Jump to content


Photo

Better Lenses & Better Lighting


  • Please log in to reply
19 replies to this topic

#1 Evan Winter

Evan Winter
  • Basic Members
  • PipPipPip
  • 202 posts
  • Director
  • Los Angeles

Posted 12 June 2007 - 12:43 PM

I've paraphrased the already short article and I've attached the link to the original article at the very bottom of my post:

Researchers in New York have developed a new type of nanostructured coating that can virtually eliminate reflections, potentially leading to dramatic improvements in optical devices.The coating stops reflections from nearly all the colors of the visible spectrum, as well as some infrared light. As a result the total reflection is 10 times less than it is with current coatings (get on this Zeiss and Cooke!)

LEDs, already one of the most efficient ways to produce light, could also become much more efficient. A remarkable 40 percent improvement could be seen in LEDs, where a large amount of light generated by a semiconductor is typically trapped inside the device by reflections.

I wonder if this could lead to more powerful LEDs and thus increase their overall use in film lighting.

It's also interesting to consider the possibility of film lenses that lose 10x less light due to reflection. Depending on how much light is lost to reflection in the current systems we could see high quality lenses that are significantly faster becoming the standard (T0.4 anyone?). :)

http://www.ecogeek.o...ntent/view/707/
  • 0

#2 Leo Anthony Vale

Leo Anthony Vale
  • Basic Members
  • PipPipPipPip
  • 2010 posts
  • Other
  • Pittsburgh PA

Posted 12 June 2007 - 01:45 PM

It's also interesting to consider the possibility of film lenses that lose 10x less light due to reflection. Depending on how much light is lost to reflection in the current systems we could see high quality lenses that are significantly faster becoming the standard (T0.4 anyone?). :)


The T stop won't be faster than the f/stop. For practical purposes they'd about the same.
The lenses might become so contrasty, a lowcon or fog might be an absolute necessity.

A lot of flares would disappear; some situations good, other situations a shame.
  • 0

#3 Evan Winter

Evan Winter
  • Basic Members
  • PipPipPip
  • 202 posts
  • Director
  • Los Angeles

Posted 12 June 2007 - 02:59 PM

Hey Leo,

I don't know if you're 'quoting' me when you say, 'the t-stop won't be faster than the f-stop' but if so I may not have communicated my thoughts clearly enough. I'll try again:

If light transmitted to the film plane is increased by reducing the amount of light lost to reflections then this would result in lenses with the ability to open up to faster t-stops than is currently possible.

T-stops (being an indication of the actual light that hits the film plane vs. the f-stop being a measure of the amount of light that a metering tool indicates should hit the film plane) are slower than 'corresponding' f-stops on a lens.

e.g., if a lens showed both f-stops and t-stops for each position it would likely look something like:

note: For illustrative purposes I'm imagining that lenses lose 1 stop of light from front element to film plane, whereas, modern lenses more typically lose only 1/3 of a stop or less largely because of advancements in film coating technology.

1. f4.0(amount of light hitting front element) = t5.6(f-stop amount of light hitting the film)
less light hits the film than hits the front element of the lens

2. f2.0(amount light hitting front element) = t2.8(f-stop amount of light hitting the film).
less light hits the film than hits the front element of the lens

So, if my ambient meter tells me I need an f4.0 to properly expose a scene and I'm happy, creatively, with this assessment then I set the t-stop on my lens barrel to t4.0. This will transmit f4.0 to my film. Although, it is likely that the amount of light entering the front element is closer to f5.6. (if my lens only had f-stops and I set my lens to f4.0 then I would be underexposed - because less than f4.0 worth of light would make it all the way through the lens to my film)

F-stops, on lenses, represent the amount of light entering the front element. T-stops (transmission stops) represent the amount of light that actually makes it through all the elements to the actual film itself.

At the end of the day, let's imagine most lenses we have now can open up to T2.0. If this new coating technology reduces the loss of transmitted light to the film plane then we'll have lenses that are effectively faster because they will be able to open up more with no loss in image quality. i.e., t1.4.

Hopefully this post makes my intent more clear.

And wow, that got wordy fast. I may have even confused myself. :) :) :)

Evan

Edited by Evan Winter, 12 June 2007 - 03:04 PM.

