Why Four Thirds is better - Lets continue here

[Joseph S Wisniewski]

The only inherent advantage the Four Thirds system has is size.
Because
of the smaller sensor size, the lenses can be made smaller as can
the camera
bodies. Smaller sensor size can also result in reduced power draw
so smaller
capacity batteries could be used.

Except that smaller sensors don't have "reduced power draw". Given equal sensor technology, power consumption is proportional only to megapixel count.

You can compare sensors from 1/2.5 inch point and shoot to APS sized DSLRs, full frame DSLRs, and even those 36x48mm monsters in medium format digital backs, all CCDs draw 16-18mW/megapixel. (in fact, I made that comparison a few days ago, but the dpReview search is (surprise, surprise) down again).

The flip side to that is the smaller sensor size creates a
significant image
quality challenge vis-a-vis the larger APS and Full Frame sensors
used in other
DSLRs. So far, the Four Thirds system has not been able to equal
the high
ISO performance of the large sensors. It will also be interesting
to see how
Four Thirds sensors will do at increased densities such as 10MP or
12MP.

The noise problems will scale.

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Ciao! Joe

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[Zuikoholic]

Size of the lens is one factor, brightness is another. The could produce either smaller lenses, or lenses that are normal sized but also brighter. This would offset the great DOF characteristics of the 4/3 sensor somewhat - by having f/1 and f/0.75 lenses.

Will they do this? Perhaps one day, but lenses with normal apertures are expensive at present, so prices will need to drop a lot before we can afford to buy f/1 lenses from them.
--
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[Joseph S Wisniewski]

There was a Thread discussing Four Thirds.

The content showed, the header "Why FT is in..."
is not justified.

I just got an advertizing email from an amateur photography
supplier, which said "you can" - so I smell, the only reason
for much sold cameras of "that other brand" is heavy advertizing
for not so good cameras.

No, the other cameras really are good.

So lets continue the discussion here under "Why Four Thirds is
better" to balance the meaning of the header.

I think a more interesting discussion is what will be the impact of the offset microlens sensor on the future of digital photography.

I've been advocating offset microlenses for years. Now Kodak, Oly's original four thirds (tm) partner, is supplying such a sensor to Leica.

http://www.dpreview.com/news/0609/06091501kodakccdleicam8.asp

An offset microlens sensor negates the arguments about needing new "near telecentric" lenses for digital photography. So, if this spreads, and larger sensor cameras can actually have wide angle lenses that are more compact than those of equivalent coverage on the four thirds system, and the price on larger sensors continues to drop, is there really a reason for the four thirds system to continue?

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[Joseph S Wisniewski]

Size of the lens is one factor, brightness is another. The could
produce either smaller lenses, or lenses that are normal sized but
also brighter. This would offset the great DOF characteristics of
the 4/3 sensor somewhat - by having f/1 and f/0.75 lenses.

Will they do this? Perhaps one day, but lenses with normal
apertures are expensive at present, so prices will need to drop a
lot before we can afford to buy f/1 lenses from them.

They would be unusually heavy and complex lenses. Remember, to be "near telecentric", a lens requires a retrofocus design (normal lens, with a big "wide converter" in front of it) even for normals and short telephotos in the four thirds (tm) system.

The Sigma 30mm f1.4 is a good example of the side effect of this type of construction. An old fashioned double Gauss 50mm f1.4 (Nikon, Canon, Oly OM, Pentax, etc) is near symmetrical, so its exit pupil near its focal length. That makes it about as small, light, and simple as it can be. A Canon 50mm f1.4 with ultrasonic motor AF and stepper motor aperture is 290g, the Nikon and Sony without these mechanisms tip the scales at 220g.

The 30mm f1.4 is 430g, much heavier than even the Canon. The 30mm is also larger in diameter, longer, and requires larger filters. That's all a side effect of the near telecentric design. And the 30mm f1.4 only has a ratio of about 2.14 (exit pupil at 64mm, focal length 30mm). A 64mm exit pupil isn't quite enough to meet Oly's idea of 8 degree telecentricity, it would have to be about 85mm to do that.

