Red Lens Conversion Scale

evinsky

evinsky

Well-known member
Lens conversion scales for RED.
(These are rounded to the closes whole MM for ease of use)

35mm Still (3:2*) 1.0X (True Normal 43mm)
Super 35mm Mysterium 4k+) 1.5x (TN 28mm)
Super 16 (Mysterium 2K Windowed) 3.3x (TN 13mm)
2/3" HD/Cinealta/Varicam (Mysterium 1080P Windowed) 3.5x (TN 12mm)
1/3" HVX200/DV/HDV 7x (TN 6mm)

True normal is defined by a focal length that exactly matches the diagonal of the format.

Example: Nikon 17-35mm 2.8 In still would be...
S35= 26-55mm
S16= 56-116mm
2/3"= 60-123mm
1/3"= 119-245mm

I believe this is correct, if anyone has the time to double check me please do.

* 35mm Still is a 3:2 aspect ratio format where as all HD is 16:9 format.

I'll also give credit to Proteus who actually made this chart that we seem to have overlooked.
table.png
 
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.... what does all that mean? I am not good with maths and charts.

Anyone care to give the 'in a nutshell' post for the stupid people like me out there?

El Stupido
 
EL_STUPIDO said:
.... what does all that mean? I am not good with maths and charts.

Anyone care to give the 'in a nutshell' post for the stupid people like me out there?

El Stupido
Click to expand...
ok just for you el stupido i made a horrible visual reference that may make a little more sense..
1155033806.jpg


the magnification factor may be what is throwing you off.. A CROP is the better way to explain it.

look at the photo above. The 35mm lens circle matches the 35mm sensor just right.. you have a 1:1 crop factor, the image is getting cropped at the same size as the lens. Now if you take a DSLR camera, which has a smaller sensor, it can only "read" the middle part of the lens, even though the entire image is still being shown to the camera. This makes it look like you are zooming in to the photo, as its cropping only the eye area of the frame. Its an optical crop though, so your not throwing away data.. it would be the same as if you zoomed in. This is why they call it magnification.

So because of this, a 18mm 35mm lens put onto a DSLR camera will give you more like a 25mm lens because it "looks" only at the middle part of the image, so you dont get as wide as you would normally on a 35mm camera.

This isnt necessarly bad, as lenses normally get worse as you hit the edges of the glass, so pulling off the center theoretically will give you a better image.

Make more sense?

to go backwards,
if you put a 16mm lens on a 35mm camera, the hole on the back of the lens isnt big enough, so you would actually see the black round part.. this is why red has a "windowed" mode , where it just shoots the middle of the sensor ( so the big square above that is the actual size of the sensor just turns on the area of the small sensor) .. so you can use smaller lenses on it without shooting the black part... or of course, you could use a 35mm cine lense and shoot both modes.
 
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This is all very useful but I think a table of the horizontal angle of view of various focal length lenses used on each of the RED formats would give people a much better grasp of what the lens "sees".
 
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ok just for you el stupido i made a horrible visual reference
Click to expand...

Jarrad how could you be so horrible to that nice female:crybaby:

Gregs point about a horizontal chart would also be nice. I agree about the sticky but would also add Gregs suggestion AND if Jarrad could continue to put in the relevant boxes to indicate the size of s16mm/2/3rd and 1/3rd in the picture then there would be no excuse for anyone not to fully undertand the whole concept (i think)

Michael
 
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Jarred, that is an excellent primer on exactly how the concept of lens magnification works! As they say, a picture tells a thousand words, and that sort of picture will be very handy for a lot of people who may otherwise be confused as to exactly what is happening when they select say 1080p mode with an S16 lens, for example, and why that will still work but be the highest you can go (I think 2K is reality but 1080p is what I will be looking at using the camera for if/when I get one).

Nice work!
 
Greg Lowry said:
This is all very useful but I think a table of the horizontal angle of view of various focal length lenses used on each of the RED formats would give people a much better grasp of what the lens "sees".
Click to expand...
go ahead Greg, who better than you to drop that onto us :)
 
Jarred - thats a good example of something I've never fully understood.. It's an area im green to.

So looking at this example, does this mean throwing my DSLR lenses on Red I could shoot 4K and the full 35MM sesnor? And if I decided to shoot 2K cropped then I would get an image similar to what I'd get with the same lens on my DSLR?

can you also shoot 2K scaled and make use of the wider field of view?

Finally, this would bring me to another question. Lenses made for DSLR's have obviously been manufactured and tested shooting on the Smaller field of view. Are we likely to see more imperfections in the glass if the whole area were to be used on Red?

Thanks Jarred

Karl
 
evinsky said:
I believe this is correct, if anyone has the time to double check me please do.
Click to expand...

Although the normal lens is defined by the diagonal of each format as you said, to make any comparisons between HD and still lenses, either for what will be a normal lens or a focal length multiplier, we should use the same aspect ratio (16:9 in our case), because this is what the RED camera will see. Other than 16:9 frame will introduce errors.

Also, by using the same aspect ratio there is no need to calculate the diagonal. You can just divide between the horizontal dimensions to find the multiplier except for the normal lens which should be calculated from the diagonal of each 16:9 frame.

