new Metabones adapter gives nex crop factor higher-quality full frame look.

Holy cow,http://gopb.co/ga  because it condenses the optical view it increases MTF and decreases lens defects. The Canon 40 mm pancake 2.8 becomes a lightweight actual 40mm F1.4 quite revolutionary.

Well that's just nutty. Very excited to see how it plays out, even though a $600 adapter and the quality full-frame lenses one would want to use with it are well outside my price range.

No, 40mm becomes 28.4mm.

It's a bit confusing, but I'm pretty sure it stays 40mm. APS-C sensor lenses are still listed at their FF focal length, so the 40mm without the reducer is 60mm FF equivalent on APS-C. When paired with the optical reducer it would remain 40mm instead of being cropped.

If you could hypothetically (it wouldn't actually work) put the reducer in front of a FF sensor, it would be reduced to 28mm.

I was excited until I saw the price. For a few hundred more I'd rather buy a used 5DII.

Okay, so I can (halfway) understand how the adapter is reducing the focal length by reverse-magnification, thus giving shallower depth of field at "equal" focal lengths comparing with the adapter and without.

However, I thought the actual LIGHT that could go through a lens was dependent on the size of the diameter of the front element divided by the focal length? This adapter isn't letting more light in...right?

Taking a supposed 10mm lens with a 20mm front element, the f-stop would be f/2. If this adapter reduces the focal length, so now the 10mm lens is now 5mm (or whatever the value is), we get 20mm/5mm, or f/4.

Then again, maybe Metabones is doing some weird voodoo after all.

http://matthewdurrphotography.com

Now you got me confused.

• The reduces compresses the optical circle from a FF lens to just over that of a DX lens, which has the same effect of using a wider focal length. So the FOV is affected, and the FF equivalent value would be changed, from 40mm to 28mm.

• The same happens with tele converters, in the opposite direction. 

The reducer compresses by a factor of 0.71, or 1.4x. This is equivalent to one light stop.

• So a 40mm/f4.0 lens becomes a 28mm/f2.8 lens.

• A 35mm/f1.4 lens becomes a 25mm/f1.0 lens. 

• A 28mm/f2.8 lens becomes a 20mm/f/2.0 lens.

I like the idea, especially if it maintains high IQ.

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Cheers,
Henry

That's my mistake. I was confused by the original post and some weird mental gymnastics I did to make it work in my brain. It seems bizarre that the FL would actually become wider, but I guess it makes more sense to think of it becoming "shorter."

You're a slightly off (see http://en.wikipedia.org/wiki/F-number#Notation):

f-number is focal length / aperture diameter, but the f-number is expressed as f/X, where X is the previously calculated ratio.

So in your example, with focal length 10mm, and diameter 20mm, the f-number is 1/2, which would be expressed as f/0.5, not f/2.

Decreasing the focal length to 5mm then gives you f/0.25, not f/4.

HTH

There are numerous articles about how DOF isn't a function of sensor size.  In the same vein, a "speed boosted" FF lens will simply project more image/light onto the sensor, not actually make the lens "faster", meaning decrease depth of field.

Thank you, that clears it up, but it still begs the question, how is an attachement behind the lens allowing more light to hit the sensor?

Is it because of this: with the adapter's element catching all the light from the rear element, it focuses it all at the smaller APS-C circle, whereas that light without the adapter would cover all around the sensor as well, thus light "lost"?

http://matthewdurrphotography.com

Then ask yourself Matt after all that voodoo, can adding anything to the original optical formulae actually increase IQ !!

All the best mate.

Danny.

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Birds and macro. NEX and m4/3
http://www.birdsinaction.com
http://www.flickr.com/photos/nzmacro/

I believe that to be the case, hence the term "crop factor".

You are over thinking this. Adding another lens element, in the adapter, changes the focal length of the lens.

Aperture is merely defined as lens focal length/lens diameter. So by reducing the lens focal length, you also reduce the aperture, making the lens faster.

A tele converter does the opposite, making the lens slower.

Problem with  converters has always been IQ, or lack thereof. Because the lens is added between the exit of the lens and the sensor, it can cause all sorts of side effects.

But I applaud Metabones, the thought of taking a FF lens and compressing it into a DX lens is a clever one.

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Cheers,
Henry

There is another thread going on about this.

Listed are about 4 similar EF/EFS to NEX adapters which permit full AF/aperture control. They run over $130 and should work OK.

Then there are numerous cheap $20 ones that are manual only...not so good for a non-manual lens.

Then there are some intermediate model for about $30 to $60 which are typically called, "Build in Aperture Canon EOS EF Lens to SONY NEX E Mount...."

They incorporate their own aperture mechanism as part of the design. You still need to MF. Like!

http://www.ebay.ca/sch/sis.html?_kw=Canon+EOS+EF+Lens+to+Sony+NEX+adapter+Build+in+Aperture

Oops, I meant optical formula of course. Doh !!

--
Birds and macro. NEX and m4/3
http://www.birdsinaction.com
http://www.flickr.com/photos/nzmacro/

These adapters are usually listed as designed for use with both EF and EFS lenses. EFS lenses are not, of course, FF lenses. They are APSC 1.6 crop-factor.

Perhaps I am. Just need to accept it and say "Because...Math!"

http://matthewdurrphotography.com

Well, perhaps it can. Same idea how downsizing a file makes per-pixel sharpness better, by "downsizing" the whole lens, rather than just using a section without the adapter, it could in theory produce sharper shots.

In theory.

http://matthewdurrphotography.com

This little adapter could end up being a very BIG thing for the NEX E-Mount system.  It's really about who the primary buyers will be, those who have a big stockpile of Canon EF lenses (lots of pros, both stills and video, have big collections of top quality Canon EF's).  Could be a great foot in the door item for those pro's curious about shooting video on the NEX system.  Especially those looking for 1080/60p video with FF glass, this adapter plus a cheap used NEX 5N for $300 or so could be great cheap way into the NEX system for one heavily invested in Canon EF lenses.