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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

pinhole lens

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georgewde

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Just out of curiosity -
has anybody ever tried a pinhole lens? Would that work in principle?
 
georgewde said:
Just out of curiosity -
has anybody ever tried a pinhole lens? Would that work in principle?
Click to expand...

Yes, it would work. Of course it would be diffraction limited, so don't expect Master Prime glass speed or quality :biggrin:
 
f/64

f/64

Pawel Achtel said:
Yes, it would work. Of course it would be difraction limited, so don't expect Master Prime glass speed or quality :biggrin:
Click to expand...

If you put an small achromatic lens behind a small hole you can get more sharpness than just a very small pinhole.

You cannot get 4K at f/64 because of diffraction but you will get deep DOF. f/64 will give you a little less than SD resolution...

The lens should have a focal lengh a little shorter than the distance from the hole to the sensor, so if you want a 25mm lens angle of view, you can use a 20mm lens. You can use a miniscus lens if you can correct the CA in software later.

Even if you make an f/11 lens it could be useful, you could make a full set of small opening prime lenses for maybe $100 with surplus optics and some tubing. like 25mm to 1000mm... You can get old binoculars from pawn or thrift stores and take the elements out of the front and eyepiece to get different focal lengths, as long as you stay between f/11 and f/64 the images might be usable... there are some drawings for this in one of my older posts...
 
neathedo said:
Sure, as long as you don't mind running 30 seconds per frame instead of 30 frames per second. (Slight exaggeration, but you get the point).

Dave
Click to expand...

C'mon you don't even need expensive ND filters and no IR contamination problems. No need for matte box because there is no flare, no glare and no ghosting. In fact, there is no CA and no image distortion either.

Sure, there is some softness in the image, but hey, it is still 4k, bit of sharpening and it can't get any cheaper than a couple of toilet paper tubes (for a zoom - you can get a prime with just one toilet paper tube).

I guess this also answers wayno's Avatar...
 
Pajo Takamatsu said:
I couldn't find the drawings that you mentioned in your other posts...
could you post a link if possible?
thanks in advance...
Click to expand...

These, if you want to make a 10mm for S35 the PL hole is too deep, so I show a two lens four element retrofocus deep-focus "pinhole" lens drawing also there, i.e. to clear the PL hole so as not to vignette.

http://www.reduser.net/forum/showthread.php?p=222321

If you are making a long lens, you can use two lenses in a symmetrical design one on each side of the "pin hole" outside facing out and inside facing in, that cancels the lateral CA so you can get a good image from like 75mm to 1000mm if you go f/11 to maybe f/32, from f/32 to f/64 the image may get a little soft, past f/64 maybe too soft. Two telescope lenses would work.

You can also make a Petzval like lens if the rear lens is shorter in focal length, then you might get sharper results.
 
Filter out CA, UV and a pin hole

Filter out CA, UV and a pin hole

www.DANCAD3D.com said:
These, if you want to make a 10mm for S35 the PL hole is too deep, so I show a two lens four element retrofocus deep-focus "pinhole" lens drawing also there, i.e. to clear the PL hole so as not to vignette.

http://www.reduser.net/forum/showthread.php?p=222321

If you are making a long lens, you can use two lenses in a symmetrical design one on each side of the "pin hole" outside facing out and inside facing in, that cancels the lateral CA so you can get a good image from like 75mm to 1000mm if you go f/11 to maybe f/32, from f/32 to f/64 the image may get a little soft, past f/64 maybe too soft. Two telescope lenses would work.

You can also make a Petzval like lens if the rear lens is shorter in focal length, then you might get sharper results.
Click to expand...

If you are going to shoot for monochrome output you can use a dark green filter to reduce the CA that adding a lens can introduce. Shooting through a green separation filter may work better than zeroing the Red and Blue in the de-bayer images since more bandwidth may go to the green parts of the image?

That trick would also help with wide angle lenses that have CA if you are going to go for monochrome or day for night as well.

Because blue light has about half the diffraction as red light using a blue filter with a pin hole lens will make the image about twice as sharp at a given f/stop. Shooting in UV light with a UV pass filter and a pinhole would be even sharper than using a blue filter.
 
I have a Skink pinhole system on the way from Russia (rugift.com) for my EOS and will let y'all know how it works.

PS- just got a Peleng 8mm for the EOS from RuGift and everything worked out well. Fisheyes are COOL.
 
...and then we discuss to death about still lenses versus cine lenses...
Well, I'll see if can have one tube PL-mounted.
The selection will be very strict.
 
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