Media Technology

If you follow this blog, you’ve seen photos taken with decentered SLR camera lenses, on the Sony a7R. Those photos typically show a lot more blur on one side of the image.

So if lenses can be that bad, what about the adapters that they are mounted to? Can the cheap NEX emount adapters be crooked somehow, and cause decentering? There is a ton of hype surrounding this issue. Lets just cut to the chase, and sum up the two photos below. All shots were taken with the Sony a7R.

The first picture combines horizontal sections of two photos, both taken with the same Canon FDn 24mm f/2.8 lens, shot at ~f/10. That lens was mounted on a generic FD to NEX emount adapter and a Fotasy FD to NEX emount adapter. Both pictures are nearly identical, so at this ~f/10 aperture, neither of the emount adapters appears to be having any effect on the picture.

The second picture combines horizontal sections from four photos, same aperture, taken with a Tamron 28-70mm Adaptall-2 zoom, model 159A, shot at 28mm. That lens is not one of the Tamron SP lenses, but it uses the same Adaptall-2 adapters. So three out of the four sections of this second pic were shot using a combination of Adaptall-2 adapter and NEX emount adapter. Stacked adapters like that have to be the worst-case scenario, right? Won’t all that “misalignment” cause major decentering?

To recap this second photo: one lens, four pics sliced together, shot using seven combined adapters.

Well, as it turns out, the lens was already heavily decentered on the left-hand side, it’s a blurry mess; all of those stacked adapters didn’t magically move the decentering effect over to the right side, because cheap adapters don’t have any glass to alter the path of the light coming in.

The first horizonal slice is probably the worst, largely because the center focus point on the “5610″ address number was slightly off. As we saw with the Konica Hexanon 24mm f/2.8 lens, a very slight center misfocus with certain lens designs, can have a significant effect on how field curvature affects the sides of the image. The remaining three horizontal slices are more consistent, but still not perfectly identical. This Tamron lens was difficult to focus, because it has a long focus throw, in the critical focus area, so this Adaptall-2 exercise needs to be repeated with a different lens design.

As always, view these photos at 100% full size:

SonyNEXemountAdapterComparisonFDn24mm.jpg

SonyNEXemountAdapterComparisonTamronAdaptall2zoom28to70.jpg

Dan Euritt

Death Valley is the largest national park in the continental United States. It’s a harsh and unforgiving environment, where summer heat waves of over 120 degrees are common. Google the phrase “Death by GPS”, and you’ll see what happens when people get lost in the summertime heat of Death Valley.

While it can be dangerous, it’s also very picturesque, as the following landscape pictures illustrate. These photos were taken with a Sony a7R camera, using a Pentax FA35 f/2.0 lens, or a Pentax Takumar 50mm f/1.4 lens. The first photo is 3826×1080, the rest are 1920×1080, if you want to see the full size version, right-click on the photo and choose “open link in new window”.

Some of the Death Valley locations pictured here include Aguereberry Point, Zabriski Point, Borax Works, Dantes Point, Mesquite Flat Sand Dunes, which is near Stovepipe Wells, and Father Crowley Vista Point, which is located by Panamint Springs.

[Show as slideshow]

Dan Euritt

Need a better eyecup than what Sony gave us on the a7R? Try this Nikon DK-19 eyepiece, it cost $11 shipped, from a vendor on Ebay.

It was difficult to stretch over the Sony factory eyecup, but hopefully that means that it won’t come off. Thanks to le_alain on dpreview.com, for the tip. He’s been using one of these for four months with no problems.

Custom eyepiece for Sony a7R

Dan Euritt

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/

See more Drag racing photos from the Match Race Madness #4 drag race at Barona.

Dan Euritt