8mm Forum: How Do I Modify ST-1200 For More Light?

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Topic: How Do I Modify ST-1200 For More Light?

Jan Bister
Darth 8mm

Posts: 2629
From: Ohio, USA
Registered: Jan 2005

posted February 03, 2005 11:33 AM

I must confess that when I read Joe's post wondering about why Elmo etc. didn't incorporate features such as the 2-blade shutter into their designs, I'm glad nobody did... the increased light output vs. a 3-blade shutter is certainly nothing to scoff at, but I wonder if I'm the only one who would be bothered by the reduced amount of light/dark cycles per second? ... Am I? [Confused]

Here's the thing - I grew up in Germany (moved to the States about 9 years ago) so I was always accustomed to watching PAL TV with 50 fps... and I always noticed some flicker as well, though at the time I didn't think it was all that bad! Fast-forward a few years, and suddenly I'm watching NTSC TV at 60fps and I'm simply stunned at the difference that an extra 10 light/dark cycles make in providing a much steadier picture with less flickering... so easy on the eyes, I can almost understand why Americans are such TV junkies. [Big Grin]

Since then I've been back to Germany to visit my parents, and believe it or not, I cannot watch PAL TV anymore without getting a headache after a while... an hour at most, maybe.

But before I digress... one of the reasons I love film is, you have a rock-steady projection image with 72 light/dark cycles per second (at 24fps), and that's all the more important since the picture is so large vs. a TV screen. Now, going back to a 2-blade shutter and putting up with only 48 cycles per second on that huge screen... I could not do it!!! I would want to scream. Maybe I just have unusually sensitive vision - I can even tell the difference between 75fps and 85fps on my PC monitor - but I can't be the only one who wouldn't be bothered by the increased flicker of a 2-blade shutter. [Eek!]

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Call me Phoenix. *dusts off the ashes*

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted February 03, 2005 12:04 PM

Hi Jan,
Yes I have the same reaction when I visit the UK. But apparently the flicker does not bother the Brits. When I remark about the flicker on their TV they wonder what I am talking about!
Regarding the 2-bladed shutter on the GS1200, I have made this conversion on one of my machines, and the incresed brightness is very noticeable. I have found that the flicker only becomes noticeable if you project a small picture. And remember, your local Muliplex projects with 2-bladed shutters.

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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted February 03, 2005 12:26 PM

I too have a 2 blade conversion in my 'new'GS 1200. My earlier example had the standard 3 blades and in a direct comparison to my other projector, a ST180, yes the extra 100w from the GS gave a brighter picture, allthough both looked good.
Now against the 2 blades the ST180 really is just a pale shadow and now I only use it on my camping holidays running off the car battery using an inverter.
I eaven now show all my 18 fps film on the 2 bladed machine, yes there is noticable flicker in very light scenes, but speeded up slightly this is hardly noticable.
For what is actually free exrta light from the bulb a 2 bladed conversion is the way to go.

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Tony Milman
Phenomenal Film Handler

Posts: 1336
From: United Kingdom
Registered: Jun 2003

posted February 03, 2005 12:34 PM

Mark,

You now have my attention. You take you r projector on holiday [Eek!]

I am truly humbled

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Tony

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Jan Bister
Darth 8mm

Posts: 2629
From: Ohio, USA
Registered: Jan 2005

posted February 03, 2005 12:41 PM

Paul: yeah, that's what I meant... the Brits just don't know any better (sorry, folks) [Big Grin]

and although I was once in the same boat, now that I do know better you couldn't pay me enough to go back... no 2-blade for me, thanks [Smile]

Are you sure about the big multiplex cinemas using 2-blades though? I swear they all operate on 3-blade, as I really notice practically no flicker on the big big screen. In fact, I once heard many moons ago that some theatre systems use no shutter at all but use a special lamp that actually turns on and off 72 times per second in synchronity with the intermittent motion of the 35mm film. [Eek!]

I'm not sure if that's true (or even possible), it's strictly hearsay and I may well have been fed a bunch of crock there. [Wink]

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Call me Phoenix. *dusts off the ashes*

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Barry Johnson
Master Film Handler

Posts: 358
From: United Kingdom
Registered: Jul 2003

posted February 03, 2005 12:49 PM

Simple,but often overlooked is the original lamp alignment.I have increased light output on many machines by simply paying attention to this small but important feature. [Cool]

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Standard8 rules!!

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Tony Milman
Phenomenal Film Handler

Posts: 1336
From: United Kingdom
Registered: Jun 2003

posted February 03, 2005 04:13 PM

Jan,

Apparently in the UK they use Strobe lights at Disco's but only the Yanks notice

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Tony

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Jan Bister
Darth 8mm

Posts: 2629
From: Ohio, USA
Registered: Jan 2005

posted February 03, 2005 05:47 PM

LOL!!!!!!! [Big Grin]

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Call me Phoenix. *dusts off the ashes*

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Brad Miller
Administrator

Posts: 525
From: Dallas, TX, USA
Registered: Jun 2003

posted February 08, 2005 12:21 AM

quote:
Are you sure about the big multiplex cinemas using 2-blades though? I swear they all operate on 3-blade, as I really notice practically no flicker on the big big screen. In fact, I once heard many moons ago that some theatre systems use no shutter at all but use a special lamp that actually turns on and off 72 times per second in synchronity with the intermittent motion of the 35mm film. [Eek!] I'm not sure if that's true (or even possible), it's strictly hearsay and I may well have been fed a bunch of crock there.

Since I install and service 35mm and 70mm commercial equipment, trust me when I say YUP, you're looking at 2 bladed shutters! The only place 3 bladed shutters are used is in very special screening room situations where there is plenty of light to throw away.

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John Clancy
Phenomenal Film Handler

Posts: 1954
From: Cornwall
Registered: Jun 2003

posted February 08, 2005 01:43 AM

Jan and Paul, you must have been watching duff television sets if you were picking up flicker. Likewise when I visit the States the appaling standard of televisions provided in hotels, bars etc. does make me wonder how anyone in America can ever stand to watch television at all. However, I realize what I'm watching is cheap rubbish and despite the fewer lines resolution modern NTSC reproduction is actually very good.

With a two-bladed shutter, a big enough image will mask any flicker some may pick up. Personally, I rarely use 18fps so it's not a problem.

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British Film Collectors Convention home page www.bfcc.biz. The site is for the whole of the film collecting hobby and not just the BFCC.

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Jan Bister
Darth 8mm

Posts: 2629
From: Ohio, USA
Registered: Jan 2005

posted February 08, 2005 09:12 PM

I beg to differ as I just have very good vision, that's all ... please trust me on it. [Wink]

Yeah, TV overall is rather poor nowadays; the HDTV standard is long overdue and still only beginning to establish itself among average consumers.

Brad: I'm honestly surprised... but my guess as to why there isn't any flicker to be noticed even with a 2-blade shutter is that the actual duration of the dark phase is very short whereas the light phase is pretty long... unlike TV where the picture is really a series of lines that light up one by one only to rapidly fade out again, before the TV has even completed one full field. (Two fields make one full, interlaced frame.)
Am I right? [Smile]

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Call me Phoenix. *dusts off the ashes*

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