8mm Forum: Question about Bell & Howell 8D 644

This is topic Question about Bell & Howell 8D 644 in forum 16mm Forum at 8mm Forum.

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Posted by Arturo Glez (Member # 4700) on July 16, 2016, 03:43 PM:

Dear friends,

Do you know how I can change the wide screen? B&H 8D 644 16mm

I only see the framer and focus lever, but I do no know how to make more big the screen.

The manual of another model B&H says that the lever is over of the projection lens but i do not see nothing.

Thanks in advance, kind regards, Arturo.

Posted by Barry Fritz (Member # 1865) on July 16, 2016, 05:44 PM:

I don't know anything about that projector, but if you do not have a zoom lens, the only way to enlarge the picture is to move the projector farther away from the screen.

Posted by Lindsay Morris (Member # 3812) on July 16, 2016, 08:54 PM:

Arturo,

The 636 model as it was labelled for use in Australia had a variable aperture plate fitted.
It varied from 1.85 to 4.3 ratio & was activated by sliding a knurled lever right alongside the gate itself. I had a couple of dead 636 units & friends with earlier & later models were able to remove their original gate assemblies & fit these from the dead 636's I had.
Once the B&H company moved to the Japanese style the gate assemblies changed & one could no longer swap things about.

If you have NOT got that little lever near the gate then yours is not fitted with a variable aperture. Try & find a 636 unit & do a swap over. The 636 units were AC/DC 240V models..NO transformer & a LOT used in Australia...& possibly elsewhere if 220V supplies were used.

Posted by Maurice Leakey (Member # 916) on July 17, 2016, 05:14 AM:

The 636 was made in 1960 and is entirely different from the 8D644 which came out in 1964.

The new design projectors were introduced in 1962 with the 641, 642, 643, 644 and 652. Some of these had a variable mask.

The variable mask is actually called a Variable Aperture Plate and is a finger-tip control on top of the gate assembly which closes in or opens up the masks to reduce the film aperture to show a wide-screen effect.

The purpose of the mask is to exclude the light completely from the top and bottom area, and the mask should only be set to blank off these areas when prints bearing the reduced frame size are being projected.

The mask can only make the projected frame smaller. It cannot make it bigger!

Posted by Arturo Glez (Member # 4700) on July 17, 2016, 08:06 AM:

Dear friends,

Thanks everybody for your comments, I really appreciate it.

Maurice, please, can you show me a picture where I could see this variable aperture plate located? I am not able to locate it.

Thanks in advance, regards, Arturo.

Posted by Maurice Leakey (Member # 916) on July 17, 2016, 08:18 AM:

Arturo

If you cannot find it, I expect your projector has not got one!

Go to the Film-Tech Manuals page.

http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=reply;f=5;t=001462

Click on 16mm projectors.

Click on B & H Models 641 642 Instruction Manual.

The Variable Aperture Plate is just above the gate and shown as item number 12.

Go to page 7 under "Wide Screen Projection".

Posted by Arturo Glez (Member # 4700) on July 17, 2016, 08:27 AM:

Hi Maurice,thanks for your reply, here is the picture of my B/H.

What do you think? has the variable aperture plate? (I have the service manual but i am not able to confirm what piece is it or not)

http://subefotos.com/ver/?e071fe344d3253f7d2f42a16178708f5o.jpg

Thanks regards,Arturo.

Posted by Maurice Leakey (Member # 916) on July 17, 2016, 08:45 AM:

Arturo
Stop looking.
Your projector does not have a variable aperture plate.

Posted by Arturo Glez (Member # 4700) on July 17, 2016, 09:01 AM:

Hi Maurice thanks a lot.

Then I will move the projector far from the screen in order to make the image more big.

Thanks again, regards, Arturo.

Posted by Maurice Leakey (Member # 916) on July 17, 2016, 09:36 AM:

Arturo
You could not have made the picture bigger with an adjustable gate mask.
For a bigger picture, as you are doing, move the projector further from the screen. Or, fit a wider angle lens than the standard 50mm (2 inch).

Posted by Arturo Glez (Member # 4700) on July 17, 2016, 03:06 PM:

Hi Maurice thanks a lot.

Do you know what are the name valves that he has?

The service manual only shows 641 642 models.

I am not sure. Mine is b/h 8D 644

Regards, Arturo.

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