Now, on a four thirds camera, that 30mm f1.4 is a mild telephoto (actually, a pretty horrid length, too short for most portrait work, too long for a normal). A real 25mm f1.4 normal would be even larger than the 30mm f1.4 Sigma, figure at least twice the weight of a conventional 50mm f1.4. If you extend that doubling of weight to a 50mm f1.0, well, the Canon 50mm f1.0 weighed in at about 700g, so figure 1.4kg (3 pounds) for a 25mm f1.0 in four thirds...

A 14mm f1.4 wide angle gets even more complicated, and I bet they couldn't do it in even twice the weight of the famed Nikon 28mm f1.4.

Now, by using a sensor that didn't require telecentricity, like that new offset microlens Kodak sensor on the front page of dpReview today, you really can have small, fast light lenses. A Voigtlander 40mm f1.4, for example, weighs in at 175g. It's such a cute little thing.

The second thing working against fast lenses is Oly's four thirds patent. Four thirds is the only major lens mount currently protected by patents (Nikon, Canon, Pentax, and Sony's Minolta mount) have all expired in the last few years. In the patent, Oly states that, because of angular sensitivity issues, lenses faster than f2.0 shouldn't be built, and indeed, they haven't launched anything faster than f2.0 themselves.

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[Louis_Dobson]

need differently offset microlens for each lens?

Wide angle size isn't the issue, it is big teles that break your back.

As I understand it, chip sizes are coming down (not sensors, juts microchips in general). This will make larger chips ever more specialised and expensive.

The main gripe about FT is noise. Doesn't bother me, but it is a genuine problem for some and some kind of totem to all sorts of people who know no better.

However, soon enough pixel counts will hit the resolution of affordable optics. Soon after that, noise will fall, on all systems, to negligable.

After THAT, FT may start to look too large a sensor size.
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[E1derful]

An f2.0 on a system that didn't need to be quite as telecentric
than Olympus.

Possibly...but I doubt it.

For example...let's take a Canon F2.8 lens and make it an F2 lens. What percentage of change in size and weight do you expect?

Also, one can assume that Canon would NEVER make an F2 zoom for the EF-S mount. F2 lenses will need pro-support, hence, we will see F2 zooms from Canon offered for 1Ds mkVIII support...hence...no size savings there.

I would expect the weight to go up by at least 1/3 (maybe more) and also, the size would increas by 1/3. These are just assumptions.

Also, are you comparing real focal length, or adjusted focal length?

Digital camera manufacturers have done a good job blurring the differences between the effective focal lengths. Crop factors are annoying and misleading. So how are we to compare the hybrid Canon lens with the current Olympus offerings?

 

[marf]

So lets continue the discussion here under "Why Four Thirds is
better" to balance the meaning of the header.

W H Y ?

Because hundred threads named "is FT in trouble", "Why APS (22mm) is better than FT (18mm)" ( people with exagerated self confidence because their sensor is 4mm longer ), "Leica said that FT is not enough" ( Leica did not say it, Leica did release its first FT DSLR and a DSLR for users of the 50 years old M-Mount ), bla bla, hurt FT. Despide that FT is well and living but if a new user comes to dpreview and reads that negativity he puts FT aside. Thats simply unfair

 

[Jay Turberville]

Size of the lens is one factor, brightness is another. The could
produce either smaller lenses, or lenses that are normal sized but
also brighter. This would offset the great DOF characteristics of
the 4/3 sensor somewhat - by having f/1 and f/0.75 lenses.

At the very least, the design of the mirror box means that you get diminishing returns for faster lenses starting at around f/1.4. You might get some of the benefit of greater DoF, but unless Olympus redesigns their mirror box, the mirror box's aperture will eclipse a fair amount of the exit pupil of a lens faster than f/1.4.

