Tag: correction

Using the 10-18mm OSS zoom on full frame

Posted on By

The Sony E-mount (not FE) 10-18mm f/5 OSS lens can be used effectively on full frame for creative work and within limits for technically more demanding shots. Below, an uncropped A7R shot of the concourse at Abu Dhabi Airport, taken at 13mm setting, f/6.3 with my lens profile as provided below. Check the straight lines in the floor tiling, if you doubt that this lens would be of any use for architecture.

However, you don’t get this without a lens profile, and without due care to limit the focal length to a range of 13 to 16mm – not the full 10 to 18mm. Below, you could get this if you try 12mm straight out of camera…

uncorrected12mm

This is a pretty awful case of vignetting and distortion – as you would expect. It’s from an APS-C format wide angle zoom, the 10-18mm f/4 SEL OSS lens for NEX, used on the Alpha 7R full frame mirrorless body. Early in the launch period of this camera, various far more attractive images appeared on-line using subjects like roads, rail lines, beaches and even shop counters where the lines look straight – rather like that drainpipe – because of where they fall in the shot. As you can see, anything with a horizon near the long edge of the framewould have given a very different impression.

However, Adobe offers a free utility which enables you to make lens profiles to correct vignetting and distortion.

I created a lens profile for ACR/LR using full frame and the 10-18mm on the A7R. The vignetting is such that the profile creator really can’t handle it, and overcorrects the extreme corners as a result. I’ve done f/4, f/8, f/16 at 12, 14, 16 and 18mm focal lengths using an A2 chart; for a lens like this, a much greater working distance and an A0 chart would really be desirable. The link below is to a zip file of the Adobe Lens Profiles I produced – for A7 and A7R, with .lcpp files for final use, and .lcp files for different settings of the 10 18mm I found useful.

10-18AdobeLensProfiles

corrected-customprofile12mm

At 12mm you can probably see the vignetting artefacts in the corners, the magenta corner shift and incomplete correction of the horizon line. You’ll also be quick to spot that the 12mm coverage has been reduced to something much less, lens profiles always reduce the field of view (they can not do otherwise).

The profiler simply can’t handle the degree of sudden fall-off in illumination given by the 10-18mm used on full frame. Manual distortion corrections can actually do a better job. At other focal lengths, the profile I’ve made works well enough, and if the frame is cropped slightly (still exceeding the APS-C area the lens is designed for) it’s possible to get good results and wider angles.

I have sold my Sigma 12-24mm HSM II which was used with the A99, and also sold a Voigltander 15mm f/4.5 I bought to test (zero cost fortunately, as it made a small profit between Gumtree source and eBay destination). The Sigma was not only very difficult to focus using CD, its HSM motor won’t play with Sony CD.

My .lcp full-frame file can be downloaded from:

//www.photoclubalpha.com/AdobeCameraProfiles/ILCE-7R FF (E 10-18mm F4 OSS) – RAW.lcp.zip

Just for good measure, here is an uncropped A7R 13mm focal length shot of the church of Maila Dumpara in Kerala taken to use dramatic converging verticals – which fail terribly unless the lines are properly corrected, the last thing you want in a strong upward angle is lens distortion. It’s very stiff test of any lens to do this. I have left the vignetting uncorrected. I rather like it. Click either this or the Abu Dhabi photo and you’ll get a larger image, about 1000 x 1500 pixels.

Samples produced for a dPreview forum question

There’s been a lot of discussion on dPreview forums of which lenses work on full frame E-mount, as Sony saw fit to put a Disable APS-C crop option in the menus of the A7 and A7R (almost as if they wanted owners to experiment). They have made other welcome changes of a similar kind which I’ll cover in a full review of the camera – which I can not do yet as I have no FE mount lenses for it, and with the current choice and prices, I can see I may never use FE mount lenses on this camera.

So, to answer some questions on dPreview’s E-mount forum, I posted these images and comments.

Here is a ‘native’ uncorrected shot of a local building taken on the 10-14mm on A7R at 11mm, f/10, ISO 100:

View: original size

Here is the result of using the profile, doing a crop and some straighten of slight rotated tilt, and pulling the scale down (with the profile applied, the roof apex is clipped off at the top as the lens has so much distortion its 11mm probably becomes more like 15mm when corrected):

View: original size

I’ve used some clarity and local burn adjustments on the sky to treat the image more or less as I would (except that I wouldn’t actually photograph this building at this time of day, with blinds drawn, etc).

