Achieving 35mm full frame FOV with FD lenses on the GH1

commanderspike

commanderspike

Carbonite Member
Forgive me if I sound naive, but I had a though just now...

Since I am buying a load of FD lenses, a 50mm prime becomes 100mm on the Micro 4/3rds format.

Is there a way to prevent this, even theoretically?

My understanding of something probably quite widely understood is maybe a little shaky, so correct me if I'm wrong. Wouldn't some optical correction between the sensor & lens do the trick?

My guess is that it could be done, but not without a huge degradation in image quality and loads of distortion.

A lens is pretty simple - it collects light and channels it onto a flat surface, i.e. the film or sensor. Obviously, a full frame 35mm sensor (like on the 5D MII) has a larger surface area, so collects all of what the lens is able to give, from the flange back distance it was original designed to operate from.

Would changing the flange back distance on a Canon FD lens adapter of adding some kind of magnifier / reverse magnifier trick, enable the whole 24mm of a 24mm FD lens to fit inside the Micro 4/3rds sensor area?
 
Wouldn't you lose focus on the image circle hitting the sensor? Could be some kind of thicker adapter so the lens rests further away from the sensor, and then would allow a back focus adjustment using internal lenses. It could degrade your image quality or at least cut down on light (maybe a stop?).
 
You're asking for an optical reducer. Not easy, and will most likely cause light or quality loss. The old Nikon/Fuji collaboration produced DSLRs which used such things.

There really isn't much you can do. I mean, if there was, I'd have done it myself. I've got a nice lovely set of Nikkor primes I'd love to use at its intended FOV...
 
Hi everybody,

I have a GH1 since last week and bought myself a Canon FD Adapter and a Canon FD 28mm lens. I don´t know much about lenses and physics, but if I understand things right, the picture with tis 28mm Canon FD should be comparable wth the picture of the kit lens with roundabout 56mm. It is not. It is exactly the same looking picture with 28mm adjust on the kit lens. Is that because of the scala on the kit lens? Means 28mm on the Kit Lens is like 56mm with a standard size?

Colna
 
No no, it doesn't work that way.

To be precise, what everyone means is that a 28mm focal length on the GH1 will look as though you've taken a photo with a 56mm on a 35mm camera.

That's the important part. It looks like a photo taken with a 56mm on a 35mm still photography film camera.
 
35mm still camera. 35mm movie cameras have near identical FOV to GH1 at same focal length.

Think of your 28mm as 'normal' and everything shorter than that wide and everything longer as tele and you have your reference.
 
colna said:
Hi everybody,

I have a GH1 since last week and bought myself a Canon FD Adapter and a Canon FD 28mm lens. I don´t know much about lenses and physics, but if I understand things right, the picture with tis 28mm Canon FD should be comparable wth the picture of the kit lens with roundabout 56mm. It is not. It is exactly the same looking picture with 28mm adjust on the kit lens. Is that because of the scala on the kit lens? Means 28mm on the Kit Lens is like 56mm with a standard size?

Colna
Click to expand...

Use the GH1 kit lens as a reference.

Your Canon FD 28mm will look like your kit lens does at 28mm. The GH1 kit lens at 14mm looks like 28mm on a 35MM camera, which confusingly is still used as the benchmark reference point for lenses, despite a huge range of different formats now on the market.

14mm looks nice and wide on the GH1, but on a full frame camera like the 5D MII or a 35mm film camera, the 14mm kit lens would look twice as wide.

Think of it in terms of getting the same picture from the lens on whatever camera you use the lens on, but crop it (like in Photoshop) around the centre. The GH1 is a 2x crop compared to the 35mm equiv. lens rating. So 28mm = not very wide, more like 56mm.
 
Allright! I thought the scale on the Kit lens refers to the 35mm size - so if I adjust it to 50mm I will have a view "as if working on full frame". So that a "real" 50mm lens like from Canon will be comparable with about 100mm on the Kid Lens.
But I understand (can anybody follow me?). Never mind. I think I got it! ;-)
 
50mm on the kit lens = 50mm on the Canon FD lens, or any other lens.

On the GH1, a 50mm is 100mm 35mm equiv.

When you look down the GH1 viewfinder with the kit lens set to 50mm, that is the same as what you will get from your Canon FD 50mm lens. It would be 100mm in 35mm camera terms because of the 2x crop.

Can be confusing... sorry for repeating all this, but I think using the kit lens to frame your shot will give you a good idea of how any potential lens purchases turn out on the GH1 in 16:9 mode in the Micro 4/3rds format. :cheesy:
 
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