This is why I calculated the table based on 16:9 frame for all formats including the still 35mm. So the correct multipliers are the ones shown in the depth of field column, rounded for one decimal.

For more precise factors look at the first page of http://www.dvxuser.com/V6/showthread.php?t=64685 (the values in red color).
 
Darkline said:
So looking at this example, does this mean throwing my DSLR lenses on Red I could shoot 4K and the full 35MM sesnor? And if I decided to shoot 2K cropped then I would get an image similar to what I'd get with the same lens on my DSLR?
Click to expand...
No, Reds sensor is roughly the same size as your DSLR, APS-C cropped to 16:9 Aspect ratio.

Darkline said:
can you also shoot 2K scaled and make use of the wider field of view?

Finally, this would bring me to another question. Lenses made for DSLR's have obviously been manufactured and tested shooting on the Smaller field of view. Are we likely to see more imperfections in the glass if the whole area were to be used on Red?
Click to expand...
DSLR lenses should perform very well on Red, if you have a 10,12 or 16MP DSL you can easily see how your lenses would perform on Red.
 
Proteus said:
This is why I calculated the table based on 16:9 frame for all formats including the still 35mm. So the correct multipliers are the ones shown in the depth of field column, rounded for one decimal.
Click to expand...

That accounts for the diffrence in our numbers. I though about that but since people have a specific mental image about what 35mm focal lengths look like I decided to leave it. The diffrence is actually quite small, 16:9 35mm still crop normal is 27mm Vs. 28mm.
 
here is a different way to look at it.. to understand what different lenses do to the equation... the actual frame sizes obviously are not accurate but it will give you a greater idea.
1155022415.jpg



So as you can see.. you can use a 35mm lens on a 16mm camera, but you cant use a 16mm lens on a 35mm camera.. because the 35mm sensor is bigger then the back plane of the 16mm glass.. (or the 2/3 inch lens etc..)
 
The central brighter circle, looks very nice!
Why have we stuck with rectangular frames anyway?
Imagine a full movie shooted (or post processed to be) ..aspectless!
In a circular format, projected in a large circular screen! Or maybe an eliptical screen! (that would have a ratio of course) :)
 
Proteus said:
In a circular format, projected in a large circular screen! Or maybe an eliptical screen! (that would have a ratio of course) :)
Click to expand...
There actually is an ecliptical format for movies known as Omnimax! The entire movie wraps around you and you're surrounded by film wherever you look. It's an awesome experience! From my knowledge, there are only a handful of Omnimax theaters in existence, but one of them is in San Diego (I think it was the first, actually), and that's where I grew up. So I was fortunate to see several Omnimax movies in my childhood and teens. Wiki has a somewhat small entry about it that's lumped into their IMAX page, but does have a little more information if you're interested:

http://en.wikipedia.org/wiki/Omnimax#IMAX_Dome.2FOMNIMAX

Here's a pretty cool picture of an omnimax theater, too, though obviously it's only showing you a fraction of the room. The projector is insane!

http://www.in70mm.com/newsletter/1997/50/tbp/images/omnimax.jpg

Anyway, just food for thought in case you've never heard of it! :)



Jarred, I have a question based on your "35mm vs. DSLR" image. I'm not an expert on this, but don't different DSLR cameras have different crop factors? Specifically, I was under the impression that there are several higher-end cameras (including Canon's new 5D) that are "full frame" DSLRs that have a 1:1 crop factor and are no different than a standard 35mm SLR. I was also under the impression that Red was to be "full frame" and that was one aspect they were really touting - identical field of view and DOF compared to 35mm. If there is a crop factor involved, how is the FOV the same? Proteus' chart indicates that the sensor of Red One is a full 46% smaller than a 35mm frame, which is a huge difference. Can you (or anyone else that has a better grasp on this than I do!) elaborate a little on the differences between the formats? Thanks.
 
Some DSLRs namely the Canon 5D and 1dsII are indeed 24x36mm "Full 35mm Frame" but the vast majority of DSLRs including Canons are 1.5x "APS-C" size sensors. This is mainly becasue of the cost of manufacturing these chips is so high. However cinema "Super 35mm" film is actually about the same size as APS-C 18x24mm. Only Vistavision, which was a horizontal running camera used primarily for VFX had a frame size roughly equivelent to 35mm still cameras.

APS-C 1.5x sensors actually have some very important optical advantages over thier larger "Full Frame" brothers. Mainly vignetting and wide angle optical charachteristics. Very few wide angle lenses perform well on the FF Canons. In fact the best performers are adapted Zeiss, Leica and Nikon wides. The smaller sensors allow for the use of the much sharper and uniform center of the lens to be utilised, or in the case of DX specific digital lenses the optical designs can be optimised to much greater degree becasue the ratio of lens mount size to sensor size. The amazing 18-200 VR Nikkor would not be possible for FF. Look at the diffrence...
18-200 DX VR Nikkor $750
408518.jpg

And the Canon 28-300mm equivelent for FF. $2100
319784.jpg

The Canon is twice the size and weight as well as almost 3x the cost.
 
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