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Discussion Starter · #1 ·
Hello guys,

I'm struggling to understand why lens that are labeled "for 4:3/5:4 to 16:9" made by Runco (labeled "Widevision") cannot be used for CIH today. I've read the discussion here and here and here but I do not understand the logic. If Runco used these for CIH anamorphic 1080p setups, why can't they be used for 1080p setups with more modern projectors? The noted thread claims the lens are not the correct stretch ration (1.42x instead of 1.33x) but again, how would Runco themselves use it on a 16:9 projector for 2.35 if that were the case? Or is the argument that the lenses are just not very good? Note, I am not referring to the Runco lens that are clearly just ISCO III clones but to the ones with the "4:3/5:4 to 16:9" label noted above and in the picture below. Thanks!

3144329
 

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It's simple math... if your projector is 16:9 then you need a 1.33x lens to expand to 2.35:1 (scope). This lens ONLY expands a 4:3 or 5:4 projector to 16:9....NOT scope (2.35:1). I can't remember the actual magnification for this lens but I think it was 1.5x or 1.9x (don't hold me to that though)....found it...this was a 1.42x lens. Not wide enough for a native 16:9-to-scope.

BTW, Runco never ever used that particular lens for their 16:9 projectors. That is why it is labeled as 4:3 AND 5:4 to 16:9.
 

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Discussion Starter · #3 ·
It's simple math... if your projector is 16:9 then you need a 1.33x lens to expand to 2.35:1 (scope). This lens ONLY expands a 4:3 or 5:4 projector to 16:9....NOT scope (2.35:1). I can't remember the actual magnification for this lens but I think it was 1.5x or 1.9x (don't hold me to that though)....found it...this was a 1.42x lens. Not wide enough for a native 16:9-to-scope.

BTW, Runco never ever used that particular lens for their 16:9 projectors. That is why it is labeled as 4:3 AND 5:4 to 16:9.
Thanks for your reply.

I still don't understand. Notice, the expansion from 4:3 to 16:9 is very close to the expansion from 16:9 to 2.35:1. In order to expand from 4:3 to 16:9, one needs an expansion of 1.33x (4:3 x 1.33 is 16:9) which of course is the expansion needed to go from 16:9 to 2.35 (or 21:9).

What am I missing?

Thanks for the help.
 

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Thanks for your reply.

I still don't understand. Notice, the expansion from 4:3 to 16:9 is very close to the expansion from 16:9 to 2.35:1. In order to expand from 4:3 to 16:9, one needs an expansion of 1.33x (4:3 x 1.33 is 16:9) which of course is the expansion needed to go from 16:9 to 2.35 (or 21:9).

What am I missing?

Thanks for the help.
Runco sold that lens for two different chips (4:3 AND 5:4) and neither is a proper ratio to fit a 16:9 image so the 1.42x expansion gives both those chips a correct aspect ratio for 16:9 (AR) but BOTH will crop a bit off the top/bottom to fit the 16:9 AR without any distortion.

The correct expansion magnification for a native 16:9 chip (either 1920x1080 or 1280x720..etc) is 1.33x. The newer JVC/Sony projectors are actually 4096x2160 (17:9) therefore you need a 1.25x lens (DCR or ISCO DLP Cinema) to properly show scope using the full 17:9 chips on these projectors. JVC/Sony allow to display UHD and any other 16:9 media in their native 16:9 AR by just NOT turning on the unused pixels on each side so using a 1.33x lens on a 17:9 projector also works.

BTW, can you use that 1.42x lens on a native 16:9 projector...YES! But the expanded image will be the wrong aspect ratio and it will look weird. It's simple math.
 

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Discussion Starter · #5 ·
Runco sold that lens for two different chips (4:3 AND 5:4) and neither is a proper ratio to fit a 16:9 image so the 1.42x expansion gives both those chips a correct aspect ratio for 16:9 (AR) but BOTH will crop a bit off the top/bottom to fit the 16:9 AR without any distortion.

The correct expansion magnification for a native 16:9 chip (either 1920x1080 or 1280x720..etc) is 1.33x. The newer JVC/Sony projectors are actually 4096x2160 (17:9) therefore you need a 1.25x lens (DCR or ISCO DLP Cinema) to properly show scope using the full 17:9 chips on these projectors. JVC/Sony allow to display UHD and any other 16:9 media in their native 16:9 AR by just NOT turning on the unused pixels on each side so using a 1.33x lens on a 17:9 projector also works.

BTW, can you use that 1.42x lens on a native 16:9 projector...YES! But the expanded image will be the wrong aspect ratio and it will look weird. It's simple math.
Thanks again for the reply and for helping me understand. I do not mean to be dense but I still don't understand why expansion from 4:3 to 16:9 needs 1.42x instead of 1.33x. I'm sure my math is wrong, here's what I got:

4:3 = 12:9
12 * x = 16 (since the lens is used to expand 12:9 to 16:9)
x = 1.33

Thus, the expansion needed to go from 4:3 to 16:9 is the same as that going from 16:9 to 2.35, namely, 1.33x.

I'm sure there's just something obvious I'm not getting.
 

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Thanks again for the reply and for helping me understand. I do not mean to be dense but I still don't understand why expansion from 4:3 to 16:9 needs 1.42x instead of 1.33x. I'm sure my math is wrong, here's what I got:

4:3 = 12:9
12 * x = 16 (since the lens is used to expand 12:9 to 16:9)
x = 1.33

Thus, the expansion needed to go from 4:3 to 16:9 is the same as that going from 16:9 to 2.35, namely, 1.33x.

