Setting aperture hack ?

[Andy1712]

Hi folks, I am currently working on making an old Canon Vid lens into a working lens for my Nikon 1. Focus and zoom work great as manual; but, aperture is electronic.

I have opened the lens and the spring Iris mechanism moves smoothly, easily opening the lens up to 1.4. Once released the click-less Iris slams shut tight.

The lens is meant to be f 1.4 to 2.1, thus should I count it as a maximum 3 stop range? Or could I set it to to a smaller Iris settings of 5.6, 8 or even 11.?

My idea is to drill small holes into the aluminum casing, then cut a thin slit across their tops and insert a tiny 'stick shift' to be placed into the holes as lighting requires.

Maybe 6 holes will be too many for such a small distance.

Any ideas out their?

 

[Heritage Cameras]

Hi folks, I am currently working on making an old Canon Vid lens into a working lens for my Nikon 1. Focus and zoom work great as manual; but, aperture is electronic.

I have opened the lens and the spring Iris mechanism moves smoothly, easily opening the lens up to 1.4. Once released the click-less Iris slams shut tight.

The lens is meant to be f 1.4 to 2.1, thus should I count it as a maximum 3 stop range? Or could I set it to to a smaller Iris settings of 5.6, 8 or even 11.?

If this lens is the Canon CL 8-120mm, then f/1.4-2.1 is just the maximum aperture - it varies from f/1.4 at 8mm to f/2.1 at 120mm. The diaphragm will almost certainly stop down further than that.

 

[FrancoD]

That lens was made for a camcorder with an 1/2" sensor (6.4x4.8mm aprox)

That is 1/4 the size of the N1 sensor. (13.2 x 8.8mm2)

 

[Andy1712]

Thanks for the replies.

I succeeded in roughly mounting the Canon onto the V1 last night, using the mount from a broken N1 lens. The one screw that held the heavy Canon onto the fragile , plastic Nikon mount plate made things a bit hairy. I had the camera on a tripod, the lens in one hand and my thumb nail opening the Iris.

By pre-setting focus distance on a lamp in the dim room then tilting and tilting the lens I got the 3mm extra focus distance , quite nice actually. I recorded the attempt and yes as we all suspect the image was a round circle, yet It is over half the 1920 width. I plan to measure it once the footage is on the computer.

My neighbor and I plan to make the 3mm shim and drill 3 new holes for the Nikon mount this week.

I am determined to understand this lens with a camera I know, then switch to the smaller Raspberry Pi HQ camera system as telephoto. Think about it; a white, red stripe Canon L at 700mm and f 2.1! Although I wonder why the high end big lenses are often 5.6 and up? Sharpness?

If people have ideas please feel free to express them.

 

[FrancoD]

That is an interesting project.

On the Rasberry the reach will be about twice the one on the camcorder so, as you stated, about 700mm at the tele end , starting from about 45mm at the wide end. (all equivalents of course...)

Could work well on video , not sure about still images but nice project anyway.

There are a good number of those lenses that are not in use given that the Hi8 format they were designed foir was doropped not long after they came out. .

 

[Andy1712]

You're right in both your responses, and thank you.
I have not really considered the lens for stills and I will bet it is a pretty small dot even on the 1 inch sensor. If the camera and lens in your photo are yours then that mount on the camera becomes the cats meow. Assuming that the camera has malfunctioned.
Are you aware of anyone who has created a aperture hack mechanism? There is a Russian who mounted this lens onto a drone camera. He crafted a kind of thumb slider and he deserves credit for inspiring me to try my way.

I will post his photo tonight.
He uses a 2x but his Youtube night sky footage looks pretty rough.

I hope to post a frame of my test tonight also.

PS, I did not need to tilt the lens as much as you did in your photo. LOL.

 

[FrancoD]

That photo is from Google but I sold those cameras . Called EX 1 and 2 here in Australia.

 

[Andy1712]

Hi Franco, I have been slowed down by some jobs that needed doing before a week of rain. So I have not prepped any photo's. I'm planning on making a little series of pics on what I have done with this lens. Plus some of the screws are super tiny and tight for a novice tinkerer.

On another -related - subject; The 8-120 has two lens wrench holes in the exposed final element. I feel like they are begging me to turn them. Do you think it's possible to leave the lens as is, but replace that final element with another which would 'fan' out the image. I mean without mad distortion or paying an arm and leg?

Or I wonder if the image would expand by partially unscrewing and opening up the element? Closer to the sensor would probably be smaller?