Lens changing size

[BingoFishy]

I know nearly nothing about photography, bear with me.

 

Is it possible to make a lens that gets bigger and smaller rather than just raising the ISO? This would allow for less noise, and it's also quite similar to how many animals (like humans)'s eyes work. 

[ALwin]

30 minutes ago, BingoFishy said:

snip

You mean the iris blades inside the lens that control size of the aperture.  Not the actual glass elements of the lens.  You can change the diameter of the iris opening inside the lens to change the amount of light passing through, which also alters the DOF.

 

But if you want to make a lens that actually changes physical size (and I don't mean zooming), what kind of material will you use in place of the glass elements?  Considering the conservation of mass, if you can replace the solid glass with some sort of material that can stretch and compress the problem will be that when it stretches it will become thinner and when it compresses it will become thicker. This change in the physical dimensions of the liquid glass elements will also change the properties of the light passing through.  Not only that it will also change the specifications of the lens, such as focal length.

[Evanair]

Just thinning about *expanding lenses* makes my head hurt. Imagine the f/stop table.

 

Especially if it was able to expand (diameter) and zoom (length)...

[.spider.]

5 hours ago, BingoFishy said:

 This would allow for less noise, and it's also quite similar to how many animals (like humans)'s eyes work. 

I have never seen my eyes getting bigger.

All that's visible is a change of the pupil like the aperture of a lens.

Also the effect on you vision is quite small in comparison to the retinas changing sensitivity.

[ShadowCaptain]

8 hours ago, BingoFishy said:

I know nearly nothing about photography, bear with me.

 

Is it possible to make a lens that gets bigger and smaller rather than just raising the ISO? This would allow for less noise, and it's also quite similar to how many animals (like humans)'s eyes work. 

Cameras lenses already have an iris

 

[BingoFishy]

@ShadowCaptain Oh, okay. Yeah, that's what I meant.
 

Turns out I'm not the first person to think of this. 

[ShadowCaptain]

2 minutes ago, BingoFishy said:

@ShadowCaptain Oh, okay. Yeah, that's what I meant.
 

Turns out I'm not the first person to think of this. 

yeah and ever lens has a differnet range of apetures and most lenses have a wide range of stops

 

example a lens can go from F1.8 (wide open) to F22 (small iris) so is very versatile 

there are some VERY special lenses that are less than F1, at f0.9 or F0.7 - these lenses actually gather more light than the human eye!! but are generally expensive  (or from chinese third parties) and are more specialist manual only lenses

 

some cameras also have great low light sensitivity like the A7S2 that can shoot clean files at like ISO 100000 but its rare to have this



 

[Evanair]

2 hours ago, ShadowCaptain said:

these lenses actually gather more light than the human eye

I'm curious where you got this statistic.  Can you site a source? 

[ShadowCaptain]

21 minutes ago, Evanair said:

I'm curious where you got this statistic.  Can you site a source? 

Well a human eye is like f2.4 actually but yeah

 

Canon and Leica have often advertised lenses as "faster than the human eye"  as shooting on like an f0.95 lens gives quite an ethereal look at night as the scene is brighter on your photo than how you see it yourself

 

I mean human eyes are pretty SHIT in the dark

 

 

Example here on lens rentals

 

https://www.lensrentals.com/rent/leica/lenses/normal/leica-50mm-f0.95-noctilux

 

"When used in available light photography, the lens exceeds the perception of the human eye. Even the light from one candle can be sufficient for handheld photography"

[Evanair]

I'm not meaning to be nit picky, but having an f/stop of f/.95 just means the focal length is less than the iris (which in itself is amazing that someone can do that with glass...).  Granted, that's a much faster f/stop than the human eye, it just means a hell of a shallow depth of field.

 

Fstop = Focal Length / Diameter of Iris

 

I am still wondering about the comment on making light "brighter" in a photo, as the actual brightness of any object is a set value and having an iris at f/1 vs f/64 doesn't change that, just the amount of light that hits the sensor but not it's intensity.

 

Would you mind giving an example?  I googled for a bit and cannot find anything, doesn't mean it's not there, just I can't find it.  Fastest I've shot is a the Nikon 50mm f/1.2. 

