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Forum: Pentax Camera and Field Accessories 05-22-2015, 12:29 PM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
Update:

I've tried this thing out with two lenses now: an M42 135mm f/2.8 and then the DA 50mm f/1.8.

In the former case (described above), using the published tables yielded quite acceptable results. The camera detected that there was a flash and set a sync speed of 1/180 s.

In the latter, things got more interesting because the camera knew which lens was grafted to it. It chose a sync speed of 1/90 of a second. In AP mode, the results were as described above. Excellent results were achieved out of nominal maximum range by opening the lens right up. In program mode, altering the ISO produced aperture settings according to the table in the instruction manual and this stayed true all the way up to ISO3200, at which point I was up at f/22 anyway and it couldn't close down any further.

I will have to try it with the 28mm M mount lens and see what it does with that.

UPDATE: Again, the camera sensibly detects that there is a flash (albeit an older one) fitted. In M mode, with the Vivitar 28/2.8 applied and the tape trick used to let it stop down, the camera applies a ceiling shutter speed of 1/180 and from that point all is pretty much routine. Ironically the old M42 with its stop-down metering is the friendlier of the two to use as it can be shot in Aperture Priority mode and all you have to worry about is the focusing and selection of aperture according to desired ISO!!
Forum: Pentax Camera and Field Accessories 05-22-2015, 10:26 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
Let me rephrase that more explicity - the best available to me with a reasonable amount of effort in a reasonable time frame.
Forum: Pentax Camera and Field Accessories 05-22-2015, 07:44 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
True. That's one reason WHY I had it done the way I did - my multimeter is an electronics-shop cheapo, and I didn't want to put my camera at risk by doing it wrong with shoddy instruments. The multimeter that was used is also used to repair machinery that keeps very sick people alive, so I could trust them to have the best.
Forum: Pentax Camera and Field Accessories 05-22-2015, 07:20 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
I have tried all the combinations from ISO 100 to 1600 in the table provided with the instruction manual linked above, and I can't tell the difference in exposure looking at them in-camera (I photographed my bookshelf from across my darkened office). I also went beyond, to ISO 3200 and f22, and things looked okay there too. Results for f/2.8 and ISO 80 were near enough to everything else that I don't feel uncomfortable using that in future (naturally more trials will be needed).

The next thing is to see what happens when the flash is nominally out of range and compensatory amounts of aperture are dialled in. I don't expect stellar results here, but it should be fun!

---------- Post added 05-22-15 at 11:53 AM ----------



The measuring was done by a professional who works in hospital biomedical engineering, so I think I can trust the competence of both the device and the person using it. I also showed him the instructions from the article quoted above before we started, so we've got it as right as we possibly can.
Forum: Pentax Camera and Field Accessories 05-22-2015, 07:01 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
Someone who knows what they are doing (because they do it for a living) and who also knows cameras has measured it for me at 7.58 volts, so I should be good to go.
Forum: Pentax Camera and Field Accessories 05-20-2015, 11:23 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
Thanks all. I think I've got a multimeter somewhere at home, along with a whole lot of batteries. Which contacts do I touch between? Or should I just try them all and look for the highest result?
Forum: Pentax Camera and Field Accessories 05-20-2015, 10:17 AM  
Older flash - safe for my K5??
Posted By pathdoc
Replies: 14
Views: 1,142
I am aware that older and/or not-completely-compatible third-party flashes have the theoretical ability to send power pulses into a DSLR that can scramble the electronics and produce expensive paperweights. But what of older brand-name equipment?

I have in my hot little hands a Pentax AF200SA flash, which appears to originally have been bought for a Pentax P3. It's brutally basic, with a head that neither tilts nor swivels, and it demands four AA batteries. On the back is a single on-off switch and a ready/test switch. There is a statement describing the control range as 0.8 to 5 metres (presumably as master) with equivalent feet measurement, and a red sticker with "For Pentax Program" on it, plus "Asahi Opt. Co. Japan". That ought to date it for the experts!!

On the shoe (which secures with a knurled wheel), there are three contact points arranged in a roughly equilateral triangle - one central and two towards the rear, abreast each other.

Do I dare to mount this flash on my K5? And what should I expect if I do?
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