SIGMA FOUR THIRDS LENS

30mm F1.4 EX DC HSM

fast 'standard' lens on test (v1.03)


MANUFACTURERS DESCRIPTION:

30mm F1.4 EX DC HSM

Large Maximum Aperture of F1.4

New special lens coating reduces flare and ghosting in digital SLR cameras

Two SLD (Special Low Dispersion) glass elements and a hybrid aspherical lens provide the utmost correction for all types of aberrations. Equipped with HSM (Hyper Sonic Motor) system. The large maximum aperture of F1.4 produces a versatile lens that performs superbly in a great range of applications including portraiture, indoor and studio work and landscape photography.

TECHNICAL SPECIFICATIONS: (thanks to Sigma Imaging UK Ltd).

Focal Length: 30mm

Maximum Aperture: F1.4

Minimum Aperture: F16

Lens Construction: 7 Elements in 7 Groups

Angle of View: 45

Number of Diaphragm Blades: 8pcs

Minimum Focusing Distance: 40cm (15.7)

Maximum Magnification: 1:10.4

Filter Size: 62mm

Lens Hood: Petal Hood

Dimensions: Diameter 76.6mm (3) x Length 59mm (2.3)

Weight: 430g/15.2oz

Available fittings: Sigma AF; Canon AF; Nikon AF; Four Thirds.

Suggested Retail Price: UK 319.99; EUR 460, US $525



INTRODUCTION:

I've always been a great believer in 'premium' lenses i.e. those made by the same manufacturer as the camera. Certainly this held good in my OM days when the vast majority of 'other' makes than Zuiko's just couldn't cut the mustard. There are always exceptions; some Tamron SP's and Tokinas for example. Times have changed and since Olympus opened up 4/3rds as a 'standard' it seems to me that non-premium lenses should now be much closer to premium than ever before. Obviously there will be differences otherwise one lens company would make every lens on the planet but that's not going to happen. But those differences should lead to more choice for us users, and that's a good thing. On the lens front there is only Sigma and Panasonic (Leica branded) presently offering a choice over the Zuiko Digital. If Tamron would sign up to 4/3rds I'm sure its future would be even more secure.

In my OM days I used the 55mm x 1.2 lens as my 'standard' for many years. Like all fast primes they are not easy to use due to the narrow DofF but when you get it right the results are superb. I also found that I rather liked the slight telephoto of the 55mm, as I had done with the 42mm (60mm EFL) of my earlier Pen F/FV days. So when I moved to the E-system I missed a 'standard' fixed FL lens and found myself using the standard ZD zooms more often than not at around the 25-30mm mark. The ZD zooms are good, but they have their limitations, especially indoors. There is nothing in the OM Zuiko range that equates to a FL of 55-60mm that is useable enough to forego the in-built AF of the ZD zooms, so I feared I was stuck. When the Sigma 30mm fixed FL lens in the 4/3rds mount arrived as a top of Sigma range EX designated offering with a Hyper-Sonic Motor for AF, I was more than interested. Having prevaricated for a few weeks I eventually decided to have one in mid October. Ha, not that easy as no-one had stock. After much searching and with a bit of assistance from Sigma UK, I found the last one in UK. It seems that around PhotoKina is not the best time to try to buy a lens.

Following some very swift delivery arrangements the lens duly arrived just in time to see the heavens open and gloom decend for several days.

Recommended retail price is 320. I managed to buy mine for 270 + 10 delivery. Not a huge saving; never mind, I didn't have any choice.

FIRST IMPRESSIONS:

The box is in Sigma's usual livery of black with red markings. Inside is a nicely made case, well padded and with a shaped rubber inset in the lid to hold the lens in place. In the bottom is a black pad about an inch thick to give protection to the rear of the lens. The manual is the familiar mulilingual A3 sheet with the basic specifications and the do's and don't's.

The now standard 'petal' hood is provided finished in an unusual 'suede' like coating in a dense matt black. The inner surface of the hood is the black plastic of its construction, closely ribbed for maximum light absorption. It is very well made.

