Metabones Speed Booster

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eosfun
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p.9 #1 · Metabones Speed Booster

alundeb wrote:
eosfun wrote:

- chromatic aberrations, if the primary system is not APO corrected (which most fast lenses are not) this is going to be amplified by the condensor effect of the speed booster. Even if the primary lens is not suffering from chromatic aberrations the speedbooster will probably introduce some colour fringing.

Can you elaborat a bit on this? How will the condenser amplify chromatic aberrations at the same time as it compresses the resolved detail?

Dispersion characteristics of different types of glass, as well as the effects of the glass shape; convex, concave, some kind of aspheric curvature, etc. do have different effects on part of the light spectrum. One of the most difficult challenges in lens design is to keep focus for different visible segments of the spectrum together. The complex systems that todays lenses have become are for a great part a result of calculations to compensate side effects of aberrations in lens elements in front of each other. If the lens system attached to the speed booster is not without chromatic aberrations to start with, it would be a coincidence if a lens system that has been designed for general purpose applications on many lenses for it's speed enhancing effect also corrected the chromatic aberration of the original system. In most cases the CA will stay to exist and the extra CA errors of the speedbooster will be added. It's like noise in a copy, it never disappears, you only add extra noise in every other step of processing. This is true for sound noise, this is true for photographic images, this is true for every process that emulates reality in another copy. The speed booster is another extra step in light processing and since it's a general purpose design it will most probably introduce new aberrations in the lens system that is mounted. Just do a mind experiment to imagine what it is. Mount this speed booster to a great lens and one of those super 1.4x teleconverters you mentioned. Would you expect to get the very same image as with the native lens system without the speedbooster and the teleconverter with no quality loss? I guess everyone understands that there is some loss in this setup. The question is just, how much. Tests and reviews will prove, but I bet it's more than a few of us will like. With the exception hopefully for a few of those lenses that combine very well with the speed booster. I guess, by the nature of the optical design that some symmetrical designs (Gauss type) standard lenses and a few short and medium tele lenses will work best together with a speed booster. However retrofocus designed lenses and most standard zooms will probably exhibit more from the aberrations I mentioned above.

eosfun wrote:
There aren't a lot enthusiasts about the optical results of teleconverters among the high standards photographers. I guess they won't be over enthusiast about a speedbooster either. It's definitely an interesting creative tool that will be able to get you shots that you couldn't without the speedbooster and your current lens setup, but by the nature of optial design it won't come without compromises.

The latest generation of teleconverters from Canon leave little to be desired regarding image quality. But I haven't seen satisfactory results from teleconverters of any other brand.

The reason is that these converters have been designed specifically for Canon's long whites which share their basis optical design. Just compare the 300, 400, 500 and 600 diagrams and you will notice a great similarity. The converter system has always been designed to work best with these lenses. It's also the reason why the converters don't work very well with some other lenses. And even on the long whites they are not flawless. Most reviews just analyze the "sharpness / resolving power" combination of lens characteristics combined with the teleconverters. But these converters still have their negative effects on distortion and bokeh quality.

Anyway, I can afford to be an early adopter on this, and I don't expect FF quality

That's good and a realistic expectation. We look forward to your results, please share it with us. Tusentakk og ha det!

Jan 16, 2013 at 10:03 PM

wolfloid
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p.9 #2 · Metabones Speed Booster

Good luck focusing non rangefinder-coupled lenses on the M9. Not to mention the M9 is huge compared to the smaller NEX cameras.

I Don't really get this remark - why would you want to focus non rangefinder-coupled lenses, when the rangefinder lenses are generally smaller, lighter and better?

As for size, well yes the NEX cameras are smaller, but I don't see the Leica as 'huge' in comparison.

Anyway, once the Leica M is out (eventually), you can focus almost any SLR lenses on it with an adapter and its focus peaking.

Jan 16, 2013 at 10:27 PM

HelenB
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p.9 #3 · Metabones Speed Booster

theSuede wrote:
Let's compare the Zeiss Contax 50/1.7 (Semi-symmetrical Gauss/Ultron) with the modern ZF35/2 (Distagon):

Exit pupil distance & size:
50/1.7 >> 38mmBFD+29mm = 67mm, 41mm diam (almost symmetrical).
35/2.0 >> 38.5mmBFD+27mm = 65mm, 35mm diam (short distagon) - from memory, might be wrong!

