DP70 Head Serial # 806 - History Questions

[Henry Atkinson]

Henry...Here are some pictures of the Westate's Machines...

Thanks so much for the pics! I think the head shown there is the one we have - the blanking plate we have where the mag head belongs also has no holes in it or anything mounted to it (its currently installed in 806 after this machine replaced it). When we got it, it had no optical head and only had the 35mm gate (no swap kit box). Any idea what its serial number was? in70 doesn't seem to have Westate catalogued.

Also, tangentially related - very funny to see another Big Sky lamphouse on it. We currently have L3000s - looking to replace them with Kinoton Universals - but I find it very funny that 806 got to us to wind up with a similar Christie lamphouse to what it was last used with for Borealis... and that this one got to us and wound up with another Big Sky.

[Mark Gulbrandsen]

I'm glad the pictures were able to help. That is also the projector they opened the gate on while it was running. On the L3000's, they were actually a pretty good bang for the Buck, but the 8 Plex only ran 35mm. At first there was an arc over issue with those lamps when the lamp was struck. But Big Sky sent out fixes for them, however I don't remember what the fix was. Plus far as I know, Big Sky is kaput as far as parts go. On 806, that might be the lamphouse used at Borealis. 007 retrofitted in a Kneisley reflector as per Louis Bornwasser in Louisville. The flat plate was put in machines that had SRD readers on top. That's about all that comes to mind for now. Am glad that these machines live on.

[Henry Atkinson]

I'm glad the pictures were able to help. That is also the projector they opened the gate on while it was running. On the L3000's, they were actually a pretty good bang for the Buck, but the 8 Plex only ran 35mm. At first there was an arc over issue with those lamps when the lamp was struck. But Big Sky sent out fixes for them, however I don't remember what the fix was. Plus far as I know, Big Sky is kaput as far as parts go. On 806, that might be the lamphouse used at Borealis. 007 retrofitted in a Kneisley reflector as per Louis Bornwasser in Louisville. The flat plate was put in machines that had SRD readers on top. That's about all that comes to mind for now. Am glad that these machines live on.

That projector suffered another booth monkey gate-open-while-running shutter crash incident in 2020 (before I got here, but documented here on FT) which also resulted in thousands of dollars in damages. BLS fixed that one for us, and knock one wood, I think we've now instilled into people to not do that. A lesson learned the hard way unfortunately.

Correction above - that was a different incident with the same machine, there was another before that which consumed a shutter drive fiber gear and involved a BLS call - still ironic that this was the same machine - I see now you even mentioned the 8 Plex in that thread. Maybe its cursed?

That being said, I'm quite happy to know the origins of all 3 of our machines now - your knowledge is hugely appreciated. 806 being just spares makes me a bit sad since it has a much more interesting history, but having spent more hours than I could hope to count getting both of our machines into perfect order, I'm not over-keen on swapping the heads out right now. 873 and 1642 (assuming as much) carry on. 806 carries on in bits and pieces - most visibly that beautiful blue door. They're probably going to be here until this building comes down.

Big Sky has been a mixed bag for us - they were pretty cheap, but they got installed here in 2020 (bought used in 2015 then sat around for 5 years). It became urgent as our Christie's were suffering from the asbestos-flaking issue. For 35mm, I'd imagine they're fine. Ours have new reflectors in them (via BLS), and as a "projection light source," they're fine.

However... they're really not designed with 70mm in mind, and they get hot. Going between 35mm and 70mm lamp focus causes other adjustments to drift and require constant adjustment. We are running 2 kW lamps right now, and the lamphouses get pretty warm to the touch (apparently 3kW before I got here and actual burn hazard) - I doubt that you can actually pull anything close to 300 CFM through those louvers in them (we have an exhaust fan on each lamphouse plus a bigger in-duct exhaust for the booth system). I'm considering adding an intake fan on top, but don't really want to go through that hassle until the bulbs need to be out for another reason. I've also CADed up a bracket for heatglass, but need to do some math on how much that's going to hurt airflow - there's not a ton of space in there, and it would all but totally block the snood airflow-wise in order to cover the entire 70mm aperture while being slightly angled.

If we could get a pair of Kinoton Universals (in the low-power trim) or Strong Super 80s, that is my end-game over spending a bunch of time trying to bodge these into something more suited to our use case. I'd really like heat glass (especially as we look at screening more archival prints - I'd like to not cook any) and a beam expander (or focus mechanism that doesn't cause everything else to go out of whack) would be huge as we swap gauges very frequently. I'd also like our lamphouses to not be burn hazards - 2kW is a bit hot for our screen, but that's what we are stuck with bulb-wise at the moment. Under-running as far as we can go without causing lamp flicker, and its still too bright.

[Mark Gulbrandsen]

Henry, I remember that other thread after reading the posts... Pretty amazing how all this connected together, and was happy to help out.

[Ryan Gallagher]

If we could get a pair of Kinoton Universals (in the low-power trim) or Strong Super 80s, that is my end-game over spending a bunch of time trying to bodge these into something more suited to our use case. I'd really like heat glass (especially as we look at screening more archival prints - I'd like to not cook any) and a beam expander (or focus mechanism that doesn't cause everything else to go out of whack) would be huge as we swap gauges very frequently. I'd also like our lamphouses to not be burn hazards - 2kW is a bit hot for our screen, but that's what we are stuck with bulb-wise at the moment. Under-running as far as we can go without causing lamp flicker, and its still too bright.

