Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-24-2013, 07:30 PM   #166
Site Supporter
Aristophanes's Avatar

Join Date: Jul 2008
Location: Dartmouth, Nova Scotia
Photos: Albums
Posts: 3,922
QuoteOriginally posted by Digitalis Quote
I think all things Zeiss and Leica are of more interest to collectors, several of the lens collectors I know have an almost fetishistic view of Leica cameras. Frankly, I find it to be a bit disturbing. I really don't consider cameras to be objects d'art....they are tools, nothing more.
The price of Zeiss is that to get sharpness across the frame you need to manual focus and have very strong shoulders. That's the thing wit the Zeiss; any company could just make their lenses much larger and get the same outcome. NO company now has anything on the optics. CAD/CAM has totally levelled the playing field and almost all companies can make good to great glass. In fact, you have to work hard to make sub-par optics (like a certain Canon pancake).

Leica is now just luxury brand glass married to a poor sensor.

06-24-2013, 07:46 PM   #167
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,795
QuoteOriginally posted by Aristophanes Quote
The price of Zeiss is that to get sharpness across the frame you need to manual focus and have very strong shoulders.
I recall Contax commissioning a 24-70mm lens from Zeiss - what they got was a f/2.8 zoom lens of superb optical performance - but was considerably heavier than the competing 28-70mm lenses and made use of some very exotic glass types and numerous precision ground aspherics that would have given the lens a price tag that would make most high performance Cine lenses look cheap. Allegedly three prototypes of this lens were made - and I have no doubt whatsoever that a collector has them and they will never see the light of day, which to my mind is a complete waste.
06-24-2013, 10:57 PM   #168
Pentaxian




Join Date: Jun 2009
Location: GMT +10
Photos: Albums
Posts: 10,843
QuoteOriginally posted by Aristophanes Quote
The price of Zeiss is that to get sharpness across the frame..
Maybe once upon a time, but as DxOMark said of a bunch of Zeiss lenses they looked at a little while ago...
QuoteQuote:
"On the other hand, these lenses also show some weaknesses - the most obvious being the lenses’ measured sharpness. Oh, most of them are sharp, and sometimes very sharp. But all too often they are not the sharpest lenses, and it can happen sometimes that a $1300 Zeiss lens can be outperformed by a $400 lens from Canon or Nikon. This is not so rare a case, and a user looking mostly for higher resolution could be a bit disappointed. Take the 85mm range, for instance; the $380 Canon 85mm f/1.8 USM is almost 10 lp/mm sharper than the $1300 Planar T85mm f/1.4ZE on the same full-frame 5D MkII sensor. That’s quite a big difference, especially when the cheaper lens also has less distortion, LCA, and vignetting.

So although these [Zeiss] lenses are masterpieces of build quality, their results may not always be as good as expected."
As you said, more companies than ever nowadays can do good optics (and are learning better build quality too).
06-25-2013, 01:26 AM   #169
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,795
QuoteOriginally posted by rawr Quote
for instance; the $380 Canon 85mm f/1.8 USM is almost 10 lp/mm sharper than the $1300 Planar T85mm f/1.4ZE on the same full-frame 5D MkII sensor
It is important to note that the newer ZE,ZF lenses are all made by cosina - not by Zeiss in Germany. The original Carl Zeiss lenses originally made for the Contax SLR cameras included leaded glasses - which in the name of keeping things "green" is strongly discouraged these days. So the newer lenses do not perform quite as well as the original Carl Zeiss lenses did. Though the funny thing is according to my tests the FA77 limited is even sharper at f/5.6 than the canon EF 85mm f/1.8 lens.

06-25-2013, 03:52 AM   #170
Veteran Member
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by Aristophanes Quote
NO company now has anything on the optics. CAD/CAM has totally levelled the playing field
I'd rather see such a statement made from an optical engineer, or not at all.

IMHO, it is disrespectful wrt the achievements of the engineers.

I agree that CAD/CAM has made it easier and faster to construct lenses.

But at the same time, lens constructions have increased to a complexity where such advantages are compensated.

To be on topic, the 18-35/1.8 has 17 lens elements, 5 are ED, 4 are aspheric (that's what I guess from the schema drawing on http://www.sigma-foto.de/produkte/objektive/18-35mm-f18-dc-hsm.html ).

This creates a parameter space of a huge volume. Esp. aspheric elements make the volume of the parameter space explode.

