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Old Jan 7, 2007, 10:25 AM   #1
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How do these compare? Which is the better value? I believe the prices are close after my Wal-Mart discount and the Pentax rebate (if it's still good). I just want to know which is the better flash, and why?
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Old Jan 7, 2007, 12:14 PM   #2
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Hi inneyeseakay,

I think that the choice between these two is dependant on what you see as your priorities for future use of flash in your photography. Both flashes have red LED AF assist lights and can do slow speed synch which will allow you to balance indoor background and subject exposures so your subject doesn't look like he's in a dark room.

If you only want a more powerful and versatile flash for general picture taking, and don't see the future possibility of using multiple external flashes, then the Sigma is probably the better bet. It's about half again more powerful than the Af360 FGZ and the ability of the head to swivel will help with bouncing the flash for portrait oriented shots. The extra power would be useful for bouncing in rooms with higher cielings and at greater camera to subject distances, or when using diffusers or bouncers at greater distances. It's also less expensive.

One of the potential negatives is that Sigma apparently reverse engineers Pentax's P-TTL technology as opposed to licensing it from Pentax (as indicated by their admitted incompatibility with K series bodies and the free rechip update offered). They obviously didn't get it 100% right the first time, and potential incompatibilty with future bodies might crop up. As long as they're willing to correct problems that arise, then this problem isn't really serious.

The AF360 FGZ has a number of more advanced features. The major negatives are lack of swivel head, the fact that the head locks in the horizontal position and you have to push a button to raise it for bounce (the latter is just an annoyance), and less power (but it's still about 8 times more powerful than the onboard flash). On the plus side are:

high speed synch which allows you to balance the exposure between subject and background in outdoor fill flash situations,

a built-in optical slave trigger which allows you to use it as a manual slave to another non-P-TTL flash (it fires on the first flash, so it won't work correctly with the onboard flash as that is always P-TTL)

wireless TTL compatibility when used with another wireless TTL compatible external flash, which allows fully metered multiple flash use.

trailing curtain synch (which fires the flash just before the shutter closes as opposed to the normal leading curtain synch which fires as the shutter opens - this can give you a subject moving across the frame with a slow shutter speed a trailing motion blur with the subject frozen at the end of the blur).

Auto Thyristor mode which uses a sensor in the flash to meter the exposure and eliminates the preflash of P-TTL if you run into a subject who always gets caught blinking when using P-TTL. You do have to match ISO and aperture manually, but the info on the flash will tell you what to do.


Practically, the High speed synch and Auto Thyristor mode are probably the most important features for the more casual flash user, but if you really get into using flashes as a totally controllable light source the wireless TTL capability might be a real cosideration.

Only you can decide which features (or omission of features) might be important to you.

Sorry for the long post -- I figured that some of the features needed some explanation.

Scott



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Old Jan 7, 2007, 12:32 PM   #3
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How fast does the af360 sync? I noticed that my auto thrysister flash only goes off when shutter speed in under 1/180", will the af360 fire at shutter speed above 1/180"?
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Old Jan 7, 2007, 1:00 PM   #4
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When set for high speed synch, the AF360 will synch up to the limits of the shutter.

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Old Jan 7, 2007, 1:04 PM   #5
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...and the Sigma only to 1/180"?
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Old Jan 7, 2007, 3:05 PM   #6
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Unless they're hiding something in their specs, the ST doesn't have high speed synch capability, so it'd be limited to 1/180 or longer. The EF 500 DG SG Super P-TTL is not much more expensive than the AF 360 FGZ and has all it's features plus a couple more, so it might be something to consider.


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Old Jan 7, 2007, 5:18 PM   #7
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I'm kinda leaning towards the cheaper Sigma due to the fact that a new baby will be here soon and money is an issue, but at the same time, I don't want to mess with my manual flash while trying to capture the essence of her childhood. So any suggestions on possibly an even less expensive P-TTL compatible flash than the Sigma 500 ST?
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Old Jan 7, 2007, 6:25 PM   #8
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The only other credible alternative that I've heard of is the Promaster 5750 DX with the Pentax Digital module. A number of users from different forums are happy with them, but AFAIK they are more expensive than the 500 ST. For full P-TTL compatability, Pentax, Sigma, and Promaster seem to be the only players.

I have heard of one guy who bought a Digital Concepts that was supposed to be P-TTL , but the first one died after a few flashes, and the replacement actually blew up! . . . needless to say, I crossed it off the list of possibilities.

Auto thyristor flashes like the $80 Sunpak 383 are a very good option. They can be used with any camera that you can set aperture, shutter speed, and ISO. They have a sensor in the flash which cuts off the flash when it senses that enough light has reached the camera. All you have to do is set the ISO speed and a shutter speed 1/180 or slower, then match your ISO speed on a slider and choose a power range on the flash, then set the aperture on the camera according to what the flash tells you. The flash will then give you at least a close exposure over the distance range indicated on the slider on the flash ( it's a lot easier than it sounds). Film guys relied on these for years with great success, and it's even easier with digital where you can do an instant review and make whatever adjuxtments might be needed. With just a little experience, you'll just know what settings are needed. I use a number of flashes in this mode with my K10 and am very happy with the results. P-TTL is easier, but only a little.

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Old Jan 7, 2007, 7:08 PM   #9
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I have an auto thrysister flash that I picked up for about 40 dollars from Ritz camera, but I really would like something that communicated with the camera and something that I have to do less work with, I guess you can call me lazy.
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