MAX 8 <-> super-duper 8 ?

[Mitch Perkins]

I just recently looked at the promo DVD of Pro8mm and especially spent attention to the Max8 transfers. Each transfer of this wider format appears to have a density shift on both sides of the screen. It is more notable on one side than on the other, but it’s definitely present on both.

I'm guessing it's more notable on the right side. This [after all the flipdidoodling of the lenses], is the non-perf side, or the side that would have held the sound stripe.

If the projector gate is widened beyond the full image area, light from the projector lamp "bleeds around" the right side edge of the film, and through the perfs. More noticeable on the negs than on reversal...as just about any little problem is.

Since the perf is only a fraction of the height of the right side edge of a given frame, less light bleeds through the left side into the image area.

I had to go back and install light "blockers" either side of the projector gate. It's a pain, because really the blockers should be flush with the film plane, or else you get darkness encroaching from the sides - this is because the blockers are out of focus [if not flush with the film plane], and therefore "feathering" into the image.

Bottom line - the projector gate must be widened to *precisely* the edge of the film on the sound strip side, and to *precisely* the inside edge of the perf on the perf side. Such precision is not required when widening the camera gate, since only the non-perf side is widened, [image usually encroaches around the perf], and the Super 8 cartridge pressure plate is black, eliminating any danger of halation.

This is not a lens vignette, but instead appears to be caused by either the camera gate or the telecine gate.

Joerg Schodl, Cinematographer, Los Angeles

Telecine gate, based on above observations. Good eye, Joerg.

Mitch

[Mitch Perkins]

"BUT... each camera lens will cast a different image. Some lenses will cover the full Super-Duper 8 frame, while others will vignette at wide-angle settings."


"thats the reason why pro8mm centers the lens which results in a better quality compared to DIY trys at home by only largen the gate?"

Regardless if the lens is recentered or not, the image circle that the lens projects on the film must be large enough to cover the extended gate area. Some lenses project larger image circles than others. The distance that a lens focusses on also affects the size of the image circle.

Most cameras will give decent results within their particular limitations/parameters. Larger front and rear diameter lenses are best. It can be difficult, though not usually impossible, to check the rear diameter. This applies to the issue of camera lens vignetting only.

For telecine, the projector must be moved from its normal position to eliminate aberration on the right side - you cannot just pan it to the right, you must move the whole projector perpendicular to the film plane, otherwise grain on the right side "flies off" with a circular directionality.
Front element diameter of the projector lens is not an issue, but a larger rear element, to better cover the larger image area, is key.

Mitch