  • 0

#4 Brian Drysdale

Brian Drysdale
  • Basic Members
  • PipPipPipPip
  • 5070 posts
  • Cinematographer

Posted 12 June 2007 - 04:01 PM

With modern lenses (even zooms) you only lose about a 1/3 stop due to transmission loses, so the impact wouldn't be great in that regard. As mentioned, the greater impact would be reduction of flares and improved contrast.
  • 0

#5 Leo Anthony Vale

Leo Anthony Vale
  • Basic Members
  • PipPipPipPip
  • 2010 posts
  • Other
  • Pittsburgh PA

Posted 13 June 2007 - 01:15 PM

At the end of the day, let's imagine most lenses we have now can open up to T2.0. If this new coating technology reduces the loss of transmitted light to the film plane then we'll have lenses that are effectively faster because they will be able to open up more with no loss in image quality. i.e., t1.4.

Hopefully this post makes my intent more clear.


Transmission loss is not the limiting factor in lens designs. In the 30s and 20s when there was no lens coatings, it was more of a limiting factor than now. Not that Tessars weren't good lenses.
Now there are complex designs with about 1/3 stop loss.

Those T2 lenses are f/1.8 not f1.4.

And you did mention T 0.4 lenses. Maybe a typo.

It's more complicated designs probanly with some aspherical elements, more so than improved coatings, that will make those super lenses.
  • 0

#6 Patrick Neary

Patrick Neary
  • Basic Members
  • PipPipPipPip
  • 873 posts
  • Cinematographer
  • Portland, OR

Posted 13 June 2007 - 07:35 PM

[/i]So, if my ambient meter tells me I need an f4.0 to properly expose a scene and I'm happy, creatively, with this assessment then I set the t-stop on my lens barrel to t4.0. This will transmit f4.0 to my film. Although, it is likely that the amount of light entering the front element is closer to f5.6. (if my lens only had f-stops and I set my lens to f4.0 then I would be underexposed - because less than f4.0 worth of light would make it all the way through the lens to my film)

F-stops, on lenses, represent the amount of light entering the front element. T-stops (transmission stops) represent the amount of light that actually makes it through all the elements to the actual film itself.


Don't take this the wrong way, but I see some problems with your explanation- and I'm sure others here will chime in too (and then correct whatever I've muddled up)

If your meter says f4.0, then you have a certain number of footcandles falling on your meter. That doesn't change between your meter and the front element of your lens.

A simpler explanation might be:

An f-stop is mathematical; the ratio of the focal length of the lens to the diameter of the aperture in the lens.

A T-stop is just an f-stop adjusted for light loss within an individual lens (which is what I think you were getting at in a kind of roundabout way) :)
  • 0

#7 Nick Mulder

Nick Mulder
  • Basic Members
  • PipPipPipPip
  • 1023 posts
  • Other
  • Auckland, New Zealand

Posted 13 June 2007 - 07:46 PM

Don't take this the wrong way, but I see some problems with your explanation- and I'm sure others here will chime in too (and then correct whatever I've muddled up)

If your meter says f4.0, then you have a certain number of footcandles falling on your meter. That doesn't change between your meter and the front element of your lens.

A simpler explanation might be:

An f-stop is mathematical; the ratio of the focal length of the lens to the diameter of the aperture in the lens.

A T-stop is just an f-stop adjusted for light loss within an individual lens (which is what I think you were getting at in a kind of roundabout way) :)

thats a fan-bloody-tastic icon you've got there - reminds me of work :rolleyes:
  • 0

#8 Jon Kukla

Jon Kukla
  • Basic Members
  • PipPipPipPip
  • 399 posts
  • Other

Posted 14 June 2007 - 12:07 AM

The reason that lenses tend not to dip much below T1.3 has less to do with transmission factors and more to do with the image falling apart at such potential apertures bc of general optics principles. It's not that they can't/haven't been made before, but more what you have to trade-off for that. And with modern emulsions and fast lenses, there's less need to pursue such a target.
  • 0

#9 Chris Cooke

Chris Cooke
  • Sustaining Members
  • 246 posts
  • Cinematographer
  • Lethbridge, AB Canada