The lens itself is beautifully presented in the full EX tradition. The dense matt black coating has tiny bright specks of 'dust' within its depth that reflect the light and sparkle. (This sounds terrible but is tastefully achieved). The foucs ring is ribbed like Zuiko Digitals and very tactile. The small AF/M switch is placed on the left upper rear part of the barrel just behind the brand name 'SIGMA' in white lettering. The distance window is on the top of the barrel but has no DofF scale and to the right is the lens nomenclature: 30mm 1:1.4, DC, HSM. On the left of the lens is the gold embossed 'EX' insignia matched to the gold ring around the front aspect of the barrel. The serial number is on the front underside of the barrel along with the filter size (62mm) and the lens is marked 'Made in Japan'. The mount is stainless steel. There are no markings to the frontal aspect of the lens dress rings making it completely anonymous viewed from the front. Lens comes with plain matt black front and back caps.

Weight is 430g (almost 1lb). Size is 3" diameter by only 2.3" front to back giving it an undersquare attractice 'chunky' look. The front element is around 40mm dia, the rear element an impressive 30mm. The front glass reflects mainly green and purple with some gold and blue, indicating multi-coating.



AESTHETICS:

Not until it is mounted on the E-1 (especially) do you appreciate the aesthetics. No doubt the 30mm Sigma is extremely handsome. I can't describe why, but the above photo says it all. It's not quite as well suited to the E-500, and I'll have to wait to see if it looks any better on the new E-400. The only other modern Sigma I have is the budget DC 55-200 which, frankly, looks like a toy compared to the 30mm. Aesthetics play a huge role in how we respond to something new. We all know folks who wouldn't consider a model ZX 14G (whatever), regardless of how good it is at its function, because it offends their eye. Powerful stuff, aesthetics. Whoever designed the 30mm Sigma certainly got it right. The other bonus for me is that due to its undersquare dimensions it does not tip the E-1 (plus HDL2) forward when you put the camera down.

ERGONOMICS:

I found myself immediately at home with this lens. The left hand automatically reaches up to cup the bottom of the lens giving the correct support, regardless of whether the grip is attached or not though slightly better balance is achieved with the grip fitted. Not only does it look right, it feels right. There is nothing for the left hand to do (unless using manual focus) but act as a support as there's no zoom, so improved stability is inevitable.




Above: Unlike some of the heavier zooms in the lenses available for the E-system, the Sigma 30mm prime does not over balance the E-1 when fitted with the battery grip. The camera and grip will happily sit without risk of tipping forward. I find this inherent fault annoying, especially with the ZD7-14mm and similarly, the ZD 14-54mm. I realise there is little that can be done about it, however, I find it irksome.




Above: As can be seen from the above images, the 30mm prime has few controls and nothing that requires constant adjustment unless you use the lens in manual mode. The lens design and dimensions alongside its EX construction, materials, colour and texture to my eyes anyway, make this the most aesthetically pleasing lens of any I own. I hope its performance matches its undeniable good looks.

VIEWFINDER IMAGE

One might think this Sigma super bright lens might improve the viewfinder imaging capabilities of E-system machines. It does, but it's only marginal. The difference between it and the ZD14-45 is noticeable; between it and the ZD14-54 the Sigma gives a slight advantage but, as said, the improvement is marginal. Do not buy the Sigma 30mm for improved VF imaging alone as you will be disappointed.

AF SPEED & ACCURACY

The HSM mechanism is exceptionally quiet, more so than the ZD's. You can 'feel' the AF working more than hear it. It sort of ticks and clunks and I found this quite reassuring. It is fractionally slower than the ZD but less prone to not locking on the target. The Sigma lens behaves in all ways just as a ZD (except for the HSM ticking - see next section) and my example seems totally accurate. All mistakes made were operator error. The distance window is more or less an unnecessary luxury; it's an 'indication' of distance in AF mode and a pretty coarse measure in manual mode. That it has no DofF scale adjacent makes it redundant; nice to have but of practically no use.

