Tag: Sigma

Sigma ultrawide zooms – old and new 12-24s versus 8-16mm

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For almost a decade the Sigma 12-24mm full frame ultra wide angle zoom has been unrivalled by any other makers – not Nikon, not Canon, not Tamron, not Tokina, not Sony. No maker has ventured where Sigma went, to the extremes of over 120° coverage combined with well corrected straight line geometry.

Today, the original 12-24mm is in its fourth incarnation, having progressed through EX to EX DG (digital) and then with added HSM hypersonic motor focusing, which never arrived for Alpha mount in the original design. The fourth version is an entirely new design, and does have HSM for Alpha. It is very similar to the new 8-16mm design, introduced three years ago for APS-C cameras, which also offers HSM focusing in Alpha mount.

Update five years later, 2017: there is now a constant aperture 12-24mm f/4 ART lens. This is a completely new design and has an almost-perfect performance, especially in terms of corner detail wide open. I’ve tested it in Cameracraft magzine. However, I did not have the various older models to make direct comparisons. The MkII remains available as the current non-ART, lower priced Sigma option.

Here you can see, from left to right, the EX DG 12-24mm f/4.5-56, the DC 8-16mm f/4.5-5.6, and the DG HSM II 12-24mm f/4.5-5.6. Don’t be fooled into thinking the original is wider in diameter, it actually shares exactly the same lens cap module as the new design; it’s smaller and around 100 grams lighter. Both the 8-16mm and new 12-24mm are surprisingly solid items.

First, we’ll look at the difference between old and new 12-24mms. I have used the old one in several versions on several different camera makes. and I’ve never had one which was truly sharp at all point across the frame wide open. The field is not perfectly flat, and autofocus modules are very bad at getting an exact focus at 12mm. Combined with lens mount tolerances, sensor flatness problems (mostly in Canon full-frame, which historically have not had very ‘plane’ sensors), sensor parallelism problems (all makes, Sony not excepted)… it was always a good idea to stop this lens down to f/11.

How bad is that? Perfectly normal for any lens covering over 85°. Even the best large format lenses, single focal lengths like Super Angulons, have always been used in the awareness that full aperture is for focusing and you stop down to between f/11 and f/32 for the actual shot. On 35mm format digital, using anything much below f/16 is counter productive for sharpness and my normal choices on the Alpha 900 have been f/10, f/11, or f/13.

The good news is that the latest version has a different kind of field flatness. The old one tended to have a zone, like a doughnut, of closer effective focus surrounding a sharp middle. At 24mm, where this older lens performed at its worst, this zone was pushed out to the far edges and could result in the corners looking softer than they do at 12mm. The new one has a simple barrel distortion in place of a wave-form distortion, and along with this goes a simple curvature of field.

The bad news is that the overall level of distortion is much higher than the old design. At 12mm, it’s close to needing the fingers of two hands. Adobe Camera Raw had a correction profile for this lens from Sigma almost the day it became available. That profile fixed the distortion perfectly but leaves you slightly less of a 12mm than you’ve paid for, because it reduces the angle of view.

Here are some comparative views. First of all, I’ve used only 10 megapixels of the Alpha 900 frame, cropping from the top of a vertical shot, to get this architecturally correct view. This is like using the 12-24mm as an extreme 12mm shift lens on an APS-C camera. As and when we get a 36 megapixel Alpha full framer, the crop to do so will be more  like 16 megapixels. This is the full frame:

Below you can see the crop used to 10 megapixels, and by rolling your cursor over the image, the change between a profiled conversion and a raw conversion with no lens corrections. On this crop it does not look extreme.

But this is a relatively kind way to use the new lens. Here is an example pushing straight lines into places where extreme wide angles don’t like ’em:

This is an uncorrected 12-24mm DG II HSM shot out of the Alpha 900 at 12mm. It’s not exactly what you want, and in fact, it’s not as ‘good’ as the old design despite being sharper. Hovering your cursor over the image shows the same raw file with the Adobe Camera Raw Sigma-generated Lens Profile (also works in Lightroom) applied. As you will see, straight lines have been restored along with even illumination. But – how much of that 12mm, 122° angle has been lost? Is it now really only a 12.5mm?

