My turn to beat on the 2.37 vs 2.35 vs 2.40 discussion w/ a 1.33x lens - AVS Forum
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post #1 of 6 Old 05-30-2012, 08:55 AM - Thread Starter
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I know that this is not a make or break deal for CIHand typing this out makes me realize more that they all will work fine..but here we go

Ok if I use an ISCO IIIs 1.33x lens and a CIH set up.that's a 2.37?

So no matter the content (assuming I want true CIHno zoom adjustment for each format) I'm physically bound by a 1.78 image chip and a lens that expands 1.33x.

1.78 chip X 1.33 lens = 2.37 projected image


If I'm looking at a 53 tall screen my math tells me this:
2.35 = 124.55 wide
2.37 = 125.60 wide
2.40 = 127.20 wide

So 2.37..or go with a 2.35 and spill .5 on each side?

It seems like a 2.40 screen is just setting up to have very very small black bars on the side or the need to spill a very small bit on top and bottom.

Am I missing anything?


Lastly at a 2.15 TR how much pincushion will I have?

Thanks!!!

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post #2 of 6 Old 05-31-2012, 02:33 AM
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post #3 of 6 Old 05-31-2012, 02:35 AM
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Quote:
Originally Posted by Yzfbossman View Post

Ok if I use an ISCO IIIs 1.33x lens and a CIH set up….that’s a 2.37?

Yes, but in theory only.

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Originally Posted by Yzfbossman View Post

Am I missing anything?

All anamorphic lenses and adapters will introduce a degree (small as it may be) of grid distortion. So pending how much, the said 2.37 image may actually be 2.40 or wider when measured. GD is also made worse with shorter throw ratios (as is Pincushion Distortion).

Will you project into a flat screen or a curved screen? A curved screen optically compresses the image (to a very small degree) which may assist to cancel out grid distortion.

When I curved my screen, the goal was just to correct pincushion, but as it turns out, it also helps with GD and even though my lens has multi-aspheric ground glass lenses (technically they are ground to correct for GD), there is still going to be some GD when projected onto a flat screen. There is none on my curved screen.

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post #4 of 6 Old 05-31-2012, 07:38 AM - Thread Starter
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Quote:
Originally Posted by CAVX View Post

Yes, but in theory only.

I thought that might be the casemore than two variables

Quote:
Originally Posted by CAVX View Post

All anamorphic lenses and adapters will introduce a degree (small as it may be) of grid distortion. So pending how much, the said 2.37 image may actually be 2.40 or wider when measured. GD is also made worse with shorter throw ratios (as is Pincushion Distortion).

Will you project into a flat screen or a curved screen? A curved screen optically compresses the image (to a very small degree) which may assist to cancel out grid distortion.

When I curved my screen, the goal was just to correct pincushion, but as it turns out, it also helps with GD and even though my lens has multi-aspheric ground glass lenses (technically they are ground to correct for GD), there is still going to be some GD when projected onto a flat screen. There is none on my curved screen.

I just got my used ISCO IIIs & Cineslide in yesterday! so my set up *as of now* (all is subject to change) will be Epson 6010 to ISCO IIIs to flat AT 53 high micro perf 1.3 screen. My TR is 2.20

Will my long TR help the pincushion and GD? Also any guess on what that does to the aspect ratio?

Thanks for all your input into the forum Mark!

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post #5 of 6 Old 05-31-2012, 03:23 PM
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Quote:
Originally Posted by Yzfbossman View Post

I thought that might be the casemore than two variables

It wasn't that long ago when we were all concerned about CA and Astigmatism. Of course with a properly ground glass lens like the ISCO III (or my MK5), these issues are no longer a concern. Yet even with the best in optics, we seem to need to find something wrong - hence Grid Distortion.

Quote:
Originally Posted by Yzfbossman View Post

I just got my used ISCO IIIs & Cineslide in yesterday! so my set up *as of now* (all is subject to change) will be Epson 6010 to ISCO IIIs to flat AT 53 high micro perf 1.3 screen. My TR is 2.20

Will my long TR help the pincushion and GD? Also any guess on what that does to the aspect ratio?

Thanks for all your input into the forum Mark!

Congrats on the purchase. It is a great combo and will serve you well, regardless of how many projectors you upgrade.

You will still have pincushion and GD, but the amounts will be so small that I doubt you will see any signs of this in actual video program. Load test patterns and I am sure you will see something.

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post #6 of 6 Old 05-31-2012, 05:38 PM - Thread Starter
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Thanks Mark!

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