MANUAL FOCUS:

The Sigma 30mm, like Zuiko Digital's is equipped with a manual focus option (via a small switch on the barrel) and therefore a manual focus ring. On ZD lenses manual focus achieved electronically or by 'fly by wire' technology which some folks hate and others forgive! I was quite surprised to find the Sigma 30mm has a fully mechanical manual focus ring. I believe it is due to some issue with the HSM AF but I'm still researching this. Focus towards infinity is by turning the ring to the right and all focussing movement is internal (IF). Its focus ring direction is not capable of change, as it is with the ZD's. Focus confirmation (green dot) via the V/F information panel seems a little hit & miss, and is not as good as with a ZD lens. However, as you are focusing through the V/F anyway this is not a major problem. I note here that my example manually focuses well past infinity. It is highly unlikely I will use the lens in manual mode as its AF is very accurate and solid.

TEST ONE - TABLE TOP:

The Sigma 30mm arrived just in time to see the wonderful weather we've enjoyed through our British summer and so far this autumn come to an abrupt end! Typical. Today is gloomy, mist-ridden and cold so I'm going to do the first series of tests indoors without flash. The fast nature of the lens should make it at home in these lighting conditions. With any fast lens, especially fast primes used wide open, great care is needed when focusing. There is no margin for error. It's no good believing depth of field will save the day because wide open these lenses have a particularly shallow DofF. A fraction of an inch either way will easily ruin your shot.

The first set of comparisons are achieved using a simple table pose. The larger intricate ornament is 120mm in diameter by 80mm high. 'Stinker' is 55mm high on a base of 40mm square and placed about 50mm from the base of the larger model. The camera position is determined by the nearest distance that can be achieved while maintaining good AF function with no hunting or 'ticking'. Ticking refers to noise from the AF motor as it tries to lock on a subject that is fractionally too close. It produces a very quiet 'tick-tick' that you can feel through the lens barrel more than hear it for as long as the finger depresses the shutter button. If the camera is gently moved backwards the AF mechanism will 'lock on' and the exposure will be completed. This must be a feature of the HSM AF motor as I have not experienced it with any ZD's or the budget Sigma 55-200mm.

Images are straight from camera with no post processing other than resizing. There is a slight but obvious difference across the images showing a (descriptive) progression from dark, lighter, slightly lighter still, darker, darker and darkest. When I noticed this in the first series I repeated the test several times alternating between CW and ESP. The progressive and noticable difference repeated itself across these separate test sessions indicating minute equivalent exposure calculation differences.

By examining the hedgehog bristles you can see how little focus depth there is wide open. 'Stinker' endeavours to show the amount of focus lattitude available outside the immediate focus target area as the lens is stopped down.

For this 'table-top' session I've set the E-1 centre focus point on the hedgehog snout. This took several attempts and I'm not entirely convinced it is spot on here. A mode, ESP, ISO = 200, WB shady, File = SHQ; all else my standard E-1 settings which I do not change.




Exif: Image 1: f=1.4, 1/50th, comp -0.3




Exif: Image 2: f=2.8, 1/13th, comp -0.3




Exif: Image 3: f=5.6, 1/3rd, comp -0.3




Exif: Image 3: f=11, 1.3 sec, comp -0.3




Exif: Image 5: f=16, 2.5 secs, comp -0.3




Here's a 100% clip showing detail taken from image 5 above.

The tiny porcelain flower is 10mm wide.