--
Jay Turberville
http://www.jayandwanda.com

 

[Jay Turberville]

Now, by using a sensor that didn't require telecentricity, like
that new offset microlens Kodak sensor on the front page of
dpReview today, you really can have small, fast light lenses. A
Voigtlander 40mm f1.4, for example, weighs in at 175g. It's such a
cute little thing.

So is the inexpensive little 40mm f/1.8 Hexanon. It appears to be a near symmentrical design. By that assumption and visual inspection, I estimate the exit pupil is around 12-15mm inset from the lens mount. I think the 4/3 flange distnace is around 38mm, so that puts the exit pupil only 50-53 mm from the sensor. Horror of horrors, this is way out of the Olympus spec for telecentricity.

Imatest tests give me a mean corner falloff of .635 stops (48bit dcraw conversion gamma = .997) at f/1.8 with this Hexanon. At f/2.8 it drops to a mere .227 stops. Meanwhile, the 14-45mm ZD kit lens, when shooting at 45mm, gives a mean corner falloff of .778 stops.

In fairness, the kit lens is very even over most of the frame with a falloff of probably less than .2 stops until you get right to the corners. Most of the falloff happens rapidly right when you get near the corners. This corner falloff is pretty clearly caused by the exit pupil being exclipsed. This happens with the 40-150mm kit lens also. You can see it in the out-of-focus bright spots in this image.
http://www.jayandwanda.com/dpreview/40-150_40mm_vign_5130499.jpg

I assume that Olympus does better with their more expensive non-kit lenses. Frankly, I'd prefer a more gradual falloff. I find this more rapid falloff more likely to be visually distracting. Though as a practical matter, I seldom notice it.

The sensor in the E-500 (which is what I used for these tests) certainly does not have a problem with an exit pupil distance of around 50mm. At least not from the standpoint of vignetting. My experience is that it doesn't from the standpoint of other image problems either.

I agree that Olympus has overemphasized the importance of near telecentricity.

--
Jay Turberville
http://www.jayandwanda.com

 

[Jay Turberville]

You can see that my target wasn't quite evenly lit, being brighter toward the top. That is why I referenced the mean corner values. Note how all the falloff happens rapidly near the corners with the 14-45mm ZD lens.



The Hexanon mounted to an E-300.

The Hexanon mounted to an E-500 and compared to a C7070.



--
Jay Turberville
http://www.jayandwanda.com

 

[LJSmak]

I think a more interesting discussion is what will be the impact of
the offset microlens sensor on the future of digital photography.

None.

It seems that you are expecting too much from the offset microlenses; it is obvious this "solution" will be counterproductive with telephoto lenses, which is probably the reason it is only used in the M8, which has no (real) telephoto lenses. For optimal results the microlenses should have a different offset for each lens, and even in the optimal situation it isn't a 100% solution. Well, soon we'll have tests on-line that will make this painfully visible.

Lourens.

 

[Jon Ragnarsson]

I do it all the time... It's a no biggie...

--
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http://jonr.light.is

 

[Agramer]

...for a few years and:

I'm in 4/3 because of lenses. I have just two fast and sealed lenses with minimum distortiona, CAs and wigneting for 28-400 range. Canon can't offer me that, Nicon can't offer me that. . .there is no system which can offer me that.
for instance:
100-400 is too slow and I dont like push/pull design.

zuiko 50-200 (100-400) is much faster, better sealed and smaller. It isn't expencive. Just cca 1000€ (or$)
sorry on bad english.
Cheers

 

[Agramer]

Probably slightly smaller.

Smaller than what?

An f2.0 on a system that didn't need to be quite as telecentric
than Olympus.

Which digital system don't need to be telecentric?
Just film systems don't need that.

Leica add microlenses on sensor, but thaT can be good just if every lens in line have the same dispersion. And that is almost impossible.
Sorry on bad english
Cheers

 

[Forrest41926]

I'm in 4/3 because of lenses. I have just two fast and sealed
lenses with minimum distortiona, CAs and wigneting for 28-400
range. Canon can't offer me that, Nicon can't offer me that. .
.there is no system which can offer me that.

