Blackmagic Forum

Is there a MFT adaptor that will allow us to use this canon macro tv zoom lens?

liquidvisual wrote:Is there a MFT adaptor that will allow us to use this canon macro tv zoom lens?

Is that a C-mount lens? If so, there are many C-to-MFT lens mount adapters available from a variety of manufacturers.

Whatever mount the lens has, was the lens was designed to "cover" a sensor S16 size or larger? If so, then you can use it with the BMPCC pocket cam. If the lens was designed to cover a sensor smaller than S16 then it'll vignette on the BMPCC.

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I think it's a B4 mount lens designed for half inch sensors ? According to a page on Wikipedia, 16mm (not S16)'s diagonal is 12.7mm and half an inch is exactly 12.7mm... so there will probably be vignetting? but it'll be minimal?

The vignetting would be very visible. If you add the 2x extender you would clear the vignetting but you would lose 2 stops of light.

Here is an example of a B4 lens on a Super35mm sensor with the MTF adaptor:

Surely the vignetting will be tolerable because he's wanting to use the lens on the Pocket camera ?

check my test

Aaron Scheiner wrote:Surely the vignetting will be tolerable because he's wanting to use the lens on the Pocket camera ?

Even on the Pocket Cinema Camera!s S16 sensor it will visibly vignette without the 2x converter.

Ah well good to know... seeing as I also own this lens and have pre-ordered a BMPCC .

thanks all! any idea of 35mm equivalent of yh14x7.3 with or without 2x extender?

With or without the extender, a lens designed for 1/2" will have about a 1.7x crop factor on S-16 film format imagers. As most 1/2" lenses just barely cover 1/2" without an extender, your chances of that lens covering at any focal length without the doubler are fairly poor.

To be on the safe side consider that lens a 14.6 - 204.4mm lens. Which in 35mm (motion picture) is 29.2 - 408.8mm. Keep in mind the Pocket camera has (at minimum) an HD+ res imager. If you are planning to put a lens that never had to work harder than 800 lines of res in front of it (without a doubler), you will be looking at some soft, low con images.

All this being said, I don't think you should consider any lens built for 1/2", if you are going to attempt this for some kind of ENG style convenience, start with 2/3" and a lens designed for HD shooting, and a PROPER adapter (we don't make such a thing, and they are not sold by any ebay only seller). I would also recommend testing a lens before offering up a penny for something on the used market. I know people who have been burned badly purchasing lenses untested from ebay.

However, I'll now attempt to dissuade you (and anyone else) from doing this (ever) without the before mentioned proper adapter. This adapter will require a unique prism inside that will retime the light passing through.

I can tell you that you WILL get image artifacts from any 1/2" or 2/3" ENG lens you put in front of a pocket camera without a proper adapter. These lenses were designed to pass light through a prism which delays the RB photons before hitting each of the 3x sensors in the camera for which the lens was designed. With a single imager (like the Pocket camera) no prism means you get R and B trailing G (not good).

Here's a diagram for those that are having a hard time visualizing what's going on.

For those of you who say...but wait I read about some guy in a forum, or blog, or my cousin told me about some dude who said "it works great". The truth is, anyone who said that doesn't care about the artifacts and that person did those who do give a damn about what they're shooting a real diservice. If you need a good lenses, start looking at some fully manual DSLR lenses, and older S-16mm cinema lenses.

I humbly suggest a Nikon mount Tokina 11-16 with iris adjusting Nikon to MFT adapter, Voigtlander (Leica M and MFT) and Rokinon (any with appropriate adapter) lenses if you need a place to start for new lenses. If you are dead set on a zoom instead of a prime, older manual DSLR lens will probably be less expensive than a S-16mm cine (converted or original) zoom lens. There's many regular 16mm zooms that won't cover on the wide side. No doubt that once the first demo Pocket Cameras hit the street someone will spend an afternoon figuring out which 16mm zooms cover (or at what focal length they start covering).

In the interest of full disclosure, the company I work for does sell both Voigtlander and Rokinon lenses.

Illya Friedman
Hot Rod Cameras
www.hotrodcameras.com

Illya Friedman wrote:I can tell you that you WILL get image artifacts from any 1/2" or 2/3" ENG lens you put in front of a pocket camera without a proper adapter. These lenses were designed to pass light through a prism which delays the RB photons before hitting each of the 3x sensors in the camera for which the lens was designed. With a single imager (like the Pocket camera) no prism means you get R and B trailing G (not good).

Here's a diagram for those that are having a hard time visualizing what's going on.

Illya Friedman
Hot Rod Cameras
http://www.hotrodcameras.com

Excellent post. I was wondering... do people in the business actually use the word "delay" the red and blue photons? The prism provides a 10um and 5um longer path to account for the slightly longer focal length to focus those red and blue rays to remove chromatic aberrations. Given the speed of light, 300,000km/sec, I don't know if that results in any measurable physical delay of those photons at the scale involved, just those few microns within the prism.

Rick Lang
Sent from my iPad using Tapatalk HD

Illya -

Thank you for spelling out such apparently excellent info. To summarize, because of the negatives you list, I'd conclude the answer to my question is "no."

cb

rick.lang wrote:Excellent post. I was wondering... do people in the business actually use the word "delay" the red and blue photons? The prism provides a 10um and 5um longer path to account for the slightly longer focal length to focus those red and blue rays to remove chromatic aberrations. Given the speed of light, 300,000km/sec, I don't know if that results in any measurable physical delay of those photons at the scale involved, just those few microns within the prism.

The difference in transmission speed between red and blue light through glass is enough to cause chromatic aberrations in a lens.

rick.lang wrote:[quote="Illya Friedman"
Excellent post. I was wondering... do people in the business actually use the word "delay" the red and blue photons?

In regards to semantics, no, delay is not the scientific vernacular, velocity would be more correct. However, a 'reduction in apparent velocity' is 4 words and my momma always told me to use one word instead of two whenever possible.

Given that this is not a forum for optics nerds, I'm of the mindset to keep it as lay as possible. I tried to be as descriptive as to what's occurring without going too deep or being technically inaccurate, most of my clients are more artist than plumber- and tend to appreciate that, so it's my modus operandi.

My understanding is as follows: a "delay" is what's being observed while the photons are inside a prism even if you need to measure it in microseconds. Upon entering and leaving the prism the speed of light is always a constant c, there was no actual reduction in the speed of photon throughout the entire journey, however the light is no longer in the same phase, as thus we observe a measurable delay.

Hope this helps,

I.

Illya Friedman
President
Hot Rod Cameras
http://www.hotrodcameras.com
Hollywood, California