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08-22-2010, 04:11 AM   #1
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Flash compatibility

I don't use flash very often - I'm more of a natural light kind of guy. I have an old flash that I bought second hand about 15 years ago, which is good enough for the rare occasion I want artificial light.

It's a "multi-dedicated" off-brand flash with lots of hot shoe pick-ups and a switch to select between major (in the day) camera brands. It worked just fine on my Ricoh XR-10, on my Pentax MZ-7, and on my Samsung GX-10.

I recently upgraded to a K-7. My old flash doesn't work with my new body. Just doesn't fire at all.

Did something change between the K10-D / GX-10 and the K-7 that my old flash is now incompatible? Or am I doing something wrong?

I'd rather not waste good lens money on a new flash, but if I gotta, I gotta...

tim

08-22-2010, 05:52 AM   #2
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What is the brand/model of the flash? There are some that don't use the center pin to trigger the flash.

In general though, most old flashes will trigger just fine with modern cameras.

You should check your camera against this list though to see if the voltage is safe: Photo Strobe Trigger Voltages
08-22-2010, 06:07 AM   #3
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If it triggered (and still does) with the GX10, so should it with the K7. The only thing I can think of is you aren't pushing the flash all the way on to the hot shoe. Sounds silly but it does happen once in awhile. I do agree that you should probably make sure the trigger voltage is within tolerance (and proper polarity) before mounting any 'old' flash to your camera.

08-24-2010, 08:16 PM   #4
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It's an Achiever flash - I've never seen nor heard of the brand, but there it is at the top of the list AlohaDave posted, so they mustn't be as obscure as I had believed. Not sure of the model (don't have it with me right now), but will check. Never realised that there was a potential to damage a camera with a flash this way, so I'm glad I didn't damage my GX10 (and hope the K7 is okay too!).

I definitely pushed it right on, as far as it would go. There was quite a bit of "foot" hanging out the back of the hotshoe, so I looked to see if there was any way to push it in further, and it was hard up against the front of the shoe.

Can't re-test it on the GX10 (to confirm that it's not a flash failure that coincided with getting a new camera), because it was stolen - the K7 is my insurance replacement

Thanks for the comments - seems there's no obvious reason why it shouldn't work, so I should investigate further.

tim

08-24-2010, 08:27 PM   #5
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QuoteQuote:
Thanks for the comments - seems there's no obvious reason why it shouldn't work, so I should investigate further.
Is there a test button on the flash? That would at least tell you if the bulb/capacitor are working at least.

If there isn't a test button, you can short the center pin and the side pin on the foot together (a paperclip will work fine) and it should fire if everything is working correctly. That should isolate if the problem to the flash or the camera.
08-24-2010, 11:40 PM   #6
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Oh sure, the test button fires the flash. No problem there.

I'll short across the various contacts on the shoe to see if there's a pair that cause the flash to fire.
08-25-2010, 08:17 AM   #7
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QuoteOriginally posted by barefoot Quote
Oh sure, the test button fires the flash. No problem there.

I'll short across the various contacts on the shoe to see if there's a pair that cause the flash to fire.
The two you want to short are the center pin and the one in the groove on the side of the shoe. The one in the groove makes contact with the lip of the shoe on the camera and the center pin fires the flash.

The others are for the more advanced features, such as TTL, or telling the camera that the flash is ready.

The MZ-7 used the TTL protocol. That means that the camera had a flash sensor that read the light reflected off the film to control the flash duration. The K10D uses P-TTL, which pre-flashes the flash BEFORE the mirror flips up and reads the light with the sensors in the prism. Pentax dslrs no longer have the sensor in the mirror box, so TTL won't work. It will fire, but it won't expose properly.

You must either use it in manual, or, if the flash has its own sensor, in auto mode.
08-25-2010, 01:16 PM   #8
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...make sure your shutter speed is less than 1/180. The K-7 won't fire an external, non-dedicated flash at any speed above that.

08-26-2010, 03:55 AM   #9
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OK, some real answers to your helpful questions.

The flash is an Achiever TZ 250.
Shorting from the centre pin to the contact on the edge of the shoe fires the flash.
I'm putting the camera in "X" mode, locking it at 1/180s.
The flash is pushed as far into the shoe as it will go.

When I fire the camera, the flash doesn't go off, and the photo is (of course) under-exposed.

This occurs whether the flash is in manual, half- or full- power auto modes.

I think my next step will have to be to take the camera to a shop and test a new flash. If a new flash that is supposed to work on a K7 doesn't work on mine, the camera goes home to be fixed. If a new flash _does_ work... I guess I'll have to buy one :-|

tim
08-26-2010, 11:44 PM   #10
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The flash seem to have negative polarity. Achiever TZ250 Flash as a slave-Photography So I would think that is the issue.

Thank you
Russell
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