24-105 IS + USM and 100-400 IS + USM will do just that, for the Canon camp. With Nikon, I don't know what the quality is like, but a popular option seems to be the 18-200 VR + AF-S and 80-400 VR.

I chose Canon in large part because of the lenses myself. I have four of them, and each one is specialized, almost perfect, at a type of photography that I like. I have a 50 mm f/1.4, a 135 mm f/2, a 300 mm f/4 with IS and very close focus abilities.

This was the 300/4 in action - no cropping:

 

[Agramer]

I'm in 4/3 because of lenses. I have just two fast and sealed
lenses with minimum distortiona, CAs and wigneting for 28-400
range. Canon can't offer me that, Nicon can't offer me that. .
.there is no system which can offer me that.

24-105 IS + USM and 100-400 IS + USM will do just that, for the
Canon camp. With Nikon, I don't know what the quality is like, but
a popular option seems to be the 18-200 VR + AF-S and 80-400 VR.

Hmm. . .a friend of mine have 24-105/4 IS on his EOS 5D and he isn't pleased. . .to much vigneting and distortions. focusing isn't much better then with 14-54 on E1 (I can't notice faster focus lock) He use his old 28-70 much more.

100-400 is too slow and i dont like push/pull design. . .dust isn't friend of that lens. . .and that lens is not very sharp, not for 17mpix that is for shure.

my friend have a wide colection of lenses for Canon, Nikon and Minolta mount. I tryed lenses which interested me and I finished with Oly. He use canon EOS 5D and EOS 1Ds MKII with 28-70/2,8, 85mm prime, 135mm prime and Sigma 120-300/2,8 ussually. That combo is too big and havye for me ...for tele range he uses 400mm prime and that is out of question for me .)

About Nikon 18-200 and 80-400: That lenses can't compare with Zuiko 14-54 or 50-200. They are slower, darker, have more distortions... 70-200VR is veeeeeeeery nice lens
Cheers

 

[Agramer]

My choice from Canon closet would be 24-70/2,8; 70-200/2,8 IS; 1,4 TC and 85/1,2.

from Nikon choice would be 17-55/2,8; 70-200/2,8 VR; and 1,7 TC (I'm not shure for portrait prime).

now I have E1; 14-54/2,8-3,5; 50-200/2,8-3,5

I'm waiting for new pro build 4/3 camera with 5fps, cca 10mpix and some kind of IS/VR/AS... If it shows untill next summer i'll buy it + 11-22/2,8-3,5 and 35-100/2,0. If it doesn't show next yaear . . .? I'll see next year
Sorry on bad english
Cheers

 

[Forrest41926]

My choice from Canon closet would be 24-70/2,8; 70-200/2,8 IS; 1,4
TC and 85/1,2.

I'm shooting a 5D, 50/1.4, 135/2, 300/4 IS, and a 15-30 EX by Sigma, which is likely to get replaced by a 20/1.8 and a fast 24 mm lens. I'm actually not a fan of zooms, for several reasons ( among them that f/2.8 is the fastest you can get for C&N, but also that when I want to change the view on a hike in the mountains I use my feet ... so doing the same with a camera is more natural to me ). But in the range you describe, I'd also rather have a 24-70 than 24-105, even though I'm not interested in either, because of the f/2.8 ... that's more valuable to me than IS in most cases.

I'm waiting for new pro build 4/3 camera with 5fps, cca 10mpix and
some kind of IS/VR/AS... If it shows untill next summer i'll buy it
+ 11-22/2,8-3,5 and 35-100/2,0. If it doesn't show next yaear . .
.? I'll see next year

Well hopefully you'll get what you want from Olympus, because you seem to enjoy your lenses ... and good glass ( by whatever measure is important to you ) is a joy to use.

This is the part of being a gear-head that I actually enjoy ... it doesn't matter so much exactly what the specs are; it's good to know why one person chooses this and another person chooses that ... sometimes they both have good reasons, and different approaches ... and it makes me think.

