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Meet the Forbes 70 - an IMAX 70mm motion picture camera prototype


Andrew Reid
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The digital Forbes 70 is based on a heavily modified Blackmagic Pocket Cinema Camera using 65mm ground glass for the IMAX 70mm look to medium format lenses.

Recording in Cinema DNG raw the camera delivers an utterly spellbinding image but is currently only at the prototype stage with just two in existence.

 

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I'm confused. How did they get that big imaging area with the pocket camera sensor? Did they use 4 of them?

It's like the good old 35mm cinema adapters, the image is projected on groundglass which is then captured by the camera.

The results are very good, great job Richard!

 

But the zero light loss intrigues me :O

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Guest d5f8611fa423d0e628c016f9d5c93b47

Where is that Metabones EF-HB Speedbooster?! My dad has a set of Zeiss medium format glass gathering dust and I want this kind of image available to me!

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It's like the good old 35mm cinema adapters, the image is projected on groundglass which is then captured by the camera.

The results are very good, great job Richard!

 

But the zero light loss intrigues me :o

 

it sounds too good to be true.  and the close to zero light loss is pretty amazing.  as in - if you put a f2.8 lens directly to the black magic pocket and shoot, you will end up with a very similar exposure as this hasselblad lens is delivering through all of the optics within the unit.

 

The taking lens within the system is ultra fast, as it the ground glass and the condenser optics.  what the system becomes in in effect a speed booster since f2.8 on medium format is approximately 4 times the light transmittance of f2.8 on full frame, and about many many times the transmittance of f2.8 on s16.  If you can efficiently capture that glowing illuminated ground glass onto such a small imaging area you're pretty much losing no light (as far as working with f numbers and iso's is concerned)  

 

800iso on forbes + a 80mm f2.8 lens will be a very similar exposure to 800 iso on full frame with a 50mm lens at f2.8 

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This needs to be coupled with a sweet anamorphic ;)

Also would love to see shots with a medium format wide angle with shallow dof!

 

 

the iscorama 36 copes on 150mm.  any wider and it vignettes.  Just wish I had nice footage that I deem worth sharing.  Will shoot in the next couple of days i promise.

 

40mm f4 for the wide angle is quite crazy on shots 1m and closer.  

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the iscorama 36 copes on 150mm.  any wider and it vignettes.  Just wish I had nice footage that I deem worth sharing.  Will shoot in the next couple of days i promise.

 

40mm f4 for the wide angle is quite crazy on shots 1m and closer.  

This is strange, I have placed an isco ultra star optic in front of a pentax 67 105 2.4 and a mamiya rz 110 2.8 and there is only very little vignetting, I thought an iscorama would show no vignetting at all.

 

When you are talking about condenser optics, you mean you have a focal reducer inside and project on a smaller area than 70mm?

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What kind of lenses will fit onto this beauty?

 

 

The FFD is 20mm allowing any lens to be used via a correct mount as long as it covers the image circle required.  So the options are:-

 

some medium format lenses :- Hasselblad, Rollei 6000, pentacon 6 etc

6x7 lenses

6x9 lenses

large format lenses

aero recon lenses

 

 

 

This is strange, I have placed an isco ultra star optic in front of a pentax 67 105 2.4 and a mamiya rz 110 2.8 and there is only very little vignetting, I thought an iscorama would show no vignetting at all.

 

When you are talking about condenser optics, you mean you have a focal reducer inside and project on a smaller area than 70mm?

 

 

The condenser is after the 70mm imaging area to deliver even illumination over the entire frame

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I don't want to be a Debbie Downer, but I don't see how this is any different than the DOF adapters, like Letus, made for camcorders before DSLRs.  You can get a beautiful, shallow DOF, but the image will be very soft.  Don't get me wrong, it will produce a stylized image not possible in post (because depth can't be ascertained from a 2D image).  Still, a one-trick pony.  Am I missing anything?

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I don't want to be a Debbie Downer, but I don't see how this is any different than the DOF adapters, like Letus, made for camcorders before DSLRs.  You can get a beautiful, shallow DOF, but the image will be very soft.  Don't get me wrong, it will produce a stylized image not possible in post (because depth can't be ascertained from a 2D image).  Still, a one-trick pony.  Am I missing anything?

You are missing the fact that the video shows a very good image (have you seen the crops that he shows in the video?) and that he states that light performance stays the same. The DOF adapters I know were very dark and fuzzy.

Another thing to keep in mind is that compared to 35mm DOF adapters, this one has a 4x larger surface. This means the grain is much finer.

Can't wait for the second part.

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You are missing the fact that the video shows a very good image (have you seen the crops that he shows in the video?) and that he states that light performance stays the same. The DOF adapters I know were very dark and fuzzy.

Another thing to keep in mind is that compared to 35mm DOF adapters, this one has a 4x larger surface. This means the grain is much finer.

Can't wait for the second part.

 

The DOF adapters also had surfaces 4x larger than their sensors, if not a lot more.  Again, I'm not saying it isn't a nice image, only that it's only good for shallow DOF.  

 

I was thinking along HurtinMinorKey's lines too.  Having 4 BMPCC shooting parts of the plate and stitching them together, that would be something!

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The DOF adapters also had surfaces 4x larger than their sensors, if not a lot more.  Again, I'm not saying it isn't a nice image, only that it's only good for shallow DOF.  

 

The DOF adapters projected a 35mm surface (because they were designed to work with FullFrame lenses), this one projects a much bigger one (because it works with 6xX lenses)

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The DOF adapters projected a 35mm surface (because they were designed to work with FullFrame lenses), this one projects a much bigger one (because it works with 6xX lenses)

 

 Exactly. I think it very neat, but to me IMAX is about negative size, not shallow DOF, so thought the original post a bit misleading.

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This is truly fascinating. Reminds me of the 35mm adaptor days. As wonky as they were, I loved the look. I'd actually shoot a project on one now just to bring the funk back. If it had a moving ground glass that would really bring it back. Keeping an eye on this.

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