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The Complexities of Large Formats and Lenses


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36 minutes ago, Phil Rhodes said:

I'd be a bit cautious about creating any system that relies on referring to something as anything other than what it is. We've suffered this already with crop factors on stills cameras, creating a generation of stills photographers who end up going through all sorts of mental arithmetic to express what they mean and risking confusion. Now, was that the actual 50mm we wanted, or the 50mm multiplied by some intermediate factor?

There isn't a straightforward way of expressing this stuff without least three bits of information. Most obviously that's the focal length, the squeeze factor if any, and the size of the sensor. You can manipulate numbers and state these in various ways, but in the end, it's always going to be a three term equation.

These days, with the proliferation of non-standard sensor sizes and mixing of formats, you also need to know the useable image circle diameter of the lens, which gives you an upper limit on what sensor size (or more accurately what resolution and aspect ratio within the sensor area) you can use. This is one of the issues Greg is facing, mixing a 28mm anamorphic designed for S35 with a 40mm designed for full frame, and why the 40mm ends up having a wider angle of view. The sensor size is a variable dependent on the lens design.

I agree that it’s best to keep the system as it is, with lenses simply labelled by focal length and squeeze factor if anamorphic, although I think it would be handy to also have image circle diameters engraved on the barrel as well (I think Sigma cine lenses do this.) In Greg’s case though, it definitely makes sense to have some additional information at hand. 

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Posted (edited)

What’s crazy to me is, after all the variables are calculated, how wide this anamorphic format ends up on the large format sensor. Pictured are 2 images made with my custom Technovision 1.5x, 50mm Close Focus lens at 19 inches (minimum focus) and 2.5 feet. The aspect ratio is 2.39:1 with a 93% extraction on the Alexa LF. 
 

G

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Edited by Gregory Irwin
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6 hours ago, Gregory Irwin said:

What’s crazy to me is, after all the variables are calculated, how wide this anamorphic format ends up on the large format sensor. Pictured are 2 images made with my custom Technovision 1.5x, 50mm Close Focus lens at 19 inches (minimum focus) and 2.5 feet. The aspect ratio is 2.39:1 with a 93% extraction on the Alexa LF. 
 

G

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Does this mean your in-camera pixel aspect ratio will be 1.59:1 before de-squeezing? But you will still be recording the full 1.44:1 open gate?

Also very curious to hear about your experience with these lenses - I notice a slight amount of barrel distortion which gives the image a rounded feel to me. Really pulls the eye towards the center of the frame. Seems to be on contrasty side as well, very nice.

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2 hours ago, Satsuki Murashige said:

Does this mean your in-camera pixel aspect ratio will be 1.59:1 before de-squeezing? But you will still be recording the full 1.44:1 open gate?

Also very curious to hear about your experience with these lenses - I notice a slight amount of barrel distortion which gives the image a rounded feel to me. Really pulls the eye towards the center of the frame. Seems to be on contrasty side as well, very nice.

We are definitely recording on the full sensor, 1.44. The only aspect ratio we care about is the 2.39. We don’t really refer to the desqueeze. But you do have a keen eye! The lenses do have a very slight horizontal stretch. But faces are shown to be accurate. No anamorphic mumps. 
 

G

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11 hours ago, Gregory Irwin said:

What’s crazy to me is, after all the variables are calculated, how wide this anamorphic format ends up on the large format sensor. Pictured are 2 images made with my custom Technovision 1.5x, 50mm Close Focus lens at 19 inches (minimum focus) and 2.5 feet. The aspect ratio is 2.39:1 with a 93% extraction on the Alexa LF. 
 

G

93D21015-E446-493A-94E9-855705D63C4A.jpeg

1AFEA644-69DE-42FC-8B9A-501286656BBD.jpeg

After watching Lupin on Netflix (which was shot with the lenses you're testing at the moment) they remind me a bit of the Xtal Xpress. 
Also, the close focus is fantastic, 19 inches!

You changed a bit Greg 😛



 

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4 hours ago, Gregory Irwin said:

We are definitely recording on the full sensor, 1.44. The only aspect ratio we care about is the 2.39. We don’t really refer to the desqueeze. But you do have a keen eye! The lenses do have a very slight horizontal stretch. But faces are shown to be accurate. No anamorphic mumps. 
 

G

Very cool, thanks for the details Greg.

Good luck on the film!

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greg, with many different lenses selected for a final package, how do you go about making sure the iris markings/T stop readings are consistent for the DP?

i have seen people re-stripe a few lenses which give a different reading than most other ones in the kit... and i'm on a show now where we have atlas orions and panavision T series anamorphics. the T series are consistently darker than atlas, at same T stop reading on the barrel

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9 hours ago, Kyryll Sobolev said:

.. i'm on a show now where we have atlas orions and panavision T series anamorphics. the T series are consistently darker than atlas, at same T stop reading on the barrel

Presumably you’re renting through Panavision, so have you asked their lens tech about this? Some branches may have a T stop tester, but a tech can also compare luminance readings on an oscilloscope with other lenses set to the same T stop. 

There can be play in an iris mechanism, or iris cages can sometimes shift especially with motors driving them forcefully into end stops, or an iris drive pin can get bent, or the aperture index ring may have shifted or sometimes manufacturer’s measurement processes and quality control can vary. 

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yes pana here has that T stop reading device, and i have seen the tech here restripe lenses with tape and marker

i should rephrase my question to more organizational aspect - if you have many various lenses, do you select some to act as "base" lenses, and match others to them (if the lenses actually do give different readings)

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3 hours ago, Kyryll Sobolev said:

yes pana here has that T stop reading device, and i have seen the tech here restripe lenses with tape and marker

i should rephrase my question to more organizational aspect - if you have many various lenses, do you select some to act as "base" lenses, and match others to them (if the lenses actually do give different readings)

In my experience, we don’t restripe lenses. Most of the variations are slight and we can instantly see them on a calibrated monitor and compensate if necessary. There are so many other variables that can also affect exposure, you can drive yourself crazy. Keep it stupid simple. 
 

G

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  • 1 month later...
Posted (edited)
22 hours ago, Shawn Martin said:

How's the shoot going so far, Greg? Curious to hear what lenses you ended up choosing to complete your set!

The show is going very well. I’ve attached my cheat sheet of the main unit lens package for you to see. 
 

G

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Edited by Gregory Irwin
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That's a ton of lenses! Thanks a lot for that info.

Are there any there besides the new Technovision ones that you haven't used before?

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1 hour ago, Shawn Martin said:

That's a ton of lenses! Thanks a lot for that info.

Are there any there besides the new Technovision ones that you haven't used before?

No. The Technos are the only new lenses to us. We’ve used all of the others many times over the years. 
 

G

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