[stewart_photo]

I've seen the specs for the Pentax AF540FGZ, but I'm just as interested in actual user experiences.

1. The recycling time is listed at 6 seconds with any battery. Is this a fairly accurate number with Lithium batteries?

2. Those same specs claim approximately 350 flashes with Lithium batteries. Is this fairly accurate?

3. B&H Photo lists the Pentax TR Power Pack III for this flash unit. Do either of the above two numbers truly improve with this power pack and, if so, by roughly how much? Enough to justify the $150 price tag? Opinions welcome on that question.

4. Finally, have you discovered anything unusual (a feature, a problem, whatever) a new user should pay special attention to?

Greatly appreciate the kind assistance.

stewart

[and]

Dont have it, but according to specs, the power pack will have a recycle time of 4.5 sec instead of 6 sec.

[fwbigd]

I've seen the specs for the Pentax AF540FGZ, but I'm just as interested in actual user experiences.

1. The recycling time is listed at 6 seconds with any battery. Is this a fairly accurate number with Lithium batteries?

2. Those same specs claim approximately 350 flashes with Lithium batteries. Is this fairly accurate?

3. B&H Photo lists the Pentax TR Power Pack III for this flash unit. Do either of the above two numbers truly improve with this power pack and, if so, by roughly how much? Enough to justify the $150 price tag? Opinions welcome on that question.

4. Finally, have you discovered anything unusual (a feature, a problem, whatever) a new user should pay special attention to?

Greatly appreciate the kind assistance.

stewart

The recycle time is less than 6 seconds if you are using the 540 in the P-TTL mode. This is because the flash does not completely discharge. The recycle time will be the full 6 seconds if you use the flash at full power.

You will get more flashes using the P-TTL mode than the 350 flashes listed in the manual. My current set of lithium batteries is well over 500 flashes, and the recycle time is under 6 seconds in the P-TTL mode.

I know nothing about the optional power pack.

Extremely user friendly. No unusual problems for a new user.

[Entropy]

A lot of users (including myself) have had exposure problems (typically significant underexposure) with the 540.

To get (at least) acceptable exposures:
Do not use the 540 when the camera is in P mode - set it to X.
In many situations (pretty much anything but macro photography) you will get more consistent results with the unit set to "Auto" (turning it into an auto-thyristor flash) than to P-TTL mode.
Do not set the camera to spot metering. Spot metering will result in severe underexposures, even in situations where a severe overexposure should result (such as spot metering on a black object.)

I'll try to post some example shots this weekend.

Personally, if it weren't for the fact that I occasionally like to take macro pictures (in which case P-TTL plus wireless functionality is great to have) and shipping items back to any vendor is a major hassle, I would have sent my AF-540 back to B&H two weeks ago.

If you don't need the wireless triggering, I'd suggest the Sigma EF500 instead - it's cheaper and seems to perform more consistently than the AF-540 from what I've heard.

[RBellavance]

To get (at least) acceptable exposures:
Do not use the 540 when the camera is in P mode - set it to X.
In many situations (pretty much anything but macro photography) you will get more consistent results with the unit set to "Auto" (turning it into an auto-thyristor flash) than to P-TTL mode.
Do not set the camera to spot metering. Spot metering will result in severe underexposures, even in situations where a severe overexposure should result (such as spot metering on a black object.)

Really ? This is almost ridiculous on Pentax's part if true, since the AF540FGZ was designed especially for P-TTL operation.

If you don't need the wireless triggering, I'd suggest the Sigma EF500 instead - it's cheaper and seems to perform more consistently than the AF-540 from what I've heard.

Note that the EF500 SUPER can be triggered wirelessly if updated to the latest firmware by Sigma.

[stewart_photo]

The recycle time is less than 6 seconds if you are using the 540 in the P-TTL mode. This is because the flash does not completely discharge. (snip)

As it should be. However, I tend to strain the limits of my flash units (bounce at fairly considerable distances), so I'm more concerned about those maximum recycling times.

The recycle time will be the full 6 seconds if you use the flash at full power.

That's more what I'm interested in. Thanks.

