I have just ran my first edited film through my Elmo St 180 projector. I used cement splices and these were hardly noticeable at all during projection. They all held up too which was good. The problem is that the film seems to go slightly out of focus at different points in the film and it remains out of focus until I readjust it. All the camera footage is sharply focussed from when I was shooting it.
I guess it is probably the slight difference in thickness between the splices and the rest of the film that is doing this. Although this difference in thickness is only very slight. I am thinking that the design of the projector may make it succeptible to going out of focus when using cement splices. However, I thought that a highly reputable brand like Elmo would be above this. Frustratingly, I have to keep adjusting the focus throughout the film which is a real drag for the audience. Is this common with edited films and something that many of you have to put up with?
Edited film going out of focus
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Old Uncle Barry
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8O
Your ST180 has a natural aversion to tape splices.Mine did until I played around with the gate tension.This is adjusted by a tiny cross-head screw at the base of the gate nearest to you.If you carefully trim this to the desired level of sharpness for tape splices you should have no further problems.It certainly cured mine.
On the other hand,and I mean no disrespect in this,are you sure that your tape joins are correctly made and flat at the edges of the film.This too could have an adverse effect upon projection.
Your ST180 has a natural aversion to tape splices.Mine did until I played around with the gate tension.This is adjusted by a tiny cross-head screw at the base of the gate nearest to you.If you carefully trim this to the desired level of sharpness for tape splices you should have no further problems.It certainly cured mine.
On the other hand,and I mean no disrespect in this,are you sure that your tape joins are correctly made and flat at the edges of the film.This too could have an adverse effect upon projection.
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Patrick
CEMENT SPLICES were used in the film. All filmstock was Kodachrome. I do notice one thing with this projector though. When you have just finished watching a film which was in good focus, I open up the side cover and swing the lens out to the side to clean the gate. Then after replacing the lens and the side cover and thread the next film through, sometimes this new film will be out of focus and I must refocus. Even though when opening up the side cover and swinging the lens out to the side, I am sure that I do not touch the focus knob or the zoom at all.
Whatever is causing this to happen, could possibly be related to the inconsistency of focus when using cement splices. Would you agree?
Whatever is causing this to happen, could possibly be related to the inconsistency of focus when using cement splices. Would you agree?
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MovieStuff
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I think you will find that scenes of similar densities will maintain the same focus. What I mean by that is, if you focus on a scene that is light, a dark scene that comes up next will go soft but if a light scene follows after that, it will be back in focus again.
This is a common problem with most all projectors because the darker scenes absorb more light and heat and will warp slightly in the center of the frame due to expansion. It isn't much but is enough to throw the focus off. Then when the lighter scene comes along, the film contracts back into original focus since the lighter footage doesn't absorb as much heat. Adding to this problem is the rear element of the projection lens ALSO will expand and contract, depending on the amount of light (and heat) it receives. To make matters worse, the lighter film segments allows MORE light and heat to the rear element while the darker scenes give the lens a chance to cool down, relatively speaking, until the next thermal blast during a light scene. I am surprised that movie projectors can maintain any kind of focus, actually. In fact, if you go the first showing of the day at the local movie theater, you will notice constant focus shifts as the projector warms up, since an experienced projectionist will have pre-set the focus on warm projector.
For home projection, the only method I've seen to combat this is to pre-heat the film and the projector a bit. Let the projector run with the lamp on so the gate gets nice and toasty. The film can be pre-heated by placing it in a metal can under a 60 watt lamp about 6 inches away. Even if the can gets pretty hot, it won't hurt the film because the metal of the canister acts as a heat sink and spreads the heat around quite a bit. You don't want to roast the film but the hotter it gets the better, to a point. Leave it in there a good 15 minutes or so. The longer the better if it's a long reel!
The idea is for both the gate and the film to be warm so that there is less or no unwanted expansion from one cut to the next. Assuming your projector is working properly, you should have little, if any, focus issues.
Roger
This is a common problem with most all projectors because the darker scenes absorb more light and heat and will warp slightly in the center of the frame due to expansion. It isn't much but is enough to throw the focus off. Then when the lighter scene comes along, the film contracts back into original focus since the lighter footage doesn't absorb as much heat. Adding to this problem is the rear element of the projection lens ALSO will expand and contract, depending on the amount of light (and heat) it receives. To make matters worse, the lighter film segments allows MORE light and heat to the rear element while the darker scenes give the lens a chance to cool down, relatively speaking, until the next thermal blast during a light scene. I am surprised that movie projectors can maintain any kind of focus, actually. In fact, if you go the first showing of the day at the local movie theater, you will notice constant focus shifts as the projector warms up, since an experienced projectionist will have pre-set the focus on warm projector.
