Photoclub Alpha

Continuing to make profiles when time permits, here is a reasonably detailed profile for the Sony DT 16-80mm f/3.5-4.5 ZA Carl Zeiss zoom (2007) created using the Sony Alpha 550 14.2 megapixel camera using Manual Focus Check Live View at 14X to set the lens focus and ensure the chart is positioned to use 100% of the frame.

http://www.photoclubalpha.com/DSLR-A550 (DT 16-80mm F3.5-4.5 ZA) – RAW.lcp

Right click to download this 56Kb file which should be placed in the Lens Profiles/1.0/Sony folder of the directory on your computer which holds Adobe Lens Profiles.

This profile has been created at full aperture and f/8-f/11 depending on focal length, at 16mm, 24mm, 35mm, 50mm and 80mm focal lengths and involved 90 raw captures.

It is possible in ACR/Lightroom to use profiles which are not created on your own camera type. This profile can be applied to any APS-C Sony or Minolta camera using the 16-80mm lens; because the A550 is currently the highest resolution body, the CA data gathered is more accurate than would be possible using a lower resolution body but may need a saved adjustment in defaults. Individual lenses differ slightly and may also need adjustments.

I have checked the operation of the profile on files from A100, A700, A200, A380, A350 and A550 and it’s very effective in removing CA. Illumination is much improved at 80mm (notably). You may prefer to turn the geometric correction down to zero (off) when the angle of view matters more than perfect straight lines – and also, where people are in the shot near the edges at 16mm. The distortion of the lens is optimised to lessen ‘stretched faces’ at the ends and corners of the shot, applying the profile removes this slight barrel distortion and does not improve groups. It’s most useful for horizons, rooms, seascapes, and subjects where a good straight rendering is critical.

It has been suggest I should add a donation button for these profiles. By all means see our subscription page, there’s a downloadable PDF of the latest Photoworld magazine for $3. I could easily have zipped profiles and sold them in the same manner, but that is not why photoclubalpha is here; Adobe provide the software to do this free (OK, I know what the rest of their stuff cost me…) and profiles should be made public domain by creators.

- David Kilpatrick

Although it’s far from a perfect lens, this small 1999 Minolta RS optic is my favourite for general travel and everyday use on the Alpha 900. It is a convenient size and weight, performs well when stopped down a little, and has exactly the range and minimum focus I need.

Mouseover image to see effect of this profile used on a shot taken at 70mm focal length.

The profile created for ACR6/LR3 is at four focal lengths – 24, 35, 55, 85 – and two apertures, wide open and f/9. The chart distance ranges from about 120cm to about 4m.

To download:

http://www.photoclubalpha.com/DSLR-A900 (24-85mm F3.5-4.5) – RAW.lcp

Right click and save. Correction of CA and distortion is pretty good, and this profile identifies itself correctly as a Minolta lens. It should be placed in the Sony directory of Adobe Application Support>Camera Raw>Lens Profiles.

- David Kilpatrick

I have made a simple (f/2.8 and f/8 chart set) Adobe Lens Profile for the 16mm f/2.8 NEX E-series pancake lens. It seems to work well for closer distances, because that’s how it had to be made; CA is reasonably well corrected, vignetting is eliminated, and distortion of closer lines – maybe if you are looking through a door frame, etc – is very accurate. The profile was created using NEX-5 and 16mm.

You can get this profile here:

http://www.photoclubalpha.com/Sony NEX-5 (Sony E 16mm F2.8) – RAW.lcp

Right click to download/save the target file, and install this in:

Library>Application Support>Adobe>Camera Raw>Lens Profiles>Sony

Uncorrected 16mm shot

Using Adobe Camera Raw 6.2 RC with the profile active at default settings

JPEG profile added (17/08/10)

I have now added a JPEG profile from the same set of images as the raw – this is lucky, I didn’t think people would need a JPEG profile but happened to have the camera set to RAW+JPEG when the test shots were made, and this has been requested for those using HDR or other JPEG-only modes.

http://www.photoclubalpha.com/NEX-5 16mm JPEG.lcp

Above: HDR three-shot with 16mm, straight JPEG

HDR shot opened in Camera Raw without adjustments, but with the Profile enabled

Using the profiles

A full Adobe Profile is undertaken at several focus distances, apertures and zoom settings (or for prime lenses, just at a range of distances and apertures). The largest chart I can print is A2+ using the Epson 3800, and with a 24mm equivalent lens, this means having the camera surprisingly close to the target. The profile is therefore only 100% correct for subjects at 115cm from the camera, which corresponds to the 4X minimum focus distance suggested by Adobe.

I have found from using the 16mm that its optimum aperture for central sharpness is probably f/5.6, and that chromatic aberration and vignetting do not improve at stops smaller than f/8. There is a slight improvement in detail sharpness in the extreme corners at f/11 and f/16, but this is due to extra depth of field helping to cover a curved focus field. I therefore made test sets at f/2.8 and f/8 for this profile.

