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Old Jul 18, 2005, 3:18 PM   #1
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When I bought my fujifilm s5100 I failed to notice that it lacked a hot shoe. I had been planning to purchase an accessory lens and use my external flash unit with it since many digicams' internal flashes do not work effectively with a large lens attached.

So, without a hot shoe, I have to consider a slave flash. My question is: Can the accessory lens be used with a slave flash triggered by the 5100's internal flash?

I fear the exposure will be uneven due to the internal flash being shadowed by the attached lens. The manual and box clearly state that the internal flash is not usable with accessory lenses. My current reasoning for this is that the lens shadows the flash.
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Old Jul 18, 2005, 8:44 PM   #2
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ohgeez wrote:
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My question is: Can the accessory lens be used with a slave flash triggered by the 5100's internal flash?
Yes, as long as the slave sensor can see the burst from the camera flash. I suppose the slave is bracket mounted and a won't be bother by the attached lens.
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Old Jul 18, 2005, 10:05 PM   #3
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Well, yes, I am sure that the flash will be trigger. This problem I'm aware is hard to understand, perhaps the way I worded it. What I am wondering is, if the attached flash is not usable with the accessory lens because it is shadowed BY the lens, when fired (in order to trigger the slave) when the lens is on, will a uneven exposure occur (due to a portion of the attached flash's light being shadowed by the lens)? Or will the slave overpower it and achieve an evenly lit picture?

If using the internal flash and a slave with an acessory lens DOES result in uneven flash...then I have only been able to come up with these solutions:
1. reflect the internal flash sideways towards the bracket-mounted slave so that the slave fires but the internal flash's effect is not shown in the picture
2. I think there is a device that can be attached to the flash, covering it, and electronically triggering an external flash. If this exists, it would be what I go for.
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Old Jul 18, 2005, 10:50 PM   #4
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ohgeez wrote:
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What I am wondering is, if the attached flash is not usable with the accessory lens because it is shadowed BY the lens, when fired (in order to trigger the slave) when the lens is on, will a uneven exposure occur (due to a portion of the attached flash's light being shadowed by the lens)? Or will the slave overpower it and achieve an evenly lit picture?
No, the slave will not over power anything by itself because it is a dumb slave (There is on the market one manufacturer, I forgot the brand, who sell a "TTL mimic flash", but that's another story, I will search an old discussion FYI later)
A slave (slaves that are on market today) can only operate in 2 modes max: manual (full and/or partial power) and auto mode (aperture set).

ohgeez wrote:

Quote:
If using the internal flash and a slave with an acessory lens DOES result in uneven flash...then I have only been able to come up with these solutions:
1. reflect the internal flash sideways towards the bracket-mounted slave so that the slave fires but the internal flash's effect is not shown in the picture
2. I think there is a device that can be attached to the flash, covering it, and electronically triggering an external flash. If this exists, it would be what I go for.
1: Excellent, this is the simplest and academically logical way based only on the slave power , depending on manual or au to mode.
2:This called a slave cell, sold for around 10 box, but the "normal" 10 box cell will fire the connected flash at the first camera flash burst. "Digital slave flashes" have the ability to ignore preflash of digital camera. Wein also have slave cell that integrate this function (ignore preflash), but I can't pronounce about those devices because I never used them.

But in all case, you won't have TTL, of course.





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Old Jul 18, 2005, 10:56 PM   #5
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And:

A)If you can disable the camera preflash, you can go with a normal cheap slave cell + any generic flash

B)If you you can not disable camera preflash, then you have to go with:
- a "digital ready" slave flash
- a Wein device + any generic flash
- There is also Sunpack or Cobra bracket that integrate a "digital slave" function, allowing you to use a generic flash on it.
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Old Jul 18, 2005, 11:07 PM   #6
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Ohgeez,

This is an old thread about the subject. The device I built is functionally equivalent to the circuitry on some "digital ready slaves flashes", but it is manually selectable (no learn mode).
Also, Padeye mentioned Ikelite , what I referenced above about "TTL mimic flash".

http://www.stevesforums.com/forums/v...mp;forum_id=53
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Old Jul 18, 2005, 11:46 PM   #7
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TTL flash...this I don't understand so much. I understand how the light reflected on the film or ccd is measured to determine flash length...but does this mean the camera controls the flash? I assume it does, but only with certain dedicated flashes I am guessing. I have this old vivitar flash that you tells you a set aperture to set the camera at depending on film speed, then it automatically determines it's exposure.
Perhaps this is just a thyristor technology flash, but is it in any way controlled by the camera through the hot shoe?