Then, you not only optimize for optical quality. No, at the same time, you optimize for numerical stability of solutions (in order to make the required production quality manageable and keep warranty claims low) and for overall production cost.

Any engineer will tell you that when confronted with so many variables, computers cannot replace experience (optimization algorithms don't converge anymore). It is just another tool.

Aristophanes, what you just said is about the same as if, e.g., a farmer said to a painter: "Hey, photo cameras have totally levelled the playing field for images" ...

QuoteOriginally posted by Digitalis Quote
Though the funny thing is according to my tests the FA77 limited is even sharper at f/5.6 than the canon EF 85mm f/1.8 lens.
That could be true. A former German optical lens designer who is in private communication with me told me that fast lenses have been optimized to perform good enough over the entire field wide open. Which means that center performance at smaller apertures may have to be sacrificed.

Of course, more modern aspherical designs can avoid such compromises. However, most current 85mm designs are fairly old school.

Last edited by falconeye; 06-25-2013 at 03:59 AM.
06-25-2013, 06:15 AM   #171
Site Supporter
Aristophanes's Avatar

Join Date: Jul 2008
Location: Dartmouth, Nova Scotia
Photos: Albums
Posts: 3,922
I wasn't impugning optical engineers.

I am making the point that any company with an optical pedigree could have done the same. Specialized knowledge is much more fungible now.

The trade-off of complexity as we see with this lens is mass and volume; it's a big beast.

Why companies don't all do this mostly has to do with economics, not engineering.

Sigma looks to be putting in a high-cost design and manufacturing lens to exploit a big glass/fast glass weakness in the APS-C market. Their aggressive pricing is apparently aimed at securing their brand as a viable option. Unlike the volume brands of Canikon, Pentax, Sony, Olympus, etc. Sigma can do smaller, more discrete runs of targeted projects.

In the same way that engineers have to make trade-offs between wide open/sharp and stopped down/softer centre, Sigma had to make a choice between a complex optic and its high costs and gaining market share by exploiting a gap. They did the same with their 30/1.4, 10-20's, and now this.
06-25-2013, 09:02 AM   #172
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,795
QuoteOriginally posted by falconeye Quote
A former German optical lens designer who is in private communication with me told me that fast lenses have been optimized to perform good enough over the entire field wide open. Which means that center performance at smaller apertures may have to be sacrificed.
One lens I own in particular demonstrates this property - the Noct-Nikkor 58mm f/1.2 ASPH, this lens offers superlative image quality at wider apertures. However as the noct nikkor is stopped down resolution is not competitive with most standard 50mm lenses, in fact in some situations it is worse. There is also another famous and rare Nikon lens, the Nikkor 28mm f/1.4 ASPH which also shares this tendencey for slightly lower optical performance as it is stopped down - but the losses aren't anywhere near as pronounced as the Noct-Nikkor.

QuoteOriginally posted by falconeye Quote
Of course, more modern aspherical designs can avoid such compromises. However, most current 85mm designs are fairly old school.
Aspherics are only as good as they are made to be, bonded aspheric lenses like that used in the design of the DA15mm f/4 could have been more effective if superior materials (like a solid glass) were used. GMO aspherics have the advantage of being made of homogenous materials, there are often higher tolerances* involved in their manufacture and they tend to be easier to mass produce than precision ground aspherics. But when it comes to the old school, most of the designs for modern short telephoto of the 70mm to105mm range lenses originate from the 1890's

QuoteOriginally posted by Aristophanes Quote
The trade-off of complexity as we see with this lens is mass and volume
Also an increase in air-glass surfaces. Sigma has not improved their coatings all that much over the years, mark my words - this lens will probably not be as resistant to flare as a standard 24-70mm f/2.8 lens will be.**

*especially in terms of dimensional variability, though there will always be very slight variations from batch to batch depending on the glass chemistry involved.
** for the sake of comparison the current Nikkor 24-70mm f/2.8G ED has 15 elements in 11 groups - the Sigma 18-35mm f/1.8 has 17 elements in 12 groups.The more glass and air-glass interfaces a lens has in it increases the chances that flare will be problematic.
06-25-2013, 09:13 AM   #173
Veteran Member




Join Date: Dec 2008
Location: Zagreb, Croatia
Posts: 535
QuoteOriginally posted by Digitalis Quote
Sigma has not improved their coatings all that much over the years, mark my words - this lens will probably not be as resistant to flare as a standard 24-70mm f/2.8 lens will be.**
for now, reviewers have only had one bad thing to say about this lens (except the obvious things like short range, weight..) and that was flare resistance

06-25-2013, 09:32 AM   #174
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,795
If there is any criticism that I have for the entire range of sigma lenses, it would be their decidedly below par flare resistance. Not to mention their preference for lenses with sharp center and abysmal corner performance (especially with the 30mm f/1.4). When it comes to flare control Fuji EBC and Pentax SMC coatings remain unchallenged.

