Barco lens adapter

[Allan Barnes]

Does BARCO have a LENS ADAPTER so I can use the lens from my Barco 1500 / 2000 / 20c on a Barco 23B ?

[Jerry Bian]

As far as I know, there is currently no second-generation projector B series to C series lens conversion bracket available in Barco
Only the fourth generation projector B-series and C-series lens conversion brackets or NEC and Christie conversion Barco brackets are available for sale

[Steve Guttag]

S4 "C" style projectors can be ordered with either a B or C lens mount (they do not offer a conversion kit but likely one could mount the other lens mount however the "R" type of the projector make prohibit utilizing it.

Onto the question...no you cannot use a "C" lens on a "B" projector. You have a completely wrong back focus (lens to prism exit) combined with an inlet pupil that likely would vignette the larger imager or have an extremely restricted shift range due to the inlet pupil. Additionally, you would have to do the math on the magnification because throw-ratio has that cooked in. Throw Ratios only make sense when the imager size is known.

The reason they can offer "B" lenses for their SP4K-C projectors is that they also have a suitable lens adapter that corrects the back-focus issue and the larger inlet pupil only helps the lens shift situation as they can offer 110% vertical shift (and a similarly increased horizontal shift). They have also done the Throw Ratio conversion (in their documents, not on the lens itself). But you can't go in the reverse (C-lens into a "B").

[Allan Barnes]

Thank You, Steve & Jerry. To quote that TV show "You know I learned something today."

[Leo Enticknap]

In short, you'd be trying to use a lens that was designed to magnify the image produced by a .98" chip (DP2K-xxC) to magnify the much bigger image from a 1.38" chip (DPxK-xxB). The distance between the light engine's prism and the rear element of the lens would magnify that image such that it was bigger than that rear element, hence the vignetting. Plus, an adapter would likely increase that distance even further, thereby exacerbating the problem.

In reverse, however, not only is it doable, but the image hitting a smaller area of the larger lens would improve the picture quality, because it would be magnified through the less convex part. It's the same principle whereby some hobbyists built brackets onto the front of their 16mm projectors on which to mount prime lenses designed for 35mm projection, to improve the picture quality.

S4 "C" style projectors can be ordered with either a B or C lens mount (they do not offer a conversion kit but likely one could mount the other lens mount however the "R" type of the projector make prohibit utilizing it.

When I took the Barco S4 level 2 class, the instructor told us that while it was theoretically possible to swap a projector between the two models of lens holders in the field, Barco do not recommend trying to do so, because adjustments to the optics of the light engine are needed to optimize its output for one or the other. So SP4K-C projectors ship from the factory with the light engine tuned up for either B or C lenses.

[Elia Orselli]

Barco do not recommend trying to do so, because adjustments to the optics of the light engine are needed to optimize its output for one or the other.

Moreover, as Steve said, the sim card will not allow the different lensholder to work at all

[Steve Guttag]

I don't think that the lens holder is the big stumbling block on the swap, with respect to the projector's software...it is that the B lenses will likely not show up in the selection list so it will not know how to move the motors (including that older B-lenses don't have a focus and use the lens mount to focus while later B lenses center the lens mount's z-axis and focus within the lens like a "C" lens).

I'd have to check to see if the B lenses show up. My guess is not. The same way, in a series 2 projector, the 15C and 20C are the same projector but the R number of the projector precludes running a 4KW lamp in a 15C (the same is true for the 19B versus 23B). The projector's R number defines what it is capable of doing.

[EDIT: I just checked, and the "B" lenses are not offered within the software when running on a "C" lens mount SP4K-C projector. So, even if you changed the lens mounts, the projector won't offer you the lenses to use/calibrate]

[Elia Orselli]

I meant that (as we were told at the training): it's technically possible to swap the two lens holder on a projector and find a way to align them properly, but the sim card that give the PN and SN to the unit will accept only a specific lens holder model. Same thing happens with other parts, like laser plates: you can connect a different laser plate, like one with more laser banks, but the system will recognize that it's not approved for that projector model and it will not work.

[Leo Enticknap]

I wasn't told that at the S4 L2 training I did, though I remember the SIM card being covered for S2 (specifically, the importance of remembering to swap it when replacing the backplane). We were definitely told in the S4 class that changing the lens holder for the other type in the field was possible but not recommended, because of the alignment of light engine components. I would speculate, therefore, that if you insist on doing this in the field, Barco would supply a new card along with the lens holder, programmed for the other type.

IIRC, the actual replacement of the lens holder is a bit more fiddly in an SP4K-C than it is in a Series 2 projector, but not hugely so. What really takes the time and attention is resetting the back focus and Scheimpflug after you've done it.