In practice, the new 12-24mm gives you a great range of creative choices when confronted with a building. Here is a revisit to the first subject, taken at different focal lengths, getting closer to the building with each shot:

24mm

20mm

17mm

15mm

12mm

When it comes to comparisons with the older design, the new one is much sharper at the edges. It does not need stopping down to f/16 to pull in the worst aberrations, though it does still display some around f/8 to f/11. Here’s an original 12-24mm EX DG design shot (12mm, f/9, vignetting corrected but distortion not corrected):

And here’s the new 12-24mm under the same conditions (small exposure difference due to changing light) processed similarly, without any geometric corrections:

On this shot, the corrugated barn sides have clean ribbing to the extreme ends, with some softening; on the old design, they begin to look a bit of a mess in the outer quarter of the frame.

Trying the 8-16mm extreme

But when doing these tests, I decided to throw a novelty into the mix. What if I put my 8-16m APS-C format Sigma DC HSM zoom on to the Alpha 900? Because it is not an Alpha lens, the 900 does not automatically crop the full frame. This is what I actually got with the lens set to 8mm:

And in Adobe Camera Raw, I just dialled up the Scale in Lens Correction to 146%, which blew up the central 12 or so megapixels of the frame to become a full 24 megapixel image:

And here, for comparison, is what the 12-24mm set to 12mm could produce:

This is a little tighter than the 8mm using the maximum I could get (including some extra image height), so the 8-16mm used this way can produce something closer to an 11.5mm full frame lens. However, I have not yet done the obvious – to get an engineer to remove the petal lens shade from the 8-16mm (it appears to be part of the front element assembly). This would enable even more angle without shading, and the possibility of square or 10 x 8 shape format crops.

What was particularly interesting about this experiment was the quality of the 24 megapixel file extracted from a smaller section of the Alpha 900 sensor by Adobe Camera Raw upscaling. Full size files are available to download for subscribers to Photoclubalpha – it’s well worth the $10 for a full year of access to any of the extras we provide. See the download links at the end of the article, which will become visible if you are a registered subscriber to the site.

The 8-16mm also achieves full frame coverage on the Alpha 900 when set to 16mm, though with fairly marked vignetting:

Here are some more samples from the 12-24mm DG II HSM: first, 17mm at f/8 – no geometry correction:

Next, at 12mm at f/13 which on the A900 seems to be the limit for good detail sharpness without extra effort in processing:

And 17mm at f/22 – beyond the diffraction limit, but processed carefully for detail:

And 12mm at f/9, an optimum setting for detail with plenty of depth of field for this subject:

So, what was my own decision? I own the 8-16mm and an Alpha 77. That’s what I use for travel and general work. I own an original EX DG 12-24mm. I decided not to buy the new 12-24mm because I concluded that the 8-16mm used on APS-C was effectively as good. The angle is not quite a match for the 12-24mm on full frame, as APS-C is not a true 16 x 24mm. For those occasions where a 12-24mm on full frame is needed, I’m nearly always able to work on a tripod at f/13 and focus manually (which overcomes most of the issues with the earlier lens). Since it needs less drastic geometric correction, it offers a very small angle of view advantage over the new lens in return for the risk of poor sharpness if not used well stopped down. I have no doubt the new lens is better, but it’s not £400 better which is what the ‘trade-up’ would cost – and the old lens is lighter and smaller, which I appreciate.

The test made me even happier with the 8-16mm, especially with the thought that some modification could make it a unique lens to use on the Alpha 900 or a future full frame EVF model (A99). After doing these tests, I decided it was not necessary to take the Alpha 900 and a 12-24mm despite the investment in two weeks’ shooting in the Sierras and Pacific Coast of California – the A77 and 8-16mm would do everything I needed.

But for those buying a 12-24mm, for full frame on any system, the new Sigma represents even better performance than the 8-16mm (better edge and corner sharpness at one stop down from wide open) and has none of the failings of the older lens even if it does need more post-process geometry correction.

Download full size images [private] 24 megapixels 12-24mm EX DG at 12mm f/9 Download Link
Download full size image 24 megapixels 12-24mm DGII HSM same as above Download Link
Download full size image 24 megapixels 8-16mm lens scaled to 24 megapixels from A900 ‘crop’ Download Link
Download full size image 24 megapixels 12-24mm DGII at 12mm compared to 8-16mm at 8mm cropped Download Link
Download full size image 24 megapixels 8-16mm at 16mm filling full A900 sensor Download Link
Download full size image 24 megapixels 17mm f/8 fence example shot boat Download Link
Download full size image 24 megapixels 12mm f/13 sequoia tree example shot Download Link
Download full size image24 megapixels 17mm f/22 boat Download Link
Download full size image24 megapixels 12mm f/9 riverside tree Download Link [/private]

To check the weight, specifications and other details of these three lenses we suggest you visit Sigma’s own site – for the new 12-24mm, here’s the UK site info. And here is the 8-16mm, which they oddly don’t class under wide zooms, but under DC lenses.