The geometric distortion is most visible with closer subjects such as the subject above (The Slave Girl, a bronze c. 1870 by John Bell, at Cragside House in Northumberland). This is a hand-held exposure of 1/4 at f/8, and is perfectly sharp despite the lack of stabilisation; every word of the interpretation can be read at 100%. I have found most shots are perfectly sharp with the 16mm given reasonable care, as you would take with a Leica, to breathe correctly and make a shake-free exposure. This is not the case with SLRs where the mirror action nearly always causes shake.

For more distant subjects, the 100% default setting of the ACR/LR Lens Correction panel can be reduced and where there are few straight lens removed entirely to secure the maximum field of view. Similarly, the vignetting correction can be reduced or removed entirely as the natural darkening towards the corners with this lens is attractive.

Although this profile is named to match perfectly the naming convention used by Adobe for the 18-55mm, I find that ACR 6.2 can not be relied on to use it for Auto as a default (if you work with more than one lens, Adobe Lens Correction soon proves unpredictable in this anyway). If you select Auto, then select Sony, the lens profile will be selected but the Auto button changes to Custom. If you then save new Lens Correction Defaults, or Camera Raw Defaults, ACR will attempt to force this profile on the 18-55mm and the reverse will also happen. So it’s necessary to check which profile is selected. Using ‘Previous Conversion’ for shots taken on the same lens is a quick way to get there.

The additional Manual Controls can be used on top of the profile (the second tab of the interface). The most useful are the geometric distortion (camera angle) corrections. The Chromatic Aberration/Colour Fringe controls can be fine tuned as the correction for CA while very effective relates only to the tested focus distance. CA may change with focus but my particular lens doesn’t seem to suffer from this. All that is necessary is to enable Defringe All edges as a default, and this will remove any hint of colour remaining. As a tip, setting Colour Noise Reduction to a high value can help remove CA and purple fringes in many shots processed through ACR/LR. The colour NR detects 1-2 pixel fringes just the same way it detects individual pixels, and neutralises much as it does noise.

- David Kilpatrick

OVER the past few days I’ve been looking at the NEX-5 and a range of lenses and optical systems. I’ve got adaptors for C-mount (16mm/TV/CCTV) lenses, Leica 39mm screw, Minolta MD and the LA-EA1 for Alpha A-mount. The NEX-5 has proved able to provide a surprisingly bright focusing image through a classic German microscope:

It also proved very competent with the Sigma 70-300mm f/4-5.6 OS lens, the adaptor providing power for the OS which is fully functional, and also for auto exposure, leaving only manual magnified focusing to tackle.

Sony, which has a UK event taking place on Thursday July 15th showcasing new products for the Christmas market, has surprised us by launching its NEX mount HD camcorder with 14.2 megapixel CMOS sensor and 18-200mm OSS interchangeable lens much sooner than anyone expected.

SONY has shown itself to be lagging behind the competition as we reach the third bend on the second lap of the development of HD-video capable DSLRs. At PMA 2010, nothing ‘real’ was shown and the closest they came to further launches in the Alpha range was an advanced pre-production prototype of a 24mm f/2 Carl Zeiss T* ZA SSM.

But Sony may prove yet to be the tortoise – or perhaps to be Brer Rabbit. They could make the finishing line, the goal of a truly useful video DSLR, before Nikon/Canon/Pentax/OlySamPanny get there.

TOKINA lenses – the brand name for optical giant Hoya’s interchangeable range – have always been renowned for their tank-like build quality and resistance to plastic trends. They compare so well with Nikon’s own lenses it is hard to tell the difference by feel, and the current design also matches Nikon more than it does Canon.

The latest news is that Tokina is to introduce the 11-16mm ƒ2.8 in Sony Alpha mount. Tokina stopped making Minolta mount lenses shortly before their parent company Hoya acquired Pentax. The Tokina factory has been producing

The Alpha System celebrates its Silver Jubilee or 25th Anniversary this month.

We have a full length revision of the article which appears in the latest Photoworld now online as a page here.

Read our 25th birthday review of the Alpha system’s history now!

Sony has announced the Alpha 850 today, without a press conference, but via email to editors. The press release follows, confirming pretty much everything we have already been able to reveal about the 850. One exception – it does have dual BIONZ processor, not single, just a slower image throughput perhaps due to clock speed, buffer, processing firmware changes. We must hope that the slower capture rate is accompanied by superior image quality, as that is a real possibility. I have marked in bold any phrases which I think might indicate something new. Apparently the body-only deal is to appear one month before the kit.

Tamron’s 18-250mm lens – later adopted by Sony – was so good that it really takes some effort to beat it. Sigma has put that effort in, but the cost is a very much larger and heavier lens. If all you got was some better performance, it might not be all that exciting. But you get potentially superior anti-shake through its built-in OS, and faster focusing with HSM, the Sigma equivalent of SSM.