For me, the 10-18mm on A7R with our without the profile correction offers the same options as using assorted lenses on 5 x 4 sheet film. It never mattered whether a 47mm didn’t cover the entire film, you got an image circle and could use whatever part of it you want. At 10mm the image, with the profile used, has strong corner cut-off but the overall circle of usable image greatly exceeds APS-C provided you stop down (f7.1 seems just OK, f/10 is maybe optimum, I’d certainly try f/16 despite fears of detail loss).

View: original size

The red crop mark is square – my ‘Hasselblad SWC killer’, as the classic SWC had just a 38mm wide angle lens. You needed to get an Arcbody with 35mm Rodenstock to go any wider on 56 x 56mm film (6 x 6). With the A7R and 10-18mm at 10mm, you get the equivalent of a 24mm lens. Not a 24mm fisheye on 6 x 4.5 like the widest ever offered by Mamiya… a 24mm rectilinear on 6 x 6.

The yellow crop mark represents a significantly larger area than APS-C (which is actually just a little under the 24 x 24mm square in width). It is shifted vertically, as if the lens was being used as a shift lens. If only the APS-C area is considered, its approximately 16 x 24mm area can be positioned right to the top of the frame, equalling a 4mm rise, or the equivalent of using a 6mm rise on a full-frame PC lens (most actually go to 11 or 12mm rise). There is only one lens made which can compete with this, and that’s the Canon 17mm f/4 TS. Admittedly this is a superb lens and when stopped down to f/11 and used on the 6D (Canon’s most shift-friendly sensor) will blow this result away for clean rendering of detail toward the frame edges.

And then, you can still use the 10-18mm in APS-C crop mode as a snapshot wide angle with pretty much perfect correction (Adobe’s own Sony profile for APS-C), for videos too.

– David Kilpatrick

3
DK's ramblings, Lenses - E mount, NEX System, Photo Techniques, Sony Digital Cameras, Sony Digital Csmeras, Uncategorized

Free software and a cut-price lens

Posted on By

You have until November 3rd to grab a free download of a truly excellent utility for Mac OSX, created by DxO Optics Pro software team – DxO Perspective. It normally costs $19.95 (or local equivalent) as an Apple App store download, but they have made it free for a few days. It’s a fully working, standard version with no time limit.

Download link for DxO Perspective from Apple iTunes, free until November 3rd

Here’s what they say:

“DxO Perspective corrects all kinds of perspective problems, even the most complex. Using its Rectangle tool, when a photo contains two perspective flaws, DxO Perspective’s Rectangle tool immediately reestablishes a full-frontal view of the object — essential when shooting a photo of a poster or painting! In 8-point correction mode, DxO Perspective handles even more complex perspectives: the independent placing of horizontal and vertical guidelines provides highly precise corrections on multiple planes.”

We can vouch for that. Here’s the software window with a straight shot, uncorrected, Sigma 12-24mm zoom on Alpha 99 at 12mm.

perspective-addpoints

Now on this example, you have a choice of adding points to correct both vertical and horizontal perspective (four indexes clicked/moved) which I have done if you examine the faint blue lines, and this will produce an extreme result:

perspective-extreme

However, for this example, you would normally onle correct the verticals and omit the four-square connections. This produces a natural result relative to any other correction method:

perspective-final

This is a 100% correction. DxO Perspective lets you reduce the degree of correction. Here is what they describe as a ‘natural’ look, 75% strength:

perspective-natural75percent

I preferred the result between 90 and 95% correction.

Midi-Pyrenees

You may ask how this differs from Adobe Camera Raw lens correction perspective control, or similar functions within Photoshop (without using special plug-ins). First, DxO Perspective is a stand alone program and does not need Photoshop, it only requires a JPEG to select and work on. Secondly, here’s the result from ACR/LR type correction, kept slightly on the ‘natural’ side of :

Midi-Pyrenees

The greatest difference is that DxO Perspective makes automatic corrections to the vertical aspect and retains the sense of height, at the same time ensuring that the sky is not compressed.

So, enjoy this free download until November 3rd 2013.

