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Old Oct 21, 2006, 4:43 PM   #1
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Just spotted this little lens on the 4-thirds site - another prime, 24mm f1.8 from Sigma.

http://www.four-thirds.org/en/produc...le.html#pana25

Its a big bit if glass - 77mm filters and weighs in at 500+ grams.

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Old Oct 22, 2006, 8:58 AM   #2
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Looks like it sells for about $300. Should be about the same in four-thirds. But I still wish they'd release the 28mm f1.8 for under $250.


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Old Oct 22, 2006, 10:22 AM   #3
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Whats really suprised me is the size and weight of the fast primes - I had always been under the assumption that prime lenses esp within the 50mm focal range were small and leight weight but looking at the Sigma 30mm, 24 f1.8 and the PanaLeica 25mm f1.4 this doesn't appear to be the case. The 24mm f1.8 is priced at £299.99 on sigma's site so it could be a wee bit cheaper on the street and according to the sigma UK site its a macro lens.

http://www.sigma-imaging-uk.com/lenses/wide/24mm.htm

Sigma 30mm f1.4 $429.90
Sigma 24mm f1.8 £299.99
PanaLeica 25mm f1.4 TBC


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Old Oct 22, 2006, 11:05 AM   #4
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HarjTT wrote:
Quote:
Whats really suprised me is the size and weight of the fast primes - I had always been under the assumption that prime lenses esp within the 50mm focal range were small and leight weight but looking at the Sigma 30mm, 24 f1.8 and the PanaLeica 25mm f1.4 this doesn't appear to be the case. The 24mm f1.8 is priced at £299.99 on sigma's site so it could be a wee bit cheaper on the street and according to the sigma UK site its a macro lens.

http://www.sigma-imaging-uk.com/lenses/wide/24mm.htm

Sigma 30mm f1.4 $429.90
Sigma 24mm f1.8 £299.99
PanaLeica 25mm f1.4 TBC


Cheers

HarjTT

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In the case of these Sigma primelenses, you need tothink about what they were originally designed for. These are not "digital" lenses. They pre-date digital- they are made to create an image circle big enough to cover a 35mm piece of film. If they had been originally made to cover the APS-C sensor everyone else seems to use todaythey would be smaller. Typical consumer "normal"50mm f1.4 SLR lenses don't have to be huge. a 50mm f1.4 Nikkor is fairly small, but the Canon 50mm f1.4 is fairly large...part of the difference in sizeis Canon puts the AF motor in their lens, in the case of the 50mm f.14 Nikkor. Nikon does not. The wider and faster you go the optics get progressivly bigger to cover the angle of view and the fast apertures. A 24mm lens is wide in 35mm film terms, andanything f2 or faster are allfast lensesand have to have wider openings than a lens such as a24mm f2.8 lens, so I am not surprised the Sigma 24mm f1.8is fairly big.

Look at the Canon 28-135 zoom, made for 35mm SLR's and compare it to their 17-85 EF-S lens that covers the same equivalent focal lengths, but is made to cover only the APS-C sensor. The difference is size is substantial. If makers made "digital only" primes they could be just as substantially smaller, but that is not where the money is today. I doubt seriously we'll ever see very many new "digital only" primes from makers who's main/largest set ofcustomers are the Nikon andCanon usersof the world, and that includes Sigma.

Manufacturing methods also play a role. Have you ever seen the lenses Zeiss (in this case, the REAL Zeiss) made for the Contarex 35mm SLR of the 1960's and early 70's? They are huge compared to equivalent primelenses made today for 35mm SLR's. This to a degree explains the Panasonic "Leica" lenses. They are using higher grade materials and standards to produce those than the mass produced Canon and Nikon-type primes.

Fast primelenses designed for the 35mmSLR's will always be physically bigger because of the aboveAND the fact they have to be designed to allow for the rear element to clear the mirror (retrofocus deisgn)when it swings up and exposes the film/now sensor. That latter reason is why Leica rangefinderlenses can be made so muchphysicallysmaller than their equivalent R-series SLR lenses, but the fast M lenses are still pretty hefty because of the bigger glass needed for f2 or f1.4 apertures. In many cases M lenses go so far back into the body they just barely miss the shutter curtain.


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Old Oct 22, 2006, 11:31 AM   #5
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I think this may be an example where we see some extra benefit from using the 4/3 system.

Like Greg says, we are dealing with a lot of Sigma lenses that were designed to cover a larger sensor or film frame area.

Virtually all lenses experience some degree of performance loss at the outer areas of their coverage. Even the best OEM brands can demonstrate some softness and vignetting in the corners. I've read tales of some lenses inflicting several stops worth of vignetting in the corners of a Canon image. Aftermarket lenses are even more prone to such problems.

With the 4/3 system, we get the benefit of the central portion of the image coverage which is almost always optimized for the best quality. We have to worry less about the troublesome frame corners and image circle edges.

I'm hoping we may discover that Sigma lenses which give "mediocre" performance on Canons may prove to be good quality bargains on 4/3 cameras.
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