Here's this device's basic problem:

It's $250 for a device that is basically a gimmick.

Aside from the initial humor of pairing your professional L glass with your decidedly not-professional cell phone camera, there's little to gain from this.

The Pros

Portability

You'll be able to leave your pesky camera body behind! You know, that thing that weighs half as much as the 70-200 you see attached to that tripod in the first picture? Not to mention size; surely a 3 inch long, 2.5 inch-wide cylinder plus an ugly iPhone case that doubles the thickness of your phone is more portable than an SLR body, right? That'll fit right in your pocket.

Cool factor

It's both an accessory for your trendy iPhone 4 and your SLR lenses. This will prove your photographic superiority over your friends.

The Cons

Ergonomics

The ergonomics are going to suck -- you'll need three hands to properly operate this thing:

• One to focus (remember, no autofocus)
• One to tap the screen to take a picture
• One to hold the lens up

The iPhone is going to see an inverted image, which is going to be plain awkward. You might get used to it, but it's still a downside.

Focusing is going to be a pain in the rear end -- read how Photojojo describes the process:

Your iPhone will try and auto-focus on the focusing screen inside the mount. So you'll need to use manual focus on the lens itself to try and get things as sharp as possible. A few extra taps on your iPhone screen will also help it focus. You may have to keep making small adjustments again with the lens to get your phone and the lens in sync.

Your fancy new L lens that you just spent 3 grand on? You probably won't even be able to adjust the aperture on it:

Can I adjust the aperture of my SLR lens while I'm using the mount?
Depends on what lens you're using! Most old school film SLR lenses have an aperture ring on them. If you're using a newer digital lens then you're out of luck.

Picture quality

The pictures are going to suck. In order to maintain the 35mm field of view, they've got a 36mmx24mm focusing screen in there. This has a number of downsides:

Light loss.

We've found that you'll lose about 1 to 2 f-stops when using the adapter. Using an older lens with a manual aperture ring helps control this. Otherwise you may need to brighten up the images in post.

Dark images means longer exposure and/or higher ISO, leading to motion blur and digital noise, respectively.

Fingerprints, dirt, and focusing screen grain.

The Lens Mount uses a focusing screen just like your DSLR. It can get dirty easily since it is relatively unprotected (it's exposed each time you assemble the mount). Be sure to clean it using an air-duster or soft cloth each time you shoot. You may still see some particles, that's normal.

There's also an extra layer of glass between the focusing screen and the iPhone's lens, which is another place for fingerprints, flare, softness, focus issues, color casts, etc. to appear.

To top that all off, you're forcing the iPhone camera to focus at a few inches away -- almost certainly not the focal distance it's designed for.

---

In all, are you going to really use this thing? More likely, you'll use it a few times just for laughs, and maybe so you have an unfair advantage in the Flickr iPhone pool. Is that really worth $250 to you? Remember, for $250 you can probably buy a used 2006-era DSLR off craigslist or eBay, which will almost certainly have better image quality, ergonomics, etc than this Rube Goldbergian contraption.

Plus, for all its trying, the iPhone just doesn't have the satisfying click that an SLR's mechanical mirror and shutter have.