Brian Caldwell

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 . . .

Yes. 

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 . . .

Its a garbage patent.  The fact that it expired several years ago - and hence is now in the public domain - and yet nobody has used the "technology" to produce anything should tell you something.  The Kodak patent example is huge, slower than f/5, and basically doesn't work.  The clue that something is seriously wrong is that the entrance pupil of the attachment - which must lie at the exit pupil of the attached lens - is tiny and located right next to the first surface of the adapter.  This will result in severe vignetting with just about all lenses.  I can't imagine that any prototype was ever made.
If you restricted yourself to telephoto lenses having an extremely long back focal length you *might* be able to design one that works, although US5499069 is non-enabling and you would have to invent something from scratch.  The Kodak patent is completely useless if you want to make a general purpose focal reducer that will work with any SLR lens.

The Panavision DXL is basically a re-housed Red Weapon 8k, and their new "70mm" lenses in fact cover just a bit larger than FF/Vistavision.  A few years ago they were developing a larger format camera with a 48x20.25mm sensor (52mm diagonal) along with a separate set of lenses to go with it, but issues associated with the custom sensor doomed that project.

Different sensors sizes provide different pixel sizes and resolutions and abilities to use different lens sizes. Smaller sensor cameras tend to be more compact and lower cost. Nothing magical happens with DOF as sensor size increases. I got killer shallow DOF with the Voigtlander F.95 25mm on the GH4. Is the 50mm F1.4 or F1.2 shallower on the FF 5D3- sure, but these shallow DOFs aren't usable very often for video, right? And just being shallower isn't a special, magical property.
The Alexa looks killer because of the ALEV III sensor design and associated image processing and color science. They used S35 as that is the standard for filmmaking and for lens compatibility. If a larger sensor size would create a magical image better than a smaller sensor size, ARRI would have made it, right? What about the Alexa 65? That's just their way of using the ALEV III sensor (3 of them rotated 90 degrees) to get higher resolution without changing the sensor, pixel size, image processing, and color science. It's about resolution, and that's it. Nothing magical about the sensor size by itself.
If larger sensor sizes produce a better DOF look (vs. just shallower via available lenses), it should be easy to prove. The reason there's no proof is it's a myth.

You are expecting a level of precision in this comparison that is entirely unreasonable.  Little things like changes in distortion and entrance pupil position during zooming make it impractical to make a blink comparator test completely perfect.  What the comparison does show - with more than sufficient precision - is that you can optically reproduce all aspects of an image shot on a large format with one shot on a smaller format - or vice versa.  
The notion that, say, an 80mm medium format lens has some inherent "80mm-ness" or "medium formatishness" that somehow stays with that lens after you attach a focal reducer is just silliness.  The combination of a 0.7x focal reducer and an 80mm lens is a 56mm lens.  Period.  Put that 56mm lens on a 24x36mm format camera and it will behave just like any other 56mm lens attached to that camera, the only caveats being related to aberrations and other flaws in the lens and focal reducer.

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Do the experiment properly and you'll find that the perspective is the same.  Surely you must have heard countless times before that perspective depends only on the subject distance.  This is a truth that you shouldn't ignore.  More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens.  For this reason, the entrance pupil is sometimes called the center of perspective.  I suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.
The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

Let me get this straight - are you denying that the combination of an 80mm lens with a 0.7x focal reducer is a 56mm lens?

Let me get this straight - are you denying that the combination of an 80mm lens with a 0.7x focal reducer is a 56mm lens?

Let me get this straight - are you denying that the combination of an 80mm lens with a 0.7x focal reducer is a 56mm lens?

So if we focus on the art, the emotion of the combined 'lens filter', we can categorize looks so others can replicate themselves* and quit arguing about sensor size. I think Mattias' pics look cool, and if a MF->FF focal reducer plus cheap MF lenses can be used to recreate those looks, that's pretty neat- gives new love to neglected unused MF lenses
 
* this was not meant as a cloning comment  

Character/rendering are entirely separate issues from photographic basics like DOF and perspective.  Certainly, if you like the character then there's nothing wrong with that.  Heck, if you find that using an 80mm lens with both a 1.4x teleconverter and 0.7x focal reducer (in series!)  to get back to 80mm but with some funky aberrations gives you the results you want then you should certainly do it.  My only real objection is with pseudo-explanations - basically "fake physics" - that cross the line into mysticism.
Mini correction:  techically, aberrations can and do influence DOF.