Personally I think it is a bit daft to expect a 18-35mm f/1.8 lens to be light and compact. Reviewers that complain about the weight of a high speed lenses often come across to me as being somewhat limited in their experience with them. I work with some of the fastest lenses ever made, I don't complain about it*.

*though If I had a significant other, I'm pretty certain they would complain...though at my point in life I consider personal relationships to be rather superfluous, a distraction I simply cannot afford. If I want opinionated rants on my expenditure on photography I can listen to my accountant....or my mother.

Last edited by Digitalis; 06-25-2013 at 09:41 AM.
06-25-2013, 10:26 AM   #175
Site Supporter
Aristophanes's Avatar

Join Date: Jul 2008
Location: Dartmouth, Nova Scotia
Photos: Albums
Posts: 3,922
Criticism: it's freakin' huge!
06-25-2013, 10:44 AM   #176
Veteran Member
scratchpaddy's Avatar

Join Date: Feb 2013
Location: Phoenix
Posts: 2,360
QuoteOriginally posted by Aristophanes Quote
it's freakin' huge!
No, it's not.

This is huge.



That's the 200-500mm f/2.8. I guess it's the price you pay for fast glass. Well, that, and the $26,000 price tag.
06-25-2013, 10:55 AM   #177
Site Supporter
Aristophanes's Avatar

Join Date: Jul 2008
Location: Dartmouth, Nova Scotia
Photos: Albums
Posts: 3,922
QuoteOriginally posted by scratchpaddy Quote
No, it's not.

This is huge.



That's the 200-500mm f/2.8. I guess it's the price you pay for fast glass. Well, that, and the $26,000 price tag.
You are right.

That kid's Photoshopped forearm is freakin' huge.
06-25-2013, 07:33 PM   #178
Site Supporter
Clinton's Avatar

Join Date: Feb 2010
Location: Salt Lake City, UT
Photos: Gallery | Albums
Posts: 1,826
I could do this with the 1200/8

QuoteOriginally posted by scratchpaddy Quote
No, it's not.

This is huge.



That's the 200-500mm f/2.8. I guess it's the price you pay for fast glass. Well, that, and the $26,000 price tag.
06-26-2013, 12:12 PM   #179
Veteran Member




Join Date: Feb 2011
Posts: 4,893
QuoteOriginally posted by Clinton Quote
I could do this with the 1200/8
And you just need a friend to focus it for you.
06-27-2013, 08:11 AM   #180
Pentaxian




Join Date: Nov 2011
Photos: Gallery | Albums
Posts: 3,735
QuoteOriginally posted by scratchpaddy Quote
That's the 200-500mm f/2.8. I guess it's the price you pay for fast glass. Well, that, and the $26,000 price tag.
I'll settle for the Apo-Lanthar 90/3.5 on my Q.
Don't need that extra fraction of a stop.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
18-35mm, angles, aperture, cameras, canikon, canon, dc, f/2.8, f1.8, fisheye, hsm, iso, k-3, landscape, length, lens, lenses, motor, mounts, nikon, pentax, pentax news, pentax rumors, review, sigma, sigma 18-35mm f1.8, sr, uk, zeiss
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sigma 35mm F1.4 for Pentax: ETA 4/30 Adam Pentax News and Rumors 181 02-16-2014 06:44 PM
Sigma 18-35mm f/1.8 detail. rlatjsrud Photographic Industry and Professionals 42 10-06-2013 01:41 PM
New Sigma 18-35 F1.8 APS-C yygomez Pentax SLR Lens Discussion 10 04-19-2013 04:11 PM
Pentax 35mm F2.4 AL DA L Lens vs Sigma 28mm f1.8 Aspherical orchid Pentax SLR Lens Discussion 8 04-22-2011 12:44 AM



All times are GMT -7. The time now is 01:43 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top