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Comparing current PTTL-compatible flash options
Posted By: mattdm, 03-19-2008, 08:05 AM

UPDATE: Further updates to this article will be done on a web site dedicated to this purpose.

The Definitive Guide to Pentax and Third-Party P-TTL Flash Options

This is available for collaborative editing and released under the Creative Commons Attribution-Share Alike 3.0 License. Please follow the link above for the latest version. Thanks.


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There are currently three flashes made by Pentax which work with the P-TTL flash metering system, plus two from Metz, one from Sigma, and three from Promaster.

There's also a "generic make" flash sold as the Soligor DG-420 Z, Sakar / Digital Concepts 952AF/PEN, Dörr D-AF42, and perhaps other names (Praktica / Exacta DPZ 38AF?). This apparently also has P-TTL support. It doesn't have high-speed sync or work as an optical wireless slave.

The Sigma flash comes in two models, with the "Super" version including the ability to work as a wireless slave and in high-speed sync mode. The most basic Pentax flash (AF200FG) can't work as a wireless slave either. Both Metz models can, although only the more expensive one can act as an on-camera controller. (All slaves can be controlled by the built-in flash of the K10D or K20D, making that at least good for something.) The Promaster models don't have the ability to work as wireless slaves or in high-speed sync mode.

The relative power of these flashes is quite hard to compare because the manufacturers don't deign to list their flash power specs by luminosity, only via guide numbers. And to make things worse, they all provide a random sampling of different focal lengths at which they've measured the GN, so correlation is difficult. And there's not an industry of rigorous third-party testing for flashes, so we have to take them at their word. With some scouring, though, I put together this list manufacturer-claimed guide numbers for ISO 100 @ 50mm:
  • Pentax AF540FGZ = 148'
  • Metz 58 AF-1 = 137'
  • Sigma EF-530 DG = 132'
  • Sakar 952AF/PEN, et al115' *
  • Metz 48 AF-1 = 114'
  • Promaster 7500EDF = 112'
  • Promaster 7400EDF = 100'
  • Pentax AF360FGZ = 94'

* For the Sakar/generic flash, there's no published spec for 50mm, so I'm interpolating. I trust this number least of all.

Also, the following flashes can't zoom to 50mm, so presumably this data is roughly the same as the coverage for 28mm on the zoom flashes. However, that would make the Promaster 7200 more powerful than the 7400 or 7500, which seems dubious. So, I'm not quite sure exactly what to make of either of these numbers.
  • Promaster 7200EDF = 100'
  • Pentax AF200FG = 66'

The guide number gives the (nominal) number of feet away a subject can be to be lit at that focal length and ISO, at f/1. Divide by aperture to get effective distance stopped down to the realm of real lenses — that is, the Metz 48 AF-1 is listed as providing full lighting at about 14 feet away at f/8.

If we assume they're all lying equally then that makes a somewhat useful list. The power in terms of light output is proportional to the square of the GN, so the Metz 48 AF-1 is (again, going on claimed numbers) about 1.5× more powerful than the Pentax AF360FGZ.

Here's the whole list in terms normalized to AF360FGZ as 2.0 (I had the AF200FG as 1.0, but since that really can't zoom to 50mm, the AF360FGZ makes a better base. But it still makes the other numbers come out nicer if we make it 2.0 instead of 1.0)
  • Pentax AF540FGZ = 5.0×
  • Metz 58 AF-1 = 4.3×
  • Sigma EF-530 DG = 4.0×
  • Metz 48 AF-1 = 3.0×
  • Promaster 7500EDF = 2.9×
  • Promaster 7400EDF = 2.3×
  • Pentax AF360FGZ = 2.0× (Of course.)

Which comes out nice and satisfyingly close to whole numbers, eh? That's probably not coincidence. The K10D's built in flash, by the way, comes out at ¼×.

Probably an even more honest answer would show the power at the widest setting, not with the reflector zoomed to 50mm. (Although, hard to argue with the practicality.) And I wouldn't be terribly surprised if there's a discrepancy here in some manufacturer using 1.5× crop-factor converted focal lengths (that is, claiming the 50mm numbers for the field of view of a 75mm full-frame lens). So this really ought to be tested somehow to give a perfect answer, but this is what I can do with the publicly-stated data.

