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Old Jul 18, 2009, 4:50 PM   #81
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Default Low Priced Flash Unit Alternatives

Two weeks ago, while shopping at a rural garage sale, I found an almost new Sigma EF 500DG flash in the box that proclaimed it was adapted to handle the Pentax PTTL protocol. I managed to purchase the flash unit for $(US) 10.00. It is not as powerful as the Sigma EF-530 DG Super flash unit, but it does work very well with my Pentax KM/K-2000 camera.

So garage sales, and auction sites can also be a potential source for PTTL flash units. However, I would stick with the Pentax, Metz, or Sigma branded units. The Pentax and Metz brands are very well constructed and finished. However, you must keep in mind that Sigma does not get as good a fit and finish score and that before the Metz 58 the were flash units that did not take full advantage of the Pentax PTTL Flash System.

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Old Jul 18, 2009, 6:04 PM   #82
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Default Metz 58 AF-1 Flash

Most Pentax folks are familiar with the look of the Pentax AF-360 and AF-540 flash units. Here is a look at the Metz 58 AF-1 flash unit. Note the smaller flash fill-in repeater in the lower portion of the case front on the flash unit.

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Old Jul 18, 2009, 6:08 PM   #83
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Default Sigma EF-530DG Flash Unit-Front View

here is a photo of the current Sigma flash unit designed to operate with the Pentax PTTL Flash System. It is the Sigma EF-530DG. Here is the front view.

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Old Jul 18, 2009, 6:10 PM   #84
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Default Sigma EF-530DG Flash Unit-Back View

Here is the back view of the Sigma EF-530DG flash unit.

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Old Jul 18, 2009, 8:43 PM   #85
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Sarah,
Did you turn anything up in your research that speaks to the metering question I asked and when users might encouter over/under flash exposure and might want to use FEL?
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Old Jul 18, 2009, 9:14 PM   #86
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No, John-

I am sorry to say in all my research, and it has been very thorough, I have found very few found specific complaints about over and under exposure problems while using the Pentax PTTL Flash System. In virtually every case, the exposure errors are directly attributable to setting up the camera/flash combination incorrectly.

Personally, I have seen several examples of exposure variations in my own photos, but it has always been attributable to me. Once, I personally resolve setting up the photo correctly, it works without a problem. In all cases it is a matter of carefully setting up the conditions, and then everything works as published. I will admit, it is fairly complicated, but most errors are those involving the photographer and the initial set-up.

Sarah Joyce

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Old Jul 18, 2009, 9:35 PM   #87
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That's kind of the point Sarah. There isn't anything specific per-se about P-TTL. But, with your flash experience you should be able to help students out with what situations will cause such problems and how to use techniques like FEL to deal with them. After all, just like you can't always let the camera decide everything for you, same goes with flash.
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Old Jul 18, 2009, 9:55 PM   #88
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No, John, you are very correct-

Once the photographer become familiar with the Pentax PTTL system and learns how to effectively program it for their purposes, it smooths out a great deal. I would be the first to agree with you that both the Nikon I-TTL System and the Canon TTL Systems are easier for the end user to make use of in the average flash photo situation.

In large measure, the problem occurs when complicated flash techniques are not used very often. As you know, I also use the Canon and Nikon Flash Systems, and I would be the first to agree with you, that each of those systems are measurably easier to use in real world flash photo circumstances.

Sarah Joyce

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Old Jul 18, 2009, 10:55 PM   #89
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Sarah - still missing the point. Both Nikon and Canon systems still encounter problems. The point is - an experienced photographer has to know when to NOT trust the camera (or in this case the flash). It's not a pentax thing - it's a "experience with flash thing". As an experienced instructor who is putting on a flash tutorial I simply was asking you to draw on your experience and explain the types of real-life flash situations which are likely to cause the camera's flash metering to give a wrong answer and require the PHOTOGRAPHER to make a decision and based on your experience what those decisions might be. Herein lies the difference between reading literature and actual hands-on experience. This wasn't a trick question. It's something everyone who tries to master flash use comes across - just like anyone who realizes the camera's normal (non flash) metering is wrong sometimes and thus ventures into Exposure compensation and manual exposure. They're very basic photographic concepts. The same is true with flash. Flash exposure compensation and Flash exposure Lock do the same job with flash output / metering that their counterparts do with non-flash photos.

You see, when the flash meters off the pre-flash, different color's subjects reflect that light differently. So, a strong amount of dark or very light portion of the subject in the frame will skew the flash metering - not unlike how they would skew a camera's metering. What I was interested in hearing was whether Pentax had various different metering modes for PTTL (evaluative, center weighted). I haven't come accross any literature that suggests it does so I'm guessing it's mostly an evaluative mode which looks at the whole scene. Likely a person well versed in Pentax flash use would know or could hazard a guess if that were true or if it used more of a center-weighted approach. So why is this important? Well, it's important so you know how much, if any, a portion of the frame is going to affect the flash metering. Just like camera metering. Knowing what metering mode your camera is in and understanding it helps you predict when a portion of the frame may or may not cause camera metering issues. Same here.

Flash exposure Lock (FEL) is a fairly common tool - it locks in the Flash Exposure on a specific portion of the frame (in most cases the center focus point - although I certainly admit I don't know if it will work using a non-center point as I always use center).
The common technique then - especially with a person is to perform a lock with the focus on a FACE - because that's usually the most important part.

But this isn't something you read in a camera manual. It's not something you can copy from the pentax website. It's something you learn when you use flash in the field. I'm sure Mark can elaborate - he's had a good amount of wedding experience and knows quite a bit about real-world flash use. As you might guess - weddings in particular often have white/black so flash use can certainly encounter some metering issues.

And, of course - FEC is another tool - just like Exposure Compensation for non-flash work where you evaluate the scene and determine whether you believe you need more or less flash. Another example from real life experience? Bouncing the flash off a high ceiling. Guess what? The flash/camera doesn't know how high the ceiling is so normal flash output is probably not enough. You might have to use + FEC.

Use a diffuser and you might find you need +1/3 or so - especially for smaller flashes.
Personally I often shoot with -1/3 or so because I don't like a stark look.

So, a reader might ask - when do I use FEC vs. FEL? To that I would ask you to ask yourself - what might sway your decision for non-flash on whether to use Exposure lock vs. exposure compensation (assuming you're not using a manual exposure which would make either rather pointless).
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Old Jul 19, 2009, 4:10 PM   #90
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JohnG-

I apologize that I missed your point the first time around. FEL and FEC are valid tools, and I have used them on Canon DSLR cameras in the past. However, the only Pentax DSLR I currently have in hand is the KM or K-2000 model. The KM/K-2000 DSLR camera does not have either the FEL or FEC features. I have ordered the K-20, but I might not receive it before I depart on the next contract. It most probably does have the FEL and/or FEC features.

The person's face is certainly the logical spot on which to lock the exposure. It would be logical to lock the exposure on your primary subjects face, particularly if the person was positioned measurably forward or aft of the flash exposure point in the photo.

From my research, it appears that the metering point is the center spot on the viewfinder. When using the KM/K-2000 camera, I find the best and quickest procedure for me is to take the initial photo and then to evaluate the exposure results on either the camera's LCD or a computer. Then, I make the adjustments on either the external flash itself, or in the camera with the Flash Compensation feature.

That is a work around rather than than the FEL or FEC features themselves. But, it get the job done on this, the lowest priced of the Pentax DSLR cameras. You see, John, you are lucky with your much more expensive Canon 5D that you have those FEL and FEC features.

Have a great weekend, JohnG!

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