The Turtleback SLR Jacket, sold by Photojojo in the U.S. as the iPhone SLR Mount, includes an aluminum case for your iPhone 4 or 4S, a depth of field adapter and an SLR lens adapter for Canon or Nikon lenses. Photo courtesy of

Turtleback SLR Jacket - compatible with Apple iPhone 4 and 4S, and Canon or Nikon lenses, $249

"Is it homemade or can you buy that?"

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That was the very reasonable question posed to me by a passerby while I was shooting with my iPhone 4S plastered onto the camera end of a Canon EF 70-200mm lf/2.8 IS USM lens, via the iPhone SLR Jacket. The SLR Jacket is a veritable time machine that will take you back to a time when cameras were made of sturdy pieces of metal and photographers manually focused upside-down images on glass viewing screens.

The SLR Jacket, made by Turtleback and distributed under the name iPhone SLR Mount in the U.S. by Photojojo, is composed of three elements: a very solid aluminum iPhone 4/4S case with two built-in tripod mounts, a metal depth of field adapter tube and an adapter ring that allows you to mount a Canon or Nikon SLR lens. (An iPhone 5 version is currently available from the manufacturer, but no word yet on whether Photojojo will carry it.)

The DOF adapter is a metal tube with a simple lens on the end near the iPhone lens and a matte focusing screen in the middle. It’s the same kind of focusing screen as in an SLR viewfinder. The DOF adapter allows the iPhone lens to focus on the focusing screen, which is what you’re taking a picture of when you shoot with the SLR Jacket.

To assemble the SLR Jacket, you first slide your iPhone into the two-piece case and secure the two parts together by turning a large flathead screw, which you can do easily with a coin or thumbnail. Then you mount the DOF adapter on the case’s threaded 37mm ring, in front of the iPhone’s lens. After you’ve mounted the DOF adapter, you attach the lens adapter ring to that, then mount your SLR lens.

This was taken with a Canon 50mm f/1.4 lens. If you look at this image at full size, you can see the focusing screen pattern clearly in the sky, as well as lots of dust.

Putting it all together is pretty quick and straightforward, but there are a few details to attend to: You have to align the rectangular focusing screen with your image frame properly. Otherwise, its edges will show in the corners of your photos. You align it by opening up the DOF adapter and rotating the metal plate in which the screen is mounted. If only a slight adjustment is needed, loosening the adapter a little and jiggling it sometimes works.

Adjusting the screen with the adapter open requires some care. You should never touch the focusing screen itself, since its surface is very delicate. Residue from your fingers can damage it or leave smudges that are hard to remove. The focusing screen plate is not secured by anything when you open the DOF adapter up, so you have to be very careful not to drop it. Any dirt or dust on the focusing screen presents a problem, since its delicate surface is difficult to clean. During my testing I found myself wishing that there were an exterior ring that I could turn to align the focusing screen without opening the adapter.

The lens adapter ring requires the proper technique to loosen as well: Pull the adapter ring out and then turn it. If you try to rotate it before pulling it away from the lens, it won’t budge.

This image was taken at sunset with a Canon 50mm f/1.4 lens. Notice the relatively strong vignetting, which isn’t necessarily a bad thing. Because the light level was low, there’s some visible noise in the image that masks the focusing screen pattern and any specks of dust. In the upper right corner you can see a tiny bit of the focusing screen plate, because it wasn’t aligned perfectly.
Tilt-shift apps aren’t doing it for you? You can mount a compatible Lensbaby on the SLR Jacket. This image was taken with a Lensbaby 2.0. Notice the bit of lint you can see on the lowest flower when you look at the image at full size. That’s why it’s important to keep the focusing screen free of dust and debris.

While the SLR Jacket seems at first glance to be a tool that will open up your mobile photography options by letting you use an interchangeable lens system, in fact, it imposes a number of limitations.

Because there is no mirror in the SLR Jacket to flip the image formed on the viewing screen by your lens, you’ll frame your shot upside down. The manufacturer makes a free Turtlehead camera app that will flip the viewfinder image for you, as will the $1.99 Almost DSLR app. If you want to use your favorite camera app, though, you’ll have to hone your upside down compositional skills or hold a hand mirror below your iPhone screen to see the viewfinder image right side up.

The Turtlehead app also has a calibration feature that focuses the iPhone’s lens on the focusing screen, to ensure that you capture the sharpest image possible. After you calibrate the focus, you focus your lens manually. You can also focus easily in other apps by first focusing the iPhone lens with your app and then focusing your lens manually. To control depth of field by adjusting the aperture, you'll need to mount an older, manual lens with a mechanical aperture control. Newer Nikon G lenses, and any Canon EF lenses (among others), won't give you that flexibility. An SLR lens adapter that converts a Canon or Nikon lens mount to another brand's lens mount would allow you to use the system with even more lenses.

Another limitation of this system is image quality. You can mount a $5,000 lens with the SLR Jacket, but you’ll still be taking a picture of a $100 focusing screen. And you'll have paid $249 for the priviledge. In my test images, the ridges on the surface of the focusing screen show faintly, and in some shots they actually create a noticeable moire pattern. It's no surprise that image sharpness isn't as good as you'd expect from the iPhone 4S without an adapter mounted, but dust is also a problem, since the focusing screen is exposed when you mount a lens. Whatever crud gets on the screen will show up clearly in your images.


The bottom line is that if you’re looking for creative options for your iPhone 4/4S and have a compatible lens collection, the SLR Jacket will give you some new tools to play with. And don’t forget that you can mount any filter or accessory lens with a 37mm thread on the case, not just the DOF adapter. However, if you’re hoping to make a leap in image quality or want to utilize the full depth of field control of recently made lenses, those are tricks this contraption won’t pull off.

What we like: Being able to play with a serious lens on a smartphone. This one-of-a-kind device is well made and versatile.

What we don't like: The delicate surface of the focusing screen is difficult to clean and keep that way, you'll frame your shot upside down unless you want to shoot with a specific app that will flip the viewfinder image, control over depth of field is limited when using newer lenses and at $249, this is one of the more expensive iPhone accessories we've seen. Moreover, image quality is nothing to write home about.

Aimee Baldridge is a writer and photographer based in New York. For more than a decade she has specialized in covering imaging technology, digital media, and the world of photography. You can see more of her work at