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Andrew Reid

F0.74 - new Metabones Speed Boosters break boundaries

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Guest c2dd7b52878779b55f43cc8c269267c1

OK. cool. Although I think I have another way to explain it if you need.

Yes please (see above)  :lol:

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Would you mind explaining this a bit further please, or putting it a different way? I can't quite get my head around what you're saying …  :unsure:

 

EDIT: Don't worry, I just got it ...

 

No, actually I didn't, lol  :lol:

 

Ok. Let’s say we have a Camera A with a large sensor and camera B with a smaller sensor. And we have two identical lenses to put on them.

 

For simplicity we will say that the area of the Sensor A is twice as big as Sensor B.   And that when you put a speed booster on camera B  the same image that the lens delivers to Sensor A is compressed to fit on sensor B.  So we have the same angle of view and the same depth of field.

 

Let’s say that sensor A’s area is 100mm squared and sensor B’s area is 50mm squared.

 

Let’s say for simplicity that the lens is letting in 1 photon of light per square millimetre every 1/50th of a second.  So sensor A has 100 photons of signal every frame.

 

If we imagine camera B without the speed booster, it isn’t getting light from all the lens. The lens is still letting in 1 photon per square millimetre every frame.  So camera B without the speed booster has 50 photons of signal per frame.

 

Exposure or brightness is light per surface area.  So even though sensor A has more photons per frame, When you divide the number of photons by the area both cameras in this case have the same: 1 photon per square millimetre so they have the same brightness.

 

Now if we put the speed booster on camera B the full image from the lens: All 100 photons is compressed onto sensor B.  So we now have 100 photons and 50 square millimetres. So we have 2 photons per square millimetre.  The image is therefore twice as bright in camera B.

 

But both camera A and B are getting 100 photons of signal per frame.  The same signal to noise ratio.   So even though you will have to boost the iso/gain of camera A to match the brightness of camera B, the noise at that higher iso will be the same as the noise of camera B at the lower Iso.

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Shouldn't this work on the GH2?

 

Correct me if I'm wrong, but if it's only the physical shutter getting in the way, then the GH2 should be fine right? As in, the default state of the shutter on the GH2 (Even when powered off) is open. So video would be fine. Just don't take photos with it?

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Shouldn't this work on the GH2?

 

Correct me if I'm wrong, but if it's only the physical shutter getting in the way, then the GH2 should be fine right? As in, the default state of the shutter on the GH2 (Even when powered off) is open. So video would be fine. Just don't take photos with it?

 

Id imagine that this new speed booster is optimised to put an apsc sized image onto a 2.3* crop sensor, and so wouldn't cover the sensor of the GH2 and you would get a black ring.  Whereas the original micro 4/3rds speed booster is designed to put a roughly apsh sized image circle on to a regular micro4/3rds sensor.   I cant be sure, but that's what I would guess.

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There are two questions at hand here.

 

1. does this (the effect you mention) happen

 

2. Does this happen with the speed booster.

 

 

1.  I have always had a feeling that this happens.  Smaller sensors with faster lenses never seem to give as strong a subject isolation.

However, I have never seen someone prove this, either with a demonstration or with scientific theory.  If you have more info on this I would love to hear it to confirm my suspicions.  I would also love to see you try and present your case in the dpreview open talk forum.  Particularly with a provocative thread title. There are some hardcore equivalency crusaders there, and you would really get their hackles up

 

2.  I don't actually think it is happening with the speed booster.  It isn't actually changing the focal length at all.  The booster cant change the properties of the lens. Its just taking the image that comes out of the back of the lens and squeezing it into a narrower image circle.  besides any distortion or refraction or whatever that the booster ads, the image will look the same apart from minor variations in the crop.

 

 

(incidentally, for the people saying the speed booster increases iso performance.  It depends.  increasing it compared to what?

Compared to using the same lens on the BMCC without the speed booster? Yes.

Compared to using the same lens on a native apsc sensor camera? No.  The image will be brighter at a lower ISO, but the noise will be the same as the apsc camera at a greater ISO.   The signal to noise ratio is the same, because the signal is the same. It cant get any extra signal from somewhere.)

 

 

I've just done a very crude test using the APS-c crop mode on my A7R.

 

Full Frame:-

'>

APS-C + Speed booster

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point of focus was on the eye balls of the squirrel.  the lens was a zeiss planaer at f2.8.  I downsized the large 36mpx image and overlayed it over the aps-c shot to even the odds resolution wise (the full frame shot was 36mpx and the aps-c shot was 16mpx..

 

notice how the defocus on the lenses in the background is the same, yet more of the squirrel's face and shoulders are in focus on the full frame shot.   this should be less obvious as you move further away from the subject, however to me I seem to see it becomes even more obvious on medium/wide shots where the distance between the camera and the subject is greater.

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Shouldn't this work on the GH2?

 

Correct me if I'm wrong, but if it's only the physical shutter getting in the way, then the GH2 should be fine right? As in, the default state of the shutter on the GH2 (Even when powered off) is open. So video would be fine. Just don't take photos with it?

