Film-Tech Forum ARCHIVE: Can a person be "Focus Blind"?

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Posted by Randy Stankey (Member # 64) on 03-23-2003, 08:40 AM:

Hypothetical question: Can a person who has otherwise good vision have the inability to tell when an image is in proper focus?

When asked to focus the projector running RP-40 test film, this hypothetical person would be able to quickly get it right almost every time, in less than a second.

When asked to focus a real-life picutre... a movie, a trailer, even the credits at the end of a film... the person would not only be unable to get the picture right but would often not able to even tell whether the picture is in forcus or not.

I would be able to holler up to the booth from downstairs (or call on the phone) and say, "Check your picture". The answer would be "What do you mean?"

OR... Maybe I'm being to hard on this hypothetical person? Do yo think I could be so demanding that the person is afraid to do anything on their own and waits for me to say that the picture needs "touching up"?

Posted by Mike Fitzgerald (Member # 1304) on 03-23-2003, 08:51 AM:

Years ago back in the early 70's I was the projectioinist at a local drive-in. The manager kept telling me that it was out of focus, to me it looked ok. What I found was that I needed glasses, but it was a very minor correction and it only showed up when all the lights were out. So when the booth was totally dark I could not focus properly. During the setup I had the lights on in the booth and I had no problem.

Posted by Bill Langfield (Member # 818) on 03-23-2003, 09:48 AM:

Focus blind?

Yup, when well and truly hung-over. I hate that.

I've never tested it, but I can imagine it would easy to focus the RP-40, but the depth of field focusing of an actual picture would be harder.

Perhaps your mystery person is in fact 'hung over' or on a drug??

Bill.

Posted by Charles Everett (Member # 889) on 03-23-2003, 10:22 AM:

Princeton Garden Theatre yesterday: I'm the first patron in for the 5 PM show of Spider. The usher has made adjustments to the projector that handles the preshow slides. He comes out of the booth and asks me if the slides are in focus. I more or less demurred -- the lights were up full.

Posted by Bernie Anderson Jr (Member # 410) on 03-23-2003, 11:12 AM:

Well, I know myself, that when I'm at the Loew's Jersey with a 180 foot through from the booth 5 floors up I can't focus the picture. I use binoculars to get up to the image for help. Most of the time there's someone in the audience on a two way with me to tell me if it drifts or not. Especially, if we're running an IB Tech print. They tend to drift sometimes. What I was always told was to look for the grain of the film. Now with the newer Vision and Vision 2 stock it's getting harder to see the grain but it's always been helpful to focus the grain. If you can see it, then you're usually right on the money. With faded prints and IBs sometimes you can't focus them. Early IB widescreen (Vista Vision and C-Scope) prints had issues with sharpness so they'll never look like they're in focus. "White Christmas" and "Knights of the Round Table" suffer from this.

Posted by Manny Knowles (Member # 1171) on 03-23-2003, 12:05 PM:

I will never forget the first time I saw a movie after I got my first pair of glasses. Up to that point, I thought movies were a little fuzzy and there was nothing anybody could do about it. I was about 18-20 years old and I got a little bit emotional about wondering just how many movies I hadn't truly seen. I think the movie I saw was THE DOORS but I could be wrong -- I was so distracted by the clarity! I kept taking my glasses off and putting them back on again.

To answer your question, Randy...

Yes I know this is possible because I can focus RP40 without my glasses. It takes a little longer without glasses but I can focus until it looks "as sharp as possible." It's all relative; even without my glasses I can still track the effects of moving through focus...the image getting gradually and comparatively worse when I've gone too far in either direction.

An actual movie is another matter, especially if the target isn't holding still. Also, it isn't always obvious what's supposed to be in focus from what isn't. If they are in motion, credits aren't that easy for me without my glasses. Stationary credits aren't that much trouble, though.

Posted by Paul Mayer (Member # 355) on 03-23-2003, 12:12 PM:

I seem to run into that myself more often these days--being able to focus quickly on RP40 or focus leaders and not so quickly on real-world stuff (especially today's trailers--so soft!).

I used to work with a TV cameraman who was notorious for always being soft on focus. The ADs would call "x, check your focus" so much that we in video would try to help the guy out, iso'ing his headset momentarily so we could tell him to check focus without the whole production PL hearing it. It didn't work--the guy would consistently rock through focus and just miss it. It finally got to the point where a famous sports director we routinely worked with called out during a shoot "Quick! Take x, he's in focus!" AFAIK the guy doesn't work as a cameraman any more--the free-lance world is merciless.

