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09-12-2021, 07:38 PM   #1
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Use of older flash units on Pentax K-70

Thanks for the information forum members provided on if the Af500 FTZ flash on whether it could be used on a K-70 without damaging the camera electronics as I have heard could happen if you used older flashes on the new digital cameras (in some postings on other sites), However I have another related flash question, I remembered I also have a couple of Vivitar 285s that I used with slave triggers and umbrellas. Although they are not TTL These units had an auto mode that would meter the light coming back to the flash and will cut it off for correct exposure, All you have to do is set the film speed and distance. I fired them up and and reformed the capacitors using fresh batteries and they seem to be working quite well in metering light for exposure in their auto mode considering they have not been used in about 15 years. I tried them with my first Pentax digital a istDs using a remote flash trigger and exposure seemed to be correct in the few tests that I did. Has anyone out there tired a Vivitar 285 with a K-70 and did not fry the electronics on the camera. If this could be fired from the hot shoe of the my K-70 this would save me the effort of putting the camera on a bracket and having to use a slave to fire the Vivitar from the K70 pop up flash. That would solve my problems for the occasional time I need a long range flash as it has a guide number of around 140 and auto feature works up to 70 feet.

If Uncle Vanya sees this I can also say that this old grandfather had a Spotmatic and it was the best up until the k1000 then the MX, SF10 and my last film Pentax a Z-1p which I am still using regularly. Being new to this forum and not quite sure how this works I previously did a quick reply to the reply you sent to me and found out I replied to myself. .

09-12-2021, 07:53 PM   #2
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QuoteOriginally posted by Alex10 Quote
Has anyone out there tired a Vivitar 285 with a K-70 and did not fry the electronics on the camera.
Measure the trigger voltage. Newer versions of the Viv 285 will have a voltage below 20V. Vintage versions may be as high as 300V which is high enough to damage your camera unless paired with a Wein Safesync or similar device.

Pulled from another thread...How to measure

QuoteOriginally posted by demp10 Quote
Turn on the flash and let it charge fully. Then use a volt meter and measure between the pin at the bottom of the shoe (positive) and the metal strips at the side groves of the shoe (negative). Make sure that the range in the volt meter is set high enough (200~300V) for the non "HV" version of the 285 flash (the "HV" is around 6V).

If you short the contacts you will fire the flash and the voltage will drop momentarily to 0.



Steve

(...really like my Viv 283, but almost never use it on-camera with the K-3 and then only with protection...)

Last edited by stevebrot; 09-14-2021 at 05:24 PM.
09-14-2021, 12:57 PM   #4
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If it is an old Pentax flash unit, even those with TTL capability, (recent models like the K-70 cannot function with TTL- only P-TTL or manual) if it has an auto mode as you say, which uses its own meter to regulate the flash duration, I have used such a flash with this setting on a modern DSLR, though not recently. Results were quite good for my uses. One of my favorites for on-camera use in this manner has been the AF 280T.

09-14-2021, 04:27 PM   #5
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The AF280T is one of the best flashes I've ever used...

The AF360 can work with TTL or P-TTL. I use one with my K1, and it's terrific.

I would suggest you test any old flashes you have around, and then mark the ones with high trigger voltage so you don't accidentally use them on the newer cameras.

I have a couple of old flashes from film cameras I still use on film cameras but not with the newer stuff...

-Eric
09-14-2021, 04:57 PM   #6
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QuoteOriginally posted by TwoUptons Quote
The AF280T is one of the best flashes I've ever used...
Another vote for the AF280T as a safe flash with "auto" as an option. One should be aware that the K-70 will respect its flash dedication features and that may influence its behavior depending on exposure mode. I was able to detail the quirks in my AF280T review:

PENTAX AF 280T reviews - Pentax Camera Accessory Review Database

QuoteOriginally posted by TwoUptons Quote
I would suggest you test any old flashes you have around, and then mark the ones with high trigger voltage so you don't accidentally use them on the newer cameras.
I keep my high voltage units in a separate box with a caution note.


Steve

Last edited by stevebrot; 09-14-2021 at 06:29 PM.
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