 

It won't go, I just did a little exploratory test and got nowhere - the sensor housing blocks the optics and you can't mount it at all. Certainly not something to try forcing. It's a no-go. Same with the other MFT cameras. What the BMD specific boosters have done here is to absolutely make use of ALL the bigger available space around the sensor and mount on those cameras.

 

The MFT Speed Booster is not superseded, not replaced, not old… It is optimised for the larger 2x crop and 1.86x crop sensors in the GH3 and GH2 and other MFT cameras so if you have those cameras don't think twice about picking one up. The image is beautiful. Especially with Contax Zeiss 50mm F1.4.

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Hi! I am a big fan of this site and of this forum, but I have never felt the need to post myself. There is however one thing about these new speedboosters for the BM cameras that makes me curious. I hope I can write this in a way that makes it understandable, as I hardly understand it myself. It is regarding the question of f-stops, t-stops and pixel vignetting.

 

So, I have a Metabones Speedbooster for Sony Nex and I bought it hoping that it would give me an extra stop of light (besides increase in field of view of course), and usually it does, but not at all f-stops.

 

Pixel vignetting (as explained in this dxomark article http://www.dxomark.com/en/Reviews/F-stop-blues) seems to be causing light loss at digital sensors at wide apertures. This is something I have experienced myself when using the speedbooster (but it is not the speedboosters fault, it is the digital sensor).

 

All of my lenses gain one full stop of light with the speedbooster up to and including f2.8. At f2 the lenses I have tested gain 1/2 to 1 stop (usually as much as that specific lens gains on that specific camera when going from f2-f1.4 without the booster). At f1.4 the speedbooster "only" gives me an increase of 1/3 of a stop compared to when I am using the lens at f1.4 without the booster. I have not tested any faster lenses than f1.4, but dpreview found something similar in their first impressions report (http://www.dpreview.com/articles/2667195592/first-impressions-metabones-speed-booster), and there should be even less of a gain when using lenses with maximum apertures of f1.2 or more (with or without speedbooster).

 

Anyhow, this might not be true for the BMCC and the BMPCC as I guess they have a lower pixel density than digital photography cameras, and, on top of that, the speedbooster might not make the angle of incoming light more oblique when exiting the pupil (my speculation) than when entering (so at f2 the t-stop could still be about 1.2 on the bmpcc, as intended).

 

I think it would be interesting to know how these new speedboosters behave in regards to brightness increase at wide apertures, if t0.74 really is possible when using a digital camera. Especially since low light performance could be a decisive factor when choosing between, for example, the 5d mark III, the BMCC and the BMPCC.

 

And as a side note I am very satisfied with my speedbooster, despite the minor issues at f1.4.

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Interesting, thanks for that. With the new Speed Boosters, maybe by bringing the glass closer to the sensor you improve efficiency. Or maybe not. Image certainly looks very bright to me. Time to get the light meter out :)

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Oh wow... I literally JUST GOT my black magic pocket and nikon to mft speed booster today!  I really hope I can return it in exchange for the BMPCC specific speedbooster: the test footage looks amazing!

What adapters do people recommend for getting Leica-R's to Nikons?  I tried a fotodiox one a while back, and it involved removing the mounting plate on the leica (which failed miserablly, as I lost the little spring that holds the important bits in place.)  Needless to say, it soured my experience, but I would love to get some easier adapters to put my lieca lenses on the nikon to mft speed booster.  Any recommendations would be much appreciated!  Thanks!

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 Nikon's focus and aperture ring direction make me nervous because of my hand makes a mistake every time. It's opposite direction of all my Noktons, Zeiss ZE, Canon FD lenses. It prevent me of buying Sigma 18-35 and Metabones M43 combination. I'd very like if them make also M43-to-M43(BMPCC) Speedbuster, I think it possible because it need optical correction anyway, but it not required to engineer MFT-to-MFT electronic adapter, there are already macro extension rings at market.

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Guest c2dd7b52878779b55f43cc8c269267c1

But both camera A and B are getting 100 photons of signal per frame.  The same signal to noise ratio.   So even though you will have to boost the iso/gain of camera A to match the brightness of camera B, the noise at that higher iso will be the same as the noise of camera B at the lower Iso.

 

Thanks, very clear explanation - but I'm struggling with the last paragraph. I'm probably being really slow here, but why will the noise be the same? When you boost ISO doesn't the signal-to-noise ratio deteriorate?

 

Of course there is also the 'real world' issue that the larger sensors we're talking about are generally on hybrid cameras that often downsample in ways that don't make all of the surface area count toward signal-to-noise. Whereas the Blackmagic cameras are native video resolution, so have larger pixels with full readout (i.e. all surface area does count). Correct?

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Thanks, very clear explanation - but I'm struggling with the last paragraph. I'm probably being really slow here, but why will the noise be the same? When you boost ISO doesn't the signal-to-noise ratio deteriorate?

 

Of course there is also the 'real world' issue that the larger sensors we're talking about are generally on hybrid cameras that often downsample in ways that don't make all of the surface area count toward signal-to-noise. Whereas the Blackmagic cameras are native video resolution, so have larger pixels with full readout (i.e. all surface area does count). Correct?

