Wider Fov with a 28 mm and wrong adapter!

AlbertZ

I've bought a Pentax K Mount lens (28mm) and since I haven't yet an adapter ring pk-mount -> m4/3, I've tried to use directly on my gh1 with an adaptor FD-m4/3. Of course, the adaptor doesn't fit correctly but..if you watch the result just holding the lens attached to the ring,you will able to focus and...you will get a remarkable WIDER FoV than 50mm eq (28x1.8 on gh1)!!! Anyone could explain me the reason?

balazer

Putting the lens closer to the camera makes the image circle smaller and reduces the focal length. It also shifts the focus range away.

AlbertZ

thanks @balazer, it could be a ghetto-trick to get a cheap fast wide lens ;) what are the main drawbacks however? it will be more difficult to focus close subjects, but at the same time it should be easier to achieve a "deep focus" look...is it?

p_hawks

your focus marks will be off, so if you go by those, that could be an issue, but as far as I know, if would be the opposite of a macro ring. Really wish I had a 3D printer right about now so that I could make some adapters and see how everything works through trial and error

fatpig

@p_hawks: even better idea would be CNC machining :) @AlbertZ: can you get infinity focus? If yes, one could build such an adapter for daily use.

AlbertZ

Yes, I can get infinity focus :) @fatpig @p_hawks Yes, focus marks are off, but I don't care about them ;)

AlbertZ

I think I will modify directly a fd adapter! ;) the Fov seems to me close to 30mm (so the lens performs as a 18mm 2.8). Quite good wide open, but it's impossible to focus at 0,5 m. perfect for interior scene...and it's damned cheap!

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