You can check worldwide shipped prices from B&H Photo in New York.

– David Kilpatrick

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DK's ramblings, Equipment Reviews, Lenses - Alpha Mount

Zeiss, Cosina, Sigma and Tamron – NEX E-mount future

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Sony Corporation announced today it will disclose the basic specifications of its “E-mount” for interchangeable single lens cameras, without fee, to manufacturers of lenses and mount adaptors, starting April 1st, 2011. This was previously confirmed at the photokina press conference – now they have revealed that Carl Zeiss AG, Cosina, Sigma and Tamron will all be working on the E-mount system as independent lens makers.

“This opens the way for manufacturers of various lenses and mount adaptors to effectively develop products conforming to “E-mount” specifications”, say Sony.

The NEX E-mount revealed – ten contacts, three flanges and a mere 18mm of register distance…

“Users of the Sony’s NEX-3, NEX-5, NEX-VG10 and other E-mount compatible Sony digital imaging products to be launched in the future will now be able to use interchangeable lenses from both Sony and various other manufactures, while they will also be able to attach non-Sony lenses to their Sony digital imaging products via a mount adapter. Sony believes the growth of digital imaging products employing the “E-mount” will further increase the enjoyment of photography and video shooting among an even wider range of users.

“These basic specifications will be disclosed to manufactures of lenses and mount adaptors following a predefined process of approval and the signing a license agreement with Sony.

“As of today, the decision to disclose basic specifications of the E-mount has been endorsed by the following companies.”

(there follow these manufacturer statements)

Carl Zeiss AG
As an independent lens provider, Carl Zeiss welcomes the disclosure of the E-mount specifications by Sony. It helps manufacturer’s product development, benefits customers and therefore assists in establishing E-mount as a new, healthy and strong system on the market.

Cosina Co., Ltd.
Cosina Co., Ltd is excited by the potential of Sony’s E-mount which enables to a large-size image sensor to be incorporated in a compact, interchangeable lens camera. We have high expectations for the E-mount with its aims to create a new photography culture, and express its assent to Sony’s decision to provide information related to E-mount.

Sigma Corporation
Sigma Corporation fully supports Sony’s decision to disclose basic E-mount specifications. We believe this move will spur the further growth and diversification of camera system across the industry, provide photo enthusiasts with a wealth of choice and enrich in their photographic lifestyles.

Tamron Co., Ltd.
Tamron Co., Ltd endorses Sony’s decision to disclose basic E-mount specifications. We aim to offer our customers new solutions and unprecedented photo-shooting enjoyment through the manufacture and sale of E-mount lenses.

Editorial comment: at the photokina conference, the wording used seemed to imply that independent E-mount camera bodies were also a possibility. Of the makers above, three already have a history of making rangefinder or compact style large sensor bodies – Zeiss (to date, film only); Cosina (digital, in the form of the Epson Leica mount bodies with 6 megapixel Sony sensors) and Sigma (the DP-1 and 2 series have fixed lenses, but would be a natural candidate for conversion to E-mount form). If this was to be the case, in a future announcement, the E-mount would be established as an alternative to the Micro FourThirds system with a capacity to use sensors in formats between 2X and 1.5X with existing lenses, and possibly up to full frame in a secondary configuration with a different range of lenses (backwardly compatible with smaller sensors).

Is this the same Sony people rant about being protective and exploiting their customers? No. It is Sony listening to their customers. It’s Alpha becoming the 21st century equivalent of Leica.

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News, NEX System

New Photoworld edition available

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The latest Photoworld edition, No 1 2011, is now available to electronic edition subscribers (Normal or Premium) and is being printed to mail out before the end of January to all print edition subscribers.

The cover shot is by Shirley Kilpatrick, and is an uncropped capture very rapidly taken using the Alpha 550 with Sigma 18-250mm OS zoom at 250mm, a single frame as the hoopoe changed position and flew off immediately. With no time to make adjustments and the camera set to ISO 200 and aperture priority at f/8, the metering produced the dark result which would be expected from this situation and a shutter speed of 1/500th:

The Alpha 550 14 megapixel file is extremely low noise, so adjusting the image using Adobe Camera Raw produced hardly any loss of quality – including lens corrections for the Sigma automatically loaded, as all Sigma lenses are now included in Adobe’s database. For a rapid grabbed shot, the focus is spot-on and the Sigma lens at full focal length and only 2/3rds of a stop down from full aperture has performed extremely well. Shirley was testing the Alpha 550 for a week in November, after two years of using the Alpha 700. She found the smaller viewfinder acceptable and the general success rate and image quality to be an improvement; she has now traded the Alpha 550 up for the 580 which is even better.