Now give the 50mm lens between +5-10% in exit pupil distance, this seems to be about right for a near-symmetric lens from the data they've published, and you get:
50/1.7 >> 33mmF1.17 with e.p. at 72mm distance, 38mm diam.
This means that you get a 33mmF1.2 with the same worst-case angle (cross-angle from furthest aperture edge to furthest sensor edge) as you get from the 30F2.0, and this is very good.

That looks strange to me. Shouldn't the exit pupil be magnified, as well as moved away, or have I missed something obvious?

Jan 16, 2013 at 10:35 PM

ISO1600
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p.9 #4 · Metabones Speed Booster

wolfloid wrote:
I Don't really get this remark - why would you want to focus non rangefinder-coupled lenses, when the rangefinder lenses are generally smaller, lighter and better?

I know for one reason, COST. There are about a million great non RF-coupled lenses out there that are more affordable than at least their Leica counterparts. There are, however, many great options from the likes of Cosina.

Jan 16, 2013 at 10:56 PM

Taylor Sherman
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p.9 #5 · Metabones Speed Booster

So, here's a thought:

Sony A-mount to E-mount Speedbooster.

The electronics might just be a pass-through. . . though, I'm not sure what the Nex would do if it got a straight connection from an Alpha lens. Anyone know if the LA-EA1 has any electronics in it? If not (just a pass-through), then they could do this. If it does, they'd probably have to emulate those electronics to make the camera happy.

I was thinking I'd buy this in a heartbeat for my 24/2 ZA + Nex-7, but then I wouldn't be getting fast AF like I do with the LA-EA2. It's not the greatest MF lens, either. But for landscape work, it'd be very tempting.

Jan 16, 2013 at 11:21 PM

theSuede
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p.9 #6 · Metabones Speed Booster

HelenB wrote:
>>theSuede wrote:
>>Let's compare the Zeiss Contax 50/1.7 (Semi-symmetrical Gauss/Ultron) with the modern ZF35/2 (Distagon):
>>
>>Exit pupil distance & size:
>>50/1.7 >> 38mmBFD+29mm = 67mm, 41mm diam (almost symmetrical).
>>35/2.0 >> 38.5mmBFD+27mm = 65mm, 35mm diam (short distagon) - from memory, might be wrong!

>>
>>Now give the 50mm lens between +5-10% in exit pupil distance, this seems to be about
>>right for a near-symmetric lens from the data they've published, and you get:
>>50/1.7 >> 33mmF1.17 with e.p. at 72mm distance, 38mm diam.
>>This means that you get a 33mmF1.2 with the same worst-case angle (cross-angle from furthest
>>aperture edge to furthest sensor edge) as you get from the 30F2.0, and this is very good.

That looks strange to me. Shouldn't the exit pupil be magnified, as well as moved away, or have I missed something obvious?

No, you're quite right, multiply - not divide - thank you for spotting that.
Also - I forgot to carry the magnification...
Total system f/# should decrease by 1.41x (one stop)
This means that exit pupil grows by 1.41x if pupil distance is constant, and 1.41 times distance increase if any.

So, about 1.5x original exit pupil size is correct, not less-than-one as I wrote first. Hence also the mechanical vignetting of course.

Jan 17, 2013 at 02:14 AM

alundeb
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p.9 #7 · Metabones Speed Booster

eosfun wrote:

Dispersion characteristics of different types of glass, as well as the effects of the glass shape; convex, concave, some kind of aspheric curvature, etc. do have different effects on part of the light spectrum. One of the most difficult challenges in lens design is to keep focus for different visible segments of the spectrum together. The complex systems that todays lenses have become are for a great part a result of calculations to compensate side effects of aberrations in lens elements in front of each other. If the lens system attached to the speed booster is not without chromatic aberrations to start with, it would be a coincidence if a lens system that has been designed for general purpose applications on many lenses for it's speed enhancing effect also corrected the chromatic aberration of the original system. In most cases the CA will stay to exist and the extra CA errors of the speedbooster will be added. It's like noise in a copy, it never disappears, you only add extra noise in every other step of processing. This is true for sound noise, this is true for photographic images, this is true for every process that emulates reality in another copy. The speed booster is another extra step in light processing and since it's a general purpose design it will most probably introduce new aberrations in the lens system that is mounted. Just do a mind experiment to imagine what it is. Mount this speed booster to a great lens and one of those super 1.4x teleconverters you mentioned. Would you expect to get the very same image as with the native lens system without the speedbooster and the teleconverter with no quality loss? I guess everyone understands that there is some loss in this setup. The question is just, how much. Tests and reviews will prove, but I bet it's more than a few of us will like. With the exception hopefully for a few of those lenses that combine very well with the speed booster. I guess, by the nature of the optical design that some symmetrical designs (Gauss type) standard lenses and a few short and medium tele lenses will work best together with a speed booster. However retrofocus designed lenses and most standard zooms will probably exhibit more from the aberrations I mentioned above.

Tusen takk!

I understand all of that, probably I misinterpreted "amplified by the condensor effect" as mulitiplicative rather that additive.

Jan 17, 2013 at 09:39 AM

alundeb
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p.9 #8 · Metabones Speed Booster

theSuede wrote:
HelenB wrote:
>>theSuede wrote:
>>Let's compare the Zeiss Contax 50/1.7 (Semi-symmetrical Gauss/Ultron) with the modern ZF35/2 (Distagon):
>>
>>Exit pupil distance & size:
>>50/1.7 >> 38mmBFD+29mm = 67mm, 41mm diam (almost symmetrical).
>>35/2.0 >> 38.5mmBFD+27mm = 65mm, 35mm diam (short distagon) - from memory, might be wrong!

Jan 17, 2013 at 09:46 AM

theSuede
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p.9 #9 · Metabones Speed Booster

As long as the aberrations don't grow by more than a factor of 1.4 (the inverse of the image enlargement factor 0.71) the used lens will indeed be sharper WITH the Speed-adapter than with a normal "empty pipe" adapter. And that's including the aperture increase.

The finished image will never be sharper than using the lens on it's intended format (to do that, you'd have to construct an adapter with the exact inversion of the aberrations in the main lens...), but if the losses are reasonably small there's indeed a real-world gain when you compare APS with adapter to APS without adapter. And I guess that's what counts for the target group, since not all have the choice to go FF/FX.

Jan 17, 2013 at 09:55 AM

HelenB
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p.9 #10 · Metabones Speed Booster

alundeb wrote:

If the exit pupil grows 1.41*1.05x and the exit pupil distance increases 1.05x, wouldn't this give a worse angle of incidence, not better as the paper claims?

The angle subtended by the exit pupil at the image plane grows (the f-number decreases), but because the exit pupil has moved away the maximum angle of incidence can be lower for off-axis points, ie the most affected. The further off-axis, the more the extra distance helps.

Jan 17, 2013 at 10:15 AM

alundeb
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p.9 #11 · Metabones Speed Booster

HelenB wrote:
alundeb wrote:

If the exit pupil grows 1.41*1.05x and the exit pupil distance increases 1.05x, wouldn't this give a worse angle of incidence, not better as the paper claims?

The angle subtended by the exit pupil at the image plane grows (the f-number decreases), but because the exit pupil has moved away the maximum angle of incidence can be lower for off-axis points, ie the most affected. The further off-axis, the more the extra distance helps.

I see.

Since the extra distance is constant for a given lens, and the exit pupil follows the aperture, there may be a net loss for large apertures and a net gain for small apertures.

Jan 17, 2013 at 10:31 AM

artur5
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p.9 #12 · Metabones Speed Booster

theSuede wrote:
As long as the aberrations don't grow by more than a factor of 1.4 (the inverse of the image enlargement factor 0.71) the used lens will indeed be sharper WITH the Speed-adapter than with a normal "empty pipe" adapter. And that's including the aperture increase.

