Sigma 10-20 and Tamron/Min 11-18 - difference shown

Started Dec 6, 2005 | Discussions
David Kilpatrick
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Sigma 10-20 and Tamron/Min 11-18 - difference shown
Dec 6, 2005

These two lenses have entirely different design aims. The Sigma uses curvilinear geometry, like a very mild fisheye, at 10mm. It has a very tight image circle and quite string progressive fall off in illumination. It is however very sharp right to the edge of the usable image.

The Tam/Min design uses orthometric or equidistant projection (not sure which in technical terms), in which equal distances on the subject are shown as much as possible as equal distances on the image, and lines are rendered as straight as possible. It has a larger image circle, with a more gradual deterioration in sharpness (wide open) accompanied by better illumination. There is then an outer image zone which falls off in both illumination and sharpness.

You can see this in a very unscientific test, taken with both lenses held so as to cover as close to the same view as I could manage by eye. Note the curved lines on the Sigma image, and look particularly at the slats of the venetian blind in the bottom half of both pictures. This shows really clearly how the 'drawing' of the Sigma and Tamron/Minolta optical systems differs.

The Tamron/Minolta design has obviously greater compatibility with AS, as a moving sensor will track across a more or less equally 'shaped' image, while on the Sigma design, image scale changes.

This picture was taken on a 9xi full frame camera on an old roll of film (I don't use film now!) and the local minilab has not centered the image circles all that well, but you can also see how much larger the coverage circle of the Tam/Min design is, compared to the Sigma.

I really like the Sigma's HSM focusing and lovely design and build quality, but I do not prefer the optical decisions made in its design, and the geometry of the Konica Minolta 11-18mm will be similar to the Tamron tested here, and very clearly better suited to the AS system as well as yielding straighter architectural rendering.

I converted the image to mono as it makes the differences easier to study.

David
f2photo.co.uk

David Kilpatrick
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Re: Sigma 10-20 and Tamron/Min 11-18 - difference shown
In reply to David Kilpatrick, Dec 6, 2005

I meant quite strong falloff, not quite string!

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santoguapo
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Very interesting...
In reply to David Kilpatrick, Dec 6, 2005

I definitely like the geometry better on the Tamron. Not only will that bode better for AS, but for architecture as well.
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jurci
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Re: Very interesting...
In reply to santoguapo, Dec 6, 2005

Nice comparison! I like the technical/pragmatical example.

Any idea how the Sigma 12-24mm/4.5-5.6 DG EX would fit into this classification. Is it fisheye-style or ortho/rectilinear based?

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Henry Richardson
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Sigma 10-20mm for KM has HSM?
In reply to David Kilpatrick, Dec 6, 2005

David Kilpatrick wrote:

I really like the Sigma's HSM focusing and lovely design and build
quality, but I do not prefer the optical decisions made in its
design, and the geometry of the Konica Minolta 11-18mm will be
similar to the Tamron tested here, and very clearly better suited
to the AS system as well as yielding straighter architectural
rendering.

I didn't notice anything on the news page that mentioned HSM. I think this would finally make the first Sigma HSM lens for Minolta. Thanks for pointing it out.

Thanks for the info comparing the two lenses. I have been waiting around wondering if I would get the KM 11-18mm, but I was hoping to see if Sigma would release a Minolta mount of the 10-20mm.

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Mauricio23
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No.
In reply to Henry Richardson, Dec 6, 2005

The Pentax and KM versions of the sigma 10-20 lens will not be HSM. The press release would otherwise have included the HSM letters in the name of the lens, just as it does for the Canon and Nikon mounts.

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Mauricio23
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Sigma 12-24
In reply to jurci, Dec 6, 2005

The Sigma 12-24 is ortho-rectilnear, and its rendering of straight lines and equal distances is even better than the Tamron / KM 11-18. Since it is a full-frame lens, you also get to use its sharpest section in a FOV crop camera. Its downsides are its size and weight (the thing is huge) and the inability to use screw-on filters because of its front-element design.