Posted 19 June 2007 - 05:52 PM

I just saw a segment on the Daily Planet that talked about another new lens design made out of crystal, calcium fluoride. The technology has been used in telescopes since I think about 2002 but this new design is more compact and will be perfect for helmet cameras and cell phone cameras. Light loss is reduced as compared to glass lenses and the resolving power is "supposed" to be better.
Here's an article for those of you who are interested.
http://www.technolog...y.com/node/5853
  • 0

#10 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 19 June 2007 - 06:37 PM

Hey Chris Cooke, (great last name)

Flourite (flouride) optical glass has been around for sometime now. Canon was using it in their cine zooms as far back as the late sixties. And it's been in telescopes long before 2002. It is something that would not be used for every element in the optical path of a given lens. It is used to correct for chromatic abberations. Even though over the years different compounds have ben created, it is not a very durable type of glass and does not stand up to atmospheric conditions very well. It is/was mainly used as one of the internal lenses in the focusing group of zoom lenses.

Chuck
  • 0

#11 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 19 June 2007 - 09:58 PM

Chuck, maybe I'm confusing things but isn't fluorite glass the one that yellows with time because it's mildly radioactive?
  • 0

#12 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 20 June 2007 - 12:23 PM

Chuck, maybe I'm confusing things but isn't fluorite glass the one that yellows with time because it's mildly radioactive?


Never mind. It's thorium glass I was thinking of. Kodak used to use it in their aero ektars (fast lenses for 8x10 aerial cameras).
  • 0

#13 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 20 June 2007 - 01:00 PM

Never mind. It's thorium glass I was thinking of. Kodak used to use it in their aero ektars (fast lenses for 8x10 aerial cameras).


Hey Chris,

Hmmm... always wondered why the eye that I used for looking thru the collimator always glowed green after viewing thru one of those old Ektars.
Just so all you people who have picked up and old cine lens or viewed thru the eyepiece of an old Arri camera and wondered why everything looked kinda yellow, it's due to the fact that the lens cement of the time was balsam which yellowed with age and is not due to any radioactivity! lol

Chuck
  • 0

#14 Tim Carroll

Tim Carroll
  • Sustaining Members
  • 2165 posts
  • Other
  • Chicago, Illinois

Posted 20 June 2007 - 02:15 PM

Just so all you people who have picked up and old cine lens or viewed thru the eyepiece of an old Arri camera and wondered why everything looked kinda yellow, it's due to the fact that the lens cement of the time was balsam which yellowed with age and is not due to any radioactivity! lol

Chuck


Chuck,

Maybe this has been discussed before, but how do you fix that? Any way to get rid of the yellow?

-Tim
  • 0

#15 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 20 June 2007 - 02:44 PM

Hi Tim,

Yeah this was talked about before, but damn if I can find it. lol What we use to do was take the offending cemented group and slowly heat it up in mineral oil just to the point that they slid apart.
Then let the two elements cool down and clean off the excess balsam with acetone. Clean both lenses with lens cleaner and recement. I had a little rig I made up consisting of a flat plate with a couple of rectangular bars mounted on top at 45 degrees to each other to act as an edge guide to hold the two lenses true to each other. Newer optical cements can be almost instantly cured with ultra violet light making for much faster recementing. Now here comes the "WARNING" part. While I never had a lens break on me while heating them up, IT CAN HAPPEN. So if you attempt this with a clients whatever, make sure they understand the risk factor as parts for older equipment just get harder and harder to obtain. But as an Arri camera tech. you already know that. Never throw any lens or camera part away, they can be money makers.

Cheers,

Chuck
  • 0

#16 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 20 June 2007 - 04:00 PM

Hi Tim,

Yeah this was talked about before, but damn if I can find it. lol What we use to do was take the offending cemented group and slowly heat it up in mineral oil just to the point that they slid apart.
Then let the two elements cool down and clean off the excess balsam with acetone. Clean both lenses with lens cleaner and recement. I had a little rig I made up consisting of a flat plate with a couple of rectangular bars mounted on top at 45 degrees to each other to act as an edge guide to hold the two lenses true to each other. Newer optical cements can be almost instantly cured with ultra violet light making for much faster recementing. Now here comes the "WARNING" part. While I never had a lens break on me while heating them up, IT CAN HAPPEN. So if you attempt this with a clients whatever, make sure they understand the risk factor as parts for older equipment just get harder and harder to obtain. But as an Arri camera tech. you already know that. Never throw any lens or camera part away, they can be money makers.