OBSERVATIONS ON TABLE TOP TEST:

These images are certainly very sharp. Even wide open sharpness appears fine, though it needs a different type of shot to determine just how sharp the lens is. It underlines how critical the point of focus is; there is only around 25 - 30mm either side of the point of focus that is rendered as sharp, or benefitting from some DofF. The up side is that the bokeh, or 'out of focus' area, is immense and to my eyes nicely achieved by the 8 blades of the diaphragm. At f1.4 the blades do not encroach into the optical path at all so the bokeh is achieved through a true circle (barrel), by default. As the lens is stepped down the diaphragm circle becomes less of a true circle because the diaphragm opening relies on straight sided aperture blades rather than the curving assymetrical design of some of the very expensive ZD's which boast a true circular diaphragm. (I note here that there are 21 individual steps to close the lens from 1.4 to 16). All that said the bokeh is, to me, satisfactory.

OUT OF FOCUS OR BACK FOCUS?

I have recently been told the Sigma might be guilty of back focus so I decided to look over these results again. On revisiting this test and looking hard at the images from the table-top test I've got to admit slight concern. I originally stated I was not convinced the AF point (hedgehog snout) was absolutely spot on, but didn't give it as much thought as I should. Is the snout just out of focus or is this back focus rearing its head?

I repeat the critical snout focus shots and this time I back the camera off a couple of inches from the minimum close focus AF point. Making sure I use only the central focus point, I use both AF and MF to achieve an image. Between shots I change nothing but the AF/MF switch on the lens and the MF/S/C switch on the body. During this second test session I notice that at close focus minimum distance the Sigma sometimes beeps focus confirmation when it is not in focus rather than locking out (I didn't notice that first time round). Backing off a couple of inches eliminates this. Here's the two shots:


1. The Sigma wide open in manual focus.

2. The Sigma wide open in auto focus.



This extra session demonstrates the original set were just off the desired focus point, the snout, by a smidgin. I suspect my choice of position and lighting was the reason as the portion of the snout used for the AF target did not have a lot of contrast and the closeness to the subject was right on the limit of the lens focus system. It serves to underline how precise you have to be when using fast primes. The repeat test shows the Sigma 30mm will lock on and focus on the desired point without having the results affected by back focus. But I can certainly see why a few readers suggested a possible back focus issue. This was a genuine case of 'operator error'.

Looking at the full size originals of the re-test, I see a slight difference; the AF result is better than the MF, confirming my eyes are not as good as they once were. It also underlines the accuracy of the AF system. To illustrate this difference and to confirm that AF is locked on to and MF is focused upon the identical area of the subject, here are the fragments:

3. Sigma in MF mode, wide open. The slightly different position and lighting makes MF 'relatively' easy as the chosen point of focus is slightly in front of the lens' minimum close focus capability and not bang on the limit of the lens.

4. Sigma in AF mode, wide open. As said above, the new position allows the Sigma in AF to properly 'lock on' the focus point and it now beeps confirmation accurately.



TESTING FOR BACK FOCUS:

Now satisfied my example of the Sigma does not appear to suffer from back focus and for further peace of mind, I decide to test it more critically. After some research I find what seems to be an accurate test I can undertake at home. It is from Leon Goodman's site at www.leongoodman.com. I'm assuming this test will illustrate back focus regardless of camera/lens comination and results can be compared. Images on Mr Goodmans site show an example of a 'good' result from his Nikon 50mm 1.8 lens. Studying this means I should recognise a back focus problem if it arises. Using the chart supplied and following Mr Goodmans instructions I get the following result:

5. This is the result from the Sigma wide open.



Looking at Mr Goodmans example of a 'good' result, the Sigma result seems just OK to me. Fuzziness is creeping in from the right hand side but it does not encroach on a circle drawn quite tightly around the point of focus used. It seems pretty close though.


WHAT SHOULD IT LOOK LIKE? To help decide if the Sigma result is OK here's the Nikon generated image classed as 'good' by Mr Goodman. Bear in mind this is from a Nikon f1.8 after adjustment to give optimum results:

6. Many thanks to Leon Goodman to whom this image belongs. All copyrights vest in Mr Goodman.



And the result from the Sigma 30mm f1.4 above, cropped and re-sized to match the Nikon result for ease of comparison.