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David Kilpatrick
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Re: Sigma 12-24
In reply to Mauricio23, Dec 6, 2005

Mauricio23 wrote:

The Sigma 12-24 is ortho-rectilnear, and its rendering of straight
lines and equal distances is even better than the Tamron / KM
11-18. Since it is a full-frame lens, you also get to use its
sharpest section in a FOV crop camera. Its downsides are its size
and weight (the thing is huge) and the inability to use screw-on
filters because of its front-element design.

Absolutely right. Over the area of an APS-C sensor it is amazingly good. I first used the 12-24mm on Sigma's SD10 camera which is a 1.7X sensor, and since then have used it on the Fuji S2 and the Kodak DCS full frame, and the Canon 1.6X sensor. In all cases it has been a must-have lens. If you could manage to SHIFT an APS-C sensor within the 12-24mm's field that would be amazing.

http://www.alamy.com/stock-photography-search-results.asp?st=0&lic=6&lic=1&ns=1&qt=sacre+coeur+kilpatrick+ANF14A&go=1&a=-1

This shot was taken using the film body (Sigma SA-9) and uses the 12mm length with full 'shift' by composition. It may seem odd to leave such a composition in place in a picture library, but you have to remember how images are used, and a large foreground like this is ideal for laying text or other photos on to.

David

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Henry Richardson
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Are you sure?
In reply to Mauricio23, Dec 6, 2005

David wrote the following in his discussion of the lens:

"I really like the Sigma's HSM focusing and lovely design and build quality"

So, it sure sounds like the KM lens he was using had HSM. Maybe I just am misunderstanding what he meant.

I just checked the photo that Phil has and it has HSM written on it. I assume the photo is of the KM or Pentax mount lens.

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HenkH
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Re: Are you sure?
In reply to Henry Richardson, Dec 6, 2005

Henry Richardson wrote:

I just checked the photo that Phil has and it has HSM written on
it. I assume the photo is of the KM or Pentax mount lens.

The photo also has the AF-M switch, which is typical for the Canon-mount (isn't it???), so I suppose Phil reused an old image.

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santoguapo
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OK, so bottom line, which would you prefer?
In reply to David Kilpatrick, Dec 6, 2005

KM/Tamron 11-18, Sigma 10-20, or Sigma 12-24 and why?

I have been drawn to the ff 12-24 for a while, but hear that it is quite soft at wide aperatures. I would use it some for interesting candid shots at weddings, so I would probably be using it as open as possible.
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GiannisK
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Re: AS ??
In reply to David Kilpatrick, Dec 6, 2005

David many thanks for posting this.

To my eyes i clearly see straight lines at Sigma whereas curvy lines at Tamron.
And sharpness and contrast is a definite bonus to me.

But i want to know more of your thoughts about AS and optical design of the two. Why do you think that AS will benefit more of Tamron's design ?

Only because KM's will be the same ?

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Henry Richardson
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Re: Are you sure?
In reply to HenkH, Dec 6, 2005

HenkH wrote:

The photo also has the AF-M switch, which is typical for the
Canon-mount (isn't it???), so I suppose Phil reused an old image.

Ahh, you are right. Still it isn't clear from what David wrote though.

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David Kilpatrick
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Re: Are you sure?
In reply to Henry Richardson, Dec 6, 2005

Henry Richardson wrote:

David wrote the following in his discussion of the lens:

"I really like the Sigma's HSM focusing and lovely design and build
quality"

Sorry, the Sigma I have here is in Nikon mount - so far as far as I know Sigma has not been able to implement HSM with the M-AF SSM system. I have no idea why, it would really be great to have all their HSM lenses in SSM compatible form.

David

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David Kilpatrick
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Re: AS ??
In reply to GiannisK, Dec 6, 2005

GiannisK wrote:

David many thanks for posting this.

To my eyes i clearly see straight lines at Sigma whereas curvy
lines at Tamron.
And sharpness and contrast is a definite bonus to me.

But i want to know more of your thoughts about AS and optical
design of the two. Why do you think that AS will benefit more of
Tamron's design ?

Is you monitor curved? Grab the picture and lay a Photoshop ruler over the lines, and you will see that the Sigma rendering is pretty curved. It does not look unnatural, but the Tamron has straighter lines within the sensor area and well outside it. Do not judge right at the extreme, where it shows pincushioning slightly. This part of the image is never included in a shot.

