Micro Four Thirds Focal Reducer Shootout

Started 5 months ago | Discussions
Andy Crowe
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Vizelex Light Cannon...
In reply to brian, 5 months ago

Vizelex seemed to get so many complaints about their Light Cannon they've resorted to selling it as a "soft focus" adapter!

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dougjgreen1
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Given your clear vested interest in the results......
In reply to brian, 5 months ago

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster?  It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

brian wrote:

Since Metabones released the first general purpose m4/3 focal reducer in June 2013 several more products have appeared on the market. To my knowledge, there haven't been any systematic high resolution comparison tests of these focal reducers, so I decided to shoot a test chart and put together a matrix of 100% crops.

The matrix below shows 100% crops from the center, left side, right side, and all four corners of test chart images taken with a 50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones. The test chart used is a standard Resolving Power Chart available at low cost from Edmund Optics: http://www.edmundoptics.com/testing-targets/test-targets/resolution-test-targets/resolving-power-chart/1665 . Note that the chart illumination wasn't perfectly uniform, and was a little brighter on the right side. In each case, focus was adjusted for maximum contrast in the center of the field. The camera used was a Panasonic G6.

DISCLAIMER: I'm the designer of the Speed Booster optics.

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Brian Caldwell

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beomagi
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Re: OM mount
In reply to brian, 5 months ago

brian wrote:

Tom Caldwell wrote:

Jack Hass wrote:

ApertureAcolyte wrote:

So why did they make an FD speedbooster then? Contax/Yashica?

The OM mount makes more sense than any other mount. Metabones would have made more sales on the OM speedbooster than the C/Y.

I think even though both FD and OM are no more, there are far more FD's out there due to Canon being a much larger user base, so it makes sense to sell to the larger audience. I agree they should have made both, but id imagine it has to be convincing before the R&D is started.

Ask Brian? The oracle started this thread, otherwsie we are just flapping our keyboards.

I don't know but I think that there are some bits that stick out of the back of OM lenses that complicate matters.

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Tom Caldwell

I would like to see Metabones come out with an OM version. However, I'm not directly affiliated with the company so I don't know what their plans are regarding this. I do recall that some of the OM lenses presented more of an interference issue than other brands such as Nikon.

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Brian Caldwell

I think to those with a lot of old lenses of various mounts, Canon EF is most logical since it adapts OM, K, M42, F etc.

Of course the reason is the shorter flange distance. Is the shorter flange distance preventing Metabones from making an EF mount version? Can the optics fit in an EF spaced adapter?

Another possibility is that making an EF which adapts most other lenses eats into their profits if they can sell multiple adapters to people instead of a more universal one.

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brian
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Re: Given your clear vested interest in the results......
In reply to dougjgreen1, 5 months ago

dougjgreen1 wrote:

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster? It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

Interpret my results however you wish.  However, there was no cherry-picking going on.  In fact, the m4/3 Metabones Speed Booster I have is on the high side of the flange angular runout tolerance of Metabones products.

My test methods aren't exactly complicated.  If you have doubts there is certainly nothing stopping you from repeating my tests and publishing your own results.

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Brian Caldwell

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brian
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Re: OM mount
In reply to beomagi, 5 months ago

beomagi wrote:

brian wrote:

Tom Caldwell wrote:

Jack Hass wrote:

ApertureAcolyte wrote:

So why did they make an FD speedbooster then? Contax/Yashica?

The OM mount makes more sense than any other mount. Metabones would have made more sales on the OM speedbooster than the C/Y.

I think even though both FD and OM are no more, there are far more FD's out there due to Canon being a much larger user base, so it makes sense to sell to the larger audience. I agree they should have made both, but id imagine it has to be convincing before the R&D is started.

Ask Brian? The oracle started this thread, otherwsie we are just flapping our keyboards.

I don't know but I think that there are some bits that stick out of the back of OM lenses that complicate matters.