Posted by Gunnar Johansson (Member # 1661) on 03-23-2003, 12:40 PM:

I know of the people I work with where some of them take a longer time of telling if it is in focus, and finding the right focus. A lot of help for us, though, is that Sweden has subtitles for all foreign movies, and when you can focus with the white subtitles, which are mostly visible, it gets a lot easier, and you don´t have to think as much on what´s supposed to be in focus.
Maybe it could be a trainging/routine thing. Knowing what to look for, what it´s suppose to look like, not be to afraid of trying, and having pretty good vision or glasses. Me? I got glasses and am still learning.
Manny: For me it was noticing that you could see separate grass straws and leaves on trees, but it was still a mindblowing experience.

//Gunnar

Posted by Christian Appelt (Member # 1067) on 03-23-2003, 03:17 PM:

As for those who have good vision, I would say there are some people who are simplys insecure about focusing. I worked with a fellow who always used to ask "Hey, take a look on the screen, you think it`s sharp?"
It always was, but the strange thing is that he never used the binoculars to make focusing easier. With older prints and changeover operation, I always used them because focus might change between reels.

So to answer your question, no, I don`t think there is a physical reason for "focus blindness", but a psychological problem. You know, that kind of nagging, uncertain feeling like "Hm, did I leave the door unlocked?" [Roll Eyes]

Posted by Paul G. Thompson (Member # 655) on 03-23-2003, 04:11 PM:

Focus blindness? If the person's eyesight is otherwise good with or without the need to wear corrective lenses, many simply do not know what to focus on. I think that is the problem.

I will admit dark scenes and fast action scenes can be very difficult to initially focus.

Posted by William Bunch (Member # 1040) on 03-23-2003, 08:16 PM:

Focus blindness. I see it all the time. My students will get perfect scores on everything else, then when its time to show a performance the whole thing is out of focus.

Because we are all on changeover systems here there is a real need for checking focus between the National Anthem, trailers and second reel of the feateure. I stress it and explain the need.

I teach them to focus on credits, brick walls or on foiliage or the twill in an actor's clothing. Also teach them how to rock back and forth to "catch the center" quickly.

But when I call up to the booth for them to check focus the answer is always "I don't see what you mean". Only a very few get it right every time without being prompted.

Maybe it's the TV generation. Just used to seeing fuzzy pictures.

Someone could make a ton of money by inventing a system to automatically focus the lenses by using a digitized camera pointed at the screen. Much like AF on a camcorder. Or is that even possible?

Bill BuncH
Misawa, Japan

Posted by John Pytlak (Member # 331) on 03-23-2003, 08:19 PM:

Many used to focus on the grain, but a well-exposed film today often has such fine grain that it is difficult to see. [Cool]

There was a system that used a digital camera and fast-Fourier analysis of the image to focus the projector automatically. I recall it was sold by a company in Sweden.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-23-2003, 08:24 PM:

Auto-focusers are available but they generally don't work that well -- especially with scope films. I usually disable them.

Posted by Randy Stankey (Member # 64) on 03-23-2003, 11:36 PM:

I try to tell people to sort of focus their vision on a fixed position at the center of the screen and focus just that one spot but I think the movement of the characters/images on the screen tends to pull one's attention away from the critcal area.

I think it just takes time to develop the "eye" for it.
The thing is... **I** get in trouble when other people don't get things right! Yes, I agree that I'm supposed to teach people how to do things correctly but I think the boss has unrealistic expectations.

I have focused and refocused THOUSANDS of projectors. To me, it's second nature. I don't even think about it. It just happens. We show a couple dozen movies every year. I can't expect a student to learn everything all at once, only working a few hours a week.

It's just that I have never met a student who has THIS much trouble. I KNOW it just takes some people more time to develop the eye. Then, I get frustrated and lose my patience with people. I'm afraid that part of the problem is my fault because, like I said before, I make them "gunshy" when I holler and they are scared to touch anything.

I think I'm just going to have to get people to go up to the booth and run some old trailers for practice... Thread - Start - Focus... Thread - Start - Focus... Thread - Start - Focus... Over and over until the concept starts to sink in.

Posted by Elena N. Solovyova (Member # 1636) on 03-24-2003, 01:22 AM:

The people with astigmatism may have a lot of trouble with focusing, even with proper eyeglasses/ contacts.

Posted by Carl Martin (Member # 1146) on 03-25-2003, 05:09 PM:

we have keystoning to a greater or lesser extent on all 3 screens. this can actually aid in focussing, if there is a noticeable focus "gradient" across the screen. eg, in #2, if i see the right side of the screen is in focus but the left is soft, i know to turn the focus knob clockwise until the focus is optimized at the center (in which case the sides normally look ok). to do this i need to look at the screen holistically, so binoculars would be a hindrance.

we have in each booth a very cheap monocular which i don't use for the above reason, and also because it's simply too hard to hold steady enough, and the shitty optics result in color separation like from a prism which is hard to distinguish from poor focus.

carl