F3: HD35 MK2 adaptor review by SPARKY FILM

[steve phillipps]

How fast is your lens? it would seem that 2 would go to 4.5-5.6 which is as fast as the sony lens, 24-105 or other options..

S

In my test (with Canon HJ18x28) I found that - as when using the built in doublers on these ENG lenses - you really need to stop down at least 1 stop, preferably a bit more, to get really good sharpness. This is the slight issue with these adapters - the HJ18 starts at f4.9 at the 500mm end, then it needs stopping down by about 2 stops, then the HDx35 loses another 2.5 so you're at f22. The lens I was comparing it to optically was the Sigma 300-800 f5.6, which with a 2x extender is f11, but that needs to be stopped down a stop too, but still a stop faster at f16. But definitely less manageable and flexible!
Steve

 

[starcentral]

Great review Sparky, even though from a year ago.

I'm wondering what connector or cable I need to build to power the lens zoom servo from my camera body or other DC power source?

Anyone have any pinouts or know where to look? I'd probably grab 12 volts off my 2nd hirose connector on the F55 body.

 

[HD Gear Guru]

I'm wondering what connector or cable I need to build to power the lens zoom servo from my camera body or other DC power source? Anyone have any pinouts or know where to look? I'd probably grab 12 volts off my 2nd hirose connector on the F55 body.

Don't know the pin outs etc personally but we have built the cables to power the lens and provide start stop trigger from lens to camera...

 

[starcentral]

Regarding adapters, so if I got this straight:

HD35 MKII- no lens extender required, covers full s35mm sensor, 2.5 stops light loss
MTF B4 2/3" to FZ - requires 2x extender, adapter has 1.5x magnifier, 2.5x total magnification, 2.5 total light loss, covers full s35mm sensor
MTF B4 to PL (MTB4S16PL) - 0.8 stops loss, requires center-crop mode like on RED or F5/55
RED B4 to PL adapter - ? no information ?
Sony LA-FZB1 B4 mount to FZ adapter - adapter has 2.6x magnification, 2.6 stops light loss, covers full s35mm sensor

 

[Mitch Gross]

Regarding adapters, so if I got this straight:

HD35 MKII- no lens extender required, covers full s35mm sensor, 2.5 stops light loss
MTF B4 2/3" to FZ - requires 2x extender, adapter has 1.5x magnifier, 2.5x total magnification, 2.5 total light loss, covers full s35mm sensor
MTF B4 to PL (MTB4S16PL) - 0.8 stops loss, requires center-crop mode like on RED or F5/55
RED B4 to PL adapter - ? no information ?
Sony LA-FZB1 B4 mount to FZ adapter - adapter has 2.6x magnification, 2.6 stops light loss, covers full s35mm sensor

The RED adapter is similar to the 2nd MTF adapter, meant only for the 2K center crop mode.
The Sony adapter mounts directly to the FZ mount, omitting the PL mount. Thus it is only functional on the F3/F5/F55 cameras.

 

[Mitch Gross]

Great review Sparky, even though from a year ago.

I'm wondering what connector or cable I need to build to power the lens zoom servo from my camera body or other DC power source?

Anyone have any pinouts or know where to look? I'd probably grab 12 volts off my 2nd hirose connector on the F55 body.

These pinouts are available on the web or in every B4 lens manual. The Sony F5/F55 Hirose allows both the power for zoom as well as the record trigger.

 

[starcentral]

Thanks Mitch, you are an endless fountain of knowledge.

In researching the B4 adapters I read a thread on REDUSER.net which says that "proper" B4 lens adapters must contain optics to correct out the fact that the B4 ENG lenses are designed to alter convergence for a 3-chip prism block.

If this is true then it is fair to conclude that the cheaper MTF/RED adapter is not doing this and results and mileage would highly vary compared to the other designs?

 

[harddrive]

It magnifies the focal length 2.7x with a 2.5 stop light loss. So a 10mm T2 lens becomes a 27mm T4-5.6 lens. Note that ENG video zooms are labelled in f-stops not T-stops, so an f1.9 is probably about a T2.2.

