buying into flash

[radiochris]

Dear All,

I have an Minolta 5D which I find great to use. But I'm considering a upgrade to eitehr the A200, A300 or A350. What I woul dike to do is add a flashgun or two to my current system but that would also work with the new camera when funds allow its purchase. I would also like to use a flashgun off camera in a similar fashion to my Canon.

Any advice appreciated.

Chris

[harveyzone]

Dear All,

I have an Minolta 5D which I find great to use. But I'm considering a upgrade to eitehr the A200, A300 or A350. What I woul dike to do is add a flashgun or two to my current system but that would also work with the new camera when funds allow its purchase. I would also like to use a flashgun off camera in a similar fashion to my C*n*n.

I believe that any current flash that work with you 5D should continue to work with your A200/300/350. Take a look at this report for the most popular models:
http://photoclubalpha.com/2007/06/12/fl ... pha-dslrs/
(although be aware that both the Sigma and Sony models are curretly beoing updated with similar, but newer models).

[mikeriach]

Just to update you guys I have been looking for a new flash since last September and I have at last managed to get hold of a Sigma EF530 DG Super flash for the Sony system. They appear to be as rare as hens teeth however Sigma UK have been very helpfull and hopefully either later today or tomorrow I will have my greasy mitts on it (edit - it arrived today).

Park Cameras in the UK tell me they have just got stock of the new Sony HVL F42AM so things are finally moving on from the KM era.

Mike

[Glyn R]

I have been told today by my local camera shop that TTL flashes designed for film cameras do not work correctly with DSLR. I don't understand why. If the Camera TTL system talks to the flash why does it matter whether you are using film or digital. The man could have sold me a flash so he is obviously trying to be helpful. I just want to know why.

[Glyn R]

I have managed to get a sensible answer about TTL flashguns on Digital v Film. The method of exposure measurement used for Digital is a preflash just before the exposure for the sensor to detect with mirror down. Film exposure is measured from the main flash with no preflash after the mirror lifts taken from the surface of the film. Film designed flashgun will not produce preflash so the exposure wil usually be full power. I hope this is understandable took me several attempts to get a good answer.

[srt101man]

My "educated guess" regarding why the film flashes and the Sony DSLR's might not play well together is the evolution of electronic flashes has come full circle.

Originally, there was no automation and the photographer, if a correct exposure was desired without depending upon the latitude of the film, and there isn’t any exposure latitude with slide/positive films, was to calculate the correct aperture size by how powerful the flash being used was, which is it’s guide number, what the speed/sensitivity (ASA/ISO) of the film in the camera was, and how far away the subject that was to be exposed correctly was. Everything closer to the camera would be over exposed to some degree and everything beyond would be underexposed to some degree. This worked and continues to work but isn’t very fast or easy for the arithmetically challenged.

IIRC, about 1970 electronic flashes were introduced with a thyristor circuit which via a sensor in the front of the flash, “measured” the amount of flash produced light returned to the base of the flash and at a pre determined value, the flash would be switched off so that the flash output was variable, not 100% full 100% of the time. This was a big advance with negative films but there was lots of room of improvement since it was easily fooled as to the correct exposure. These flash units would work with any camera that had a flash synch connector. The next improvement I remember was the introduction of ways to adjust the field of view of the sensor to more closely match the focal length of the lens used. This was usually accomplished via a series of different sized circular holes over the sensor, with the largest used for wide angle lenses and the smallest for telephoto lenses.

I remember being told that the TTL version of this was a Minolta invention but the first camera I saw with TTL flash control was an Olympus SLR. With TTL flash control, the sensor that collects the light generated by the flash to determine when to quench the light output is inside the camera. They were placed in the bottom of the camera so that when the mirror went up, covering the pentaprism, the shutter would open fully (because electronic strobes are such a short duration that the shutter must be fully open otherwise a portion of the film will not be exposed by the flash), the light from the flash would “hit” the sensitized side of the film and a portion of the light would be reflected down into the sensor and via a circuit back thru the hot shoe, the flash would be quenched. While this system could still be fooled, it was fooled less than the non-TTL “auto” flash systems.

