Metabones Speed Boost Nikon G adapter

<p>One of these days Nikon will hopefully make a mirrorless and this adapter tech<br>

will make our fixed f2.8 lenses operate on DX virtually without a crop at F2.0 with<br>

actually according to Metabones, shallower dof. My second camera is a NEX DX<br>

16mp and the new adapter could let me use all the Nikon lenses I have even G<br>

lenses on that body. I have an olden goldie Nikon AFD 20-35mm, it would be like a 21.5mm-38mm<br>

f2.0 lens. The adapter has a reduction factor of 0.71 of the focal length which virtually negates<br>

the DX crop. I know this is using Nikon glass on a non Nikon body, but its not a big stretch to see<br>

Nikon sell a similar camera, maybe even with full electronic communication speed booster .<br>

One reason I don't care about my new D7100 shallow buffer is the NEX has an 11fps frame rate<br>

at full 16mp. I can also see my 70-200mm afs G lens being used at F2.0 instead of F2.8 since this<br>

adapter is a G adapter. </p>

<p>Here is a interesting review of the Speed booster<br>

<a href="

It shows some good examples of results using the adapter.</p>

 

<blockquote>

<p>One of these days Nikon will hopefully make a mirrorless </p>

</blockquote>

<p>Nikon already does, albe it not with a DX ... its called the Nikon "1" series..</p>

<p>T.Z. So you <em>know</em> about NEX dx ... shhhh ... it's a secret, don't tell. :-)</p>

<p>But if Nikon made a DX mirrorless, and a speedbooster that supports G lenses, AF and VR, and you used that with a 70-200 lens - what would be the advantage over using the same lens on an FX DSLR that you can get right now? When you add the speed booster and the camera together it probably wouldn't be much (if any) smaller of cheaper than a D600 and would have no real advantages since all the speedbooster does is make an FX lens on a DX camera approximately equal to the same lens on an FX camera (when accounting for "equivalent aperture").</p>

<p>I think you can rule out the possibility of having one of these gizmos adapting FX lenses to DX. It's a retro-converter - the opposite of a teleconverter - and needs a shorter camera register distance than that of the native lens to work its "magic". The native lens's focal length needs to be shortened by the retroverter optics in proportion to the format, and since Nikon's FX and DX cameras both share the same mount and register, there's no room for that to happen. So don't hold your breath for an FX-to-DX version.</p>

<p>Secondly there's going to be some (maybe a lot of) barrel distortion introduced, same as using a teleconverter nearly always adds noticeable pincushion distortion. Vignetting may also be worsened considerably, judging by the catseye OOF highlights shown in the linked video. Sorry! But you don't get anything for no cost.</p>

<p>Andy, if that is how it worked. The mirrorless Nex 3 is way smaller than the DX Dslr, and that is<br>

quite smaller than the FX DSLR.<br>

Add the price of a Nex 3 16mp, the speed boost adapter and use FF 35mm lenses. You have a way smaller package that turns all the pro lenses into F2.0 for a lot less. And the actual MP is just 22%<br>

less resolution than the 24mp D7100 and D600. That loss in resolution is just barely visible as<br>

Thom says in his review and the youtube video demonstrates.<br>

Of course I would like Nikon to be selling me the solution instead of Sony, but you cannot<br>

have everything. I bye the way use a Nex 5n mostly with Leica M lenses. I like the 11fps<br>

the articulated rear lcd screen, and I can use a HD EVF with 90 degree of movement.<br>

Focus Peaking is great for nailing focus. <br>

From what I read and see on youtube the 1 F stop pickup and the more shallow DOF<br>

Metabones claims for the unit is just the beginning, it straightens out the light so there<br>

is less vignetting, reverses the affects of the DX crop leaving lenses back to about their<br>

original focal length. My Tokina 11-16mm would be about that not 16-24mm on the DX<br>

because I believe the adapter may work fine on most of its range since while its a DX<br>

lens it cover FF from 15mm and is close even at 13mm.<br>

This adapter won't work with rangefinder lenses not enough flange distance or DX DSLR bodies because of the mirror being in the way.</p>

<p> </p>

<p>85/1.2L has catseye bokeh on a full frame 5D, too. So far I have not seen any conclusive evidence (in the form of a side-by-side comparison with FX) that Speed Booster noticeably alters the bokeh signature of any lens. So you are probably seeing the rendering characeristics of the lens alone.</p>

<p>T, I don't see it making sense to use a Tokina 11-16 on a speed booster, only to use it at the long end. But if you have a NEX, and you have Nikon FX lenses, sure, why not - but I don't think it makes sense to project Nikon making this stuff.</p>

