HomeSpecto main page 9.516 Multi-gauge 17.5 28 Pix Miscellany








I was contacted by a couple of guys from N. America about Ultra Pan 8 (hereinafter UP8). You can google this

for more info but basically it is about filming on double-run standard 8 stock, retaining the frame height but

using the full width of the 16mm frame (or maybe more) so as to get very wide screen pix. The issue, of

course, is getting it on screen and fortunately the Specto can be fairly readily adapted to do this. This is

basically about how to do it.


Before we start, a word of warning to UP8ers who may not be familiar with our ancient projectors. BEWARE!

They will try to kill you given the chance, especially as they run on 240v not the 110v you are maybe used to.

Old wiring can decay and need replacing for safety. Electrical safety standards 40 and more years ago were

not up to today's standards. Also, they need lubrication. The Specto has a gearbox; if you let it run dry you

will destroy it. And in order to open up the gate properly, you MUST first remove the lens. Treat the machine

with proper respect and hopefully all will be well. A good place to start would be reading the instructions on

the main Specto page.


OK. So, as Mrs Beeton would have said, first catch your hare. Here are some Specto pix to guide you.



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Some of these are just stock shots I happen to have on hand. First is a 9.5/16, then an 8mm which a friend

converted to 9.5. NB you want the ones with long arms like these. They do 800', but some are only for 400'.

The second is a type you don't want - pic 3 shows how its gate works, ie cut away to miss the claw when

opening. And with the 16mm claw on the inside. What you want is like pic 4. 5 & 6 show the claw retracting

lever, like in pic 1. This has to be in the lower, retracted position to open or shut the gate for cleaning. For

normal threading, all you need to do is push the rear gate back using that little lever on the side. Finally, one

I converted for UP8. Here are some pointers.


1. Single-tooth sprockets, not double.

2. Claw on outside, not inside.

3. Claw retracting lever present.

4. 8/16 machine, with lever just behind gate for 8 to 16 changeover. You can just see this on left of pic 7 above.

Many other machines (analyser models) have a similar lever but it's for speed change. They are clearly marked

but tricky to spot at a glance.

5. Lamp. Many Spectos have the old 30v 100w lamps, now impossible to source. Look for Specto 500 with a standard

pre-focus lamp base, 500w 240v or 110v (but often still 240v supply, but with an extra resistance in the lamphouse

to drop the voltage for the lamp and provide a dim/bright setting to give the lamp a soft start to prolong life).

Or if you are lucky, someone might have converted to Tungsten halogen lighting.

6. The plug that feeds power into the machine is unusual and now hard to find. Make sure it's included.

7. The usual stuff I don't need to tell you, like condition.

8. Buy an 8mm-only machine as well - you may need some donor parts.


The Conversion


Basically, we are trying to get a 16mm machine to run at half speed and pitch. A dual 8/16 machine is ideal, as it

is already set up for the speed part. What we need to change are the throw of the claw, ie to make it pull down

an 8mm frame height with the 16mm claw. Take a look at this. We'll call them pix 8 - 11.


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So far as I can make out, the 8 and 16 claws are identical. The up and down cams, too, are identical in profile

(the in and out cam is that nylon jobbie at the back in pic 7 above). What changes is the location of the main

hole thru the cam and its position relative to the fixing holes. In pic 8 we have a 16mm cam bottom centre, and

8mm cams either side of it.


Pic 9 shows an 8/16 machine, but without the 8mm claw. The slot in which the 8mm claw runs is however clearly

visible; pic 11 shows how a 9.5/16 machine looks with both claws. You will notice that the fixing arrangements

differ between pix 9 & 11. Pic 9 shows the assembly secured by a nut, the parts are seen top left of pic 8, ie a

threaded boss with, below it, a disc that has pins protruding on either side which engage with the cams. This is

a new arrangement on me. Pic 11, on the other hand, has the familiar arrangement of screws passing thru discs

and cams and into the boss. Two bosses (8 & 16) and a pierced holding disc are top centre in pic 8. The securing

screws are shown, with a standard washer which I subsequently drilled for use in the conversion. Finally in pic 8

you can see a link from a chain; the Specto often used a chain indistinguishable in appearance from that used

in Meccano, tho I suspect exact size and quality are different!


