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by Bart Arondson

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A DSLR to iPhone adapter has just been released as show here:

http://photojojo.com/store/awesomeness/iphone-slr-mount/

What are the advantages, disadvantages and effects of attaching a DSLR-sized lens to a 1/3.2" sensor?

Also: (just out of curiosity) has there ever been a gadget or camera like this before, that lets you attach a SLR lens to a smaller sensor or film format?

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Could you please provide a link? No clue what you are talking about. –  ysap Jul 15 '11 at 10:59
    
I think this is what he is talking about: iPhone SLR Mount by Photojojo. Photojojo launched this gadget last week. –  Damien Jul 15 '11 at 11:11
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"It essentially turns your iPhone into a DSLR." That is wrong on so many levels... –  blubb Jul 15 '11 at 15:49
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This is probably the most expensive and complex way to get blurry and noisy pictures out of an iPhone (and my iPhone does it out-of-the-box) -- on the positive side, you can use the iPhone to take really bad pictures with much more zoom than any other phone with a device that doesn't fit in your pocket and costs more than a completely acceptable P&S camera –  Nir Jul 18 '11 at 14:03
    
Apparently this sort of thing already existed for other formats: en.wikipedia.org/wiki/Depth-of-field_adapter –  Evan Krall Aug 16 '11 at 3:41

5 Answers 5

Well, obviously its real. (It was even linked in our own chat).

Without having used the device, the only real benefit here is probably increased 'optical zoom' from the ability to put larger lenses on the iPhone. You'll probably end up with quite the zoom range if you stick a longer lens on. Because you're probably taking a crop out of the intended image circle.

That said, the quality is obviously pretty low. The samples look rather soft and those are the sample pics they picked as best of the lot (don't expect much better). You're introducing a good bit of glass into the equation that neither the lens nor the iPhone was designed for. The iPhone has rather small pixels compared to a DSLR so diffraction will hit quickly and hard. Obviously all controls will be manual since the iPhone doesn't know how to control your lens. The mount is providing just a physical mount, not an electrical one.

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2  
"Turns your iPhone into a DSLR(sic)"! They managed to put a mirror and a prism in it ? –  Berzemus Jul 15 '11 at 12:06
    
I don't think it crops the image as much as you suppose - It has a 35mm (I think, since the Canon version only supports EF, not EF-S lenses) ground-glass focusing screen inside, and the iPhone takes a picture of the image projected onto that. –  Evan Krall Jul 16 '11 at 6:58
    
so it's not even shooting the scene, but a projection onto a screen of the scene. Makes the results even worse. A direct recording (albeit heavily cropped, which the punters would of course never expect to happen) would have had higher iq (which doesn't mean much with a phone "camera" tbh). –  jwenting Jul 19 '11 at 5:14
    
Directly attaching your phone to the back of a lens wouldn't work: try looking through a camera lens -- it doesn't look anything like the field of view you get. An iPhone's camera isn't just an exposed sensor, it already has its own lens. –  Evan Krall Aug 16 '11 at 3:40

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.

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"The iPhone is going to see an inverted image"... and you get to feel like a most serious photographer using that View camera... :-) –  ysap Jul 18 '11 at 11:26

Disadvantages:

1) You would have the typical issues with mating an incompatible lens to a camera: no auto-focus and no image-stabilization. And the lens is going to be completely unpowered, which it might not like.

2) I wouldn't be surprised if the lens ended up centered incorrectly, because a millimeter either direction is pretty big relative to the iPhone sensor. This might not matter, given the crop factor.

3) You are putting the light through the iPhone's existing lens for no purpose, so you would lose some fraction of a stop to that.

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I don't really know what device you are referring to, but I think some questions can be answered:

  1. What would be the effect - taking a lens of a given focal length and attaching it to a smaller sensor decreases the Field of View of the lens such that it behaves like a longer lens on a full size sensor. This is what Crop Factor is about. In a typical DSLR the crop factors are 1.5-1.6. For a pro DSLR, the factor is 1. You should multiply the lens Focal Length with this number to see the effective (35mm eqv.) length. In the case of the iPhone, the crop factor is far larger than that.

  2. Virtually all crop factor DSLR's let you attach lenses that were designed for a full-frame sensor. Canon 60D has a factor of 1.6 but you can attach an EF50mm/1.4 lens that is designed for a full frame body. The effective FL will be 1.6*50=80mm.

Note that in order to be effective, the lens has to be manual, so you can control the aperture (althogh for this tiny of a sensor even a fast lens is will have a hugh DoF), and obviously, you'll be full time manual with the focus.

That said, the resolution of the iPhone sensor is so high compared to it size, that the sensels are extremely small, thus render a noisy image. Also, for a given lens, you will run into the diffraction limit very fast.

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I do not think this is something else that just a gadget. I do not think it makes sense to mount a big DSLR lens on any smartphone as it has very small chip etc. and if you have a DSLR lens, then you also have the body with you.

Maybe, it could be useful to have such adapter for smaller lenses, maybe for the manual CCTV lenses with that small screw mount (I think it is called C-mount), which are enough good but much smaller and lighter and you can buy them used for a low price.

I think that these phones can only be used as cheap compact cameras. Trying to mix together good phone, pro-like DSLR, laptop and whatever else is current trend, but such approach mostly leads to devices where nothing of all the features works sufficiently.

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