Media Technology

Drag racing photos from Match Race Madness #4, at the Barona Drag Strip in Lakeside, CA. All pictures were shot with the Sony a7R, using a Pentax 28mm f/3.5 camera lens.

Taking action photographs with the Sony a7R is a challenge, because of the long shutter delay of at least .163+ of a second. Compensating for that delay meant hitting the shutter release early, in anticipation of where the apex of the wheelstand would be in the future. That procedure works here, after a fashion, but it won't work for shooting all types of action photos with the a7R.

Most of these drag racing pictures were shot at 1/2500th of a second, f/8.0 aperture, with manual focus carefully preset to the area where the wheelstand was probably going to be. The Sony HVL-F60M flash was set to full 1:1 manual power, using high speed sync, and it was mounted to an external flash bracket.

Prints of these drag racing photos can be obtained from Pete Liebig, the Barona track photographer, at: http://peteliebigphotography.smugmug.com/

Dan Euritt

Anza Borrego Desert pictures, from the mouth of Torote Canyon, and further up the road to Indian Valley. The camera being used was a Sony a7R, with a Pentax-M 28mm f/3.5 lens on it.

The road into Indian Valley is fairly easy, any pickup truck should be able to make it, with careful driving over some of the rocks. This was a mid-week visit, in the middle of April. There are a few palm trees to see, but on this visit, there was also an inordinate number of flies, which necessitated camping back down the road.

This third round of 24mm camera lens testing on the Sony a7R will focus on one item in particular, the Konica Hexanon AR 24mm f/2.8 prime lens. The first priority is to evaluate how much lens curvature interferes with picture quality, by using full width photos from a Sony a7R.

This lens is one of those mythical pieces of Japanese glass, from the halcyon days of film. Internet legend has it that Hexanon lenses were used by the Japanese government, as the standard against which all other lenses were measured. This particular 24mm lens is the latest f/22 version, reputed to have been made by Tokina, for Konica. You can find out more about these Konica lenses at:

http://www.buhla.de/Foto/Konica/Objektive/e24_28.html

Ease of focus at long distances: The focus ring on this lens is well damped, to the point of being stiff, and it has somewhere around 50-55 degrees of rotation. It was fairly easy to focus on the "5610" street number, 3 points.

Lens contrast: Certainly decent, but difficult to compare, since the conditions were cloudy. It's worth at least 2 points.

Sides of the images: f/8 is a disaster, and f/11 cleans up significantly, but none of it is up to par with the Canon FDn 24mm f/2.8, the current points leader. Zero points.

Center of the images: f/8 is slightly sharper than f/11, look just above the roof on the "5610" street number building.

Summary: This lens goes straight from f/8 to f/11, there isn't any half-stop detent point, which makes it feel a bit cheap. The addition of the f/22 aperture stop, that the earlier versions didn't have, doesn't do much to alleviate that impression. If you look at the lens diagram picture at buhla.de, it appears that there is more curved glass on this lens, verses the previous design. Could that have played a role in the blurry sides we are seeing? The third comparison picture, in the group shot below, shows how much the sides clean up with a very slight misfocus on the center "5610" number. Focusing around like that could be difficult, if not impossible, with the optical viewfinder on a DSLR, but it's easy with the EVF in the Sony a7R. The question is, can you make misfocusing a part of your shooting workflow, and is it worthwhile? Given that you don't have to do that with the Canon FDn 24mm f/2.8, probably not, so this lens gets kicked back to the consolation round.

Here is the test image, it's nearly 13mb in size, **be sure and view it at 100% size**:

http://www.codectest.com/images/24mmLensComparisonKonicaFocusPointTest.jpg

Dan Euritt

The Sony a7R and wide-angle lenses don't always play well together, as you might have seen in the 24mm lens shootout. The goal in that testing was to find a 24mm camera lens with a flat image plane, which means minimal lens curvature at the edges of the lens. These 28mm lens tests will have that same goal; find a 28mm lens that's not blurry on the sides, before starting to think about other aspects of lens performance.

The good news is that as the focal length of the lens increases, the more compatible the lens is with the a7R and other full-frame sensor cameras. The 28mm lenses that are being evaluated here tend to bear that out, with one exception, as you'll see in a minute.