The finished image will never be sharper than using the lens on it's intended format (to do that, you'd have to construct an adapter with the exact inversion of the aberrations in the main lens...), but if the losses are reasonably small there's indeed a real-world gain when you compare APS with adapter to APS without adapter. And I guess that's what counts for the target group, since not all have the choice to go FF/FX.
Do you think it would be possible to make a version for SLR lenses on a M mount camera ? ( I'm thinking of my Ricoh GXR M mount

). My uneducated guess is that the difference in registry distance between M mount (27.7mm) and SLRS (44-47mm) is too small.

Jan 17, 2013 at 12:26 PM

inglis
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p.9 #13 · Metabones Speed Booster

Brian Caldwell was just answering questions about this adapter
http://nikongear.com/live/index.php?/topic/47313-speed-up-your-lens/page__st__100

Posted Today, 03:03
rvink, on 16 January 2013 - 19:59 , said:
From page 5 of the speed booster white paper:
"Speed Booster has a very small amount of undercorrected spherical aberration at f/0.90, but this was done intentionally to improve the bokeh when the Speed Booster is used with ultra high speed f/1.2 objectives."
rvink comments:
I assume at smaller apertures, spherical aberrations are more or less perfect corrected, so that bokeh should be largely unchanged from the master lens.

I wonder what effect the speed booster has on contrast, flare and ghosting? Adding 4 extra elements is bound to cause some issues.

Brian replies,
The amount of spherical undercorrection is very slight, and is gone by the time you stop down to f/1.0. As can be seen from the MTF curves for the 50/1.2 Nikkor its not enough added aberration to prevent the Speed Booster from dramatically increasing the on-axis MTF when the combined system is used wide-open at f/0.90.

In practice the dropoff in sensor sensitivity with incidence angle will have a much bigger impact on bokeh than the tiny amount of spherical aberration present in the Speed Booster. I call this effect "sensor-induced apodization", since it acts just like a graduated neutral density filter placed at the aperture stop. BTW, Minolta used exactly this sort of ND filter in a 135mm portrait lens they developed some years ago. In any case, the effect is that the outer parts of defocused highlights become dimmer than the center, which is exactly what you want.

The coatings on the four elements have better than 99.5% efficiency, so the total transmission loss due to the Speed Booster is less than 4%. For comparison, this is half the amount of loss you get from an uncoated filter, which will reflect 4% per surface. In our tests we haven't been able to detect any flare difference with and without the SB. One reviewer has reported a small amount of flare to us in a shot he took in harsh lighting conditions, but we have been unable to reproduce this result and are still investigating whether this was due to the SB or to the objective he used.

Edited on Jan 17, 2013 at 02:12 PM · View previous versions

Jan 17, 2013 at 02:03 PM

Makten
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p.9 #14 · Metabones Speed Booster

wolfloid wrote:
I Don't really get this remark - why would you want to focus non rangefinder-coupled lenses, when the rangefinder lenses are generally smaller, lighter and better?

Because I bet 99% of all NEX users can't afford an M9 with Leica lenses. The whole idea of this thing is to get a smallish body for non rangefinder lenses that gives something close to equal to FF.

As for size, well yes the NEX cameras are smaller, but I don't see the Leica as 'huge' in comparison.

I do: http://camerasize.com/compare/#213,34

Anyway, once the Leica M is out (eventually), you can focus almost any SLR lenses on it with an adapter and its focus peaking.

At a cost that most cannot afford.

Jan 17, 2013 at 02:03 PM

alwang
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p.9 #15 · Metabones Speed Booster

inglis wrote:

Brian replies,

In practice the dropoff in sensor sensitivity with incidence angle will have a much bigger impact on bokeh than the tiny amount of spherical aberration present in the Speed Booster. I call this effect "sensor-induced apodization", since it acts just like a graduated neutral density filter placed at the aperture stop. BTW, Minolta used exactly this sort of ND filter in a 135mm portrait lens they developed some years ago. In any case, the effect is that the outer parts of defocused highlights become dimmer than the center, which is exactly what you want.