Also, the Metz, Sigma, and Promaster flashes have a reflector which can focus the beam more tightly than the Pentax and Sakar/Digital Concepts flashes — they go to 105mm (35mm full-frame), whereas the Pentax and Sakar models have zoom reflectors which stop at 85mm. The listed guide numbers for the most narrow setting are:
  • Metz 58 AF-1 = 190'
  • Pentax AF540FGZ = 177'
  • Sigma EF-530 DG = 174'
  • Metz 48 AF-1 = 157'
  • Promaster 7500EDF = 138'
  • Sakar 952AF/PEN, et al = 138'
  • Promaster 7400EDF = 120'
  • Pentax AF360FGZ = 118'

So, on a current 1.5× crop Pentax dSLR, the relative power if you're at a focal length of 70mm or above (with the difference between the numbers in the first comparison starting to kick in at around 56mm) is as follows (again normalized to AF360FGZ as 2.0).
  • Metz 58 AF-1 = 5.2×
  • Pentax AF540FGZ = 4.5×
  • Sigma EF-530 DG = 4.3×
  • Metz 48 AF-1 = 3.5×
  • Promaster 7500EDF = 2.7×
  • Sakar 952AF/PEN, et al = 2.7×
  • Promaster 7400EDF = 2.1×
  • Pentax AF360FGZ = 2.0× (Of course.)

I note in particular that even though they have the tighter zoom, the Promaster flashes don't actually have the boost in power one might expect from the more focused beam. Either the numbers are suspect or their reflector doesn't do as much good as that from Metz, which is the clear winner from this narrow (pardon the pun) point of view. (The Metz flashes "gain" about 90%, the Sigma flash 75%, but the Promasters only about 50%. 58% and 43% for the Pentax AF540FGZ and AF360FGZ, respectively. It's all very non-linear.) And again, I don't really trust the Sakar/Digital Concepts number very much — but at least this time it's based on a number they publish, not just a guess.


Last edited by mattdm; 12-06-2008 at 11:28 PM. Reason: point to google knol for latest version
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03-26-2008, 11:03 AM   #16
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You should add the Soligor P-TTL DG-420 flash as well..

https://secure.soligor.com/index.php?id=5&backPID=75&tt_products=6704

Fairly inexpensive too!

03-26-2008, 11:06 AM   #17
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QuoteOriginally posted by Tom M Quote
You should add the Soligor P-TTL DG-420 flash as well..

https://secure.soligor.com/index.php?id=5&backPID=75&tt_products=6704

Fairly inexpensive too!
Will do, thanks.

I should probably expand this entry to cover more than just flash power, which is only a tiny part of the story.
03-26-2008, 11:19 AM   #18
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And in some checking, The Sakar Digital Concepts is indeed P-TTL if you buy the Digital Concepts 952AF/PEN for about $189 or less or so from what I see..

And thanks for putting this list together. At one point in time it seemed there were no options but the Pentax. And the Pentax and Sigma both have problems, either with QC or with function.. Now of course, there seems to be more otions.
03-26-2008, 11:26 AM   #19
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I can't find a guide number rating for the Soligor flash at 50mm. Based on the rating for the 85mm (max zoom) setting it seems to be at about the power of the Metz 48 AF-1 (but less well-featured). I can't find a US retailer, either.

03-26-2008, 11:46 AM   #20
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It does seem to be popular in Europe.. And something I was not ware of, it was the first manufacturer besides Pentax to offer P-TTL for Pentax.. Metz was the second and I suspect Sigma shortly thereafter. It seems that both Metz and Soligor are German and got on the ball rather quickly with regards to P-TTL flash.

I can't find any real info on it either other than people seem to be pleased with it. Apparently it is a quality built unit.