It may have the effect of making the f no smaller by about 2.5 stops - but it's technically wrong to call it a "light loss", and that terminology is feeding a popular misconception.

No light is actually "lost" (as it would be in an ND) - the image just gets spread out over a wider area. So the image is bigger, but dimmer. The significance is that (all else equal) the larger sensor will have a higher sensitivity, so you're back to square one in performance terms.

This may just sound pedantic - but I've now heard it said too many times that "you need so much extra light when you use one of these convertors because of the 2.5 stops light loss". Which is not true. In principle, the higher sensitivity of the larger sensor should compensate for the adaptor giving greater focal length/smaller f stop.

Saying a "2.5 stop light loss" would imply you need about 6x as much minimum illumination on a scene for comparable exposure when the lens is used with s35 and adaptor, and that isn't the case.

 

[HD Gear Guru]

Thanks Mitch, you are an endless fountain of knowledge.

In researching the B4 adapters I read a thread on REDUSER.net which says that "proper" B4 lens adapters must contain optics to correct out the fact that the B4 ENG lenses are designed to alter convergence for a 3-chip prism block.

If this is true then it is fair to conclude that the cheaper MTF/RED adapter is not doing this and results and mileage would highly vary compared to the other designs?

Don't know if is fair to say that the RED and MTF adapters have lower cost because of real or implied "non compensation". It is fair to say that since those devices are only creating a 2k image, the optics needed are not as extensive and thus not as expensive to design or manufacture. Some adapters that may offer or claim special compensation for 3 prism lenses cost about the same as other manufacturers adapters that blow up to the full sensor area...

 

[Nate Weaver]

This may just sound pedantic - but I've now heard it said too many times that "you need so much extra light when you use one of these convertors because of the 2.5 stops light loss". Which is not true. In principle, the higher sensitivity of the larger sensor should compensate for the adaptor giving greater focal length/smaller f stop.

The 55, at 1250, can be a tiny bit noisy if you have a lot of black in the frame. There are times I rate it at 1000 or 800 if I need cleaner.

With the blowup 2.5 stop-loss adapters, and assuming 1250 is ok for whatever you're shooting, that makes a ISO of somewhere around 150. Not acceptable for me.

Even if you push the camera stop to 2500, which is the most I'd ever push it unless I just absolutely need to shoot bigfoot running through my living room, makes for around ISO300. Not great. And really not great for interiors if you're lighting.

You can't push the 55 2.5 stops to 4000 and get a good image. The image at 4000 is great compared to history and camera predecessors, but it's not good enough to just do it all the time and call it a day.

 

[harddrive]

With the blowup 2.5 stop-loss adapters, and assuming 1250 is ok for whatever you're shooting, that makes a ISO of somewhere around 150. Not acceptable for me.

Sorry, I don't get what you're saying? I read it as rating the F55 at ISO 1250 as a noise free limit - but how does that equate with "that makes a ISO of somewhere around 150"?

Likewise, what rating are you comparing it with for a 2/3" camera for comparable noise?

There's also the 4k factor, that photosites become smaller for a given sensor size, so noise becomes more critical. But that's not an adaptor issue - you'd have to see what ISO on a 4k 2/3" camera corresponded to ISO 1250 on your F55 for comparable noise.

I did say "The significance is that (all else equal) the larger sensor will have a higher sensitivity" and I stress the "all else equal". In the case of a HD 2/3" camera, all else is obviously not equal to a 4k s35 sensor!

I was just referring to the optics. It's like having a projector, then moving it back twice as far from the screen. You'll get a dimmer image, but a bigger one, and it would be totally wrong to say that was because light was being "lost". the same number of photons hit the screen in total in both cases.

 

[Nate Weaver]

This discussion is all about the difference between theory and where the rubber hits the road.

You might think you can push the F55 sensor 2.5 stops and get a noise level that looks like a 2/3 camera, but I assure you if you tried it you would be disappointed.