7. Result from the Sigma wide open re-sized to approx the Nikon dimensions.

To be absolutely sure I found an alternative method detailed at this site www.focustestchart.com, again Nikon inspired but can be used to test any lens/camera. This method seems more precise than Mr Goodmans. It's not complex by any means and only takes a little time and thought to get it right. Please have a look. Here is the result from Tim Jacksons test done as accurately as I could.

8. Result from the Sigma wide open in accordance with author Tim Jacksons' instructions.


BACK FOCUS TEST COMMENTS:

I realise images 6 & 7 above should not be directly compared as different setup will cause different results. I show it only to illustrate what a 'good' result should look like. In the image from the Nikon, the point of focus target appears to be evenly encircled with an 'in focus' circle. Any fuzziness is approaching equally from both left and right (the back focus area). On the Sigma image the fuzziness is less central and closer to the target area from the right. Importantly, the chosen point of focus seems free from any fuzziness.

The test using Tim Jacksons method (image 8 above) gives a almost perfect result. In my experience Olympus lenses do not have any back focus problems and the results from the above tests suggest the Sigma 30mm is similar. Perhaps the too close to the subject focus problem I accidentally identified, or mistaken point of focus have been repeated elsewhere and back focus seen to be the culprit? Would owners of Sigma lenses used on E-system cameras who think they have a back focus problem please contact me for an exchange of view.

TEST TWO - GREENHOUSE FLOWERS:

This section looks at the Sigma 30mm x 1.4 results next to the same shots taken with the ZD14-54mm zoom with the objective of demonstrating the difference between a fast fixed focal length lens and a pro-level zoom. Our UK climate makes lens testing a nightmare. For these shots I've moved into our greenhouse for although the sun has decided to appear the wind is up thus making any garden shots unreliable. This geranium is late flowering (it's mid October) and will make a reasonable subject.

Exif: Greenhouse Geranium: Sigma 30mm @ 1.4

Exif: Greenhouse Geranium: Sigma 30mm @ 3.2 (same as ZD14-54 wide open at 31mm).


Exif: Greenhouse Geranium: Sigma 30mm @ 5.6


Exif: Greenhouse Geranium: ZD14-54mm @ 3.2 - wide open


Exif: Greenhouse Geranium: ZD14-54mm @ 5.6


LH corner fragment at 100%. This is from the Sigma wide open; it's a tad soft as you might expect and bear in mind that the flowers to the bottom left of the subject may be slightly out of the very narrow zone of focus at maximum aperture. Not a bad result at all.


LH corner fragment at 100%. This is Sigma at 3.2 for comparison with ZD14-54 wide open. See how much it has sharpened up demonstrating the Sigma is sharper than the ZD at the same aperture.


LH corner fragment at 100%. This is Sigma at 5.6 - very sharp indeed; certainly sharper than the ZD at the same aperture.


LH corner fragment at 100%. This is ZD14-54 wide open (3.2) it is slightly sharper than the Sigma at 1.4 (not surprising) but not as sharp as the Sigma at the same aperture.

LH corner fragment at 100%. This is ZD14-54 at 5.6; it is definately not as sharp as the Sigma at the same aperture.


OBSERVATIONS ON GREENHOUSE FLOWER IMAGES:

I've not got much to add to the running comments above. The results are in line with my expectations; the Sigma is a good performer producing acceptably sharp images even wide open. Certaintly, as the Sigmas aperture closes the image sharpens considerably with the image at f5.6 it is very sharp, almost to the point of rendering a 3-D like quality. At 1.4 corner detail is a tad soft but acceptable to this user anyway. Across the apertures generally colour is not rendered the same as the Zuiko Digital lens, but I don't profess to know which is the more accurate; the difference is present, but marginal. Metering seems slightly off with the Sigma is mounted; more or less always demanding some minus compensation above that of the ZD. As a general comment from my limited experience to date I'd say with the Sigma 30mm mounted the E-1 is prone to slight exposure miscalculations, but again we are talking marginal differences that would be unnoticed in anything but a repetetive testing situation. (It's behaviour reminds me of the way OM Zuiko's behave, though obviously not as pronounced). This comparison between the Sigma and the ZD14-54mm is hardly fair but still enlightening and demonstrates what we already suspected - that the prime is sharper than the zoom. (Let me point out here that I did not expect 'razor sharp' images at f1.4 from a sub 300 lens). That the Sigma 30mm will deliver acceptably good images at two stops faster than the ZD14-54mm (at the same focal length) will make it a very attractive addition to many photographers lens armoury.