Subscribers can download the full size 14 megapixel ACR converted file from our Extra Content area.

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Cameras (DSLR), Lenses - Alpha Mount, News

Sigma lens incompatibility with A33 and A55

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Edited from Sigma Japan’s announcement:
Sigma’s lenses for Sony mount may have a potential aperture operation problem when used with the Sony α33 and α55 Interchangeable Lens digital cameras.
To overcome this issue, we will be offering, free of charge, a modification service to our customers who have purchased a Sony α33 and α55 and own Sigma lenses for Sony mount. This phenomenon will only occur with Sony α33 and α55 cameras. Future production of Sigma lenses will be fully compatible with these cameras.
We deeply apologize for any inconvenience caused to our customers.
Phenomenon
When shooting with a Sony α33 and α55 cameras, the aperture may not work properly and a “camera error” message will be displayed on the camera.
Lenses requiring the modification
All current Sigma’s lenses for Sony mount.
For lenses discontinued several years ago, a modification may not be available. For further details, please contact your nearest authorized Sigma Service Station.
Support for this issue
We will be offering a modification service for our current range of lenses free of charge. Please contact your nearest authorized Sigma Service Station.
World Network
Mark for compatible lenses
alpha33_alpha55
Future production of Sigma lenses will be compatible with these cameras. The above sticker will be put on the product box of compatible lenses.
For further information, please contact your nearest authorized Sigma Service Station.


Editor’s comment:
Depending on whether the aperture problem is entirely mechanical (the coupling) or also involves electronics, it would be fair to assume that problems with the A33/A55 may not be restricted to Sigma independent lenses, but may also apply to other makes, especially older lenses. Brands made by Sigma such as Quantaray are almost certain to be affected. We await Sony’s statement on compatibility with older lenses, including Minolta. Please note that the Alpha adaptor for the NEX E-mount provides normal aperture operation with Sigma lenses; how the A33/A55 mount differs we have yet to see.

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Accessories - 3rd party, Lenses - Alpha Mount, News

Sigma’s DP2 – Camera less obscure

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sigmadp2_page_02_image_0001

Sigma’s DP1 was launched in 2007 (with production models available in 2008) to great critical acclaim. occupying a unique spot in the marketplace by combining an APS-C format sensor with a compact “point and shoot” style body. There were a few controversial design choices, and the user and reviewer feedback varied greatly with the time and effort people were prepared to put in learning about the camera, yet the verdicts on the optical performance were united – the DP1 was astounding. Now the DP2 has arrived, with production-quality units available from UK retailers.
Continue reading »

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Tests / Reviews, Uncategorized

Sigma classic 400mm tele quick rechip

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There is no need to dismantle the mount of the original series Sigma AF TELE 400mm f/5.6 lens, to bring non-functional versions (old chip) up to speed with later film and current digital SLRs. The whole process takes under five minutes, and requires two tools – a small Philips screwdriver, and a precision end cutter.

The appeal of the original AF TELE and the later, identically sized, AF APO TELE should be obvious. They weigh in at less than 900g in the first non-apochromatic version, which like the later apo (1053g) will only focus to around 4 metres. The cost and weight penalty for the later, much larger, Apo Tele Macro focusing down to 1.5m is considerable.

This lens – an original version in gunmetal finish – is impressively solid, a real metal barrel with a precision made extending hood, lined like the rear lens tube with flock anti-reflection black. The mount is well made, the tripod collar is ultra-neat though fitted with only a 1/4 inch thread:

The dilemma is that inside this lens is a chip which means it won’t function at all on digital SLRs and many later film SLRs (almost anything which actually says Dynax or Maxxum on it won’t work, this lens was made for the original 5000-9000 Minolta AF series). It will not even work in a manual focus mode, as the chip reports an error, not just ‘no lens fitted’.
The answer is to rechip the lens using a new contact plate array fitted with a new chip, provided for around $60 including post by James Lao in China:
http://eadpt.cn.webz.datasir.com/eadpen.htm
This service is absolutely reliable, James emails to check the lens type you want to rechip, sends using signed-for post and I had my new chip in just four days to the UK.
Some reports on how to rechip the lens advise dismantling the entire rear mount. This is not needed, nor is any sanding or cutting with a hacksaw. A pair of miniature end cutters as used in the electronics industry for trimming wire exactly will do the job – so will luthier’s fret end cutters, and many pliers with high precision wire cutters.
The original contact array looks like this:

