Film-Tech Forum ARCHIVE: NC 3240 lens memory

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Posted by Abraham Robinson (Member # 10230) on 01-27-2018, 02:10 PM:

The 3240 at my work has issues hitting exact lens memory settings.

I know this has been discussed previously, and that NEC's method for restoring/moving between lens settings is notoriously troublesome, something to do with the way the motor measurements are recorded and then restored? if I remember correctly. But I was wondering what can be done to improve this. The venue I work at is a multi-use theater, where the primary use is lectures / presentations throughout the week, though it does also often function as a traditional cinema space.

I have noticed some occasional focus drift, but the more frequent issue seems to be with position/zoom. I have also noticed that simply pressing the same preset button again for a second (or third) time will restore the intended position setting. For example, I'll switch from a 16:9 DVI setting to a 1.85 DCP and the position is close, but not correct. If I push that same 1.85 DCP preset button again a second time the projector will make the slight zoom/position adjustment to hit the exact spot.

Or the most common example would be after a power-up, the projector loads the last preset it was on before being shut down, which is most often the standard 16:9 DVI. Again the image will be close, but not correct, after pushing that same preset button a 2-3 times (each time it making a slight change), it will hit the exact screen position it was on the last time it was used.

Typically there's enough time to make these adjustments to not affect the show, but we are coming up on a large cinema series where I will be constantly be switching between the DVI input for pre-show slides, and the flat/scope DCP settings, and I am concerned that the switch may not land exactly!

Thanks for any help!

Posted by Leo Enticknap (Member # 534) on 01-28-2018, 10:43 AM:

Mark Gulbrandsen commented in another post that this seems to be more of a problem with some models of lens than with others. Removing, cleaning, and reseating the lens can't hurt. Be careful disconnecting, though - it's easy to damage the connector (not like Barco lenses, which are almost impossible to damage when removing or reseating, unless you try to pull them out without retracting the clamp lever).

Also, ensuring that the projector is clamped to the pedestal, and that the pedestal is bolted to the floor, should help things. If either are held in place just by gravity, they will vibrate and move over time.

The only other thing I can suggest is to check that the lens positions for flat and scope are as close to the center of the lens shift as you can get (look in the lens to see where the beam is), in both directions; and to move the projector (or adjust its rake) as necessary to enable that. I spent three years working in a theater with a 3240, and found that doing this helped the lens wander a lot. But I couldn't totally eliminate it.

Posted by Abraham Robinson (Member # 10230) on 01-29-2018, 08:14 PM:

Thanks Leo, I remember seeing Mark's post.

I also thought I remember seeing a post saying that this issue gets worse over time, and that there is a way to reset to the initial lens setting which could help.

I'm going to try building some new presets this week to see if that alleviates the issue. I haven't tested extensively but it does seem like the issue is happening the most when switching into our most commonly used presets: a 16:9 DVI, and another 16:9 DVI preset with a much smaller screen-setting (to project over seated-head height for on-stage panels discussions).

I "think" the issue happens less frequently when switching into the flat/scope dcp presets (which are much less commonly used in our theater), but it could very well be that the issue is now more prevalent in-general, and that because it has been a few months since we showed a lot of dcp content I havent noticed.

Anyway any suggestions very appreciated,