a question on old non -TTL flash

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ujjwaldey8165

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Ujjwal
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I dont use flash; so I have a rather basic question here

I have an old sunpak flash; which has a manual setting; and 3 Auto setting - 2-15 ft; 4-25 ft, and 8-30 feet.

Now manual I understand; I use the camera to focus, read the distance off the lens barrel; see the aperture corresponding to that distance on the back of the flash back; set the sperture; and shoot.

On the auto setting; for 100 ASA; 2-15 feet its says the aperture to be 8. Now if the object is 5 feet away, if set the aperture to 8 and shoot. Will I get the right exposure.

Now say the object is 10 feet away. Do I still set the aperture to 8? How does the flash give the right amount of power for something which is either 5 or 8 feet away at the same exposure? Does it have a sensor system to do this?

Also the 3 auto scales overlap. So say object is 10 feet away; do I use the first scale (2-15 feet) or the second one ( 4-25 ft) or the 3rd one.

Finally, if the camera can easily tell me the actual distance and the table can tell me the actual aperture value, what's the point of the auto system? Is that the early version of TTL?
 
reads to me like 3 stop manual, though I aint sure

one wau they used to work it is a thyristor that picks up the light coming back but it doesn't read like that to me
 
Hi,

First of all , if it and 'old' sunpack flash you might want to think about the wisdom of using it on a modern camera.

Older flash guns had vey high trigger voltages hich creates a momentary spark at the flash contacts inside the camera, older cameras had mechanical contacts, newer ones are electronic and the 'spark can zap circuit boards.

However to answer you question

3 Auto setting - 2-15 ft; 4-25 ft, and 8-30 feet.
Click to expand...

On the front of the flash there will be a switch, which can be set in three
positions usualy on red blue and green.

Look on the side of the flash and there will be a dial set the ASA , set it to 100, now look at the rest of the dial you will see red blue and green colours like a rainbow you will notice that some of the colour bands are longer than others.

At the end of the colour band their will be a f stop, notice that longest colour band will have a wider apature an the shortest a smaller apature.

You will also note that the colours 2-15 ft; 4-25 ft, and 8-30 feet. corrispond to to distence and apeture

to summerise . on the side of the flash set the asa , look at the distance you want to acheive . what colur band does it fall into? once you have chosen the collour band then look at what aperture it tells you to set . finaly move the switch on the fron of the flash to the corect color.

Thie will be some overlap as far as distance but remember the lower the f number the more distance you will illuminate.

Finaly this flash gun was made long before TTL , it is the flah itself that calculates how much output is needed not the camera ( hence the sensor window on the front)

you will need to set the camera to manual say 125th of a second and set the apeture suggested on the side if the flash .

Phew
 
How does the thyristor work?
Click to expand...

Bloody hell.....:)

The thryristor is a device that linits the amount of power released in to the flash tube from the capacitor that stored the energy.

Basically it allows the flash to re cycle faster after a number of discharges
 
Holden Caulfield said:
Bloody hell.....:)

The thryristor is a device that linits the amount of power released in to the flash tube from the capacitor that stored the energy.

Basically it allows the flash to re cycle faster after a number of discharges
Click to expand...

Thanks Holden....

If by modern camera you mean digital; no I am still stuck with Contax, Leica and other sundry flim cameras. :D

I was aware what thyristor is as an electronic device (thanks :)); just didn't realise what it does in a flash; and its still not clear.

Does the thyristor measure the amount of light released by the flash and cut the capacitor out? If so ; how does it do it? Do it measure the light reflected back? If the aperture is set the same for 2-15 feet, how does it work...
 
Does the thyristor measure the amount of light released by the flash and cut the capacitor out? If so ; how does it do it? Do it measure the light reflected back? If the aperture is set the same for 2-15 feet, how does it work...
Click to expand...

The flash fires, light is reflected off the subject to the on flash sensor , sensor cuts the duration of the flash.

Light travels at 300 000 000 meters per second , the first reflected light has bounced off the subject and had come back to the flash gun before the majorty of the flash out put has been released.

The thryisor calculates the return speed of the light taking in to consideration what setting on the front of the flash you have set.