<p>Andy: "But I don't think it makes sense to project Nikon making this stuff" Perhaps you are right. Check here: <a href="http://connect.dpreview.com/post/0714061353/nikon-smartphone-point-and-shoot-slump?news">http://connect.dpreview.com/post/0714061353/nikon-smartphone-point-and-shoot-slump?news</a> . Hard to tell what's being said, (as usual). Looks like they might go into the phone business. Not much cutting edge competition there. Field's wide open.</p>

<p>"..reverses the affects of the DX crop leaving lenses back to about their original focal length." - That's not how it works at all. The converter simply reduces the focal length of the primary lens, and <em>adapts it</em> to the smaller format. And because the focal length is reduced there is no shallowing of depth-of-field, despite the increase in aperture. Nett result is that depth-of-field on the retroverted lens remains the same for the same subject distance and setting of marked aperture.</p>

<p>Try it for yourself using <a href="http://www.dofmaster.com/dofjs.html">one of the many online D-o-F calculators</a>. Divide the focal length of a lens (any lens) by some factor and divide the aperture number by the same figure. If you remember to change the circle of confusion by the same factor, then you'll get the same depth-of-field. If you don't change the C-o-C, then you'll actually get <em>more </em>D-o-F with the reduced focal length.</p>

<p>Andy, if that is how it worked. The mirrorless Nex 3 is way smaller than the DX Dslr, and that is<br>

quite smaller than the FX DSLR.<br>

Add the price of a Nex 3 16mp, the speed boost adapter and use FF 35mm lenses. You have a way smaller package that turns all the pro lenses into F2.0 for a lot less. And the actual MP is just 22%<br>

less resolution than the 24mp D7100 and D600. That loss in resolution is just barely visible as<br>

Thom says in his review and the youtube video demonstrates.<br>

Of course I would like Nikon to be selling me the solution instead of Sony, but you cannot<br>

have everything. I bye the way use a Nex 5n mostly with Leica M lenses. I like the 11fps<br>

the articulated rear lcd screen, and I can use a HD EVF with 90 degree of movement.<br>

Focus Peaking is great for nailing focus. <br>

From what I read and see on youtube the 1 F stop pickup and the more shallow DOF<br>

Metabones claims for the unit is just the beginning, it straightens out the light so there<br>

is less vignetting, reverses the affects of the DX crop leaving lenses back to about their<br>

original focal length. My Tokina 11-16mm would be about that not 16-24mm on the DX<br>

because I believe the adapter may work fine on most of its range since while its a DX<br>

lens it cover FF from 15mm and is close even at 13mm.<br>

This adapter won't work with rangefinder lenses not enough flange distance or DX DSLR bodies because of the mirror being in the way.</p>

<p> </p>

<p>This is what Metabones says on DOF<br>

"The short answer is Speed Booster™ gives essentially the same depth-of-field effect as if a full-frame camera body were used.<br>

The long answer is complicated. If we are referring to depth-of-field in the mathematical sense, that depends on the aperture, magnification and circle of confusion (CoC). Magnification in turn depends on distance and focal length. The 50mm lens now becomes a 35mm lens which behaves very differently in terms of perspective. The question is, do we still keep the distance the same? Should the CoC be kept the same? There are many missing variables we need to choose and fill-in before we could get a meaningful answer. When people claim Speed Booster™ does not change the depth-of-field, they usually neglect to state the implicit assumption that the distance is kept the same (thereby changing the object size) and the CoC is kept the same. The same logic would lead to the conclusion that an APS-C camera has the same depth-of-field as a full-frame camera, too, which under the same implicit assumptions is mathematically true (the depth-of-field formula is format-size-agnostic, after all), but with which many people would disagree from practical experience.<br>

However, when most people ask about depth-of-field, they are not interested in mathematics, but rather, they are after a certain kind of shallow depth-of-field "look". If this is the case, the short answer above applies."</p>

<p>"..the depth-of-field formula is format-size-agnostic, after all" - Incorrect. The circle of confusion is inextricably linked to the format size, and is an integral part of any D-o-F formula. C-o-C and therefore format size <strong>must</strong> be taken into consideration. Any statement that D-o-F is actually decreased is misleading at best, and technically totally incorrect.<br>

However, what was said about the converted lens holding the same D-o-F as if the lens was used for its intended format, is true. If everything except the subject distance is scaled in a D-o-F calculation, then the D-o-F obviously stays (pretty much) the same. This doesn't remain the case at really close distances, where the lens focal length is a significant fraction of the subject distance.</p>

