[ChopperCharles]

Metabones Released Nikon G to Pentax Q Speed Booster - Mirrorless Times

Charles.

[WPRESTO]

I've heard of these "speed booster" versions of Metabones adapters, but I've never seen a test of the IQ. Basically they have a "reverse TC" lens system that concentrates the incoming light rather than expanding it as a TC does. Thus it effectively shortens the FL of a lens. When used to mount a lens in front of a camera with a smaller sensor, it means you get approximately (exactly?) the same FOV you get when the same lens is mounted on a body with a larger sensor. However, because the light is concentrated, you effectively get an increase of one f-stop (= an f4 tele mounted on a Q now has light transmission equivalent to f2.8). I use a non-speed booster Metabones and can certify that the mechanical quality, the fit and finish of the metal parts, is 100% satisfactory.

RE and BTW: Unless you are using a Canon lens and the appropriate Metabones adapter, any lens you mount will lose AF and aperture control (for example a Nikon lens mounted on a Pentax Q becomes manual-focus & manual aperture). Because Canon EOS lenses use an electrical rather than a mechanical aperture control, you can get a Metabones adapter that will allow auto-aperture with aperture control from some non-Canon camera bodies and therefore all modes (AV, TV, P etc) will function normally. Some Metabones adapters (very expensive) will also allow AF with some (not all ) Canon lenses on some (not all) small-sensor bodies.

[Mistral75]

I've heard of these "speed booster" versions of Metabones adapters, but I've never seen a test of the IQ. Basically they have a "reverse TC" lens system that concentrates the incoming light rather than expanding it as a TC does. Thus it effectively shortens the FL of a lens. When used to mount a lens in front of a camera with a smaller sensor, it means you get approximately (exactly?) the same FOV you get when the same lens is mounted on a body with a larger sensor. However, because the light is concentrated, you effectively get an increase of one f-stop (= an f4 tele mounted on a Q now has light transmission equivalent to f2.8).(...)

Actually, with a x0.5 focal reducer such as the Metabones' Devil's Speed Booster, you get an increase of two f-stops: f/4 x 0.5 --> f/2.

[rrstuff]

I've heard of these "speed booster" versions of Metabones adapters, but I've never seen a test of the IQ. .

There were a lot of tests when they first came out a few years ago. Reviews were good.
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[zippythezip]

Here is a link to the website store. I read here it says a Pentax k mount is planned as at the moment only Nikon lenses can be mounted.

Metabones®

[Abbazz]

I have this adapter and am very happy with the results.

Here's a quick review that I have posted here: 0.666 Devil's Speed Booster for Pentax Q - PentaxForums.com

And a thread on another forum: Nikkor-S 55mm F/1.2 on Pentax Q with Devil's Speed Booster

Cheers!

Abbazz

[PiDicus Rex]

Thus it effectively shortens the FL of a lens.

NOPE !, No, not ever!

What Focal Reducers do, is reduce the amount of the Field of View of the lens lost by the crop factor.

No adapter ever made can increase the Field of View of a lens. The lens itself keeps the same Field of View angle regardless of what it is put in front of, be that a crop camera, a crop camera with a focal reducer, a full frame camera, or an ICL adapter for a fixed lens camera.

Take a FF lens and put it in front of an MF camera (so it would have a negative value for the crop factor) and you don't suddenly get a wider lens, you get Vignetting.

Same goes if you use a focal reducer to compress the image circle down to a negative crop.

[WPRESTO]

NOPE !, No, not ever!

What Focal Reducers do, is reduce the amount of the Field of View of the lens lost by the crop factor.

No adapter ever made can increase the Field of View of a lens. The lens itself keeps the same Field of View angle regardless of what it is put in front of, be that a crop camera, a crop camera with a focal reducer, a full frame camera, or an ICL adapter for a fixed lens camera.

Take a FF lens and put it in front of an MF camera (so it would have a negative value for the crop factor) and you don't suddenly get a wider lens, you get Vignetting.

Same goes if you use a focal reducer to compress the image circle down to a negative crop.

Well, yes, of course. Teleconverters expand the light coming through the camera-end of a lens, or in other words, they "spread out" the light. They do not change the FL of the original lens, BUT they create unit or combination that has a different FL. We commonly say that a 1.4X converter placed on a 300mm lens "effectively" gives us a 420mm lens. We also say that a 300mm lens, used on an APS-C camera body, is "effectively" equivalent to a 420mm lens on a FF camera, and we all understand that we are not claiming that the FL of the original lens has been changed. I commonly say that using a FF lens on an APS-C body is basically "pre-cropping" the image, or cropping at the moment of shutter trip rather than during PP.. SOOO: A 0.7X converter, used to mount a 150mm lens on an MFT body, concentrates the light coming out of the camera-ends of a lens, or "effectively shortens the FL of the original lens" giving the combination the equivalent of a 210mm lens on a FF frame body, or a 315mm lens on an APS-C body, whereas originally the 150mm was "effectively" a 300mm FF equivalent (450mm APS-C equivalent) lens when used on MFT. The FL of the original lens is not changed by a TC, but for all practical purposes it creates a "lens unit" or "lens combination" that has a different FL.