Unfortunately, the arrangement in pic 9 does not lend itself to conversion very readily. What I had to do was

cannibalise an old 8mm machine for a boss and cam and fixing screws, and drill a washer to extend the boss out

slightly to get the claw in the right place. What I don't know, as I do not have enough machines to give a sensible

sample size, is just how many 8/16 machines are like pic 9 and if any are like pic 11, which would be easier to


Since you ask, I think pic 10 is an 8 or 16mm-only machine I converted for UP8.


We then have the question of the gate. Before we go any further, please be warned that the fixing screws for the

gate are tiny and fit into the metal casting which is relatively soft material. It is very easy to strip the thread (which

is pretty disastrous: do not over-tighten!) or damage the head (so use a screwdriver of the right size) or, of course,

to lose them altogether.

Below are pix 12 to 15.


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By a slightly spooky coincidence, I found among my Specto spare bits and pieces this gate in pic 12, which I had never

understood. Nick Kovats tells me it's probably a relic of an earlier attempt at a format similar to UP8. It's my only one

and is now on its way to Jean-Louis Seguin. I also had the one in pic 13, which goes bigger rather than smaller. No

thoughts on the provenance of that yet.


Pix 14 & 15 are two gates I have tried masking up. Left is one masked just from the bottom; this worked well but was

right on the edge of the range of racking adjustment on the Specto. Then I tried both sides - almost impossible, I found,

to do both at once so I shall have to do one at a time. I am using brass strip fixed with a two-part epoxy glue. The brass

needs to be of a minimum thickness to be strong enough, but otherwise the thinner the better. You can see in pic 15

that I have chamfered the edges - this is found on many commercial machines - which I think gives a sharper edge, tho'

thinner material might work as well. In an ideal world, the mask would be level with the surface of the gate to get

optimum results. It is important to use small bits of mask to avoid problems when re-fitting the gate - try to stay within

the circle of the lens barrel.


Which brings me to another point - lenses. Most Specto lenses are uncoated and therefore don't perform as well as modern

lenses. However, as usual the combination of lens barrel size and optical arrangement makes it very difficult to find an

alternative. The lens barrel is a mere 1" diameter, and it is a rare lens that is small enough to leave enough thickness

to make a sleeve with the grooves on the outside for fine focussing. I have successfully used 8mm zoom lenses which

are an exact fit for the Specto lens barrel, but they have no provision for fine focussing - it's just a matter of push and

pull as best you can. And with UP8 the problem may be more tricky as 8mm lenses tend to be a bit small-bore and may

distort the edges of the pic. This, however, is well outside my area.


June 2012


This section shows, inter alia, a somewhat different method of converting a Specto to UP8.


I have been working on a Specto 8/16 for another of the UPAN8 people. There is only one possible conclusion; this

projector is sentient, evil and hates me. It is a classic example of why I dont go into the projector repair business;

this machine has cost me far more time and far more angst than can ever be repaid by whatever price I can actually



Where to start? Obviously, it needed thorough lubrication. Then the troubles really started.


To convert to UPAN8, it is necessary to move the 8mm cam to where the 16mm cam originally sat. The problem is,

the 8/16 cam set-up is not like other Specto cams. This pic shows the set-up; the 8mm claw is not present but would

run in the rear slot just as the 16 claw runs in the front slot; the cams themselves cannot actually be seen.


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In other Spectos, the assembly is held together by 2 screws passing thru the securing discs, thru the cam(s) and

into the carrier, which has a much shorter spigot. Both types can be seen in the second pic, 1st and third top row. In

the 8/16, instead of screws thru the entire assembly, there is a disc between the two cams, seen centre left. This has a

small lug on each side which engages with the cams. Because these lugs are in different places to match the differently-

placed holes in the cams ( see lower right, 1st 8mm then 2nd 16mm cams; ignore the third), it is not possible to re-assemble

this unit in a way that puts the 8mm cam in place of the 16mm one. Which therefore means that one needs an 8mm

donor machine to give up its carrier, and maybe its cam.


Clear so far?


Now, the shaft on which the carrier is mounted has a flat about 1cm long, so you can't fix the carrier in the wrong place.

The length of the flat gives scope for adjusting the position of the carrier to ensure it is in line with the pivot at the end

of the claw frame. The shaft protrudes only a short way, however, so a) there is insufficient adjustment to allow for an

8mm carrier to stick out far enough and b) there is not a lot of actual round shaft to ensure the carrier rides in a fully

circular way. What I had to do was to add a bit to the rear of the carrier. I did that b*****y job no less than three times.