I wish I could buy something other than the AF540 but since I'll need the range accompanied with a Better Beamer for extended range to use with the Bigma, I'm kind of SOL it seems.
03-26-2008, 06:48 PM   #21
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Hmmm. It seems that the Soligor DG-420 Z for Pentax and the Sakar Digital Concepts 952AF/PEN are in fact the same thing. The pictures are identical (except for branding) and all of the details listed are the same. Apparently also "Dörr D-AF42", "Praktica DPZ 38AF", and "Exacta DPZ 38AF".
03-27-2008, 06:23 AM   #22
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I have read that the Praktica and Exacta have lower output. Not sure if that's true however as I only read it in some forums while digging through google. We really need some Europeans to chime in for those units

Judging by part numbers, The Dorr 42 is the same as the Soligor and Sakar and the Exacta and Praktica at 38 are less output.
03-27-2008, 07:18 PM   #23
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QuoteOriginally posted by Tom M Quote
Judging by part numbers, The Dorr 42 is the same as the Soligor and Sakar and the Exacta and Praktica at 38 are less output.
Yeah, the latter give an GN (at max zoom) of 38m, whereas the others say 42m. Either the Exacta/Praktica models are an older or cheaper build, or else they're just less prone to exaggeration. Since I'm skeptical about all of these in general (TANSTAAFL), I'm kind of inclined towards the second explanation, although I have no evidence either way. (It's approximately a 20% difference in power.)

03-29-2008, 11:08 AM   #24
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As a service to the Pentax community here, I went out and purchased the Promaster 7500EDF.

Here are some quick impressions.

First and foremost - it is 100% P-TTL compatible.

Build Quality: Very good. Positive clicks for the tilt and swivel with position indications on the LCD. The Battery door is a slide in type, depress the batteries, slide the cover over them. A simple yet solid design with no hinges or flaps to break. Slides into the hot shoe nicely and has a positive spin-down lock. The included stand is simple, small and sturdy. Also, the included press-on diffuser holds tightly and works well (allows the unit to cover 11mm for DSLR)

Manual: Well, the unit seems simple enough so far so the lack of an overly detailed manual may not be such a big deal. It's a fold-up manual tucked in the box. EDIT: Just read the manual, took 5 minutes. It's well written, simple and informative, if maybe a bit elusive as to one feature though - The MULTI feature. More on that later.

Features: Brief for now.. So far I already love the dual-head design. Having two flashes is great. The unit has a built in fill-flash as well as the main flash head. Set it to dual-head setting, point the main flash at the ceiling, the unit knows the position, does the calculations and with a press of the shutter you have nice fill flash and bounce flash. Much more to come on the features, I've only been using it for 20 minutes! Also, the focus assist works nicely in very dark situations. It's a projected horizontal line pattern that the AF locks onto quickly (lens specific of course but it is enough to help slow lenses so it very well could improve a mediocre lens).

The unit has a feature called MULTI - it's described as being able to fire multiple flashes during a single shutter release. Using this feature and setting the shutter speed for say, 1 second, the unit will fire anywhere from 1-10 flashes anywhere from 1 through 100hz for stopping action multiple times in one frame.

It includes a Model mode which is simply a modeling light, high frequency for close up and low frequency for portraits. It works perfectly as described.

P-TTL mode, does exactly as it describes and works very well so far. Though, as we all have come to find out, every P-TTL flash seems to have it's issues. Only time will tell.

Manual mode, it allows you to select your output from 1/1 to 1/64 power.

Wireless/Slave mode works very nicely. I took a few shots just to demonstrate it works well. The first image is with the in-camera flash on with the 7500EDF off, the second shot is with the 7500EDF on in wireless mode. As you can see, it works as it should. It does not fire on the pre-flash.

The LCD is easy to read and has a backlight if needed.

Includes leading and trailing curtain as well as manual zoom.

The flashes covers from 17mm with diffuser, 24mm without (11mm on DSLR with diffuser, 16mm without) to 105mm and has a GN of 138ft with the flash zoomed to 105mm.

Bounce angle is -7deg to 90deg (-7 aims it down for macro work)
Swivel is 180deg

Additional: Has a one year warranty. Includes a Flash Stand and a Snap on Diffusor.

Price paid : $279 from a local brick and mortar.

I may very well have paid a premium but so far it is considerably nicer than the AF360 and has different features than the AF540. For one, the fact it's a dual-head design tells me it will be more useful or easier to use for portraits and indoor events. Not to mention, if you use it wirelessly, you will essential have three flashes; the on-camera flash pointed directly at the subject, the detached 7500EDF angled using the fill-flash head and of course the main flash unit angled or bounced in any direction.