 

[Joseph S Wisniewski]

I do it all the time... It's a no biggie...

Quite true, for some of us, it is no big deal. I order from everywhere, recent lens purchases from the Ukrain, Japan, and Canada, musical instruments from England, China, Ireland, India, art glass from at least 25 countries.

But for most people, especially in Oly's biggest market (entry level SLRs), it really is a "big deal". They expect to be able to walk into a "Best Buy", "Circuit City", "Ritz Camera", etc. and pick out a camera. And get a US warranty. People like us may give Oly a few persent US penetration on a particular model, but it won't give them the kind of market share that will influence Phil.

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Normally, a signature this small can't open its own jumpgate.

Ciao! Joe

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[Joseph S Wisniewski]

Now, by using a sensor that didn't require telecentricity, like
that new offset microlens Kodak sensor on the front page of
dpReview today, you really can have small, fast light lenses. A
Voigtlander 40mm f1.4, for example, weighs in at 175g. It's such a
cute little thing.

So is the inexpensive little 40mm f/1.8 Hexanon. It appears to be
a near symmentrical design. By that assumption and visual
inspection, I estimate the exit pupil is around 12-15mm inset from
the lens mount. I think the 4/3 flange distnace is around 38mm, so
that puts the exit pupil only 50-53 mm from the sensor. Horror of
horrors, this is way out of the Olympus spec for telecentricity.

I got even better results with assorted Nikkors, old and new. Jay, you're preaching to the choir on this one.

Imatest tests give me a mean corner falloff of .635 stops (48bit
dcraw conversion gamma = .997) at f/1.8 with this Hexanon. At
f/2.8 it drops to a mere .227 stops. Meanwhile, the 14-45mm ZD kit
lens, when shooting at 45mm, gives a mean corner falloff of .778
stops.

In fairness, the kit lens is very even over most of the frame with
a falloff of probably less than .2 stops until you get right to the
corners. Most of the falloff happens rapidly right when you get
near the corners. This corner falloff is pretty clearly caused by
the exit pupil being exclipsed. This happens with the 40-150mm kit
lens also. You can see it in the out-of-focus bright spots in this
image.
http://www.jayandwanda.com/dpreview/40-150_40mm_vign_5130499.jpg

I assume that Olympus does better with their more expensive non-kit
lenses.

It does. But then again, the original 14-54mm (hate that, you look at 14-45 and 14-54 and thing one of the two is a typo) that I had on the bench had a 30mm image circle at its widest setting, so I'd not expect much vignetting in the 22mm "four thirds" part of that.

Frankly, I'd prefer a more gradual falloff. I find this
more rapid falloff more likely to be visually distracting. Though
as a practical matter, I seldom notice it.

I quite agree. I know which of my lenses vignette, and compose around it. Then again, I started photography as a teenager, with a budget that meant learning how to work around the quirks of lenses that were, well, "interesting". I'm betting you were the same.

The sensor in the E-500 (which is what I used for these tests)
certainly does not have a problem with an exit pupil distance of
around 50mm. At least not from the standpoint of vignetting. My
experience is that it doesn't from the standpoint of other image
problems either.

As I've said many times, 50mm exit pupils shouldn't be a problem. That's only 12.4 degrees from perpendicular in the corners. 9.9 deg horizontal, a 2.3% drop in sensitivity on the KAF-5101 in the E-1. 7.4 deg vertical. a 2.1% drop. Combined, that's 0.06 stops of vignetting, beyond what you'd already expect from Cos4 vignetting. (This is based on using Engauge to digitize the graphs in the .pdf data sheets). The sensor in E-300 is even better.

Since I'm not familiar with any film SLR lens (including Oly OM lenses) with an exit pupil closer than 50mm to the film plane, I really wonder why Oly had to make such a fuss about needing new lenses.

I agree that Olympus has overemphasized the importance of near
telecentricity.

I agree, totally.

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