My ISO equivalents were how you have to rate the camera when you lose 2.5 stops. 1250 - 1 stop is 625. Minus another stop is 300ish. Subtract another half and you're somewhere around 200. My math was off above. 200ISO is tough nuts for night interiors, or any other thing you have to light from scratch (some talking heads).

Not saying it's completely unusable. Just that it severely limits your options.

 

[Grug]

Yeah, the lightloss in getting B4 lenses to project across the full S35mm sensor does make the whole concept a bit iffy to my mind.

The B4-to-S16mm adapters though seem like they make a LOT of sense - only a stop or so of light loss, minimal magnification, a decent 2K resolution, all whilst maintaining the lovely dynamic range that really makes the images from these cameras sing. On the F5 in particular (with it's 2000 ISO base sensitivity), I think they'd make a lot of sense.

 

[Joshua Cadmium]

Thanks Mitch, you are an endless fountain of knowledge.

In researching the B4 adapters I read a thread on REDUSER.net which says that "proper" B4 lens adapters must contain optics to correct out the fact that the B4 ENG lenses are designed to alter convergence for a 3-chip prism block.

If this is true then it is fair to conclude that the cheaper MTF/RED adapter is not doing this and results and mileage would highly vary compared to the other designs?

Don't know about the MTF, but the Red adapter is exactly the same as the Abakus 132 Super 16 adapter - which was confirmed by the head of Abakus itself. The Abakus adapter does correct each color so that red, blue, and green converge on the same plane. Both adapters were originally $3,500, due to how strong the Pound was to the Dollar at the time (it's always been 1350 GBP).

Based on Mitch Gross's experience, the IBE version is probably better, but the Abakus is really good. I'd love to test them head to head (I currently have the Red/Abakus, and used to own the Century B4 adapter as well.)

 

[Joshua Cadmium]

I agree with harddrive, lightloss is not the right word (although the argument can easily turn into one of semantics) and you do take a low light hit by moving to 4K. The photosites have to be smaller at 4K, which pushes noise up. You can't fight physics. If the F55 was 1080p, you could push it's sensor 2.5 stops and get a noise level that looks similar to a 2/3 camera. This is similar to the reason why Arri went with a 65mm sensor for 6K, and why the A7s has excellent low light abilities: massively sized pixels.

So, there's nothing inherently bad happening with these adapters themselves. A f1.8 2/3" lens is equivalent to a f4.8 Super 35mm lens. It's just the optics and physics of the matter.

So, if a f4.8 15x zoom doesn't work for you because it's too slow, it doesn't mean that the adapter is limiting. For some people, being able to use these lenses is a great option, as there aren't compact zooms with massive range designed for Super 35mm. The Fujinon Cabrios, for instance, are typically over 1.5 stops faster but do so with nowhere near the range of a typical 2/3" zoom - closer to a 5x zoom. Fuji does have a 12x Cabrio zoom, but it's only a stop faster with no wideangle coverage. If you wanted a 12x Super 35mm T2.8 zoom with no ramping, you're looking at the massive Angenieux 24-290, and even that doesn't have wide coverage.

Once you bump up the range, the lens has to either get bigger or slower. You can't fight optics.

 

[steve phillipps]

The B4-to-S16mm adapters though seem like they make a LOT of sense .

Couple of issues though - once you debayer those 2MP from the cropped area you're probably not far off 720 resolution - the 2k center crop on the Epic never looked brilliant to me - it was OK, but not "epic". Also moire issues - though these seem to be solved where you can change the OLPF - but that does mean that you can't switch 2k to 4k at the touch of a button. Good to have all these options though for sure.

Steve

 

[steve phillipps]

I agree with harddrive, lightloss is not the right word

On IBE Optics' site they say "light drop", I read that the same as light loss, but maybe that's more correct?

Steve

 

[Joshua Cadmium]

You just want to avoid describing these adapters as working exactly like a photo teleconverter - only enlarging part of the lens and throwing the rest away. That's definitely light that's lost. Using these adapters, the whole image circle of the lens is basically going to be used, it's just spread out to cover a wider sensor diagonal as well.