Extremely user friendly. No unusual problems for a new user.

That's a relief as well. Thanks again.

stewart

[stewart_photo]

A lot of users (including myself) have had exposure problems (typically significant underexposure) with the 540.

That's not good. The primary reason I'm buying the AF540 is to get away from the exposure problems I've experienced with Sigma EF-500 DG ST flash unit. The Sigma flash performs flawlessly when aimed straight at the subject (straight forward on the camera, even when using a straight-through diffuser), but exposures are occasionally unpredictable (over and under) using the tilt/swivel capabilities (into a bounce device or other). I was hoping the AF540 would be a little less troublesome. I'll keep your advice in mind.

Personally, if it weren't for the fact that I occasionally like to take macro pictures (in which case P-TTL plus wireless functionality is great to have) and shipping items back to any vendor is a major hassle, I would have sent my AF-540 back to B&H two weeks ago.

The interaction with B&H has always been fairly painless when I've returned items. Of course, that still doesn't eliminate the hassles of packing up the item, mailing it, and waiting for the replacement.

If you don't need the wireless triggering, I'd suggest the Sigma EF500 instead - it's cheaper and seems to perform more consistently than the AF-540 from what I've heard.

I suspect my first paragraph has already fairly well addressed this.

stewart

[Entropy]

That's not good. The primary reason I'm buying the AF540 is to get away from the exposure problems I've experienced with Sigma EF-500 DG ST flash unit. The Sigma flash performs flawlessly when aimed straight at the subject (straight forward on the camera, even when using a straight-through diffuser), but exposures are occasionally unpredictable (over and under) using the tilt/swivel capabilities (into a bounce device or other). I was hoping the AF540 would be a little less troublesome. I'll keep your advice in mind.

At least, to the AF540's credit, unlike what you describe, the AF540 performs BETTER when bouncing. I can get acceptable (i.e. actually just barely touches the right side of the histogram) results when bouncing in X-sync mode, but direct flash often results in severe underexposure (Doesn't even fill the left quarter of the histogram even with +1 FEC dialed in). Also, one would think that the fancy P-TTL metering scheme would let you do fancy stuff like affect flash exposure by changing your camera's metering settings, but it does not. Changing the camera from multisegment metering to spot metering will result in zero difference to exposure, even in situations where it should make a massive difference (such as spot metering on a matte black object.)

Keep in mind that these experiences are with a K10D - As I understand it, most of the AF540's underexposure problems are K10D-specific, and I haven't seen many reports (if any) of such severe problems with the K100D (and *ist units too). I've been wondering if it's related to the K10D's focusing screen, which is also apparently notorious for fouling up metering of manual lenses. I'm thinking of trying an LL-60 *ist focusing screen to see if it changes the situation any, similar to how it has fixed metering problems with manual lenses for many people.

Also, at least the AF540 does support "thyristor autoflash" mode where metering is performed by a sensor on the flash unit itself, unlike the EF500, so there is at least a workaround for all of the problems for most situations until the K10D gets a firmware fix for its abysmal performance with the 540 (which as I mentioned, seems K10D-specific). "A" mode (aka thyristor autoflash) on the AF540FGZ works extremely well in any situation in which flashhead-sensor parallax isn't a problem, better so than P-TTL currently.

The interaction with B&H has always been fairly painless when I've returned items. Of course, that still doesn't eliminate the hassles of packing up the item, mailing it, and waiting for the replacement.

Admittedly, it's the hassles of packing it up and mailing it (and having to eat shipping costs) that are why I wound up keeping it until it was too late to return it. That and the fact that Strobist didn't post the news that Vivitar had resumed production of the 285HV, a "digital safe" version of the venerable "classic workhorse" 285 auto-thyristor flash for $90 until within the past week or so. I honestly was looking for a good auto-thyristor and couldn't find one (everyone's making dedicated TTL units nowadays), so decided to go for the 540 about 3 weeks too early.

Also, at the time I purchased my 540 (3 weeks or so ago), the only information I could find was that Sigma had not yet updated firmware to support wireless triggering with the K10D, which is why I wound up not purchasing the EF500 Super (even though I was close). (Well, that and the Pentax rebate on the 540 placing it very close to the EF500 Super.)