Note that the board does allow the countersunk head screws to lie fairly flat. Removing the screws over a suitable tray, with the lens held sideways, requires a No 1 jeweller’s screwdriver – 1mm or 1.5mm will do well. I used a screwdriver set with an illuminator in the handle.

With the old board still attached to its ribbon cable, just ease it up, twist it and push it into the void the left as viewed here. If badly placed, it can inferfere with the aperture mechanism, so after fitting your new chip and testing the lens, I suggest opening up again, pulling the old board out and cutting it off for good. It will never be needed again. Check the aperture lever operation anyway to make sure the board, when pushed into the lens, is not jamming the action.

Here’s the contact side of the James Lao board. Note that it has excess substrate on the ends, which will need shaping down to fit, and that the screw holes are brass lined. This will result in the screws being very slightly raised when it is fitted, but this is not an issue, just a cosmetic difference.

On the back is the new chip, connected by small wires instead of a ribbon cable. It is not as fragile as this shot indicates, nor are you likely to damage it through static unless you groom the cat first then rub a balloon, stick it to your 8ft 6 regulation height ceiling and walk across a nylon shag pile carpet wearing crimplene trousers. But it is not 1975, so no worries there…

This is a pair of fine end cutters (so called because the clipping edge is right at the front, not set back by angled grinding/sharpening). It can be used to clip off the excess, then nibble the correct shape at each end, with minimal effort and no risk. No dust is created but little bits of board do fly off and land in watching eyes, so wear glasses or protective goggles if you do this. I wear off-the-shelf reading glasses, it makes this sort of small work much easier.

The trimmed new board will fit easily and firmly into the space left by the old one.

Here’s how I replaced the screws. My screwdriver is a good enough fit to hold the screw and introduce it to the hole with the lens safely over the lid of the screwdriver kit. Do not stand the lens upright and do it from above, you risk losing a screw inside the lens. This way is safe.

Once fitted, it is perfectly functional though the trimmed ends and non-recessed screws make it look a touch agricultural. You could black-pen the ends I guess, but this is not going to affect flare or any other aspect of the final picture quality. Note the flock-lined rear lens tube – these optics were well made, 20 years ago.

Taking the lens out on the A900, not a very good day, ISO 400 and really wide-open are the defaults, I found that it absolutely must be stopped down to f/8 to be useful. This quick snap of a blackbird on the roof actually shows very fine detail:

This is un-sharpened, with some NR, and is at +1.3 plus brightness boost in processing – in other words, really ISO 1600 on the A900, not ISO 400 as set. The tiny hair-like feathers are resolved at f/8. Not all my first attempts to autofocus the lens were as accurate, it’s easily confused and dithers even if it does not hunt. Into the light, it’s pretty awful on anything which shows the serious level of CA present in an original version at f/8, click the image for the full size view:

Colour bokeh? Yup, red and green, your own Christmas decorations provided free for every tree. It can be improved in ACR from raw, but really, this sort of subject (edge of full frame shown) is best avoided.

Here’s another quick snap in the garden, not much sun but not totally dull, again managing f/8 with a reasonable shutter speed (1/200th I think on this one). The 100 per cent clip from the A900 shows a decent level of detail, without adding any sharpening:

It’s soft but remember this is part of a five to six foot wide image. At f/11, which I may get to try in better weather, and at ISO 100 on the A700 cutting off the rather CA-prone outer field and getting that valuable effective 600mm-angle view – well, it’s probably worth it. I do not get much better than this, and often get worse, from the Minolta 500mm f/8 mirror lens on the A900 at ISO 400.
The rechipping operation is so fast and hassle-free there is no great risk in buying one of these lenses at a bargain price, against the risk it will not work on your digital SLR. You can make it work. For 7D/5D owners where the resolution is less challenging, it would be a great buy. Do not expect fast focus – it is not – but the handling more than makes up for that. Balance and feel are just great, and the sliding collar which covers the moving focusing ring is a great design feature.
– David Kilpatrick

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DK's ramblings, Equipment Reviews, Lenses - Alpha Mount
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