 

Its general equivalence theory.  Larger sensors generally have lower noise at higher ISO.  Assuming the sensors are of the same generation.  Its what makes a full frame camera better than a point and shoot.   The speed booster effectively makes your sensor bigger so you are now equal with the larger sensor but not better.  The speedbooster doesn't give you a free meal.

 

And yes you are right, black magic use all of their sensors so that is a noise advantage compared to an a camera that doesn't.  Magic lantern raw on the 5diii for example probably only uses 1/9th of its pixels.

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I've just done a very crude test using the APS-c crop mode on my A7R.

 

Full Frame:-

https://dl-web.dropbox.com/get/FF.jpg?w=AAC7BwWnC-dDmV8Wabg5d50h4rcCnqQcK82p5zzyZFocww

 

APS-C + Speed booster

https://dl-web.dropbox.com/get/SB.jpg?w=AACS4qZtmb-7CXtvNNwQgh8y0-JIuzzvTDfEd2-PNKcGgg

 

point of focus was on the eye balls of the squirrel.  the lens was a zeiss planaer at f2.8.  I downsized the large 36mpx image and overlayed it over the aps-c shot to even the odds resolution wise (the full frame shot was 36mpx and the aps-c shot was 16mpx..

 

notice how the defocus on the lenses in the background is the same, yet more of the squirrel's face and shoulders are in focus on the full frame shot.   this should be less obvious as you move further away from the subject, however to me I seem to see it becomes even more obvious on medium/wide shots where the distance between the camera and the subject is greater.

 

I just signed up for dropbox but the links are still giving me a Dropbox 403 error.  It it something i'm doing wrong?

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Guest c2dd7b52878779b55f43cc8c269267c1

Its general equivalence theory.  Larger sensors generally have lower noise at higher ISO.  Assuming the sensors are of the same generation.  Its what makes a full frame camera better than a point and shoot.   The speed booster effectively makes your sensor bigger so you are now equal with the larger sensor but not better.  The speedbooster doesn't give you a free meal.

 

And yes you are right, black magic use all of their sensors so that is a noise advantage compared to an a camera that doesn't.  Magic lantern raw on the 5diii for example probably only uses 1/9th of its pixels.

I get it now. Thanks for the thorough explanation.  :)

 

It's good to get these things clear in one's head abstractly (as you've helped me to do) and then apply the fundamentals to real world examples. 

 

Also, now that I've understood what you are saying, I think it's a very good point you are making. (though the Bm's having better pixel-to-sensor ratio than DSLR's probably puts them in the same ball park as some APS-Cs (?). Would be interesting to know this.

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It won't go, I just did a little exploratory test and got nowhere - the sensor housing blocks the optics and you can't mount it at all. Certainly not something to try forcing. It's a no-go. Same with the other MFT cameras. What the BMD specific boosters have done here is to absolutely make use of ALL the bigger available space around the sensor and mount on those cameras.

 

The MFT Speed Booster is not superseded, not replaced, not old… It is optimised for the larger 2x crop and 1.86x crop sensors in the GH3 and GH2 and other MFT cameras so if you have those cameras don't think twice about picking one up. The image is beautiful. Especially with Contax Zeiss 50mm F1.4.

 

I understand the GM1 has a different type of shutter mechanism to reduce the size.  I wonder is anyone has tried this with the GM1?

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I've just been filming with the Pocket, using the combo of a Nikon 24mm f2.8 & Iscorama (makes it about a 48mm).

Its absolutely the perfect combo for a workable FOV & it seems that its the widest one can go with the Iscorama.

 

Is that an old manual FX-lens? I saw you get those old ones pretty cheap, and I wonder why. Where is the catch?

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Is that an old manual FX-lens? I saw you get those old ones pretty cheap, and I wonder why. Where is the catch?

http://www.kenrockwell.com/nikon/24f28.htm

Just a normal old manual Nikon 24mm f2.8 AI-S lens - v.close focusing & no distortion.

So no real catch, apart from you need 95mm or 82mm diopters (Tokina 72mm vignettes) for the Iscorama.

 

I think with the new Speedbooster i'm going to go Nikon, so only really need to get a 28mm & a 50mm.

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EOSHD, thanks for posting this update.  As a night sky photographer and timelapser, I already own a number of quality EOS EF mount lenses for full-frame (11-16 Tokina, 14mm Rokinon).  I do have a decent collection of Nikkor lenses from 24mm to 300mm, but you see my problem with the speed booster already... I'd really like to use that Tokina 11-16 on the BMPC with a wider/faster Speed Booster adapter.

So my "wide" lenses are Canon mount, my telephoto lenses tend to be Nikkor.   I have to have perfect infinity focus for landscape photos, which means not using lens adapters in many cases. 

No response necessary, but MetaBones, if you're reading this, I'm likely to buy both an EF and a Nikkor Speed Booster.. so, get working on that EF model already!   (I'm sure I'm not the only person with this issue of owning mostly wide EF lenses) 

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