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Tom Caldwell

I would like to see Metabones come out with an OM version. However, I'm not directly affiliated with the company so I don't know what their plans are regarding this. I do recall that some of the OM lenses presented more of an interference issue than other brands such as Nikon.

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Brian Caldwell

I think to those with a lot of old lenses of various mounts, Canon EF is most logical since it adapts OM, K, M42, F etc.

Of course the reason is the shorter flange distance. Is the shorter flange distance preventing Metabones from making an EF mount version? Can the optics fit in an EF spaced adapter?

Another possibility is that making an EF which adapts most other lenses eats into their profits if they can sell multiple adapters to people instead of a more universal one.

A fully electronic EF - m4/3 Speed Booster should be released soon.  Its not a trivial product to design and manufacture.  Remember, the very first Speed Booster was Canon EF - to - Sony NEX, so there is no hidden agenda going on.

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Brian Caldwell

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Tom Caldwell
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Re: Hot spotting - the cause?
In reply to brian, 5 months ago

brian wrote:

Tom Caldwell wrote:

Brian

Thank you for making these tests it is appreciated.

I am always puzzled by the condition that creates these hot spots. I have no proper technical knowledge of what causes the but I have tried to explain them on forums to the best of my understanding. (For want of an alternative more knowledgeable source). It seems that the "spots" are shown and commented upon but their technical reason for occurring remains a mystery surronded in optical jargon.

If I repeat my understanding here then you might be able to comment and confirm or advise differently.

My understanding is that back in the film days the film stock was not as reflective as modern sensors and therefore the reflection of a strong light source from the film and further re-relection back off some part of the lens glass back on to the film was less of a problem. In fact some lens manufacturers did not particularly worry about it as inconsequential. Different legacy slr lenses are therefore more prone to sensor re-reflection spots/smudges than others.

Sensor reflection can be bounced back via some flatter glass surface in the form of a aperture delineated circle if from an element located in front of the aperture or as a smudge if after the aperture. According to some Canon literature even a flat filter lens surface can cause this reflection. Canon seem quite proud that they have a meniscus protective front lens to prevent this re-reflection "unlike some of their opposition". Canon's advice for those getting this hot spot on their esteemed telephoto range in extreme conditions was to try removing the lens filter.

I believe/think that good lens design can disperse this re-reflection before it is completely reflected back to the sensor surface. You are to be congratulated as the Metabones product seems to have been designed to reduce or eliminate this re-reflection that happens in more extreme circumstances very well.

I also have to make a disclaimer so that readers might understand: I share your surname, but we are not related. I have no commercial connection with Metabones nor any other Chinese focal reducer manufacturer. I buy my own focal reducers, including a Metabones Speed Booster and several other Chinese made focal reducers for the Sony E-mount. I have one RJ made M42 to M4/3 focal reducer adapter. I am not suitably qualified to make exacting tests, nor do I have any optical knowledge other than what I have read.

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Tom Caldwell

Hi Tom:

Central hotspots are a ghost image of the aperture stop. The visibility of the ghost image depends on the magnification of the ghost image (smaller means brighter), the amount of aberration in the ghost image (less aberration means a more pronounced ghost), and the efficiency of the lens coatings.

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Brian Caldwell

Thanks Brian, but do you endorse my stumbling attempt to try and describe what is happening or disagree with it?

I can understand the concept of bounced light of the sensor being bounced back as a ghost image off a lens element through the aperture which gives it the circular appearance. I think you once said that you could count the aperture blades in one example.

Do you say that the ghost can be cured by efficient lens coatings?  Would the aberration come from the sensor reflection through the adapter or in the lens itself? I mistakenly thought that the ghost image could be designed out by dispersing the rays.  But a little knowledge is a dangerous thing and I thought it truly heroic if such an adapter could be designed to deal with any old lens it might be connected to.  I can understand if you are unable to know in more than a general manner.

Alternatively the aberrations might be caused in the first pass as secondary rays and these concentrated into a second ghost shape in the form of a circle.  Sorry, I am just after an understanding of the cause.

