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03-06-2009, 01:52 PM   #16
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QuoteOriginally posted by jeffkrol Quote
you got me confused.. The 550 M/P/O is TTL capable just not p-TTL capable.
The D and I'm pretty sure DS should do TTL and p-TTL..
Ha, you're right. I knew TTL didn't work for me on film but that's because my film Pentax has no TTL sensors. I thought I was just really lucky getting decent results with the DS. Sorry for the incorrect advice, I hate it when I do that.

11-08-2010, 07:05 PM   #17
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Back from the dead!

I'm thinking about picking up one of these flashes and was wondering if it could be used on the K-x. It's compatible with my ME Super, and since the OP used it on his K20D, are the hotshoes the same between the two models?

To those who own it: is it any good? Any sample pictures?
10-01-2013, 09:25 PM   #18
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I know this is an old thread, but this info might be useful to some.

I have the Vivitar Auto Thyristor 550FD for Pentax and Minolta cameras, and have tested it on my cameras. This flash has the M/P/O markings on the far right of the film speed selector.

It does not work AT ALL on my K-x.

Turn K-x on, set to manual mode, set to 1/125 and ISO 200. Lens at f2.8
Set flash to A1.
Turn on flash, and the shutter speed bounces from 1/90 to 1/125.
If you press the shutter while it's on 1/125 the flash WILL actually fire, and the photo will be properly exposed.
If you happen to depress it at 1/90, the flash will not fire, and the photo will be black (under-exposed because no flash fired)
However, it bounces between 1/125 and 1/90 so quickly (several times a second) that it's random whether it will fire or not.
The flash does this in ALL modes on the K-x.

The flash works perfectly on the K-01 in A1, A2, and M modes. It works just like any other auto-thyristor flash. TTL does not work, it always fires at full power, but that's to be expected since there is no TTL sensor in the K-01. Wide angle lenses, such as 18mm, do not work well, especially at close distances. You'll see a circle of flash in the center. This is negated as distance increases, but it never fully seems to disappear at 18mm. The effect is diminished at 24mm and gone by 28mm.

Flash works perfectly in all modes (including TTL) on my SF-10

Flash works perfectly in A1, A2, and M modes on my Pentax Q. Tested with the 8.5mm standard prime. Since it's a 47mm equivalent, I saw none of the flash circle as I did with the 18mm.

A1, A2, and Manual work on my Super ME. The ME Super is pre-TTL from what I understand. When the flash is turned on, the shutter speed is automatically set to 1/125 and the "M" LED starts blinking rapidly. Flash fires as expected.

Dakota RZ2000 - Ritz Camera K-mount thing. Flash works in A1, A2, and M modes. (Obviously, as it's a full-manual camera)

MV, MZ, MX, etc. all work in A1, A2, and Manual.

10-01-2013, 09:38 PM   #19
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Note in all my testing, I was using manual mode. Unless otherwise noted, I set the shutter speed to 1/125.

If you wish to adjust flash exposure compensation on the Q or K01, you have to adjust the ISO on the camera or on the flash. Flash will fire up to 1/180 a second. On the Q, you have to set the flash to off for an external flash to fire.

The K01 and Q will somehow magically expose correctly at any shutter speed -- from several seconds on up to 1/180, so long as the ISO and f-stop are correct between the camera and the flash, and the range of target is within the specified area (A1 for distance A2 for closer).


10-02-2013, 09:50 AM   #20
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I just answered this question in another sub-forum. Look here:

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