If you have an overlapping distance between the say the red and the blue setting the tjhyristor will alow more light for a smaller apature before halting the flash duration

The whole calculation takes place in 100 000 of a second or less , not bad for 70's technology
 
ah...so I thought. So what about a 6 inch bronze statue 3 feet in front of a glass window? which reflected light does it read?

I get the general idea though...

And oh; camera technology has not much improved since the 70s...Contax, Leica, Hassy and rollei are still the best out there. What has improved is the editing software....Thats a different debate though....:LOL:
 
Holden Caulfield said:
Bloody hell.....:)

The thryristor is a device that linits the amount of power released in to the flash tube from the capacitor that stored the energy.

Basically it allows the flash to re cycle faster after a number of discharges
Click to expand...

No

ujjwaldey8165 said:
Thanks Holden....

If by modern camera you mean digital; no I am still stuck with Contax, Leica and other sundry flim cameras. :D

I was aware what thyristor is as an electronic device (thanks :)); just didn't realise what it does in a flash; and its still not clear.

Does the thyristor measure the amount of light released by the flash and cut the capacitor out? If so ; how does it do it? Do it measure the light reflected back? If the aperture is set the same for 2-15 feet, how does it work...
Click to expand...

the thyristor measures the light returned, like the way ttl flash works but a lot less accrurate

Holden Caulfield said:
The flash fires, light is reflected off the subject to the on flash sensor , sensor cuts the duration of the flash.

Light travels at 300 000 000 meters per second , the first reflected light has bounced off the subject and had come back to the flash gun before the majorty of the flash out put has been released.

The thryisor calculates the return speed of the light taking in to consideration what setting on the front of the flash you have set.

If you have an overlapping distance between the say the red and the blue setting the tjhyristor will alow more light for a smaller apature before halting the flash duration

The whole calculation takes place in 100 000 of a second or less , not bad for 70's technology
Click to expand...
No, ********
ujjwaldey8165 said:
ah...so I thought. So what about a 6 inch bronze statue 3 feet in front of a glass window? which reflected light does it read?

I get the general idea though...

And oh; camera technology has not much improved since the 70s...Contax, Leica, Hassy and rollei are still the best out there. What has improved is the editing software....Thats a different debate though....:LOL:
Click to expand...

camera tech has moved on ;)

70's used analogue circuits to model real life circumstances, now we use computers (thats what runs a dslr)
trust me the equations have more numbers in :D

btw no wasn't me being an asshole - it was the masters degree I'm studying in electronics talking, and no none of that is what a thyristor does
 
Thanks David...

The camera technology ( not flash technology; mark my words) ...hasn't moved on. DSLR is merely making image making accessible to many who cant be bothered with the skills of using a camera to take photograph ;)

But thats another debate....

Now time to play with the flash on a camera...


Ujjwal


( p.s : what really runs a DSLR? God, maybe...:D:D)
 
ujjwaldey8165 said:
Thanks David...

The camera technology ( not flash technology; mark my words) ...hasn't moved on. DSLR is merely making image making accessible to many who cant be bothered with the skills of using a camera to take photograph ;)

But thats another debate....

Now time to play with the flash on a camera...


Ujjwal


( p.s : what really runs a DSLR? God, maybe...:D:D)
Click to expand...

the metering has I (L) film but the way metering works is a lot cleverer since the 70s

had a lecture last week on the way differential problems were solved now vs then, was 'interesting'
 
ujjwaldey8165 said:
Yes, it has a thyristor. How does the thyristor work?
Click to expand...

LOL at Holden's response, although he's quite right. :D

Basically the thryistor is an energy saving electronic circuitry incorporated into all modern electronic flashguns. Basically, before the invention of the thryistor, electronic flashes used to dump all their charge when you pressed the shutter, whether the actual flash output was a tiny little blip for a close up shot or a massive whack of full power for a subject 30 feet away. You then had to listen to the flash working overtime to accumulate power again before the 'flash ready' light would come back on again and it took ages!

The thryistor changed all that, so that very close shots could be taken without the 'flash ready' light going out at all - the flash just discharged only the power it needed, and retained or stored the rest. This quickly led to the semi auto type of flashgun which the OP is asking about being developed, and eventually of course to the full thru- the- lens systems which we take for granted today.
 