You will remember that I hooked up a Zykkor glassed FD to EF adapter which works reasonably well in its intended use in combination with my Speed Booster and had some horrible hot spot problems using two different lenses. But I fully realised that this was coming from the Zykkor and not the Speed Booster and it was unfair to expect the Speed Booster to cope with anything thrown at it.  I have no real reason to use this combination which gave the problem in an unusual situation involving fluorescent light at night it was also only really bad at smallest aperture (at night).  In this case the spot was very bright and white at the smallest lens aperture and visibly diffused in a regular manner eventually into the full image circle.

I did not persist as I had no need to do so, but I should try this again in more normal light conditions.

None of this has diminished my respect for the Metabones product.

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Tom Caldwell

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Tom Caldwell
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Re: OM mount
In reply to brian, 5 months ago

brian wrote:

beomagi wrote:

brian wrote:

Tom Caldwell wrote:

Jack Hass wrote:

ApertureAcolyte wrote:

So why did they make an FD speedbooster then? Contax/Yashica?

The OM mount makes more sense than any other mount. Metabones would have made more sales on the OM speedbooster than the C/Y.

I think even though both FD and OM are no more, there are far more FD's out there due to Canon being a much larger user base, so it makes sense to sell to the larger audience. I agree they should have made both, but id imagine it has to be convincing before the R&D is started.

Ask Brian? The oracle started this thread, otherwsie we are just flapping our keyboards.

I don't know but I think that there are some bits that stick out of the back of OM lenses that complicate matters.

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Tom Caldwell

I would like to see Metabones come out with an OM version. However, I'm not directly affiliated with the company so I don't know what their plans are regarding this. I do recall that some of the OM lenses presented more of an interference issue than other brands such as Nikon.

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Brian Caldwell

I think to those with a lot of old lenses of various mounts, Canon EF is most logical since it adapts OM, K, M42, F etc.

Of course the reason is the shorter flange distance. Is the shorter flange distance preventing Metabones from making an EF mount version? Can the optics fit in an EF spaced adapter?

Another possibility is that making an EF which adapts most other lenses eats into their profits if they can sell multiple adapters to people instead of a more universal one.

A fully electronic EF - m4/3 Speed Booster should be released soon. Its not a trivial product to design and manufacture. Remember, the very first Speed Booster was Canon EF - to - Sony NEX, so there is no hidden agenda going on.

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Brian Caldwell

That would be fun, count me "in". I can imagine my Canon 200mm f2.0 on a new M4/3 Speed booster attached to my Panasonic GM1.  Should be a sight to behold ...

Nothing like a controller box attached to a lens.

I have used this combo quite successfully on a NEX6 using the Speed Booster giving me a 213mm approximate equivalent at f1.4 and a tiny depth of field wide open. It is quite capable of being hand held, but at least the NEX6 has a decent sized grip.

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Tom Caldwell

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dougjgreen1
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I'm not questioning your testing methodology.....
In reply to brian, 5 months ago

I'm questioning your methodology of deciding which specific units that you actually tested.   You never described how the test subjects were chosen, which is why I raised the issue.   Saying that no cherry-picking was done is not the same as explaining exactly how the test subject units were actually selected - something you still have not done.

brian wrote:

dougjgreen1 wrote:

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster? It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

Interpret my results however you wish. However, there was no cherry-picking going on. In fact, the m4/3 Metabones Speed Booster I have is on the high side of the flange angular runout tolerance of Metabones products.

My test methods aren't exactly complicated. If you have doubts there is certainly nothing stopping you from repeating my tests and publishing your own results.

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Brian Caldwell

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beomagi
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Re: OM mount
In reply to Tom Caldwell, 5 months ago

Looking forward to seeing it. I'm satisfied with my cheap Chinese adapter for now. It's probably along the lines of the Zhongi, since I've been happy with sharpness, but all my future lens decisions are based on manual picks to satisfy adapting to my Canon and MFT systems.