Our Super 80s have 4k lamps and stay relatively comfortable to the touch with a shared exhaust blower on the roof. We still have our spreader lenses but they are even harder to come by, and i'm told introduce other undesirable image issues when compared to houses that get reconfigured for 70 other in other ways. I'll see for myself this summer when we finally run 70 again after a long hiatus.

If anyone knows the Super 80 reflector working distance for 70mm when not using the spreader, I'd love to experiment with A to B comparison one day. Manual says 34in working distance for 35mm.

As for turning the lamp down, part of me would wonder about experimenting with a photo-grade ND filter beyond the lens... might get too hot and just shatter, but that would be one way to cut some lumens if you are overpowered and can't go any lower on the lamp.

[Steve Guttag]

I doubt you'll find a 70mm working distance for the Super/Ultra-80. Since strong had a beam spreader option, they wouldn't want to provide two working distances as people will get it wrong (use a beam spreader and the working distance difference.

That said, you do not need them to give you the distance. Set it up normally...run 35mm and ensure that the focus of the lamp is dialed in. then, switch to 70mm and do NOT touch the lamp focus and move the lamphouse forward (towards the projector) until the spot evenly fills the aperture. Note, you'll have a lateral offset, due to the soundtrack...so you'll need to optimize on one or the other and spill a bit more on the aperture/heat shields for "the other" format. The optics of the reflector are the optics of the reflector...what you are trying to adjust is where the film plane cuts through the cone of light coming from the lamphouse.

Beam spreaders are single-element cylindrical lenses. As such, they create an oval out of the circle...which does not precisely fit the rectangle of the 70mm aperture...and the .1" offset of the soundtrack is also still an issue between the two formats.

[Ryan Gallagher]

I doubt you'll find a 70mm working distance for the Super/Ultra-80. Since strong had a beam spreader option, they wouldn't want to provide two working distances as people will get it wrong (use a beam spreader and the working distance difference.

That said, you do not need them to give you the distance. Set it up normally...run 35mm and ensure that the focus of the lamp is dialed in. then, switch to 70mm and do NOT touch the lamp focus and move the lamphouse forward (towards the projector) until the spot evenly fills the aperture.

Thanks, I gathered this was the mechanism if not using the spreader. I was just curious about the distance if anyone knew it ahead cause I could determine if our Z adjustment lead screws on the Brenkert mount has enough travel to enable that, or if it would mean sliding the lamphouse itself on the mount (more complex and risks needing realignment). If they did have enough travel to enable that but were already using half of it, It might be motivation for me to slide the lamphouse and sled relationship to give me that travel for future testing and repeatability in format changeovers.

Brad had previously sent me a christie diagram (L being the value in question), based on that I would not expect it to be more than 1.5 inches on the Super80 if the manual WD of 34in is to be believed.

(But I didn't mean to hijack this thread with more alignment topics). ;-)

[Steve Guttag]

How did you come up with 1.5"? Even on the Christie, where they state the number, it is over 2" Since the reflectors are different, their working distances will be different and you cannot just scale one to the other.

[Ryan Gallagher]

How did you come up with 1.5"? Even on the Christie, where they state the number, it is over 2" Since the reflectors are different, their working distances will be different and you cannot just scale one to the other.

Sorry, I was mis-reading and failing at addition. Yeah just over 2in on the christie... so between 2 and 3 perhaps on the Super80 maybe?

[Mark Gulbrandsen]

At one location after the 35 and 70mm positions were determined, I put a mark on the operators side of the lamphouse foot, and two marks on the pedestal lamphouse table for 35mm, and 70mm.This made it very easy to get almost spot on. Sometimes no extra adjustments were necessary, and if there were, they were just minor touch ups. I've never used a beam spreader on Super, or Ultra 80's.

[Ryan Gallagher]

At one location after the 35 and 70mm positions were determined, I put a mark on the operators side of the lamphouse foot, and two marks on the pedestal lamphouse table for 35mm, and 70mm.This made it very easy to get almost spot on. Sometimes no extra adjustments were necessary, and if there were, they were just minor touch ups. I've never used a beam spreader on Super, or Ultra 80's.

Thanks mark. I’m considering all options as this house has historically always used the beam spreader. I think only our snood would need modifying if we changed modes, and TBD if it is doable with one lead screw and a couple reference marks. That would be swell.

[Mark Gulbrandsen]

I would do what ever multiple operators can easily pull off. If you;re on vacation, then sliding in a beam spreader is a lot easier than moving the lamphouse. At the location I marked the alignmenton the lamp base and pedestal, it was meant to be a temporary installation back in Late 1985. Last I heard, the JJ was still in place.

[Steve Guttag]

If you check these pictures out: Indy Imax
We did retrofit a beam spreader onto a Kinoton 2-7K lamphouse to work with a Norelco AA2...it worked out pretty well. That was/is on an IMAX screen so we needed all of the light we could get.

[Mark Gulbrandsen]

If you check these pictures out: Indy Imax
We did retrofit a beam spreader onto a Kinoton 2-7K lamphouse to work with a Norelco AA2...it worked out pretty well. That was/is on an IMAX screen so we needed all of the light we could get.

I did, but didn't see any pictures of an adapted beam spreader...

[Steve Guttag]

It's hiding behind that flap between the lamphouse and the projector.