Proof of concept: fullframe on MFT

[Fabian]

I wanted to test if it was possible to use 35mm lenses on Micro Four Thirds without only using the center of the lens, because I don't think I'm in the position to buy a mirrorless fullframe camera anytime soon.

I've put together a basic shift-adapter that goes left/right and up/down the sensor-size, so 17.3mm x 13mm. Fullframe is about twice those numbers.

Some lousy phonepics of the construction, but you should get the idea:



Let me emphasize I didn't go for perfect, I just wanted to know if it was possible to get reasonable results without too much hassle. The pictures are shot quickly after eachother and I just copy/pasted to align them without rotating or any editing.

Now the view went from this:


To this:


The aluminium isn't the most sturdy material ever so the lens isn't at exactly the same angle to the sensor all times and there are some light leaks because of the design, both of which contribute to the four images not being synced together at the borders.

I've come to the conclusion that without some professional machining and better design I cannot get good enough results in this setup. I was thinking maybe an adapter with only a horizontal shift would perform better because it would be a much more easy construction. (Note: a vertical shift would give virtually the same sensor as NEX so wouldn't make much sense, horizontally you get to the lens edge while being at about an 8 to 3 ratio.)

Any ideas how to improve the concept?

[luisalegria]

Interesting design and really quite good execution with just hand tools.
If you just want a horizontal shift you could build essentially a lensboard for your lens - fix the mount on a plate.
The plate will run on grooves at the edge of another plate on the camera side.
These things can be made to seal quite well. The same idea is often seen on large format reducing backs where the back can be slid from groundglass to film holder sides.

[Fabian]

Taken apart it looks like this:


Wood shaped to fit a C-mount to MFT adapter and on top the alu construction.

The lensboard idea looks quite easy to do indeed, I'll make some calculations how small it can be done.
I was looking for shift-adapters before, a lensboard didn't come to mind.

[luisalegria]

Suggestion - once you have the lensboard mechanism working, you could arrange for the plate to rotate on the camera mount side. Then you would have shift in any direction. This may need some machining, such as cutting a groove on the edge of your camera-side adapter.

[luisalegria]

Also, the idea of moving the lens doesn't seem right.
What you want to be stable is the projected image. If you move the lens, this changes.
You want to move the camera/sensor, to record a different part of the projected image.
So the lens needs to be held rigidly on the tripod.

[Fabian]

You're right the sensor-shifting-approach is better if you want to get a perfect copy of the fullframe image, but it seems much easier to just shift the lens instead of the camera: I can easily connect the camera to the tripod, but cannot easily connect every lens to the tripod firmly.

[tromboads]

As far as backyard shed work goes good on ya, but I'm failing to see the point... :p but that happens a lot with me. :p

Looks like fun tho!


I want a shed :'(

[luisalegria]

If you rotate the lensboard mechanism to the diagonal points of the sensor and then shift it, you will still get the quarters.

Alternately if you rotate the camera you can use stitching software to put the images together even if they are skewed.

[luisalegria]

Point is to achieve the equivalent of a full frame sensor with a 4/3 sensor by taking multiple shots after moving the lens around to change the portion of the image it projects on the sensor.

If you want to use a nice wide angle to its full capacity for instance, this gives you that ability.

Downside of course its more fussy to use than a camera with a proper full frame sensor.

There are also other possible capabilities, like perspective manipulation.

[Pancolart]

Some good thinking there! I was first, i was first: http://forum.mflenses.com/viewtopic.php?t=50793

Seems to me it would be easier to start with normal adapter that costs 10 EUR. Cut it to half somewhere around middle. Put sliders on each side. Wrap the hurt part in black balloon rubber and you are done. Bellow:

Worldwide patent 48752832 licensed to ©2012 Pancolart Jorge

[Fabian]

I thought about that idea, but I chose to just get a tinier C-mount adapter instead of having to cut the adapter to get a back part. I didn't think cutting thick metal precisely in two would go the way I want with only a handsaw and veil.

But I'm all for the idea of some Chinese manufacturer to produce such a shift-adapter.

[56 DIN]

seems to be fun if you want absolutely have all parts of the lens in the picture
another option would be to start in one corner and rotate the cam on an ( theoretical - don´t drill it ) axle that goes throught the inner corner of the sensor ( means the last shot is turned 270 ° )
or to explain it different: if you take a polarizer assembly without glas and mount it center to the rear end of the lens and the cam/sensor surface onto a quarter of the opening, you can turn it and get 4 pictures for the whole lens
for me it makes more sense to shift the whole set on a xy table and use only the center of the lens