Cheers,

Chuck


That's about what I did with an old large format lens. I heated it in the oven very slowly to minimize the risk of uneven heating that would cause a break.
  • 0

#17 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 20 June 2007 - 04:08 PM

Yeah Chris.
We used the mineral oil for even heat distibution and also because we were doing it on a hot plate on the work bench. That way we could poke and prod the lens with a couple of orange sticks to help them slide apart.
Oh yeah, and we would put a couple of layers of kim wipes in the botom of the pan so that when they finally did slide apart we would not scratch them on the bottom of the pot.

Edited by chuck colburn, 20 June 2007 - 04:11 PM.

  • 0

#18 Tim Carroll

Tim Carroll
  • Sustaining Members
  • 2165 posts
  • Other
  • Chicago, Illinois

Posted 21 June 2007 - 02:15 PM

Never throw any lens or camera part away, they can be money makers.

Cheers,

Chuck


Chuck,

Had a client with an old Zeiss Jena lens jammed into one of the turret sockets of an ARRI camera. He tried to remove it with a Vise-Grips and really bogered it up. When I got it out the mount on the lens was mangled, the whole thing was just a mess, and he didn't want it back. So I set it aside and when I got some time free a couple of weeks ago, I carefully took it all apart, re-machined the broken or bent parts, cleaned all the elements, reassembled it and finally collimated and re-shimmed it. Now it's a nice lens. I would have to charge a client a pretty penny to fix a lens like that, as it was many hours of work, but I'm just going to keep it and use with one of my own cameras.

By the way, speaking of the Zeiss Jena line of lenses, I know they were made in the East German Zeiss factory, as opposed to the West German Zeiss factory. This particular lens has the T symbol on the front element ring, but it isn't followed by the * symbol. I figured this indicated the Zeiss T coating was on the lens, but is the T coating different from the T* coating? Or did the East German factory just put a T on the lens instead of a T*?

Thanks Chuck,
-Tim
  • 0

#19 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 21 June 2007 - 02:36 PM

Hello Tim,

I hoped you told that guy that it's takes years of training to be qualified to use precision tools like vise-grips. Even then he would not yet be ready for the use more advanced tools such as channel locks and bench vises. These skills do not come easy.
As for the "T" on the Jena lens... I haven't got the FFI! lol

see ya,

Chuck
  • 0

#20 Leo Anthony Vale

Leo Anthony Vale
  • Basic Members
  • PipPipPipPip
  • 2010 posts
  • Other
  • Pittsburgh PA

Posted 23 June 2007 - 12:14 PM

By the way, speaking of the Zeiss Jena line of lenses, I know they were made in the East German Zeiss factory, as opposed to the West German Zeiss factory. This particular lens has the T symbol on the front element ring, but it isn't followed by the * symbol. I figured this indicated the Zeiss T coating was on the lens, but is the T coating different from the T* coating? Or did the East German factory just put a T on the lens instead of a T*?


The Zeiss Jena Arri lenses were a lot earlier the C.Zeiss T*.
At some point Zeiss Jena was injoined from using C.Zeiss trade names.
Thus sonnars becmae S-Jena & Tessars became T-Jena.
  • 0


Visual Products

Opal

CineLab

Glidecam

Abel Cine

FJS International, LLC

Technodolly

The Slider

CineTape

rebotnix Technologies

Aerial Filmworks

Willys Widgets

Gamma Ray Digital Inc

Media Blackout - Custom Cables and AKS

Paralinx LLC

Broadcast Solutions Inc

Metropolis Post

Tai Audio

Rig Wheels Passport

Ritter Battery

Wooden Camera

Rig Wheels Passport

Wooden Camera

rebotnix Technologies

Abel Cine

CineTape

Opal

CineLab

FJS International, LLC

The Slider

Broadcast Solutions Inc

Gamma Ray Digital Inc

Paralinx LLC

Ritter Battery

Technodolly

Visual Products

Glidecam

Willys Widgets

Media Blackout - Custom Cables and AKS

Aerial Filmworks

Tai Audio

Metropolis Post