At the same time, from 12.00 midnight Eastern Standard Time on October 31st, B&H in New York announced a drop in the price of the Bower (aka Samyang) 8mm f/3.5 fisheye lens for NEX, MicroFourThirds, Samsung NX, Nikon, Canon EOS, Pentax and Alpha mounts – down to as little as $209 for Alpha or NEX:

Bower 8mm fisheye for NEX – but see below!

Bower 8mm f/3.5 lenses from $209

Buy through this link and you support Photoclubalpha in a small way without paying anything extra yourself (indeed, buy any other B&H item after following this link and it will help us).

Here is some advice. The NEX model is basically an Alpha mount optical assembly with a permanently built in extension tube. We advise you to buy the Alpha version, as this is a manual focus manual aperture unchipped lens – use a NEX to Alpha adaptor, doesn’t have to be the expensive official LA-EA1 as this lens uses none of the connections. Then you have a lens which can be used on two systems.

DxO Perspective does not offer a de-fishing function but we’d make a guess that this would be a likely upgrade to the program in the near future and that’s why they are giving it away. DxO Optics Pro software itself is, after all, famous for the inclusion of lens profiles before any of the other programs (or cameras) got this facility.

– David Kilpatrick

 

1
Lenses - Alpha Mount, NEX System, Offers, Software Reviews

NEX, A33, A55 support – new ACR 6.2/LR3.2 final

Posted on By

The final release of Adobe Camera Raw 6.2, DNG Converter 6.2 and Lightroom 3.2 includes raw conversion support for the Alpha 33 and 55 models as well as the NEX-5 and NEX-3, Alpha 290 and 390 which were included in the Release Candidate versions. These August 30th releases are final version, RC versions are a form of beta test.
The bad news is that anyone using the LR3.2 RC as a temporary free solution for getting full profile correction without investing in Photoshop CS5 will lose their freebie. But Lightroom is eminently affordable, and it can function as a raw conversion front-end for any earlier Photoshop or Elements version. On its own, it is a mere 10MB of program data fatter than Adobe Camera Raw as a plug-in and runs with great efficiency on modestly specified laptops (etc). It’s a lean, keenly priced solution which offers many further benefits as a DAM (Digital Asset Management) library such as keywording, copyright control, metadata editing, version stacking and multiple catalogues.
http://www.adobe.com/support/downloads/new.jsp
I am informed that support is included for the 16mm lens on NEX (profile) but I can’t tell whether it is the profile I supplied to Adobe Labs, or a new one, because my profile has remained unchanged on my system – same names, same modification date. And there’s no NEX-3 version which might be expected if they had created new profiles. So it looks as if it could be worth sending profiles into Adobe after creating them.
It’s fantastic news that Adobe has released ACR for the new Alpha 55 16 megapixel sensor before the cameras even hits the street – mine is on order, waiting! Not so great for Nikon users; no D3100 raw conversion in this release. But Canon users get the 60D (despite Adobe missing it out from their front page list). Adobe did this Sony friendly pre-release once before, for the Alpha 100, getting the conversion into place before the camera went on sale.
The bad news is that the Alpha 580 and 560 models are not in the list alongside the fixed mirror pellucid, transflective (anything but Translucent, please…) cameras.
The instruction manual for the Alpha 33 and 55:
http://esupport.sony.com/US/perl/model-documents.pl?mdl=SLT-A33&region_id=1
is already on-line and shows a March 2010 publication date, which means that Sony has had these new cameras in existence since the beginning of the year, certainly well before PMA when mockups were shown. It’s likely that Adobe’s Thomas Knoll has been using one from the first bug-free pre-production model onwards!
Now all we need is the revised lens series with SAM or SSM motors fitted into the 16-80mm CZ, 16-105mm Sony, 18-200mm and 18-250mm Sony; the 11-18mm wideangle replacement, the 75-300mm SAL replacement, and a few other goodies. Hopefully all Zeiss glass gets SSM where possible. That 16-80mm CZ is four years old now as a design. A tweak to the maximum aperture, or the zoom range, would revive interest.
– David Kilpatrick

4
Cameras (DSLR), NEX System, Software Reviews

Adobe Lens Profile for 16mm f/2.8 NEX

Posted on By

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


3
Lenses - Alpha Mount, NEX System, Software Reviews