Erm david.

You have told us what a thyristor does not do , but did not anwer the question , how does it work in pricipal on a flash gun.

And just to clarify how fast is the speed of light if I was wrong
 
On the auto setting; for 100 ASA; 2-15 feet its says the aperture to be 8. Now if the object is 5 feet away, if set the aperture to 8 and shoot. Will I get the right exposure.

In "average conditions", Yes.

Now say the object is 10 feet away. Do I still set the aperture to 8? How does the flash give the right amount of power for something which is either 5 or 8 feet away at the same exposure? Does it have a sensor system to do this?

Set to whatever matches the ISO, range and your preferred aperture. The flash has a sensor on its front. The minimum range is important, as the flash won't be able to deliver a small enough pop if you're too close (using it head on).

Also the 3 auto scales overlap. So say object is 10 feet away; do I use the first scale (2-15 feet) or the second one ( 4-25 ft) or the 3rd one.

Choose according to your preferred aperture. Open wide to allow some ambient light in and save your batteries.

Finally, if the camera can easily tell me the actual distance and the table can tell me the actual aperture value, what's the point of the auto system? Is that the early version of TTL?

With early DSLRs with TTL flash metering (as well as pre-flash TTL metering) the flashes own "auto" mode often gives a better result than the new tech :bang: It also helps avoid the problem of a significant percentage of subjects who blink with the pre-flash.

Your Sunpak may be one of the several types with a replaceable dedicated TTL foot and a head capable of taking a filter holder or a clip-on Sto-fen diffuser.
 
ujjwaldey8165 said:
:LOL:No one still answered my 4 specific questions in the original post:LOL:
Click to expand...
Here goes then. :D

The type of flashgun you are asking about is a semi auto type of flashgun which was the dogs dangly bits before full TTL systems came in. They're easily identified by looking at the front of the flash body where you'll see a small (usually round) sensor which always faces in the subject direction. The sensor fed the light bouncing back from your subject to a flash sensor within the flash which deemed when exposure was complete and automatically quenched the flash. Because the flash was as near as damn it at athe same subject distance as the camera, these flash guns gave pretty accurate results - I wouldn't hesitate to use one today

If you look at the back of these flash guns you'll see that they have a number of 'automatic' aperture settings -the more expensive the flash gun, the more auto aperture options you tended to have and the auto options were often colour coded as Holden said earlier. If the scale under the auto f8 aperture indicates that you can use the aperture between 2 feet and 15 feet then indeed you can - the system operates in much the same way as a more modern TTL system, not quite as accurate maybe, and not so intergrated into the overall camera exposure system, but usually plenty accurate enough anyway.

The same applies to the other 'auto' aperture usage ranges, but when you use a non-auto aperture you're back to guide no etc to calculate exposure.

I'm not sure if I've answered all your queries, but I'm well down a bottle of Grouse. :D
 
Thanks everybody....

Photon..you are right..it has a dedicated foot for canon ( and as far as I can see from the manual; there are foots for nikon, pentax et al , but not one for contax...which is the one i needed :)) Also yes, it can take dedicated filters; though I dont have the filters....the model is sunpk 444 auto
 
Good flash, no worries about the voltage if you use it on a digi.

The standard foot (with the jack socket for a sync cable) is worth looking out for.

The dedicated foot should allow a bit more viewfinder info (though they cocked it up for Pentax) and the TTL will allow you to get a lot closer than the flash's own auto settings.

The filter kits turn up on eBay every few months, usually from the States. The orange filter is a bit too strong for balancing with low-energy domestic bulbs, and not something you'd bother with, for film.

There's also the fabled Bounce Lighting Kit that fixes to a clear filter and requires a filter holder, unless you tape it in position.

There were several quite similar flashes in the range (I have what details I know, filed away). Some won't have the interchangeable foot option; there's one with a sync socket, for cameras with a cold-shoe; some have a zoom head; some are more powerful.
 
ujjwaldey8165 said:
Yes, it has a thyristor. How does the thyristor work?
Click to expand...

It reads the light level bouncing back and adjusts the continuing length of flash accordingly. Hence close up may be over-exposed as there is no time to shut the light off.

Arthur
 
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