[GridUser]

I hope I can get some answers about external flash, as well. I have an old Sunpak Auto 30DX Thyristor flash that I used with my first camera, a Pentax ME (ca. 1974). On the back of this flash, it says: for Nikon FE-EM and all other hot shoe mount regular cameras. It used to work with my old Pentax but wasn't automatic, so I ruined a LOT of pictures before I figured out how to use it manually. I also have a new (year old) Canon Speedlite 420 EX for a Canon Pro-1 I have.

My question is this: will either of these flashes work with my new K-10D or will I have to junk both and pay $400 for the bounce/swivel Pentax AF540? Thanks for any help/answers you can give me.

[stewart_photo]

Of course, GridUser, neither of these flash units provide any dedicated features when used with the K10D. But if you're familiar with using the flash manually, the Sunpak will work virtually the same on the K10D. It will also work as an auto flash if you have the module (shoe) with built-in exposure sensor for that.

The Canon flash may be a different matter. It will mount onto the K10D and will likely fire as well. However, I could not determine if it has any modes other than E-TTL and TTL (neither compatible with the K10D). It will need either a manual mode or an auto mode to work with the K10D. I saw not sign of a built-in sensor, likely ruling out an available auto mode. Not enough info to say for certain about a manual mode, but unlikely since it is a relatively newer flash and most newer flash units don't include a fully manual mode.

In the end, however, I would try them both on the K10D. It costs you nothing to take a few test images to see how those flash units perform with this camera.

stewart

[Priyantha Bleeker]

I have got a AF 540 FGZ And I like it.
But I think it is not that powerful as the Canon EX580 and the Nikon SB800.
When you set all three on full power the Pentax is by far the weakest, and reaches not as far as the Canon and the Nikon's.
Is that a setting I set wrong ? Or how can it be ? Those flashes are equal I tought...

[stewart_photo]

(snip) When you set all three on full power the Pentax is by far the weakest, and reaches not as far as the Canon and the Nikon's. Is that a setting I set wrong? Or how can it be? Those flashes are equal I thought...

Ah, since I read about it years ago, that's an easy one. However, do remember that I'm going off of memory here, not actual data sitting in front of me. Anyway, flash manufacturers obtain guide numbers by taking a light meter reading of the flash at a distance of say about ten feet and extrapolate from that using a math formula (see note below). While manufacturers have agreed on this system, and it's easier than taking actual images with every flash to determine the true maximum point of proper exposure (even if everyone could agree on what is proper exposure), it's not very accurate since several factors are not accounted for at that shorter distance which can impact the actual maximum distance - the duration of the flash, the size of the flash tube, the shape of the reflector behind that tube, the reflective abilities of that reflector, the actual spread of the light leaving the flash, and so on. This is why flash manufacturers are very careful to point out, even in the very name, that these numbers are simply a guide.

This is also why two different flash units rated at the same guide number can deliver dramatically different light output levels. Indeed, tolerances in the manufacturing process can lead to very different light output levels between the same model flash units made by the same manufacturer.

Having said that, this measurement system is very effective at shorter distances. Knowing that a flash unit has an extrapolated guide number of so much, and the subject is located this far from that flash, can provide fairly accurate exposure information. The system only starts to fall apart when approaching those maximum distances, which means the guide number is less reliable at those distances. Of course, knowing that, you (the photographer) can make allowances for that inaccuracy at those distances. My only complaint is that manufacturers don't ensure that photographers truly know that. But in the manufacturer's defense, since very few complain (or even mention it), it's fairly clear few photographers actually attempt to take pictures using flash at those considerable distances (not a big issue).

Did that answer your question, or even make sense? I started getting lost somewhere towards the middle of the first paragraph, so I certainly hope you were able to follow it through to the end.

stewart

Note: Actually, manufacturers don't even take meter readings of any kind today. Instead, they use computer models filled with math formulas to gather the data needed to obtain the guide number for a particular flash design. The fundamental inaccuracies in the guide number system remain however.

