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01-02-2016, 03:27 PM   #1
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Pentax Compatible TTL Flashes

I am looking to purchase an inexpensive used flash on ebay. There are several TTL flashes for Pentax with makes such as Promaster, Vivitar, and Bower. If these flashes come out of the film era, will thay still work on my K-50 DSLR< or will mounting them hurt my camera?

01-02-2016, 03:39 PM   #2
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The shouldn't hurt the camera, but you won't get full automation unless the flash supports P-TTL.
01-02-2016, 04:30 PM   #3
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IIRC true TTL is only available in some of the high-end Pentax film cameras and the *istD; no other Pentax DSLR ever had it. It's one of the things I am hoping for the return of in the full-frame. I am almost certainly going to get one eventually, but restoration of full TTL and especially restoration of aperture linkage (or some other means of effortless wide open metering) for the K and M lenses would be HUGE incentives.
01-02-2016, 04:31 PM   #4
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I had a Bower flash that was for Pentax and it worked fine on my Kx, but it would not work on my K5. So I would advise you not to get one unless someone has already tried one on a K50

01-02-2016, 06:47 PM   #5
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QuoteOriginally posted by pathdoc Quote
IIRC true TTL is only available in some of the high-end Pentax film cameras and the *istD; no other Pentax DSLR ever had it. It's one of the things I am hoping for the return of in the full-frame.
The trouble is that restoring TTL requires introducing new flashes to support it, as the current models don't have it. It would seem that having the camera do both P-TTL and TTL would be not so good, since older flashes that do both would choose...which? I suppose it can all be worked out, of course, but it might be a consumer confusion nightmare.
01-03-2016, 08:17 AM   #6
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I've used a Sunpak 422D and 544 (via the X-sync socket) on my K-5 IIs and K10D with no problems. Just an FYI for anyone reading this thread.
01-03-2016, 08:55 AM   #7
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Thanks FotoGuy I will keep those flashes in mind.... Does anyone else have a recommendation of third party flashes that may work well?
01-03-2016, 08:56 AM   #8
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QuoteOriginally posted by MadMathMind Quote
The trouble is that restoring TTL requires introducing new flashes to support it, as the current models don't have it. It would seem that having the camera do both P-TTL and TTL would be not so good, since older flashes that do both would choose...which? I suppose it can all be worked out, of course, but it might be a consumer confusion nightmare.
This raises two questions in my mind:

1) Do flashes have reprogrammable firmware the way digital cameras do?

2) Isn't this an issue that can be solved with a mode switch, just as is planned for DA-only vs. FF lenses?

As far as I am aware, doing TTL without a pre-burst requires only that the camera be able to issue an order to shut down the flash emitter once the appropriate amount of light has been delivered. The issue, which my first question addresses, is to what extent current P-TTL flashes are able to accept such an order as they currently stand.

Current shooters of the *ist-D who also own an AF360 or 540FGZ-II are invited to comment. Also, I haven't yet done that much shooting with my 540FGZ-II, but I could have sworn when playing with the menus the other day that I saw a TTL option offered without a P prefix.

01-03-2016, 09:53 AM   #9
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QuoteOriginally posted by pathdoc Quote
Also, I haven't yet done that much shooting with my 540FGZ-II, but I could have sworn when playing with the menus the other day that I saw a TTL option offered without a P prefix.
The older AF540FGZ has a TTL mode, so I would not be surprised if the newer version does as well.

Phil.
01-03-2016, 03:59 PM   #10
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QuoteOriginally posted by gofour3 Quote
The older AF540FGZ has a TTL mode, so I would not be surprised if the newer version does as well.

Phil.
The 360 II does not. I believe Adam mentions in his review explicitly that the 540II does not.
01-03-2016, 05:22 PM   #11
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That's what I thought, but I'm sure about what I thought I saw. Will go back when I have a moment and check.
01-03-2016, 09:58 PM - 1 Like   #12
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QuoteOriginally posted by pathdoc Quote
This raises two questions in my mind:

1) Do flashes have reprogrammable firmware the way digital cameras do?

2) Isn't this an issue that can be solved with a mode switch, just as is planned for DA-only vs. FF lenses?

As far as I am aware, doing TTL without a pre-burst requires only that the camera be able to issue an order to shut down the flash emitter once the appropriate amount of light has been delivered. The issue, which my first question addresses, is to what extent current P-TTL flashes are able to accept such an order as they currently stand.

Current shooters of the *ist-D who also own an AF360 or 540FGZ-II are invited to comment. Also, I haven't yet done that much shooting with my 540FGZ-II, but I could have sworn when playing with the menus the other day that I saw a TTL option offered without a P prefix.

Yes, the camera must be able to send a signal to the flash to shut down the lamp. However, the camera must have additional hardware, within the mirror box to, somehow, determine when the proper amount of light had been received, Current cameras do not have such hardware.

In the P-TTL system, the preflash is fired while the mirror is still down. The light sensing is done using the same photocells in the viewfinder that measure ambient light. The preflash goes off, the sensors read the returning light, the mirror goes up, the shutter opens, the main flash is triggered. The shutter closes, the mirror returns. While the mirror is up, the light sensors in the viewfinder do not receive any light from the lens.

It is the requirement for additional hardware that makes a return to TTL unlikely.

And, one must be careful when reading specs for flashes. I have seen several cases in which the specs referred to TTL, when the context clearly shows that the authors mean P-TTL, I-TTL or E-TTL; that is, preflash technology, not reading the light during exposure.
01-04-2016, 06:03 AM   #13
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QuoteOriginally posted by noblepa Quote
It is the requirement for additional hardware that makes a return to TTL unlikely.
I am well aware that it cannot be done as a firmware reprogramming fix in existing, current-production DSLRs. But if they were willing to do it at all, the full-frame offered them the perfect opportunity to reinsert the TTL sensor at the design stage. We know it is possible, as they had a working system in the *ist-D. Alternatively as a firmware workaround, there might be a way to use the sensor itself, e.g. offer full TTL in crop mode only (regardless of the lens used) and use the non-imaging pixels to manage the exposure. It would not be optimal, but it could be made to work and at least having the camera in the field would buy Pentax time to reintroduce the full hardware in the second-generation full-frame body.
01-04-2016, 06:57 PM   #14
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My only concern is whether mounting the flash on the camera will somehow hurt the camera...
01-05-2016, 05:23 AM - 1 Like   #15
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QuoteOriginally posted by scwinn Quote
My only concern is whether mounting the flash on the camera will somehow hurt the camera...
Then you need to go read this.
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