TEST THREE - SIGMA 30mm WITH ZUIKO DIGITAL EC14:

I've no doubt there's a lot of interest in this lens and for those contemplating its purchase I suspect one consideration will be how it interacts with the ZD EC14 teleconverter. With this in mind I dedicated several hours to trying just this combination and I've got to say the results were disappointing. In general the 30mm requires at least minus 0.3 compensation if not minus 0.7. With the EC14 mounted I had to double the applied compensation to hold the highlights. In addition the Sigma on its own does not produce quite as good colours as the ZD zooms; with the EC14 the lighter colours seem more washed out and rather insipid, yet the darker colours (in certain cases) became colder and darker. I examined many sequenced shots taken that afternoon and the effect was repeated in all, but not at a consistent and predictable level. I used the Sigma at F=4.0 for all the sequences though it didn't matter what aperture I chose the results were the same - definate colour 'shifting'. Bearing in mind my friend Andrzej Wrotniaks expressed concern about automatic white balance, I also experimented using various WB settings other than AUTO (which I normally find very reliable). This too made no difference; it seems the Sigma 30mm (at least my example) is not in quite tune with the EC14. Here are some examples of the problem I encountered:

Here's a pond shot, tripod mounted, without the EC14:

Exif: 30mm F1.4; FL=30mm; f=4.0; 1/160th; comp = -0.7; ISO 200; WB = AUTO; CW.

This appears to be fine (remembering there is -0.7 compensation applied)

Here's the same shot a few seconds later with the EC14:

Exif: 30mm F1.4; FL = 42mm; f=4.0; 1/100th; comp = -0.7; ISO 200; WB = AUTO; CW.

Simple addition of EC14 results in this apparent over exposure.

What's going on here? At first I thought it was the composition perhaps fooling the meter (the presence of sky in the upper portion).

So the test was repeated with these windfall apples. Here there's no bright areas in the frame but the over exposure still occurs though not as pronounced.

IMAGE 1: Exif: 30mm F1.4; f=4.0; 1/60th; comp = -0.7; ISO 200; WB = AUTO; CW.

And here's the same shot from exactly the same position with the EC14 a few seconds later:

Image 2: Exif: 30mm F1.4; f=4.0; 1/40th; comp = -0.7; ISO 200; WB = AUTO; CW.

And the same shot from exactly the same position with the EC14 with -1.3 compensation applied to try and hold the highlights.

Image 3: Exif: 30mm F1.4; f=4.0; 1/50th; comp = -1.3; ISO 200; WB = AUTO; CW.

OBSERVATIONS ON TEST THREE:

In this series the over-exposure does not appear as dramatic as in the pond shots above but it is still there. Notice the highlights of the apple skins in the pale sunshine are well exposed in shot 1, are lost in shot 2 and almost preserved in shot 3. See also how the colours 'shift' from shot 1 to shot 2 with the same settings. In image three with twice the compensation applied the exposure looks about right, but the colour shift is still noticeable. (Having just accessed this article on my wifes PC the colour shift to which I'm referring is not noticeable on her monitor. The best way I can describe it is a 'cooling' of the predominant colour; as if more blue had been added. I will try to provide images that show this shift better).