For home projection, the only method I've seen to combat this is to pre-heat the film and the projector a bit. Let the projector run with the lamp on so the gate gets nice and toasty. The film can be pre-heated by placing it in a metal can under a 60 watt lamp about 6 inches away. Even if the can gets pretty hot, it won't hurt the film because the metal of the canister acts as a heat sink and spreads the heat around quite a bit. You don't want to roast the film but the hotter it gets the better, to a point. Leave it in there a good 15 minutes or so. The longer the better if it's a long reel!
The idea is for both the gate and the film to be warm so that there is less or no unwanted expansion from one cut to the next. Assuming your projector is working properly, you should have little, if any, focus issues.
Roger
after I have exchanged all gate springs of my GS1200, I have no more focus problems with Kodachrome. Problems occure only with some vingage prints. Could not recognize, that darker and lighter scenes effect the focus in any way, even when the explications sound logical. Perhaps the effect is beyond human tolerances. The expansion of the lens itself with the heat may exist also, but I think, the metal or plastic parts, that are holding gate and lens, expand much more when heated up. So the reason may be found here.
Pedro
Pedro
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David M. Leugers
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cement splices
Patrick. Cement splices will not affect the focus except for about 1/24 of a second as the splice passes through the gate. I always use cement splices on my films for projection and never suffer the effects you describe. I would bet the problem is in your projector. The focus floats whenever the slightest jiggle of the pressure plate occurs as the splice passes by. I'd recommend focusing your lens then taping it in place so that it cannot move. Project your film again and see if the problem continues. If not, your lens adjustment changes ever so slightly. If the problem continues maybe your pressure pad is sticking or weak. Hope this helps.
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Patrick
This absorption of heat from the darker scenes could be a possible cause but I have never experienced this before. The thing is, before this footage was edited, when it existed as 'rushes', there was no change of focus. This only occured after it was spliced together.
Additionally, just previous to screening the newly edited film, i projected a Cinderella cartoon and had no problems with focus at all. I have also never experienced any focus shifts with any other films either. So obviuosly, there is no problem with the projector which I only aquired a few months ago and is in almost brand new condition. Oh by the way, these changes in focus are not major but only slight - enough to be annoying though as I keep having to refocus throughout the film.
Anyway, I will also run this edited film through my Eumig 610D and see if there is any change.
Additionally, just previous to screening the newly edited film, i projected a Cinderella cartoon and had no problems with focus at all. I have also never experienced any focus shifts with any other films either. So obviuosly, there is no problem with the projector which I only aquired a few months ago and is in almost brand new condition. Oh by the way, these changes in focus are not major but only slight - enough to be annoying though as I keep having to refocus throughout the film.
Anyway, I will also run this edited film through my Eumig 610D and see if there is any change.
Maybe that the springs that hold the pressure plate in position are too weak. You can adjust them when having a spring scale, suitable for pressure measuring. The pressure at Elmo projector gates should be in the range of 60-70 g, the side pressure 30-35 g.
You can roughly check these values, using a digital kitchen scale. You fix a piece of wood on the top of the scale (tape), drill a hole into the wood and insert a wooden stick. Now you turn the projector with the open gate downwards, using some books or other support, so that the gate reaches the top of your wooden stick. Now you let the projector go down until the spings show their tension and the scale will show that tension.
The adjustment is rather critical and one of the key adjustments of any projector and should be controlled when having any focussing problems.
The heat absorption of dark scenes ir rather theoretical than realistic. Each frame is only exposed a very short time to direct radiation, much to short to allow any thermical adaption. And Elmo projectors are very cool, they have an extra lamp house, a powerful fan and a heat protection glass. The gate only becomes hand -warm!
Pedro
You can roughly check these values, using a digital kitchen scale. You fix a piece of wood on the top of the scale (tape), drill a hole into the wood and insert a wooden stick. Now you turn the projector with the open gate downwards, using some books or other support, so that the gate reaches the top of your wooden stick. Now you let the projector go down until the spings show their tension and the scale will show that tension.
The adjustment is rather critical and one of the key adjustments of any projector and should be controlled when having any focussing problems.
The heat absorption of dark scenes ir rather theoretical than realistic. Each frame is only exposed a very short time to direct radiation, much to short to allow any thermical adaption. And Elmo projectors are very cool, they have an extra lamp house, a powerful fan and a heat protection glass. The gate only becomes hand -warm!
Pedro