When I have enough decent manual glass, I'll probably upgrade to the higher quality metabones.

Would materials with a higher refractive index permit the design of a higher powered adapter?

Thanks for the tests. They're quite helpful.

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Kim Letkeman
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so was it your job to ...
In reply to brian, 5 months ago

brian wrote:

Since Metabones released the first general purpose m4/3 focal reducer in June 2013 several more products have appeared on the market. To my knowledge, there haven't been any systematic high resolution comparison tests of these focal reducers, so I decided to shoot a test chart and put together a matrix of 100% crops.

The matrix below shows 100% crops from the center, left side, right side, and all four corners of test chart images taken with a 50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones. The test chart used is a standard Resolving Power Chart available at low cost from Edmund Optics: http://www.edmundoptics.com/testing-targets/test-targets/resolution-test-targets/resolving-power-chart/1665 . Note that the chart illumination wasn't perfectly uniform, and was a little brighter on the right side. In each case, focus was adjusted for maximum contrast in the center of the field. The camera used was a Panasonic G6.

DISCLAIMER: I'm the designer of the Speed Booster optics.

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Brian Caldwell

... spread the Vaseline on the competition? Or was that hired out?

Hyuk hyuk hyuk ... kidding ...

Looks like you know your stuff.

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tomtom50
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Re: Given your clear vested interest in the results......
In reply to dougjgreen1, 5 months ago

dougjgreen1 wrote:

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster? It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

How would a tester know they had equally representative copies of two products? In theory he could buy a large number, test them until some sort of bell curve emerged, and compare using median samples.

I think we can safely assume that wasn't done as it would be cost-prohibitive merely to back up a forum post!

On the other hand he disclosed himself as the designer, and Lens Turbo performed pretty decently in the test. He has earned the benefit of my doubt.

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TheSquid
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Re: Micro Four Thirds Focal Reducer Shootout
In reply to brian, 5 months ago

For those of you wondering why there is no OM adapter.... you all are forgetting that the OM lenses are fully manual.  Making an adapter would be a nice thing to do but it's not as necessarily needed since the lenses are easily used.

However, making one with electronics would be nice.  The electronics would have to control aperture and close the lens down for the exposure via the original olympus manual stop down mechanism.  This may be too daunting a task to do.  The reasons are that it may not trigger fast enough to actually stop down and secondly, it may not be able to transfer the f-stop information to the camera making it still fully manual exposure instead of aperture priority compatible.

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dougjgreen1
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Re: Given your clear vested interest in the results......
In reply to tomtom50, 5 months ago

tomtom50 wrote:

dougjgreen1 wrote:

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster? It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

How would a tester know they had equally representative copies of two products? In theory he could buy a large number, test them until some sort of bell curve emerged, and compare using median samples.

I think we can safely assume that wasn't done as it would be cost-prohibitive merely to back up a forum post!

On the other hand he disclosed himself as the designer, and Lens Turbo performed pretty decently in the test. He has earned the benefit of my doubt.

I don't think that you can assume at all that this was done strictly as a forum post. What leads you to believe that this was not done as a guerrilla marketing exercise by Metabones the company, funded by Metabones?

Don't get me wrong - I have no issue with the tests themselves, they seem to be perfectly appropriate. But it's naive to think that the poster here just did this out of his own intellectual curiosity and with products he just happened to acquire as a private individual as you or I might. His disclosure about who he is almost certainly makes it clear that this is NOT the case. Which is why I asked a simple question - how were the sample units for each brand obtained? And note that this question has not, as yet been answered. I wonder why, if in fact the OP simply purchased individual production-rev. products for ALL 4 items on the open market, and tested them straight out of the box, why they did not in fact simply say that? Because I'm betting that's NOT how all 4 test subjects were obtained. I simply want to know how these 4 tested units were acquired, in order to draw my own conclusion about the legitimacy of the comparison and whether there was any underlying sampling bias prior to the tests being carried out.

