envelope than in others. If I limit the allowable range of
operation to just the part of the envelope where it works best, I get a
device which is limited in functionality, but performs great over that
limited range. If I allow it to be used over a larger range, I still have
the good performance in the middle, but now you can complain, "But, it
sucks near the edge!"
So, which is the better design philosophy? Well, neither, really. They're
just different.
Why do we even have variable aperture, variable focus lenses at all? For
any given image, I'm only using one setting. Let's say I take a picture
with a fixed focal length lens (f = 85mm), focusing at 15.5 feet, and an
aperture of f/8. The fact that the lens is capable of focusing closer or
further away, or adjusting the aperture larger or smaller may make the lens
useful in other situations, but for that specific image, it's all just a
waste. If I told a lens designer to design me a fixed-everything lens for
just that exact combination of settings, he or she could probably come up
with a lens that produced a better image. The only problem is it would be
such a specialized lens, nobody would buy it.
DSLR lenses not good wide open at wide angle? 
Linear Mode