<p>You really have to think of this bag-of-bones thing as a focal length divider - because that's all it is. Looking at it like that, what would be the real point of building one into a camera? It would mean that every lens fitted would be optically compromised in some way, and take away the freedom of optical design that would come with having a mirrorless body. Like buying an M series Leica and then insisting on using SLR lenses on it. Not an issue with long focus lenses, but a severe optical handicap when it comes to shorter and wideangle focal lengths.</p>

<p>A retrofocus adapter is OK as a stopgap measure to offer backward compatibility between SLR lenses and EVF cameras, but not as a long term or built-in solution. So let's leave it as a removeable accessory shall we?</p>

<p>Joe go figure that Metabones can make a statement like the one I posted from their FAQ page.<br>

Joe maybe the speed boosters glass is doing something that can't be done, or the folks<br>

at Metabones cant measure DOF with all their sophisticated optical bench gear.<br>

I enjoy a spirited technical argument though, thanks.</p>

<p>Okay, so you know how a teleconverter works? Basically (and this is the short explanation) takes the image circle coming through the lens and magnifies it. Say you have a lens that projects a 45mm image circle, and a 2x teleconverter. The image circle coming out of the teleconverter will be 90mm, and the sensor, being 44mm on the diagonal, will effectively have a 2x crop factor, doubling the effective focal length. (Again, I'm simplifying.) Because the light coming through the lens is spread out, it's less bright and you lose 2 effective f-stops (because it's an area calculation and the teleconverter factor is doubled, to 4, which is 2x2).</p>

<p>A speed booster is the opposite. (Simplifying again. Don't nobody give me a hard time over this.) If it's a 1.5x speed booster it projects the 45mm image circle to 30mm. The image is shrunk, the light is concentrated, and you gain a larger effective f-stop. The actual speed boosters aren't exactly 1.5, but they're a close approximation, and the numbers work out so that the gain is a pretty close approximation of 1 stop.</p>

<p>When you do the "effective aperture" calculation it comes out so that you give back that stop, as compared to what you'd have in DOF and total amount of light if using an FX camera. It becomes a "wash" if you compare a DX camera with a speed booster to an FX camera with the same resolution from the same generation - and if the speed booster is 100% efficient and introduces no new optical problems. (Remember that any time you add new glass to the equation you have an opportunity to cause problems.) Metabones is using quality glass here and very careful design and testing and does a pretty good job of not introducing optical problems, but nothing is perfect, and the (pretty minor) problems spotted by the reviewer are consistent with that.</p>

<p>As I understand it the total system has a 1.08x crop which is practically the same as the FX lens<br>

you attach to the mirrorless camera. All your fixed f2.8 lenses are f2.0 lenses and f1.4 lenses<br>

are f1.0 lenses. Right now you have to use your Nikon glass on a third party camera but<br>

I for one am going to request Nikon work on getting us a body to use our lenses on<br>

a short flange mount mirrorless DX. Not only the lenses I mentioned but my 85mm f1.4; 58mm f1.4 and 105mm f2.8 macro would all be a stop faster. <br>

With all these lenses now either f1.0 or f2.0 VR is not that important, as is ISO over 3200. </p>

 

<p>Because of the "f-stop equivalent" thing, yes, the f/2.8 lens is functioning approximately as an f/2.0 lens. But, say it's a 28mm f/2.8 that's had its image circle downsized, and for simplicity pretend that the speed booster shrinking factor is exactly 1.5 and the boost factor is exactly 1 stop. (Even though that combination of number is mathematically incorrect, it's close enough.)</p>

<p>So the speed booster takes care of the focal length equivalence and on your DX camera your 28mm lens comes out as 28mm equivalent. It doesn't take care of f-stop equivalence. Multiply the f/2.0 by the crop factor and the equivalent aperture is f/3.0. (Close enough that we can just think of it as f/2.8.) That accounts for the increased DOF because you're using a DX sensor, and the fact that the DX sensor is one stop worse in low light than an equivalent FX sensor.</p>

<p>Basically, the lens being boosted to f/2.0 gives no advantage, relative to using it as an f/2.8 lens on an FX camera. But it <em>is</em> a stop faster than the wide end of a 17-50mm f/2.8 DX lens. Where I see this being a good idea is on a NEX camera, for the people who bought it because they have manual focus lenses to go on adapters. When I stick my Minolta 58mm 1.2 or Nikon 105mm 2.5 on a mirrorless I want them to work the same way they would on the 35mm film cameras they were meant for.</p>

<p>Actually making the lens cover the same angle of acceptance by getting around the DX crop factor<br>

is a very useful thing, speed gain aside I agree.</p>