[Cideway]

Using the flash in Auto mode will decrease your shot to shot time, in my experience.

[Entropy]

I hope I can get some answers about external flash, as well. I have an old Sunpak Auto 30DX Thyristor flash that I used with my first camera, a Pentax ME (ca. 1974). On the back of this flash, it says: for Nikon FE-EM and all other hot shoe mount regular cameras. It used to work with my old Pentax but wasn't automatic, so I ruined a LOT of pictures before I figured out how to use it manually. I also have a new (year old) Canon Speedlite 420 EX for a Canon Pro-1 I have.

My question is this: will either of these flashes work with my new K-10D or will I have to junk both and pay $400 for the bounce/swivel Pentax AF540? Thanks for any help/answers you can give me.

Sunpak 30DX - Good chance it may destroy your camera. Older flashes (Thyristor or not) have very high trigger voltages. Modern DSLRs need flashes with much lower trigger voltages (Canons are limited to 6V for example), older flashes will destroy them. I've heard the Pentax K10D is far more tolerant of high trigger voltages than other DSLRs, but I would not risk it.

The Canon - Most likely has a "digital safe" trigger voltage. The question is whether it supports thyristor mode. (using an on-flash sensor instead of the camera's sensor) Many of the dedicated TTL flashes don't even support thyristor "auto" mode any more. Fortunately the AF540 does at least support this for the times when P-TTL utterly fails to expose properly.

There's a good chance neither of those two flashes will work well (if at all) with the K10D, I would not even try using the old Sunpak.

The good news is that there are cheaper flashes than the AF-540FGZ. Strobist has quite a bit of praise for the Vivitar 285HV, which is a "digital safe" remake of a classic thyristor workhorse. Had I known about the 285HV resuming production when I was flash shopping last month, I would own one and an RF wireless trigger set rather than my current 540. As mentioned before, I'm keeping my 540 for now as I can work around most of its limitations and there's the potential a K10D firmware update may greatly improve its P-TTL performance on that camera, but if no update comes within the next few months I'll likely sell it in favor of a 285HV plus a Pocket Wizard RF wireless trigger set, or possibly a pair of 285HVs and the Gadget Infinity "Cactus" RF wireless trigger set.

I also had lots of good experiences with the Quantaray QTB-9500A (aka Promaster 5700) in the past, but the "manual focus" modules are really hard to find these days. (Quantaray/Promaster label their modules rather confusingly - TTL modules are labeled as "for autofocus cameras", while thyristor-auto modules are listed as "manual" modules even though the flash is capable of automatic exposure with the module.) I used a 9500A along with a preflash-ignoring slave trigger as a slave flash for my old Olympus C-3000 back in the college days with absolutely great results. Not sure if the 9500A is "digital safe" with one of the autothyristor modules either. I've seen some of the "Canon DSLR flash compatibility" pages list the 9500A as having a safe 6V trigger voltage, but that may have been with a Canon TTL module mounted - I am fairly positive that when I was trying to fit that slave trigger unit inside my "manual" module I was measuring a 200+ volt trigger voltage. Unfortunately my 9500A is both in New Jersey and also was dead last time I tried to use it (although it may have been that my modified module was dead), otherwise I'd have more info on its suitability for the K10D.

Edit: As to auto mode increasing shot to shot time - of course it's going to increase shot to shot time! Proper exposure (as opposed to underexposing in P-TTL mode) requires more light, which requires the flash capacitor to be discharged more. Given a choice between lots of underexposed shots, and a reduced number of properly exposed ones, I'll take the properly exposed ones.

[Peter Zack]

My flash is fairly new and I'm experiencing a few of these issues (spot metering underexposures) but I just wanted to add that I saved my TR2 power pack from an AF500FTZ I had for the PZ-1p. Turns out that power pack works fine and the recycle times seem to be around 4 seconds or less at full power in auto. The cable fits fine and there have been no issues with over 100 shots taken with that combo so far. Keep your TR2's if you have one. Before testing the TR2 and 540 I called Pentax USA and got a helpful guy who told me that there would not be an issue. I promised never to tell anyone Lol.