I'd describe what the adapters do as an decrease in T/f stop in order to cover a larger sensor. So, light drop could work.

The term aperture equivalence, which some people in still photography don't like because of it's connotations, actually comes into play here and best describes what's going on. An f1.8 2/3" lens has an equivalent aperture of an f4.8 Super 35mm lens. These adapters, in varying quality, simply let you use that equivalence.

 

[Mitch Gross]

Well if you really want to get into the semantics of these things, there is almost NO situation in which there is true light loss. A 2x adapter only has light loss if you choose not to use the larger projection area. Otherwise the only occassions of light loss are from reflection and absorption as light rays hit the various lens elements and coatings. So yeah, no light loss here. On the most basic, practical level, the lens may say T1.4 but the light hitting the sensor is the equivalent of T4/5.6, so call it what you will as long as you remember that it is 2.5 stops less bright then what the aperture ring would indicate.

There are different generations of these adapters and I can tell you that there are HUGE differences in the optical performance between them. An old Abekus 132 compared to a modern one is night & day. AbelCine-IB/E have different adapters for various sized frames. At NAB they released the HDx1.4 (S-16/"2K" image area) to go along with the HDx35 (Super-35) and the HDx2 (MFT). I don't have all the details on the other brands.

 

[harddrive]

Well if you really want to get into the semantics of these things, there is almost NO situation in which there is true light loss. A 2x adapter only has light loss if you choose not to use the larger projection area.

Well, NDs have true light loss - the whole point of them! Same is true of multi-element lenses, exactly why we have the concept of T stops. Same is true for subtractive filtration on single chip sensors. All absorb light in the transmission - genuinely "lose" it.

And as for the 2x adaptor, then if you choose to use the larger area it's no longer a 2x adaptor!!! It becomes a format convertor, exactly what we're talking about here - with no light loss. Put in a doubler on a standard lens and it only does what it's supposed to because the sensor area stays constant! This is Joshua's point above.

On IBE Optics' site they say "light drop", I read that the same as light loss, but maybe that's more correct?

In true technical terms, the total luminous flux falling on the sensor will remain constant, but the luminance will decrease. (Luminance equals luminance flux/unit area.)

Hence talking about "light loss" is just plain inaccurate - you can "lose" flux, but you can't "lose" luminance. "Light drop" could be used to refer to luminance, so yes, better. But everything Joshua says is spot on - and the most precise description is to say "gives a smaller f stop".

What amuses me here is that so often manufacturers spin technical facts to best suit their marketing - emphasising the positive and conveniently ignoring the negative. Here it's the other way round! Talking about light drop or (especially) light loss is giving a misleading - and unduly negative - impression in people's minds of these products.

This discussion is all about the difference between theory and where the rubber hits the road.

You might think you can push the F55 sensor 2.5 stops and get a noise level that looks like a 2/3 camera, but I assure you if you tried it you would be disappointed.

Yes, but the only reason cameras produce images, and aeroplanes can fly is that their designers successfully applied theory in the design process.

The key thing is to get the theory right, do that and actual performance can be accurately predicted.

In my first post I said "The significance is that (all else equal) the larger sensor will have a higher sensitivity, so you're back to square one in performance terms., and it's impossible to stress *all else equal* highly enough. In your practical example - and I'm not disputing what you say - "all else equal" is not the case, and hence the apparent discrepancy. HD v 4k is the obvious factor, to be an all else equal comparison you'd have to be comparing to a 4k 2/3" camera - and what do you think would be a comparable ISO level for that, to give equivalent pictures to your F55 at ISO 1250?

The other way in which "all else is not equal" is that in general a 2/3" camera will be 3 chip, an s35 will be single chip - and I would expect a single chip to be less sensitive than three chip because of the subtractive filtration. And it's true this fact alone could mean (all else equal) you would need more light for the adaptor/s35 combination than on a 3 2/3" chip camera - probably about a stop.

But that's nothing to do with "light loss through the convertor" - there is no "light loss" - it's everything to do with a single chip being less sensitive than three chips of the same fundamental design and size.