Also, in the interest of full disclosure - in a prior professional engagement, I was in charge of marketing of certain bits of computer and broadband telecommunications technology, and I have a pretty in depth understanding of exactly how benchmark tests can and are used to market the supposed superiority of one piece of technology relative to it's competition, and I am well schooled at the various ways that the tests and the test subjects can be either manipulated or pre-selected to bias the results in favor of the devices that the tester might have an agenda in promoting.

As I said, I think that it's probably pretty apparent that the test itself that the OP described is a clean comparison metric.   But what is far less apparent is whether there was any sample pre-selection at all that was done prior to the tests - either with respect to the metabones unit, or the competitor units that it was compared to.

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amtberg
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Re: so was it your job to ...
In reply to Kim Letkeman, 5 months ago

Kim Letkeman wrote

Looks like you know your stuff.

I think that's a safe bet:

"Brian Caldwell earned a Ph.D. in Optics from The University of Rochester in 1988.

He has 30 years experience in the fields of lens design and optical engineering, with more than 100 different manufactured products to his credit.

In 1988 he founded Optical Data Solutions to develop LensVIEW, an extensive database of more than 30,000 optical designs from the patent literature. After working as an optical designer first at Projectavision and then at Concord Camera he founded Caldwell Photographic Inc. in 2001 to do independent consulting, and to develop and manufacture optical products.

Commercial products designed by Dr. Caldwell include a 60mm UV-VIS-IR apochromat licensed for manufacture by Jenoptik Optical Systems, a series of 12 high speed cine lenses for the new Panavision 70mm digital cine camera, and a universal photographic focal reducer currently marketed by Metabones as the Speed Booster."

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amtberg
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Re: Given your clear vested interest in the results......
In reply to dougjgreen1, 5 months ago

dougjgreen1 wrote:

tomtom50 wrote:

dougjgreen1 wrote:

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster? It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

How would a tester know they had equally representative copies of two products? In theory he could buy a large number, test them until some sort of bell curve emerged, and compare using median samples.

I think we can safely assume that wasn't done as it would be cost-prohibitive merely to back up a forum post!

On the other hand he disclosed himself as the designer, and Lens Turbo performed pretty decently in the test. He has earned the benefit of my doubt.

I don't think that you can assume at all that this was done strictly as a forum post. What leads you to believe that this was not done as a guerrilla marketing exercise by Metabones the company, funded by Metabones?

Don't get me wrong - I have no issue with the tests themselves, they seem to be perfectly appropriate. But it's naive to think that the poster here just did this out of his own intellectual curiosity and with products he just happened to acquire as a private individual as you or I might. His disclosure about who he is almost certainly makes it clear that this is NOT the case. Which is why I asked a simple question - how were the sample units for each brand obtained? And note that this question has not, as yet been answered. I wonder why, if in fact the OP simply purchased individual production-rev. products for ALL 4 items on the open market, and tested them straight out of the box, why they did not in fact simply say that? Because I'm betting that's NOT how all 4 test subjects were obtained. I simply want to know how these 4 tested units were acquired, in order to draw my own conclusion about the legitimacy of the comparison and whether there was any underlying sampling bias prior to the tests being carried out.

Financial interest is certainly a theoretical possibility, assuming that Dr. Caldwell gets a cut of each unit sold as opposed to having been hired strictly as a design consultant.  Of course another equally plausible possibility is that he's simply proud of the good work that he did and perhaps a little chapped at all of the copycat companies who took his basic idea but executed it poorly due to their relative lack of expertise.

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s_grins
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Re: Micro Four Thirds Focal Reducer Shootout
In reply to brian, 5 months ago

"50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones."

Why such a simple thing has to be so complex? Did you have a problem with selecting just a equal M43 lens?

I'm still can't fathom the depth of idea behind setup

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amtberg
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Re: Micro Four Thirds Focal Reducer Shootout
In reply to s_grins, 5 months ago

s_grins wrote:

"50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones."

