Brian Caldwell

I've built prototypes of an iscorama-style single-focus adapter, but its really only suitable for shorter focal lengths in the 35mm to 75mm range.  Also, its a bit large, and the front element moves during focusing, which may cause some issues with matte boxes.  I'm also building a second type better suited for longer focal lengths in the 75 to 200mm range.  I'm still debating whether to modify these for internal focusing, which would be good for heavy-duty cine use, but would make the adapters larger, heavier, and more expensive.  To be honest, I've put the adapter project on hold until I get a few focal lengths in my anamorphic prime series completed.
 
 
 

I've built prototypes of an iscorama-style single-focus adapter, but its really only suitable for shorter focal lengths in the 35mm to 75mm range.  Also, its a bit large, and the front element moves during focusing, which may cause some issues with matte boxes.  I'm also building a second type better suited for longer focal lengths in the 75 to 200mm range.  I'm still debating whether to modify these for internal focusing, which would be good for heavy-duty cine use, but would make the adapters larger, heavier, and more expensive.  To be honest, I've put the adapter project on hold until I get a few focal lengths in my anamorphic prime series completed.
 
 
 

I'm curious if you are using a cropped mode on the GH5, because a quick test shows you get severe vignetting with the Lens Turbo II on full-sized m43 format when paired with the Sigma 18-35 at shorter focal length settings.  This despite the fact that the Lens Turbo II has less reduction (0.726) than the Speed Booster (0.71)

Even though the 18-35 has sufficient image circle diameter at 18mm to handle 0.71x focal reduction, the lesser 0.726x factor of the Lens Turbo II does not mean you are "inside safe margin".  The issue here is that image circle diameter is only part of the story.  Equally important is the exit pupil distance of the lens, and how well the focal reducer handles longer exit pupil distances.  This is where the Lens Turbo II completely falls apart, because the 18-35 is nearly telecentric at the wide end, with an exit pupil distance of 150mm.  My simple test above shows what happens:  the vignetting with the Lens Turbo II is clearly caused by the focal reducer, and not the Sigma 18-35.

I'm curious if you are using a cropped mode on the GH5, because a quick test shows you get severe vignetting with the Lens Turbo II on full-sized m43 format when paired with the Sigma 18-35 at shorter focal length settings.  This despite the fact that the Lens Turbo II has less reduction (0.726) than the Speed Booster (0.71)

Even though the 18-35 has sufficient image circle diameter at 18mm to handle 0.71x focal reduction, the lesser 0.726x factor of the Lens Turbo II does not mean you are "inside safe margin".  The issue here is that image circle diameter is only part of the story.  Equally important is the exit pupil distance of the lens, and how well the focal reducer handles longer exit pupil distances.  This is where the Lens Turbo II completely falls apart, because the 18-35 is nearly telecentric at the wide end, with an exit pupil distance of 150mm.  My simple test above shows what happens:  the vignetting with the Lens Turbo II is clearly caused by the focal reducer, and not the Sigma 18-35.

The problem is that focal reducers naturally want to shrink the optical path, which is why a boosted lens is shorter than the same lens with a plain adapter.  To do an anamorphic focal reducer you need to overcome this tendency, which is much easier said than done.  Even if you succeeded and were able to produce an anamorphic focal reducer I don't think that people would go nuts over it.  The reason is that it would be a rear anamorphic adapter, and therefore would not produce the horizontal flares, oval bokeh, and differential depth of field that are the main reasons why anamorphic is used nowadays.  No doubt there would be a flurry of interest in the market, but then people would be spitting mad when they discovered that their newly created rear anamorphic lenses just do not look anamorphic.  And then the mob with pitchforks and torches shows up at my house.  No thanks!

Agreed about the de-squeeze options.  If I were writing the monitor firmware I'd allow a continuous variation between 1.00x and 2.00x (at least to 0.01x resolution), and then show the resulting output rectangle ranging from 4:3 to 2.66:1.  "Special" values like 1.33x, 1.5x, 1.79x, and 2x could be made available in a separate dumbed-down menu I suppose.  I think the problem is that anamorphic is confusing to many people, and Panasonic has made some lowest common denominator assumptions about their customer base.

The problem is that focal reducers naturally want to shrink the optical path, which is why a boosted lens is shorter than the same lens with a plain adapter.  To do an anamorphic focal reducer you need to overcome this tendency, which is much easier said than done.  Even if you succeeded and were able to produce an anamorphic focal reducer I don't think that people would go nuts over it.  The reason is that it would be a rear anamorphic adapter, and therefore would not produce the horizontal flares, oval bokeh, and differential depth of field that are the main reasons why anamorphic is used nowadays.  No doubt there would be a flurry of interest in the market, but then people would be spitting mad when they discovered that their newly created rear anamorphic lenses just do not look anamorphic.  And then the mob with pitchforks and torches shows up at my house.  No thanks!

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Glad to see a de-squeeze function, although 1.79x should be included since this is required to go from 4:3 to DCI 2.39:1 without cropping.  Of course, I'm biased since I'm currently developing 1.79x lenses!  Need to start lobbying Panasonic to add a few lines to their firmware . . .