[ALwin]

30 minutes ago, Evanair said:

snip

1. A photo taken with a lens that has f/0.95 at that wide aperture would be no different than any other photo because the photographer would adjust different parts of the exposure triangle to compensate.

2. The DOF would be insanely thin.

3. It's all a matter of engineering and not really anything special to design a lens with a larger diameter body overall to achieve such a wide iris opening.  Of course it becomes expensive and heavy the longer the focal length.  Try figuring out how large a 400mm f/0.95 lens is supposed to be.

 

Some examples here:

http://philipbloom.net/blog/review-of-noktor-f0-95-hyperprime-50mm-lens-for-micro-four-thirds/

[ALwin]

Here's another example:

https://www.ephotozine.com/article/slr-magic-50mm-f-0-95-hyperprime-lens-review-23001

 

[Evanair]

ALwin, I don't need to address point 1 and 2... they are given facts.

 

As for 3, the hard part wouldn't be the design of the lens itself, the iris would need to be open to 422mm, adapting to the bayonet adapter for a 35mm camera would be the difficult part. Could do it with a large format camera, possibly a medium format. 

 

Edit: I know you can change the physical iris size with optics, however, the actual amount of glass required would be insane.

Edited July 13, 2016 by Evanair
Edit for Content

[ALwin]

25 minutes ago, Evanair said:

snip

http://petapixel.com/2014/11/18/whats-fastest-lens-theoretically-possible/

 

 

[ALwin]

http://petapixel.com/2012/06/11/whats-the-f-number-of-the-human-eye/

 

So even f/1.8 lenses are faster than the human eye.

[ShadowCaptain]

14 hours ago, ALwin said:

http://petapixel.com/2012/06/11/whats-the-f-number-of-the-human-eye/

 

So even f/1.8 lenses are faster than the human eye.

Yup

 

i mean, go outside at night, you cant see fuck all, but i bet you can take a photo with a fast lens

[.spider.]

On 7/13/2016 at 3:55 PM, Evanair said:

 

[.spider.]

7 hours ago, ShadowCaptain said:

 

i mean, go outside at night, you cant see fuck all, but i bet you can take a photo with a fast lens

If it is so dark that you cant see anything you cant take a picture either. Except for long exposures. 

[ShadowCaptain]

11 minutes ago, .spider. said:

If it is so dark that you cant see anything you cant take a picture either. Except for long exposures. 

Not true, since a camera with a fast enough lens like f0.85 could gather more light than your eyes, for example Leica made them for night time recon in WW2

 

your eyes are not that great at gathering light

 

(or you can use an A7R2 and shoot at stupid iso but thats not relevant to lenses but can shoot in the dark)

[Evanair]

 

I know this is thread is about lenses, but here's an example for Spider for video shot at night when it's really dark with one of Canon's new sensors.

[ShadowCaptain]

16 minutes ago, Evanair said:

 

I know this is thread is about lenses, but here's an example for Spider for video shot at night when it's really dark with one of Canon's new sensors.

dont even need that extreme

 

 

[.spider.]

37 minutes ago, ShadowCaptain said:

Not true, since a camera with a fast enough lens like f0.85 could gather more light than your eyes, for example Leica made them for night time recon in WW2

 

your eyes are not that great at gathering light

 

(or you can use an A7R2 and shoot at stupid iso but thats not relevant to lenses but can shoot in the dark)

Not true, you are totally underestimating the retina's rod cells.

[.spider.]

24 minutes ago, Evanair said:

 

I know this is thread is about lenses, but here's an example for Spider for video shot at night when it's really dark with one of Canon's new sensors.

Where do I get that?

[.spider.]

12 minutes ago, ShadowCaptain said:

dont even need that extreme

 

These peoples do not use flashlights or night vision so it is quite obvious that they could see.  

[ShadowCaptain]

9 minutes ago, .spider. said:

These peoples do not use flashlights or night vision so it is quite obvious that they could see.  

ok when I said see fuck all I didnt mean a dark vacuum, i was talking like moonlight

 

the human eye is strange in that the rod cells give us nightvision however its shit at colour where a camera can get full colour at night

 

All I was saying was that extremely fast lenses can gather more light than the human eye