Why such a simple thing has to be so complex? Did you have a problem with selecting just a equal M43 lens?

I'm still can't fathom the depth of idea behind setup

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Camera in bag tends to stay in bag...

Umm, you seem to have completely missed what these focal reducers do.  They are designed to adapt full frame or (some) APS-C lenses to smaller formats by shrinking the image circle, which has the added benefit of reducing the effective aperture of the lens.  You couldn't attach an MFT lens to a focal reducer because it would make the image circle smaller than the sensor.

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brian
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Re: Hot spotting - the cause?
In reply to Tom Caldwell, 5 months ago

This diagram shows how you can form a ghost image of the stop by reflecting off the sensor and then off of one of the lens surfaces.  This is just one particular example of how such an image is formed.  In general, there are hundreds or even thousands of possible ghost images formed in a complex imaging system, and you have to pay attention to all of them if you want to do a good job of minimizing ghosting.

Follow the green ray, starting at the aperture stop.  At the aperture stop, which is the object, the height of the green ray is zero.  Now follow the green ray to the image plane (surface 13).  At this point we have the first ghost reflection.  After reflectiing off the sensor, the green ray refracts through the rear surface of the lens and then reflects off the second-to-last surface of the lens.  The green ray then passes back through the rear surface to intersect the image plane at an image height of zero.

Since the ray starts at the middle of the aperture stop and intersects the image plane at the optical axis the ghost image is a true image of the aperture stop.  So, if the aperture stop is a triangle then there will be a ghost image in the shape of a triangle in the exact center of the picture.

The lens system consisting of the last three elements of this particular lens plus the flat reflective sensor comprises a catadioptric (mirror + lens) optical system with two mirrors.

The fact that the hotspot imaging in this case involves a relatively flat lens surface is a complete coincidence.  Often you get fairly steeply curved surfaces involved.  Ghost image formed by reflection off of front-mounted filters are completely unrelated to hotspots.  Such ghost images show up as sharply focused mirror images of bright areas in the primary images.

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dougjgreen1
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Re: Given your clear vested interest in the results......
In reply to amtberg, 5 months ago

amtberg wrote:Financial interest is certainly a theoretical possibility, assuming that Dr. Caldwell gets a cut of each unit sold as opposed to having been hired strictly as a design consultant. Of course another equally plausible possibility is that he's simply proud of the good work that he did and perhaps a little chapped at all of the copycat companies who took his basic idea but executed it poorly due to their relative lack of expertise.

There's no evidence that two of the competing products were poorly executed. They may simply be slightly less good because they are built to steeper cost constraints. What probably IS true is that they are knock-offs, in the sense that they did not do the basic design research, but rather, copied the existing Metabones product and manufactured it more cheaply.

And BTW, it is normally the case that a someone in the OP's position might be partly compensated with an equity stake in Metabones, given the fact that it's a start-up, and it is significantly leveraged on the quality of the design work that goes into their products - this is true whether he is a contractor or a direct principle employee of Metabones.

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s_grins
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Re: Micro Four Thirds Focal Reducer Shootout
In reply to amtberg, 5 months ago

amtberg wrote:

s_grins wrote:

"50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones."

Why such a simple thing has to be so complex? Did you have a problem with selecting just a equal M43 lens?

I'm still can't fathom the depth of idea behind setup

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Camera in bag tends to stay in bag...

Umm, you seem to have completely missed what these focal reducers do. They are designed to adapt full frame or (some) APS-C lenses to smaller formats by shrinking the image circle, which has the added benefit of reducing the effective aperture of the lens. You couldn't attach an MFT lens to a focal reducer because it would make the image circle smaller than the sensor.

Well, if I understand you right, speed booster is a focal reducer, and it takes from FL and,shrinking an image circle, adds to an F-stop making lens faster.

Am I right? If I'm, than all these

1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones."

are just different brands of the same FL reducer, and there are 4 different setups. OP wants to compare different brands, which may make a sense.

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