The first time, just warming up, I made the simple error of using a 16mm carrier (remember the thru holes are in

different places for 8 and 16) just to prove I could be stupid. The second time it wasn't accurate enough and wobbled

rather than rotating straight. The third time I had to add the extension piece first and then and only then drill thru for

the central hole. When I had the claw in what I thought was the right place, the machine disagreed and was very stiff,

so I polished the claw frame and the rubbing surfaces next to the claw to help give a smoother ride.


Then everything went wrong at the same time. The claw wasn't entering the perfs, so the film didn't move, and the lamp

only worked at the low level of output; no 2nd stage of power. I tried so many different things - different gates or

combinations of gates, adjusting the in/out cam so it rode on a different part of the rear arm (then the claw dug in

too far and made a horrid noise) and finally, filing and sanding a bit off a spare cam to allow the claw to go in just a

bit further, which was all that was needed as, infuriatingly, I had easily got it to work on inching, but the moment I started

the motor it all went pear-shaped. I suppose I must confess I also actually stuck a gate in the vice and bent it. Well, I

was desperate! I had those gates on and off dozens of times, partly because each time I found a solution to part of

the problem I had to check the gates were still OK and the right ones.


I took the bottom off to get at the switches and see why the second stage for the lamp wasn't working. Zilch. In the

end, it penetrated my thick skull that with a 240v 250w lamp in a machine intended for 110v 500w, this was less surprising

than it might have been. One should never make assumptions I suppose - I just assumed it had the right lamp in. Then it

stopped working again, because I hadn't tightened up the big nuts/rings that secure switches thru their mounting holes.

As usual, access for a normal spanner was impossible - the ones that were big enough (16mm) were just too thick. In

the end I had to make my own out of a bit of flat steel. Incidentally, you may have noticed the big resistance in the

lamphouse looks a bit skewiff. It seems to be made in several sections, with just the wire holding the bits together.

Something to do with expansion, I guess.


Then I had problems with getting the picture area properly illuminated - far too much filament visibility, fringing and

uneven light. A different condenser lens helped, but I was still getting similar if reduced problems and the corners of

the pic being cut off. Then I discovered that with the 8/16 selection lever on the 8mm setting (where it needs to be),

an extra condenser lens was automatically swung into place, presumably to focus the light a bit more closely for the

8mm frame. The pix below show you this lens.


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Now, the 8/16 changeover lever changes the speed of the drive to the sprockets via the little mech best seen bottom

centre left in pic 3. The lever from the front of the machine has a slot in which rides a pin. Moving the lever cause the

arm to turn on the pivot. The arm has a couple of lugs which locate in a groove in the end of the shaft, so when the arm

moves, the shaft is moved in or out. This in turn engages or disengages a dog-clutch and Voil


The aforementioned extra lens is moved in and out of position by a link from the lever, which is inaccessible without

completely dismantling the lamphouse. So to allow me to set the lever at 16, to keep the lens out of the way, but

keeping the mech at the 8 setting, I removed the arm and pivot. Trouble is, the shaft then tends to move on its own;

when it's at the 16 setting I found my bottom loop vanishing and my top loop growing (I wish I was better at this

spatial stuff!). This was fairly simply solved by fitting a collar with a grub screw to the shaft to stop it creeping.


I now had a fairly bright, evenly-illuminated pic on the screen, but I was still missing the corners. I finally realised

that trying to show a 16mm-width pic thru a 1" 8mm lens was not working. A 2" 16mm lens worked fine.


You might think this is a long explanation, but it is as nothing compared to the length of time it all took!

Hopefully, final tests over the next few days will show the machine finally to be working properly in all respects

and ready to show UPAN8.


In communication with the intended recipient, a comment caused me to look more closely at the assemblies that

hold the film on to the sprockets - guides/retainers or whatever. On the dual-gauge machine (this one, anyway),

the rollers are split and have three thin raised bits that are likely actually to contact the film - one each side for

16 and a central one for when using 8mm. Some seemed set solid and so likely to scratch. It occurred to me that

the centre one might well scratch the middle of UPAN8 film, so I have swopped them for 16mm ones I had spare.

While I was doing this, I had to remove the lower sprocket and found was held on by a mini ball bearing, a spring.

and then a grub screw. I have no idea what this is meant to achieve. I also thought that I might as well at the same time

fit an extra roller to give a greater wrap-round on the bottom sprocket. I have always thought the way the film

pulls off the bottom sprocket looks precarious; if it works out, I shall have to do the same for my own machines.

As you can see, I've tucked it away as best I can so use is optional. I did think of a spring-loaded arm, but ....... nah!


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