But the AS system moves the sensor, the Tamron/Minolta has more of a regular grid geometry, and there will therefore be a better conformity of image size detail if a subject moves within the frame (or the lens shakes).

David

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David Kilpatrick
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Re: OK, so bottom line, which would you prefer?
In reply to santoguapo, Dec 6, 2005

santoguapo wrote:

KM/Tamron 11-18, Sigma 10-20, or Sigma 12-24 and why?

I have been drawn to the ff 12-24 for a while, but hear that it is
quite soft at wide aperatures. I would use it some for interesting
candid shots at weddings, so I would probably be using it as open
as possible.

For me, Tamron/KM. The illumination and geometry are that much better for my own uses, and the freedom from flare - a major problem with the Sigma into the light: see -

I like the 12-24mm but it's heavy, I already have an excellent 14mm f2.8 Tamron SP AF for full frame use, and the 11-18mm has a proper front filter thread 77mm while the Sigma 12-24mm really can not be used with filters at all.

David

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laguire
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how do these compare to your 14mm lens?
In reply to David Kilpatrick, Dec 7, 2005

Was wondering how these zooms compare to your 14mm lens? have you had a chance to compare to the sigma 14mm as well? Sharpness, geometry, contrast, flare, etc. Thanks for any comments.

(I just picked up a used 14mm lens and now am wondering if I should have gotten a zoom instead. Still, I can imagine that with indoor shots, say museum shots, the f2.8 will be a big help over 4.5 or so..)

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triple_kaizer
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Re: Are you sure?
In reply to David Kilpatrick, Dec 7, 2005

Seems they are having engineering issues or something of the sort. They have at some point admitted to working on the compatability, and to my emails they always reply that "no announcements of products and availability can be made at this point".

There is a faint hope that they have either bumped into some issue that takes them some time or that they decided to evaluate KMs position and future in the market not to spend unnecessary funds developing for a mount with an unsure future. The last spree of releases suggest that they have atleast some faith in KM at this point.
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Kjetil

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GiannisK
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Re: AS ??
In reply to David Kilpatrick, Dec 7, 2005

Sorry but i must insist.
Please excuse my poor English.
Grabed the picture opened at CS2, enable grid, turn picture at 1 degree CCW.

That way the horizontal shadow lines of the window touch exactly the PS grid. Examination area is the middle part of window where you see the roofs of buildings.

The left picture shows that the grid is placed exactly at the ends of lines whereas there is some pixel deviation at the middle. The vertical lines are exactly on par with grid lines.

The right picture shows that the deviation of the horizontal lines at the middle are more than double from the left one. And the vertical lines show clearly that don't fit anywhere with grid.

I've seen this at two TFT's at work and my laptop.

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Giannis Koutroulas
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Mark VB
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Re: Are you sure?
In reply to triple_kaizer, Dec 7, 2005

triple_kaizer wrote:

Seems they are having engineering issues or something of the sort.
They have at some point admitted to working on the compatability,
and to my emails they always reply that "no announcements of
products and availability can be made at this point".
There is a faint hope that they have either bumped into some issue
that takes them some time or that they decided to evaluate KMs
position and future in the market not to spend unnecessary funds
developing for a mount with an unsure future. The last spree of
releases suggest that they have atleast some faith in KM at this
point.
--
Kind regards
Kjetil

It may not be a technical issue, but rather an economic one. For example, Nikon has had camera bodies that are compatible with SW focusing (its version of HSM) far longer than Minolta has had bodies compatible with SSM focusing (all Canon bodies are compatible). There likely are far more HSM compatible Nikon camera bodies in use than SSM compatible Minolta bodies. Thus, Sigma may not want to limit its potential sales of Minolta mount lenses (already a smaller segment of the market) to only those consumers with SSM compatible bodies. As more people buy newer KM bodies that are SSM compatible, I would expect that at some point Sigma will begin to make its HSM lenses available in Minolta mount, assuming of course there are no technical reasons why it cannot do so.

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Mark Van Bergh

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