[Abbazz]

NOPE !, No, not ever!

What Focal Reducers do, is reduce the amount of the Field of View of the lens lost by the crop factor.

No adapter ever made can increase the Field of View of a lens. The lens itself keeps the same Field of View angle regardless of what it is put in front of, be that a crop camera, a crop camera with a focal reducer, a full frame camera, or an ICL adapter for a fixed lens camera.

Take a FF lens and put it in front of an MF camera (so it would have a negative value for the crop factor) and you don't suddenly get a wider lens, you get Vignetting.

Same goes if you use a focal reducer to compress the image circle down to a negative crop.

I think you are confusing field of view and focal length. A Focal reducer does just what its name implies: it reduces the focal length of a lens. A 55mm lens in front of the "0.666 Speedbooster" sees its focal length reduced to 27.5mm. It's the same for a teleconverter (focal multiplier): if you put a doubler behind the same 55mm lens, you will get a 110mm lens.

Of course, a focal reducer will increase the field of view of a lens, although there is a limit due to mechanical vignetting and lens coverage. If you put a 35mm full frame lens in front of a full frame sensor, here's what you get:



While the same lens on the same sensor with a speedbooster will give you a wider field of view, although with severe vignetting in the corners:



[Both pictures from DPReview: Old SLR lenses: full-frame, focal reducer, or APS-C?: Digital Photography Review]

Cheers!

Abbazz

[reh321]

NOPE !, No, not ever!

What Focal Reducers do, is reduce the amount of the Field of View of the lens lost by the crop factor.

This doesn't make any sense.
If you put a 25mm lens, any 25mm lens that doesn't vignette, on a Q-7, you will get the same view.
View depends on the sensor and focal length of the lens. Period.
If you put a 50mm lens on using this adapter, it will give the same view you get with any 25mm lens, and its aperture is increased .... 50mm f/1.4 lens now if a 25mm f/0.7 lens!

No adapter ever made can increase the Field of View of a lens. The lens itself keeps the same Field of View angle regardless of what it is put in front of, be that a crop camera, a crop camera with a focal reducer, a full frame camera, or an ICL adapter for a fixed lens camera.

Take a FF lens and put it in front of an MF camera (so it would have a negative value for the crop factor) and you don't suddenly get a wider lens, you get Vignetting.

Same goes if you use a focal reducer to compress the image circle down to a negative crop.

Apparently you haven't bothered to read the review by @Abbazz
0.666 Devil's Speed Booster for Pentax Q - PentaxForums.com
Compare the first set of pictures {using standard adapter} with the second set {using speed booster}
The view is wider!!!!!!!!!!!!!!!!!!!!!!

[PiDicus Rex]

I think you are confusing field of view and focal length. A Focal reducer does just what its name implies: it reduces the focal length of a lens.

No. It Does Not Alter the Focal Length (or Angle of View) of a Lens.

It Compresses the Image Circle.

I'm totally astounded that there are so many people out there who do not know this!

---------- Post added 06-07-18 at 01:19 PM ----------

Apparently you haven't bothered to read the review by @Abbazz

I read that first, and explained why the math in the review was wrong.


Y'know, I only looked in the Q-forum to find what the crop was and whether anyone's tried using small Anamorphics to film with them
I have a short film to do needing a camera on a Gimbal on a jib arm above a Dolly,... really want to try it on a Q series camera, for the colour accuracy of the Pentax colour science.

[Abbazz]

I'm totally astounded that there are so many people out there who do not know this!

If I were you, I'd rather wonder why you are the only person to know this!

Cheers!

Abbazz

[Mistral75]

Actually the focal reducer doesn't reduce the focal length of the lens it's attached to but the optical system made of the lens plus the focal reducer has a reduced focal length and a reduced image circle in comparison to the original lens.

[Mikesul]

If I were you, I'd rather wonder why you are the only person to know this!

Cheers!

Abbazz

Funny. But focal reducers have been used for quite awhile and extensively with mirrorless cameras. They were/are very popular. I never bothered with them but there was much chatter about them a few years ago.

[reh321]

I read that first, and explained why the math in the review was wrong.

I'm not interested in the math.
The accompanying images are what matter - and they show a wider view.