I suspect the exposure difference is partly due to the telephoto effect of the EC14 filling the frame to a greater degree thus altering the exposure calculation though I can't explain why this should always result in an over-exposure. I believe the colour difference may be due to dissimilar coatings. Zuiko Digital lenses will have a range of coatings that react in predetermined ways specified by the lens designers. The affects of mixing these coatings will have been tried, measured and adjusted to give a predictable outcome, much as I found when I tested the EC14 here. Perhaps introducing an unknown coating into the equation throws the results. I'm no physicist; this is the only explanation I can think of.


FRAGMENTS FROM WINDFALL IMAGES:

Clip from image 1 above - taken by Sigma without EC14 (viewed at 400%).



Clip from image 2 above taken by Sigma + EC14 with -1.3 compensation applied (viewed at 300%).


OBSERVATIONS ON FRAGMENTS FROM TEST THREE:

The fragments above are of exactly the same area - the point of focus - clipped from 'Windfall' images 1 & 3 above and equalised in size for ease of comparison. The first is from the Sigma 30mm without EC14 showing good colour rendition. It is not as sharp as the second (Sigma 30mm + EC14) because it has been increased by 400% as opposed to 300% to reach the same size. In accordance with other tests I've done with the teleconverter, the EC14 appears to lose no resolution in combination with the Sigma 30mm.


TEST FOUR - RANDOM IMAGES:

There follows a few 'ordinary' shots I've captured with the Sigma 30mm. It's been quite a while since I used a fast prime lens and find it is very easy to forget the dicipline needed to use one correctly. I believe it's going to take a few weeks before I feel totally at one with the combination of the Sigma and E-1. But I enjoy using this lens - it is challenging in many ways and having to use your mobility instead of the zoom ring is quite refreshing.

Exif: 30mm F1.4; Mode=M; f=9; 1/125th; comp = 0; ISO 200; WB = 5300K; CW; Fill-in Flash



Clip from the centre of this delicate hand painted plate - there is no more detail than this!



Exif: 30mm F1.4; mode = A; f=4.5; 1/640th; comp = -0.7; ISO 200; WB Auto; CW

OBSERVATIONS ON RANDOM IMAGES:

You can see from the flash image of the plate just how sharp the Sigma is; I've looked at the flower details with a powerful glass and literally there is no more detail to be seen than that recorded. The clip is a perfect representation of the central area; it has the fuzzy quality shown which is caused in the firing. Incidentally I've taken to using a flash system posted by Ben Herman which is simple and extremely effective - Camera in Manual, FL50 flash in TTL, ISO 200, shutter 1/125th Aperture between f7.1~9.0, flash compensation + 0.7~1.0. I highly recommend it.

The portrait pond shot shows how well the E-1 held the exposure across a nightmare scene of lighting extremes. There is some detail left in the shadows and yet the highlights are more or less preserved. Also, notice again the need to apply -0.7 compensation.

BARREL DISTORTION:

Having made myself a test board I can now post an image of the Sigma's performance in the areas of image distortion. It's a little crude but it serves the purpose, for now anyway. The board is level and plumb. The camera is tripod mounted and moved toward the target until the outer lines are hard up to the viewfinder edges. The tripod is levelled on the bubble, any final adjustments to the point of focus and level are made and when all appears right in the V/F the image is taken using the remote control.

Sigma 30mm F1.4 at f=2.8. There is barrelling though it's not offensive. In all but architectural shots you will probably not notice it.



OM Zuiko 28mm x F=2.0 at f=2.8. This is the nearest lens I have to the Sigma. Less barrelling than Sigma but only marginal.

OBSERVATIONS ON BARRELLING:

The Sigma is displaying a small amount of barrell distortion that must be expected as it is a wide angle lens after all. However, the distortion seems quite well controlled. I estimate it to be less than 1 degree at the periphery of the image. The OM Zuiko performs at roughly the same level in the same test with maybe 20% less barrel distortion than the Sigma. I intend to repeat these tests later with a better target.

