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Lisa CRT Alignment graticule

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sigma7:

--- Quote from: anotherLISAguy on October 10, 2024, 07:51:44 am ---I had one listed on eBay a while back and P/N 077-8043-A is on the original LISA Alignment Graticule.

--- End quote ---

First pic of the graticule that I know of -- thank you!

Is the graticule (the portion that is a transparency with markings) actually attached to that glare filter, or is it packed with a Lisa glare filter for protection/alignment?

How is it the graticule was single-use / washed away... is it some kind of transfer rather than an overlay or ... ?

anotherLISAguy:

--- Quote ---How is it the graticule was single-use / washed away... is it some kind of transfer rather than an overlay or ... ?

--- End quote ---

yep, one-time use and washed away (hot water) which explains why we don't see them much.
If memory serves me correctly, a LISA 1 manual discussed installing the glare screen, and how to align the image from inside the LISA, if needed. (so it must have been a tech manual).

Either way, should I relist it, it probably is best to include a second (regular) glare screen (for installation) to preserve this unique artifact.
<yeah, I say artifact because as L1s become available, their value will probably be critiqued by having period-correct components and accessories with them.>

Anyway, glad that helped alleviate guessing what they look like.

Take care.

sigma7:

--- Quote from: anotherLISAguy on October 10, 2024, 03:54:38 pm ---... glad that helped alleviate guessing what they look like.

--- End quote ---

If you can still find it (or run across another one), please measure the height and width of the two rectangles that bound the outline of the raster so we can determine the range --

One of the motivations for locating an original graticule is to resolve the confusion regarding the aspect ratio of the pixels.

Most references say the aspect ratio of the pixels is 2:3, but by drawing a rectangle of (720 x 2) by (364 x 3) it is clear it does not match the proportions of what we see on a Lisa screen. A theory is that the 2x3 ratio only applies to the full raster on the 12" CRT (ie. 6"x9"), and so a pixel aspect ratio of 3:4 is more likely correct.

But having seen the graticule pic, I now wonder if the aspect ratio is not defined as a whole number, but rather the size of the 720x364 raster was defined to fit nicely in the bezel and the pixel aspect ratio ends up as an arbitrary number that happens to be close to 3:4.

Thanks very much for your contributions!

anotherLISAguy:

--- Quote from: sigma7 on October 10, 2024, 04:53:28 pm ---If you can still find it (or run across another one), please measure the height and width of the two rectangles that bound the outline of the raster so we can determine the range --

--- End quote ---

I was able to measure it using a grid overlay.
The dimensions are noted in the attached image.
If the numbers aren't exact they are damn close.
Anyway, hope that helps.

NOTE: replaced PNG with letter sized PDF

sigma7:

--- Quote from: anotherLISAguy on October 16, 2024, 04:19:37 pm ---hope that helps.

--- End quote ---

Yes, it sure does!

If one selects the out edge of the raster to be near the middle of the inner/outer limits, that gives a width of 8.6" and a height of 6.4", and so 720x364 pixels are then 0.011944" Wide x 0.017582" High; a ratio of 1.472.

That's closer to 3:2 than 4:3.

Still, drawing a rectangle on a square pixel screen of 720x2 by 364x3 does not look right (to me)... I speculate that this may be because adjusting to the graticule dimensions will fill the vertical size of the viewable area of the CRT, but leave substantial unused margins at the sides.

ie. although the viewable real estate of the CRT in the bezel is close to 9" x 6" (more precisely 9.49" x 6.73"), once adjusted to the graticule, the ratio of the 8.6" x 6.4" raster is perceivably different at 1.3438.

The Lisa included so many great innovations, but the Mac's WYSIWYG display is arguably insanely great.

Many thanks for the measurements & drawing!

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