Interesting, I assume he's referring to the Minolta 135 STF? Because that lens had some of the most beautiful bokeh ever. Of course with the STF, you could also adjust this effect with a second aperture built into the lens (I suppose in theory they could have done that with the Speed Booster as well

)

Jan 17, 2013 at 04:24 PM

alundeb
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p.9 #16 · Metabones Speed Booster

alwang wrote:
inglis wrote:

Brian replies,

In practice the dropoff in sensor sensitivity with incidence angle will have a much bigger impact on bokeh than the tiny amount of spherical aberration present in the Speed Booster. I call this effect "sensor-induced apodization", since it acts just like a graduated neutral density filter placed at the aperture stop. BTW, Minolta used exactly this sort of ND filter in a 135mm portrait lens they developed some years ago. In any case, the effect is that the outer parts of defocused highlights become dimmer than the center, which is exactly what you want.

Interesting, I assume he's referring to the Minolta 135 STF? Because that lens had some of the most beautiful bokeh ever. Of course with the STF, you could also adjust this effect with a second aperture built into the lens (I suppose in theory they could have done that with the Speed Booster as well

)

Isn't the effect he is talking about the general effect of incident rays on digital sensors? The way I understand it, he mentions this because in his opinion the only way the SpeedBooster will affect bokeh, is indirectly via the (altered) angle of incidence. But this effect should be smaller than the variation among different sensors in how they respond to this. In other words, we should see a bigger difference in bokeh between the NEX 7 and the NEX 5N with the same lens, than from a given lens with and without this adapter. I am not sure, but that is how I understand it.

Jan 17, 2013 at 04:37 PM

mcbroomf
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p.9 #17 · Metabones Speed Booster

There are several pages of discussion on one of the Nikon fora where Brian C has started responding to some questions and speculation

http://nikongear.com/live/index.php?/topic/47313-speed-up-your-lens/page__st__80
(and a couple of pages before)

Jan 17, 2013 at 06:06 PM

Makten
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p.9 #18 · Metabones Speed Booster

I just had an idea. If the SB diminishes the image circle of any lens with the factor 0.7x, would a future FF NEX be able to use 645 lenses with the same scaling effect?

Jan 17, 2013 at 06:35 PM

ken.vs.ryu
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p.9 #19 · Metabones Speed Booster

Makten wrote:
I just had an idea. If the SB diminishes the image circle of any lens with the factor 0.7x, would a future FF NEX be able to use 645 lenses with the same scaling effect?

The nex vg-900 is already here.

Jan 17, 2013 at 06:47 PM

theSuede
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p.9 #20 · Metabones Speed Booster

alundeb wrote:
Isn't the effect he is talking about the general effect of incident rays on digital sensors? The way I understand it, he mentions this because in his opinion the only way the SpeedBooster will affect bokeh, is indirectly via the (altered) angle of incidence. But this effect should be smaller than the variation among different sensors in how they respond to this. In other words, we should see a bigger difference in bokeh between the NEX 7 and the NEX 5N with the same lens, than from a given lens with and without this adapter. I am not sure, but that is how I understand it.

The difference is actually quite small on 'bokeh' - but it can be quite large on filter pack 'smearing'.
Bokeh edges are already quite diffuse, at least in the meaning that you cannot for certain say if it's "right" or "not right". The effect on smearing though is profound - at least on most normal cameras. See the corner smearing effect on the NEX-7 as one example - but in this case (very large exit pupils) you get a part of the ray bundle that aligns correctly (the central part, F2.8 and up) and another outer part of the ray bundle that is more or less smeared.

Since the F1.4 to F2.8 doughnut shape is 75% of the light coming in through an F1.4 aperture, that means you have a weak - but sharp! - inner edge with a rather large edge blur smudge surrounding it. Like adding a Gaussian blur to a photoshop layer and setting opacity to 75%. You can see the sharp image behind the blur, but only weakly.
The other way the adapter will affect bokeh is hard mechanical vignetting towards both the corners and maybe also the top/bottom of the frame (depending on the size of the throat of the rectangular hole in front of the sensor).

Canon sensors have this "digital apodization effect" even without an adapter...

Most Canon sensors are more than 1Ev down at the edge at F1.2. Effective T-stop at the sensor surface from an 85/1.2L is close to T2.0 (but Canon hide this by increasing digital gain for very large apertures...)

Jan 17, 2013 at 06:52 PM

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