Steve: yes, I understand that it does make it "faster" in that light density is going to increase. My point is that the lens becoming 1 stop faster on an APS-C camera is not going to give you any real-world advantage over shooting with the same lens on FF 1-stop slower F value, BUT 1 stop extra ISO.
You're probably right about real world advantages. At the moment I'm just seeing it as an interesting item for discussion.
I don't know if anyone has posted this yet but here is a detailed explanation: http://www.metabones.com/images/meta...te%20Paper.pdf
You need a mirror, E.
Originally Posted by E. von Hoegh
These devices are merely reverse teleconverters and can produce as much resolution as a modern small digital sensor (about 4um), with which they are intended to be used. There's nothing magic or bullshit, they don't need to be designed in conjunction with any particular lens: is your film designed with your lens in mind? It just takes the focused image and shrinks it by 1.5x linearly, which gives exactly the same effect as a one-stop shorter+faster lens with less coverage. The recorded image on APS will be identical to the recorded image on 135.
Just because you don't understand it doesn't make it wrong.
Here's one area that I would LOVE to see this technology utilized for. And I understand I'm standing on dangerous grounds here, since, while not limited to digital, the usefulness of what I propose really only applies to the digital world.
So, you know how many Hasselblad (and other 6x6 MF) shooters are really hoping for (but may never get) a full-size 56mm x 56mm sensor medium format digital camera with which to use their legacy Hasselblad/Zeiss lenses? Again, they'll probably never get one since a square digital sensor would be a very niche market in an already niche digital MF world.
What that means is that the legacy Zeiss glass can only be used cropped on a 645 and smaller sensors.
However, let's say that in the future, we will have (1) mirrorless digital MF cameras. You can substitute this relatively easily today because we already have digital MF backs that can be attached to any box. Hartblei's H-cam comes to mind. Let's say that then there is (2) an adapter exactly like this for MF that will concentrate the image circle by 1.5x.
Then, you could have a digital MF sensor like one used in CFV-16 (37mm x 37mm) and use a legacy Hassie lens on it as it was originally intended without any crop factor, and with the same DoF. I.e., e.g., Zeiss Planar 110mm F2.0 will act like a 73mm F1.4 lens on a CFV-16, effectively giving you the same FOV/DOF as the lens would give you if you shot it with a 56mm x 56mm sensor. Of course, this could be applied to any of the larger digital MF sensors (full size 645) too, and a legacy square lover would just crop to square.
More intriguingly, if you consider that many of the Zeiss lenses have an image circle that is comfortably larger than that required to cover 56mm x 56mm (that's why you can use them with a Flexbody), it is possible that such an adapter used with legacy lens will cover a fullsize 645 sensor and give you, in this case, an even wider FOV and even shallower DoF than they were originally designed to on traditional 6x6 film.
I bet legacy Hassie users (and many others) would be very, very, very happy to shell out $600 or even $1600 for such an adapter (again, provided there's a mirrorless MF digital body with which to use it).
I'm of the camp that thinks ALL digital cameras of the future will/should become mirror less, so I'm very intrigued by this idea.
The biggest advantage I can see for this is it would permit use of wide angle lenses that I already own for wide angle performance on a cropped sensor.
And I can also see the benefit of the advantage that rawhead mentions respecting medium format lenses and medium format digital backs.
When I had a Nikon D100 about nine years ago I wondered why no one could make an adaptor to make the field of view the same as would be on 35mm film.
The answer is that they could but the lens would have to move closer to the sensor so it was not a viable option when using mating lens mounts.
However, using a lens of one manufacturer on the body of another which is significantly slimmer gets over this problem. I know it's a digital product which we are not supposed to discuss here but it's the optical design which is of interest. I think the company should be congratulated for pursuing it.
This is actually an idea which a camera manufacturer could incorporate into the camera rather than as an adaptor to give full frame coverage with existing lenses. I'm surprised it hasn't appeared already. I think a camera with an APS size sensor which could take e.g. Pentax K or Nikon F lenses (manual or auto-focus) and give full frame coverage would be very popular.
In my student days, when someone was showing off with the latest huge telephoto lens, we used to say that the length of the lens was inversely proportional to the size of his...... :)
Originally Posted by E. von Hoegh
Nothing new, check out the Nikon E3/E3S
The optics shrunk the full frame image onto a P&S size sensor