Fujinon 12.5mm f1.4 CF12.5A modification

[zcream]

In the end, the rear needed a little machining as well. I will post pics of exactly what I modified later.
Here are some quick pics of contrasty regions - all *WIDE* open at f1.4. A bit soft but I dont think many lenses are sharp at 1.4 that wide.
Picasa Album

And some of these snapshots.

 

[jwestra]

Any updates?

I would really like to use a relatively cheap wide-angle lens on my cam.

 

[zcream]

Brick Wall

 

[jwestra]

Not bad at all.:thumbs:

Can you show some pictures of the modified lens or the modification. Your aperture is completely broken, right?

 

[zcream]

Yes the aperture is broken. I think that this is causing the sharpness loss in the corners. I bought another lens off ebay - this time I will leave the aperture intact. I think this lens has a lot of potential. My next mod will be perfect.

 

[Vivek]

Yes the aperture is broken. I think that this is causing the sharpness loss in the corners. I bought another lens off ebay - this time I will leave the aperture intact. I think this lens has a lot of potential. My next mod will be perfect.

Not to douse your enthusiasm and hope...

It will always look to be of "having potential" and will never cover the frame fully (will illuminate it though). It will be soft until ~f/5.6. The CA is very troublesome and can not be corrected.

These are some the reasons why I keep saying that I would wait for the rumored 14/2.5.

 

[zcream]

Hi Vivek. For my purpose its fine. I need to shoot some dancers in a park lit only by streetlights. I need wide and fast. I can add a mask in post to brighten the corners and remove the vignetting.
I can also avoid the off-centre softness by keeping the dancers around the middle.

If I get this right, even the new copies I will get have this problem with softness ?? Is that right ?
Would you consider posting a brick wall picture with your lens as well ?

 

[Vivek]

Brick walls?

Enjoy: http://www.flickr.com/photos/vivek-iyer/sets/72157617698967864/

 

[zcream]

Nice. I can see the edge distortion but you seem to have got full coverage - not even the mild vignetting I get.
I would love to see pics of your housing and your solution for the focus end stop screw.

 

[ekoe]

I have this same lens and I'd like to attempt this modification.

I'd like to see more photos of what you've done.

I follow you until the point where the focus ring is removed and you can see a portion of the brass helicoid the focus ring set screws tighten onto... but your photos and descriptions end there.

From that point, what I see inside the lens is a c-clip which holds what I would call a circular mask, and under that I can see the aperture blades.

I have removed the rear element and the rear lens group as well.

I'm guessing the next step is to remove the c-clip and the iris assembly?

It's looking like a near complete disassembly in order to get to the part of the helicoid that needs modification.

Are the focus ring markings accurate afterward?

Any more information/photos would be greatly appreciated.

 

[zcream]

I have updated the gallery in the first post. However, this is the quick summary of what I changed in pics.

 

[zcream]

Focus is accurate, nothing changes except a larger image circle. I am getting delivery of a couple more lenses so I can modify them.
I like this lens and may well end up with 3-4 modified copies. Possibly a couple would go on ebay.

 

[jwestra]

thanks for the update!

 

[ekoe]

Thanks for that.
Now it makes sense.
Can you suggest how many millimeters need to be removed?
So I think there isn't really a need to remove the rear element.
I found out what you mean by the rear element not being attached. It's actually the lens group 2nd to the rear. Mine came tumbling out and luckily I caught them in a lens cloth in their correct order. I was able to replace them with the aid of a drinking straw and 'manual suction' for lack of a better phrase. So beware, anyone, when you remove the rear element, the lens group just above it will fall out if you tip the lens.
Shame about having to loose the hood.
By the way, I think you beat me to those other fujinons. Was it Calkovsky you got them from?

 

[Andreus]

Hey there, any plans to sell off some of these modified 12.5mm s? I'd be interested in one.

 

[zcream]

In terms of removing metal - the rear is about 2mm. When you look at the adapter next to the lens you will know what I mean.
Theres lots of meat so remove 3mm to be sure if you want.

The front part, the more you remove, the closer you will be to full coverage.
However, if its too thin you cannot attach the focus stop. So machine some off, reattach the focus stop and repeat process.

Thanks for that.
Now it makes sense.
Can you suggest how many millimeters need to be removed?
So I think there isn't really a need to remove the rear element.
I found out what you mean by the rear element not being attached. It's actually the lens group 2nd to the rear. Mine came tumbling out and luckily I caught them in a lens cloth in their correct order. I was able to replace them with the aid of a drinking straw and 'manual suction' for lack of a better phrase. So beware, anyone, when you remove the rear element, the lens group just above it will fall out if you tip the lens.
Shame about having to loose the hood.
By the way, I think you beat me to those other fujinons. Was it Calkovsky you got them from?

 

[zcream]

Here is a video of the Christmas Light show in Sydney using the Fujinon 12.5mm. Taken with a GH1 in 1080p and the downconverted to 640x480 for youtube.
http://www.youtube.com/watch?v=l4i1JFaqtAk

It is heavily compressed so dont judge the quality by it. The original video is sharper in the center. The edges are soft, as Vivek mentioned,

 

[raymondluo]

Just thought I share what was a project that went stale many months ago. My piece, which is the same model as per the thread title differs in that I took it straight off an actual CCTV product. I dismantled it and repurposed a piece of metal to use as a rear mount, which it didn't have. The only real issue is that it cannot achieve infinity focus, which i reckon wouldn't take much to resolve- but I don't have the proper tools so I've given up. It would probably take a more forgiving c mount adapter, since I use the RJ adapter- i read that the dimensions aren't suitable and hawkeyes one might be better for this piece and maybe some shaving. When that happens I reckon the vignetting with get lesser as well.

I will put this on sale next year for whatever it's worth, but these are the pictures shot on the GH-1 with a slightly larger sensor then the GF-1 so even more vignetting there.

16:9

3:2

4:3

1:1

 

[zcream]

Raymond, I dont think you moved the front element closer. Try it, from the first post, and you will achieve nearly full coverage.

 

[raymondluo]

I didn't, i have no idea how to begin dismantling it! I saw your pictures but it still leaves me uncertain. There are a few screws which seems to hold the front casing of the lens together. I'm not sure but i might try unscrewing it and seeing what happens anyway.