I'm sure there's just something obvious I'm not getting.
For 4:3 it doesn't. But you keep missing the part that this lens was made for TWO projector chips...4:3 AND 5:4. In their infinite wisdom they decided that they would use a 1.42x for both as a happy medium to make both semi-happy.

EDIT... I hate being long winded.... Forget what the lens says in the front. This is a 1.42x lens and it will NOT work properly with a 16:9/17:9 native projector.
 
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Discussion Starter · #7 ·
For 4:3 it doesn't. But you keep missing the part that this lens was made for TWO projector chips...4:3 AND 5:4. In their infinite wisdom they decided that they would use a 1.42x for both as a happy medium to make both semi-happy.

EDIT... I hate being long winded.... Forget what the lens says in the front. This is a 1.42x lens and it will NOT work properly with a 16:9/17:9 native projector.
Now I get it. Thank you very much. I wasn't taking into account that the lens was a compromise and thus is the 1.42x.
 

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Hello guys,

I'm struggling to understand why lens that are labeled "for 4:3/5:4 to 16:9" made by Runco (labeled "Widevision") cannot be used for CIH today. I've read the discussion here and here and here but I do not understand the logic. If Runco used these for CIH anamorphic 1080p setups, why can't they be used for 1080p setups with more modern projectors? The noted thread claims the lens are not the correct stretch ration (1.42x instead of 1.33x) but again, how would Runco themselves use it on a 16:9 projector for 2.35 if that were the case? Or is the argument that the lenses are just not very good? Note, I am not referring to the Runco lens that are clearly just ISCO III clones but to the ones with the "4:3/5:4 to 16:9" label noted above and in the picture below. Thanks!

View attachment 3144329
You can use this lens with a 16x9 projector if you are willing to install a 2.50:1 (really 2.55:1 would be ideal) screen and you use an HTPC or scaler that supports custom settings. 1.77 x 1.42 = a projected AR of 2.5134:1.

Don't let anyone tell you otherwise, just because the solution is slightly non-standard or the implementation is a little more difficult.

I use 1.5x anamorphic lenses in my HT with a 2.76:1 curved screen and that gives me the advantage of no top or bottom black bars on 2.55:1 and 2.76:1 blu ray titles as well as fully supporting any and all lesser aspect ratios.
I use a JVC RS-57 projector with an RS-35 for backup and less critical sources..

I found them years ago in a Dallas surplus store that bought a bunch of stuff from TI. I suspect they were used as prototypes for early digital cinema development.

Here is an example from a 2.76:1 source.
3144386


and the lens:
3144388


I use Zoom Player with LAV Filters and MadVR which allows custom settings to correct to square pixels, regardless of the horzontal expansion factor of the lens. Other Directshow based players that support custom scaling such as MPC, or JRiver allow you to do the same thing.

Granted, 2.40:1 sources don't quite fill the full width of the screen, but in a true CIH setup, neither do 2.20:1, 2.00:1, 1.85:1, or 1.77:1 sources.

So, if you are willing to do things in a slightly non-standard way and you can get one of these lenses at a reasonable price, go for it!

These lenses are NOT a compromise and will likely out-perform most other anamorphic lenses if you have a reasonable throw distance. My throw is 12' and the astigmatism adjustment is at one end of it's adjustment range.

They easily resolve a single pixel wide cross hatch pattern over the entire screen area.
 

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Discussion Starter · #9 ·
You can use this lens with a 16x9 projector if you are willing to install a 2.50:1 (really 2.55:1 would be ideal) screen and you use an HTPC or scaler that supports custom settings.

Don't let anyone tell you otherwise, just because the solution is slightly non-standard or the implementation is a little more difficult.

I use 1.5x anamorphic lenses in my HT with a 2.76:1 curved screen and that gives me the advantage of no top or bottom black bars on 2.55:1 and 2.76:1 blu ray titles as well as fully supporting any and all lesser aspect ratios.
I use a JVC RS-57 projector with an RS-35 for backup and less critical sources..

I found them years ago in a Dallas surplus store that bought a bunch of stuff from TI. I suspect they were used as prototypes for early digital cinema development.

Here is an example from a 2.76:1 source.
View attachment 3144386

and the lens:
View attachment 3144388

I use Zoom Player with LAV Filters and MadVR which allows custom settings to correct to square pixels, regardless of the horzontal expansion factor of the lens. Other Directshow based players that support custom scaling such as MPC, or JRiver allow you to do the same thing.

Granted, 2.40:1 sources don't quite fill the full width of the screen, but in a true CIH setup, neither do 2.20:1, 2.00:1, 1.85:1, or 1.77:1 sources.

So, if you are willing to do things in a slightly non-standard way and you can get one of these lenses at a reasonable price, go for it!

These lenses are NOT a compromise and will likely out-perform most other anamorphic lenses if you have a reasonable throw distance. My throw is 12' and the astigmatism adjustment is at one end of it's adjustment range.
Thanks for the explanation. My throw is also 12' so it'd be very similar to yours. I watch 95% 2.35 films and the rest 5% are 16:9/1.85, so having those films not fill the entirety of the screen would be a pretty big compromise for me. However, it is good to know that the lens quality of these is high and that it would be a sharp picture, I was a bit concerned about that. I do use mostly an HTPC with JRiver, so doing this would be reasonably easy, it is just that almost all my sources are 2.35. I've never watch 2.4+ film (although I know they're out there). Your particular lens is quite large, much bigger than the one that I was considering but I think your point is the same.
 

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I have 75 2.55:1 titles in my collection and about 15 2.76:1 titles. The most current 2.55:1 title is La La Land, but most are from the early to mid '50s when 2.55:1 was a common aspect ratio used for 4 track mag CinemaScope prints.
 
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