TTL flash systems were not impacted by the introduction of auto focus SLRs but with DSLRs, things needed to be changed and could be improved. The film SLRs didn’t care when trying to focus what the distance was, only if the algorithm used could get a “sharp” or straight line of an arbitrary number of pixels to be found. However, one of the features of the new Sony lenses for the Alpha cameras is the ability to know the distance when focus is achieved, feed that back to the camera and the camera calculates, just like the when there wasn’t any automation, what the correct aperture for the amount of flash power/output that will be used. A LONG time ago, Nikon had a “normal” lens for their SLR’s which had “GN” as part of its model number that one of the rings would be set to the Guide Number (GN, get it) of the flash and as the lens was focused, the shooting aperture would open and close so that when the shutter was tripped, the aperture would close to the correct size for the power of the flash, the sensitivity/speed of the film (ASA/ISO), and the distance of the subject (we'll assume that the lens is focused on the subject) to the camera yielding a correctly exposed subject regardless of whether the subject was or was not reflective nor what was or wasn’t behind the subject. Today’s Sony’s DSLR’s can do that with all the Sony lenses I’ve looked at so far, just like their anti-camera shake technology can be used with all the lenses one can mount on their DSLRs.

I hope this helps. If anyone has more to contribute or corrections to what I've posted, please contribute.

[David Kilpatrick]

The D-lenses came in in 1999, long before the digital SLRs, along with ADI flash control. The problem for the digital SLRs was that the glass-covered sensor is nothing at all like the surface of a film emulsion, and cells to read reflected flash from this surface could not be devised with any reliable performance (though Fuji appears to have cracked the problem. and their S-series DSLRs have always been able to work with Nikon flash units, even when those same units were not suitable for Nikon DSLRs). Early attempts by Canon and Nikon to use their existing flash system produced serious problems so Canon introduced e-TTL and Nikon i-TTL. Both were later than Minolta's ADI metering and pre-flash TTL, available in the 3600/5600, and in fact Minolta/KM was the first DSLR maker to have a functional TTL flash system including wireless TTL control.

The modern flash units will still work the same way with film bodies prior to the Dynax 9 - direct reading from the emulsion. However, any film body after Dynax 9 uses a process like the digital method (ADI) because emulsions started to appear with completely different reflective surfaces. FP4 for example is a totally different density to a typical E6 slide film or a colour neg film, so TTL off the film was never going to match with all films.

Early film flashes - 5400, 3200 etc - do not play at all for TTL metering. They are prevented from even trying to work, and locked out with manual only. It is possible to re-chip a 5400 to make it work, but Min/KM/Sony have never offered an official upgrade. Metz did this by issuing new module adaptors - M6, M7 etc for Minolta shoe. Sunpak and Sigma just replaced entire flash units, as did KM/Sony. KM also changed the wireless protocol so that you can't mix 5400 and 5600 heads on a digital body. They just made sure no gross errors were possible.

And then delivered a flash system which produced gross errors all on its own - just like Canon and Nikon did too. It's only in the last 2 years that TTL, wireless, reliable flash for digital SLRs has become reality across the brands. The new 58/42 models bring Alpha into line with Canon and Nikon for proper control of remote wireless heads.

David

[srt101man]

David,

Thanks. I didn't know that Minolta had introduced what Sony calls "distance encoder" in the "D" series lens almost 10 years ago.

Also, I always wondered if the different emulsions would reflect the same amount of light.

[Javelin]

ON the ADI mode on these flashes there still seems to be an influence from another source to determine the metering/flash power. Someone was complaining about it in the DPR forum so I played around one night and can't draw any other conclusion except that ADI is only part of the flash exposure equation.

http://forums.dpreview.com/forums/read. ... e=28667332