Coronet 6x6 Flash Unit

marcusverger

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Hi,

I have a Coronet 6x6 camera, c1953 - c1960?, with a flash unit.

The flash unit takes 2 batteries (AA Size). But what is the correct voltage? I have tried 2 regular 1.5 batteries, but to no avail....

Also what are the correct bulbs??

Any thoughts??

Thanks,
 

AgX

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That were early ones, typical for that period. Over time lesser voltages were aplied. At least later bulbs were specified for a wide range of voltages and flash manufacturers applied what was easily obtainable locally.
 

Donald Qualls

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I have a Kodak (Six-20 Flash?) that uses screw base bulbs (with an adapter for bayonet type); it has worked fine #5 bulbs on two 1.5V AA cells.

The tradeoff was voltage vs. current. A flash that wants 43V almost certainly uses a capacitor to provide enough current for reliable bulb ignition, but even screw base bulbs were apparently made for as little as 3V if there was half an amp or so available (and back in the day, "photoflash" type carbon-zinc cells were specially designed to be able to source short pulses of higher current than normal battery cells -- but modern alkalines can do better than that).
 

btaylor

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AgX

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Here in West-Germany two types of batteries dominated in bulb flashes:
first 22.5 V
later 15V
last 6 V
The designations are a lot, and I am too lazy now to look them up. But I am sure you know which types I mean... I think the situation in the UK was the same, but I can't say for the USA.
Bulb flashes with stick handles (that likely took only 3 D-cells, or?) were soon superceeded by electronic flashes and I have yet to come across such bulb flash at all.
 
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marcusverger

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btaylor said:
The site states “10cm diamter reflector powered by 2 1.5v cells”
I read 1.5v cells, not 21.5. But I could be wrong!
Click to expand...

Alas, I discovered I couldn't read - it does say 2 1.5v batteries.
I have just tested flash with 2 batteries and having discovered which way round they go, managed to get a spare bulb to fire..... !!

(I had to slightly adjust the position of the capacitor - it wasn't sitting properly)

So, 2 ordinary 1.5v batteries NOT 2 x 21.5 batteries.

Just need some 120 rollfilm and am good to go.

Thanks for all your help.
 

Donald Qualls

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Glad to hear it! Despite not having been made (other than screw base focal plane type) in thirty years or so, it's not hard to find the size flash bulb you need unless you're after something obscure (like AG-3, or IR-coated #2 like Weejie used to use).
 
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marcusverger

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Yes, bulbs seem readily available on eBay.

I have another flash related question - I have an AGFA KM flash unit of c1956/60 (I have the correct battery !) and states for B/W film use 17 DIN - 40 ASA, or for colour film use18 DIN - 50 ASA, then mentions correct f-stop / distance combinations.

How do these film relate to modern films (I include using the above Coronet Coro-Flash mentioned above) and what is best film to use??

Any thoughts??
 

Donald Qualls

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Doesn't really matter. All you have to do is back out the guide number for the flash (which will generally be the same for all flashes with the same bulb and reflector size) and use that to calculate your exposures. For instance, an M3 in a 4" polished bowl has (IIRC, and don't quote me on this) GN 100 for ISO 100 film -- that means at 4 feet you need f/22 (near enough), f/16 at 6 feet, f/11 at 10 feet, etc. -- out to around 30 feet at f/3.5.
 
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marcusverger

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Thanks for that. I think I understand the basics of getting the guide number (Sort of ? ).

I take it that the relative speed of the film hasn't changed since mid 1950's - or as it? Is '17 Din / 40 ASA' etc in say 1956-1960, still the same, equivalent speed as today? (I know it is now called ISO) or is it something different?
 

AgX

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The guide number you can calculate if there is a table at the flash.
If not, but only a guide number, it may get complicated. Basically there are two guide numbers: metric and imperial. Also at least in Europe guide numbers in the long past were based on 18 DIN, from the 70's on based on 21 DIN.
 

MattKing

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40 ASA film became 80 ASA film in 1961.
So for an 80 ISO film today, you would refer to 40 ASA on any charts.
 
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marcusverger

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MattKing said:
40 ASA film became 80 ASA film in 1961.
So for an 80 ISO film today, you would refer to 40 ASA on any charts.
Click to expand...

So, for current film, half the ISO/ASA to take it to values of 1950's/60's ?? (80 becomes 40, 160 becomes 80 and 200 becomes 100 etc ?)
 

MattKing

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marcusverger said:
So, for current film, half the ISO/ASA to take it to values of 1950's/60's ?? (80 becomes 40, 160 becomes 80 and 200 becomes 100 etc ?)
Click to expand...
Yes.
But only if you are trying to rely on something like a 1950s era table on the back of the flash, or are using a 1950s era meter.
 
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