Anyway, since the s5100 that I have does not fire a preflash...I can use any slave flash, correct?


As for using the slave with the accessory lens, I have been looking for a slave trigger, preferably a light sensor that attach to and covers camera's internal flash and attached by cord to a hot shoe-type trigger that holds the slave. Know what I mean? I doubt this exists, but seems like it could be built. Tell me if this device is possible or exists.

thanks for the help

EDIT:
Vivitar Sensor Cord SC1
I found this
^

From what I can figure out about it, it's a flash sensor attached to a PC cord. If I attached this to the front of my camera's flash, as a result also covering it up as planned, it should then result in triggering of the slave flash and the slave flash being the only flash that shows up on the exposure. Tell me if this particular sensor cord device will work.
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Old Jul 19, 2005, 12:47 AM   #8
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ohgeez wrote:
Quote:
does this mean the camera controls the flash? I assume it does, but only with certain dedicated flashes I am guessing.
Rite, the on board flash, and dedicated flash: via hotshoe with multiple pin (Canon, Nikon, minolta ... ), via hotshoe/dedicated cord (Sony), or wirelessly (many leading brands...)

ohgeez wrote:

Quote:
I have this old vivitar flash that you tells you a set aperture to set the camera at depending on film speed, then it automatically determines it's exposure.
Perhaps this is just a thyristor technology flash, but is it in any way controlled by the camera through the hot shoe?
Set aperture ... it's called the auto mode. Yes, the thyristor is just a technology, but historically,manufacturer used to call (or to label)"auto thyristor" such flashes. It's controlled via hotshoe only by the center pin (start fire signal, that's all, no stop signal as in TTL mode) that's why you can trigger it with a slave cell connected to the flash hotshoe.

ohgeez wrote:

Quote:
Anyway, since the s5100 that I have does not fire a preflash...I can use any slave flash, correct?


Yes, if you are sure that your camera does not preflash

ohgeez wrote:

Quote:
As for using the slave with the accessory lens, I have been looking for a slave trigger, preferably a light sensor that attach to and covers camera's internal flash and attached by cord to a hot shoe-type trigger that holds the slave. Know what I mean? I doubt this exists, but seems like it could be built. Tell me if this device is possible or exists.



They exist, that's what I called a cheap slave cell, arround 10 b$ like this one:

ohgeez wrote:


Quote:
Vivitar Sensor Cord SC1
I found this
^

From what I can figure out about it, it's a flash sensor attached to a PC cord. If I attached this to the front of my camera's flash, as a result also covering it up as planned, it should then result in triggering of the slave flash and the slave flash being the only flash that shows up on the exposure. Tell me if this particular sensor cord device will work.
The info and pic I saw at vivitar website is not very descriptive, i can't tell; anyway, generic parts are as good, may be cheaper.
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Old Jul 19, 2005, 12:51 AM   #9
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....... edit problem

They exist, that's what I called a cheap slave cell, arround 10 b$ like this one:


http://www.shortcourses.com/equipment/flash/slave.jpg



It's a Metz, but any generic cell will do, and cheaper

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Old Jul 19, 2005, 1:03 AM   #10
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Look, I have 3 of this , works very well, 10$ each:

http://www.ritzcamera.com/graphics/r.../221660657.jpg



hotshoe connector on the top (where your generic flash goes), cold shoe in the bottom, plus standard female 1/4-20 thread, and mines have a label saying "made in hongkong" :G


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