Agreed about the de-squeeze options.  If I were writing the monitor firmware I'd allow a continuous variation between 1.00x and 2.00x (at least to 0.01x resolution), and then show the resulting output rectangle ranging from 4:3 to 2.66:1.  "Special" values like 1.33x, 1.5x, 1.79x, and 2x could be made available in a separate dumbed-down menu I suppose.  I think the problem is that anamorphic is confusing to many people, and Panasonic has made some lowest common denominator assumptions about their customer base.

Agreed about the de-squeeze options.  If I were writing the monitor firmware I'd allow a continuous variation between 1.00x and 2.00x (at least to 0.01x resolution), and then show the resulting output rectangle ranging from 4:3 to 2.66:1.  "Special" values like 1.33x, 1.5x, 1.79x, and 2x could be made available in a separate dumbed-down menu I suppose.  I think the problem is that anamorphic is confusing to many people, and Panasonic has made some lowest common denominator assumptions about their customer base.

The "why" seems pretty obvious.  16x9 is enormously important, and to get there from 4:3 without wasting sensor space you need (16/9)x(3/4)=1.33x.  Whether or not 1.33x is "crap" or not depends entirely on the lens design.

The problem is that focal reducers naturally want to shrink the optical path, which is why a boosted lens is shorter than the same lens with a plain adapter.  To do an anamorphic focal reducer you need to overcome this tendency, which is much easier said than done.  Even if you succeeded and were able to produce an anamorphic focal reducer I don't think that people would go nuts over it.  The reason is that it would be a rear anamorphic adapter, and therefore would not produce the horizontal flares, oval bokeh, and differential depth of field that are the main reasons why anamorphic is used nowadays.  No doubt there would be a flurry of interest in the market, but then people would be spitting mad when they discovered that their newly created rear anamorphic lenses just do not look anamorphic.  And then the mob with pitchforks and torches shows up at my house.  No thanks!

The base design is for Arri Alexa open gate, with a PL mount.  I've intentionally made the BFL very long so that all lenses will be compatible with PL-EF adapters ( https://c7adapters.com/en/product/pl_lens_-_ef_mount/35 ).  Due to the positive lock feature these adapters are completely rock steady and don't introduce any play that would be noticeable during focus pulls.  So you basically have a choice of PL or EF by use of the adapter.  With EF you can use COTS Speed Boosters to go down to M43 at very high speed.  Alternatively, I may offer "native" M43 mount if the demand warrants it.  Similarly I'll be able to produce "FF" and 65/70mm versions using the same base optics plus different rear optical groups.  Either way, focus will be one-ring.

You're exactly right.  Shooting with 2x lenses on 4:3 will give 2.66:1, which also requires cropping to get to the DCI standard 2.39:1 for normal theater projection.  Which is why I'm interested in 1.79x lenses to yield 2.39:1 directly from 4:3 without any need for cropping.

The base design is for Arri Alexa open gate, with a PL mount.  I've intentionally made the BFL very long so that all lenses will be compatible with PL-EF adapters ( https://c7adapters.com/en/product/pl_lens_-_ef_mount/35 ).  Due to the positive lock feature these adapters are completely rock steady and don't introduce any play that would be noticeable during focus pulls.  So you basically have a choice of PL or EF by use of the adapter.  With EF you can use COTS Speed Boosters to go down to M43 at very high speed.  Alternatively, I may offer "native" M43 mount if the demand warrants it.  Similarly I'll be able to produce "FF" and 65/70mm versions using the same base optics plus different rear optical groups.  Either way, focus will be one-ring.

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Glad to see a de-squeeze function, although 1.79x should be included since this is required to go from 4:3 to DCI 2.39:1 without cropping.  Of course, I'm biased since I'm currently developing 1.79x lenses!  Need to start lobbying Panasonic to add a few lines to their firmware . . .

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Hi Andrew:  Any input you can give to Panasonic would be terrific - I really appreciate it!  I'm really psyched about the GH5, and think it could become a really major anamorphic camera since the format is basically the same size as a 4:3 crop of Super 35.
Regarding anamorphic lenses, I'm currently working on primes, and they are mechanical beasts due to the Panavision-style counter-rotating  Stokes lenses.  So, I'm in the weeds worrying about screws, bearings, and special tools needed to manually pre-load a whole bunch of anti-backlash gears.  One thing related to M43 and the GH5 is that they will be compatible with the M43 Ultra Speed Booster via high quality PL-to-EF adapters, which will create T/1.4 speed for all but the longest focal lengths.

Glad to see a de-squeeze function, although 1.79x should be included since this is required to go from 4:3 to DCI 2.39:1 without cropping.  Of course, I'm biased since I'm currently developing 1.79x lenses!  Need to start lobbying Panasonic to add a few lines to their firmware . . .

Glad to see a de-squeeze function, although 1.79x should be included since this is required to go from 4:3 to DCI 2.39:1 without cropping.  Of course, I'm biased since I'm currently developing 1.79x lenses!  Need to start lobbying Panasonic to add a few lines to their firmware . . .

Glad to see a de-squeeze function, although 1.79x should be included since this is required to go from 4:3 to DCI 2.39:1 without cropping.  Of course, I'm biased since I'm currently developing 1.79x lenses!  Need to start lobbying Panasonic to add a few lines to their firmware . . .