These 28mm lenses are legacy film and/or DSLR camera lenses. The generic Albinar ADG 28mm f/2.8 lens was the cheapest. It's labeled as "macro focus 52mm", wherein "52" is the measurement for the filter ring. This glass was sold under a bunch of different labels, not just Albinar. It has the "MACRO 1:10 1:8 1:5 1:4" markings on the side of the lens barrel. It's not clear who OEM'd these lenses out for so many different labels, but that same macro number configuration is also seen on Sigma prime lenses.

Which brings up the second lens being tested, the Sigma 28mm f/2.8 MiniWide II. It also takes a 52mm filter, and it's about the same size as the cheap OEM lenses listed above. However, it handles differently, and the performance is not the same. Most significantly, the Albinar lens has a noticeable vignetting problem on the Sony a7R, even at f/10. You can see the dark corners, while the MiniWide II has clear corners at the same aperture.

The classic Vivitar 28mm f/2.0 lens rounded out the bunch. This glass has a serial number of 228*****, which means that it was manufactured by Kiron. It has a reputation for oily aperture blades, which two out of the three copies being tested did indeed have. However, when shooting with a mirrorless camera in dark conditions, a good WYSIWYG electronic viewfinder means that you don't need to open the lens up all the way to set focus, because the EVF automatically turns up the gain, to duplicate the camera settings you are shooting at. That superior trait of an EVF, over an optical viewfinder, means that oily blades that drag when opened do not interfere with getting the shot, as might be the case with a DSLR. Oily blades only become a problem when the blades stick so badly that they don't fully open up at every aperture setting. All three copies of this glass were made by Kiron, but one of the three copies was rejected because of haze on the inside glass. Both copies took pictures that were virtually identical to each other, so only one result was posted here.

Ease of focus at long distances: The Sigma 28mm f/2.8 MiniWide II probably gets the nod here. The lens is like new, and there isn't any visible side-to-side shifting of the glass while focusing, as seen when looking in the EVF at magnify levels. Both of the Vivitars did that, but it didn't seem to affect the final results. The Vivitar 28mm f/2.0 is a nice big piece of glass, but the wonderful long focus throw on it almost worked against it at these long distances. One point for the Sigma.

Lens contrast: 28mm lenses overall get the nod here, over 24mm lenses. Picking a winner among the three is tedious, because very minor exposure differences seemed to affect the contrast level. No clear winner, but the Sigma, with it's more modern coatings, might have a slight edge.

Sides of the images: Both Vivitars take a decisive win here. A flat image plane is so important when choosing wide angle lenses on the Sony a7R, it makes a big difference. The lens half-stop detent at ~f10 or so improved the sides slightly over F8, but focusing slightly past infinity didn't improve the sides much at all. It was a different story with the Sigma 28mm lens, if you hit just the right past-focus condition, the sides improve dramatically, and the center sharpness doesn't get penalized too badly. But why deal with that, when you can have a lens with a flat image plane. Even the cheap Albinar ADG 28mm lens had cleaner sides than the Sigma; in fact, picture quality on the sides was a complete surprise with the Albinar. Vivitar 28mm f/2.0(3 points), Albinar 28mm f/2.8(2 points), Sigma 28mm f/2.8(disqualified).

Center of the images: Nothing stood out at the long infinity focus distances seen here. YMMV, but no clear winner seen here.

Summary: The Vivitar 28mm f/2.0 camera lens moves forward into the next round, by a big margin. The cheap Albinar had a surprisingly flat image field, but it fell apart on the left side when focused very slightly past infinity, which indicates a possible lens issue. For what it cost, you can afford to take a look at as many of these lenses as you want. Just watch out for the vignetting with full-frame sensors, it's going to keep this lens from moving into the next round. The blurry sides of the image on the Sigma 28mm f/2.8 lens was a big disappointment, because this lens looked great and was a pleasure to use. It's a contender for APS-C format cameras.

Here is the test image, it's about 13mb in size, **be sure and view it at 100% size**:

http://www.codectest.com/images/28mmLensComparisonSigmaMiniWideIIalbinarADGVivitar.jpg

Dan Euritt