Conclusion: I'm liking the purchase but, let's see if I'm still as happy with it in a week or three..
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Last edited by Tom M; 03-30-2008 at 10:00 AM.
03-29-2008, 11:25 AM   #25
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Cool, thanks. Looking forward to your report in a few weeks.

The Metz 58 AF-1 has the dual reflector feature too, although it's considerably more expensive (especially in the US).
03-29-2008, 12:27 PM   #26
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QuoteOriginally posted by mattdm Quote
Cool, thanks. Looking forward to your report in a few weeks.

The Metz 58 AF-1 has the dual reflector feature too, although it's considerably more expensive (especially in the US).
Matt, I had the two side-by-side today, the Metz 58 and the Promaster 7500 - It was very hard to justify $120 difference for HSS.. Now, the Metz is a fine unit, make no mistake about it.

And no, the Promaster 7500EDF does not have HSS, confirmed. Though, the unit IS FLASH UPGRADEABLE and it has that MULTI mode which shows me the unit is capable of HSS.

I'm going to update my earlier post with some more info.
03-29-2008, 02:02 PM   #27
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There are more owners of 7500EDF here on the forums.
https://www.pentaxforums.com/forums/151553-post17.html
03-31-2008, 08:22 PM   #28
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Two images of the Promaster 7500EDF mounted to the K10D..



04-01-2008, 04:42 PM   #29
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Thanks Tom - so in that other thread Chris says it has no auto mode - is this right, and if so, does this have any implications to the flash dummies like me who want a decent flash, but will probably have to start out in auto-everything?
04-02-2008, 07:01 AM   #30
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It has auto mode - It's called P-TTL.

Just put the unit in P-TTL mode and that's all there is to it. You can put the camera in all green mode, fire off at will. It works just like the pop-up flash would but is obviously far more powerful and much more useful. (if you don't need the most powerful setup, you can get a little less powerful unit for $169 and $200 - look at promasterflash.com or the promaster flash website might be best)

When you use the camera in a mode other than green like M or TV, etc you control the flash exactly the same as you would the pop-up flash, you can compensate for flash exposure by dialing it down -2.0 or +1.0 ... trailing curtain, leading curtain, etc..

But yes, it is a fully automatic flash that needs no other input from the user other than to attach it to the camera and make sure it's in TTL mode. It fires off a pre-flash just like the pop-up does, measures the scene from the pre-flash, then fires off the main flash for the shot with an adjusted output level to give proper exposure.

FYI: So far, so good.. I've been using it to light up birds at 50-100ft with no problems whatsoever. And if a bird is really far away, like say 150 to 200 ft or so, I've been switching to manual mode (press one button) and getting enough flash to get a catch light and put a twinkle in the eye of the little bugger. So, yes. I've been quite happy so far. And something the literature of some flashes is confusing on, when you use the the flash in P-TTL mode it has a reduced range, for this unit it's between 1-99ft, in non-P-TTL mode it's good to 138ft - All flash units are like this but some are like, 1-24ft only in P-TTL mode. In this respect this flash is good. I'm looking forward to using this unit with a better beamer for some long-distance and increased DOF shots as the unit is capable of a very wide area of coverage which when used in conjunction with a better beamer translates into very focused beam at long distances.

Another thing, I honestly thought that HSS was something I would miss. Then I thought back to 15 -20 years ago when I shot as much as I do today but in film with a flash that was no faster than 1/125 or so.. I thought, how did I stop action then? Well, simple really.. I just used a slower shutter of about 1/60th and relied on the flash to stop the action as the flash is faster than any shutter at 1/30,000 of a second

EDIT: I just realized that you meant Auto mode as in, Auto and not relying on the camera for exposure information.. That's some pretty old-school stuff. My Vivitar 283 has that. Try this Promaster FT1700 Bounce Thyristor Flash Brand new $39 and has Auto Thyristor by Promaster FT1700 (looks like my Viv 283 lol) P-TTL supercedes auto-thyristor, sort of.

Read this thread in it's entirety Wedding and social event photography Forum: Opinions about Promaster 7500DX Flash - photo.net

Oh and, god forbid you change from Pentax, you can just buy the module for whichever inferior brand you go with and still use the Promaster 5xxx series flash with the n3ew system

Last edited by Tom M; 04-02-2008 at 11:10 AM.
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