OPINION:

I alluded earlier to the Sigma 30mm meeting 'most' of my expectations. My only concern is that of its tendency to cause over-exposure. In all but a few shots I've consistenly had to apply minus 0.3, 0.7 or 1.0 compensation. I admit I regularly apply minus compensation to virtually all my images regardless of lens used, so I suppose an extra bit of tweaking isn't any major hardship. I suppose I expected to have the same response from this lens as from my ZD lenses - after all they are all constructed within the tightly drawn 4/3rds standard. It's not a huge criticism; more a small niggle. I'm disappointed in the Sigmas performance when coupled with the ZD EC14 though it will not affect me directly as I will not use this combination. Simply put the combination does not work well and this is made worse by the unpredictable nature of the results. It seems the EC14 exacerbates the general slight concern I have with the Sigma 30mm - a tendency to over-expose and take the edge off colour richness.

SHARPNESS: The results above speak for themselves. This lens gives very sharp images, no doubt.

CONTRAST: The Sigma 30mm is not quite as contrasty as the ZD range. It is contrasty enough for me for I find some of the ZD's too contrast laden, but your opinion may differ. If used in combination with EC14 contrast levels appear to fall off slightly.

COLOUR RENDERING: I've only had this lens for a few weeks. My general impression is it produces slightly less saturated images and marginally paler images than ZD's. I've not tested it in wildly differing lighting conditions so I cannot say how it might respond in various conditions. I'm more than happy with its rendering capabilities - it is just different to the ZD's colour performance to which I've become accustomed. If used in combination with the EC14 colour rendition appears to diminish.

RESOLUTION: The optical resolution of this lens well out-performs the E-1's 5MP CCD and the E-500's 8MP. I do not consider it's in the same class as the ZD7-14mm but I'd certainly put it in the same class (resolution wise) as the ZD11-22mm. I think it will be some time before sensor capabilities outstrip the Sigma 30mm x 1.4. Remember, I'm not a physicist, so please don't ask me to qualify my opinion.

CHROMATIC ABBERRATION: Generally the 30mm is free from CA. Yes you can force the error but that applies to any lens. For 98% of situations I believe this lens has no major CA issues.

BARRELLING: The 30mm displays a very small amount of barrelling; not sufficient to be concerned about.

FLARE: I had no serious issues with flare. Again used insensitively it will flare, no doubt. The petal hood does its job most of the time.

HANDLING: The way a lens handles is more of a personal thing than a measurable quality. The 30mm suits my style of photography and my hands. It is under-square and chunky which to me is attractive and leads to better handling.

PRO'S

1. Sharp

2. Fast & bright

3. Solid, reliable AF

CON'S

1. Price - rather expensive for a 'standard' lens though it is fast.

2. Some incompatibility with EC14

FINAL COMMENTS:

I must repeat my comments throughout the article about precise point of focus and being aware of the very 'thin' depth of field at wider apertures. It is easy to be caught out, as I adequately demonstrated!

I'm now perfectly satisfied with my purchase both in terms of now having a true 'standard' lens and the lens performance which, I've got to say, meets and/or surpasses my expectations in most ways. I did have some misgivings when the 'back focus' issue was raised but am now satisfied that my example at least does not suffer this. As regards the EC14 issue, it's not likely I'll use the Sigma 30mm in regular combination with the EC14 as this rather defeats the object of buying the Sigma 30mm in the first place. This latter problem is not going to detract from my initial excellent impression of the lens. Inherent aberrations like barrel distortion seem well controlled and minimal. The Sigma 30mm x 1.4 is a relatively simple piece of optical engineering and maybe there's a lesson here. The more surfaces that go to make up a lens' optical construction and performance the more the chances of importing a bad surface in its manufacture. There's a lot of truth in 'the simpler the better' and I'm sure this is why this lens is so good at its job. And it is very good indeed.

ACTUAL PRICES:

UK 330; US unknown.

NOTE: This article seeks nothing other than to inform. Only you can decide what equipment you want/need for your use. Bear in mind I own these lenses, out of my own pocket; I have nothing to gain or lose by publishing this article, photographs, examples or opinion.


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Posted October 2006 Copyright © 2005/2006 John Foster