Flash Compatability with K10D

Anthony12 · 07-17-2007, 10:31 AM

Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster?

stewart_photo · 07-17-2007, 02:37 PM

This is fairly typical behavior for multiple exposures using a flash (any flash). To speed up the recycling time, prevent the flash from using so much power on any one image by reducing the area covered and reducing the distance to the subject. Overall, the multi-exposure mode works best with portraits of individuals, for example, located only a few feet from the camera (closer to the minimum flash range rather than the maximum).

Of course, another option is simply waiting for the flash to recycle normally, however long it takes. After all, you're not that big of a hurry, are you?

stewart

Anthony12 · 07-17-2007, 02:59 PM

Thanks...is there a multiple exposure mode on the 360? As far as being in a hurry I like to take multiple shots and would like a flash to keep up with the shoot.. Sincerely Anthony12

stewart_photo · 07-17-2007, 03:41 PM

Okay, the terminology you're using is a bit confusing. Perhaps you're talking about stroboscopic flash - multiple bursts in rapid succession to capture movement and so on. This is not the same as multiple exposure, which is primarily handled by the camera (my previous message talked about that). As far as I know, the Pentax AF-360 FGZ does not have a dedicated mode (burst mode - not the same as the 10 strobes/Sec modeling function) for stroboscopic flash. However, you can achieve very similar results by opening the shutter on B, quickly firing the flash the appropriate number of times with the flash test button, and then closing the shutter. You can also use a longer timed exposure. By the way, normal multiple exposures can be made roughly the same way as well. Use the variable power option of the AF-360 to reduce the potential for overexposure and shorten recycling times. Of course, the chance of overexposure is greatly reduced if you use a dark background since dark-field multiples don't add exposure in layers. Each shot against a black background, for example, would be made at normal exposure with little or no compensation.

stewart

Last edited by stewart_photo; 07-17-2007 at 04:17 PM. Reason: clarification and spelling

Peacekeeper · 07-17-2007, 04:20 PM

Anthony

If you are talking about having the camera in Continuous Mode and taking 3 shots per sec with a K10D and having the flash keep up. Then Yes it can do that, but within reason.

As Stewart said, the limiting factor is the flash recycle time. Depending on how much of the capacitor was discharged to effect the flash will depend on how long it takes the battery to recharge the capacitor again.

If you are able to set the camera to wide aperture, high ISO, slower shutter speeds, effectively almost ambient light metered shooting, then the flash is hardly discharging at all and can fire continuously with each shot.

Just be careful of overheating the flash strobe with too many continuous flashes, you can damage your flash. I have seen one where the flash's lens face actually started to go dark and melt inside.

I have used my Pentax and Sigma flashes in continuous mode shooting. I was able to shoot without the flash but chose to use it so I could up my shutter speed a couple of stops. Paparazzi style flash photography

Blind them and machine-gun them hehe

Hope this helps answer your question.

Anthony12 · 07-17-2007, 04:32 PM

Yes ...thanks and sorry.....I am talkining about stroboscopic........I will try a few shoots as you suggest and see what happens. I love the camera but a little disappointed in the flash cycle. Thanks again

Entropy · 07-17-2007, 06:10 PM

Almost no battery-powered flashes (actually, likely none if you define "battery powered" as 4 AAs and exclude specialty external battery packs) can come even come close to 3 shots per second at full power. If you need sub-second full-power recycle times, you will need an AC strobe.

I think the best the AF540FGZ can do is around 1.5 seconds for a full power pop with an external high voltage battery pack. 3-5 seconds on AAs. (This is a fundamental limitation of the batteries themselves, which is why the external pack which uses a large number of Cs or Ds is much faster.)

If you ABSOLUTELY need consistent fast recycle times, put it in manual mode and dial down the power output. Either that or go buy a line-powered studio strobe.

stewart_photo · 07-17-2007, 10:22 PM

Originally posted by Anthony12

(snip) I love the camera but a little disappointed in the flash cycle. (snip)

Okay, how good are you at basic hand tools and soldering, Anthony? There is an easy way to dramatically shorten recycle times - build an external battery pack. Since photographers have been doing this for decades, it's not exactly a new idea. I've done this with several of my external flash units in the past. Anyway, this is an easy afternoon project, requiring only basic tools and a touch of soldering. Please read and re-read these entire instructions before proceeding.

The general idea is to use larger batteries in the external battery pack. Most AA-size batteries top out at about 3200mAh. However, C-size rechargeable batteries are commercially available in capacities up to 5500mAh, while some D-size rechargeable batteries are rated at over 12000mAh.

All standard sized batteries, AAA through D-size, are 1.2-volts. As such, voltage is not an issue here. What we're interested in is the capacity of the battery - how long it will hold a charge (rated in mAh). If one is interested in the longest battery life, the D-size batteries are the obvious choice. However, the C-size batteries are smaller and lighter in weight. Which one is entirely up to you (see below for more about rechargeable versus non-rechargeable).

Once you've made that choice, the next step is to purchase the parts for the external battery pack. Here is what you'll need...

- 1x C-size or D-size 4-battery holder (available at most electronics stores, such as Radio Shack)
- 4x rechargeable or non-rechargeable batteries (C-size or D-size, again your choice)(if you select rechargables, you may also want to pick up a charger at the same time)
- 1x round wooden dowel exactly the width of an AA-size battery (available at hardware store - take a battery with you to check size)
- 4x round-head wood screws
- 1x thin, small-guage, two lead, wire (length your preference - see below)(available at electronics stores, including Radio Shack)
- 1x case for battery holder (one of the small camera cases available at most stores is a good choice)

All of this, minus the batteries and charger, should cost less than $20. The cost of the batteries and charger varies greatly depending on brand, capacity, and so on. You'll also need some basic tools...

- 1x Screwdriver
- 1x soldering iron
- 1x very fine cut saw
- 1x drill (with bit properly sized for screw threads)

To build the battery pack, start by cutting the wooden dowels. You'll need four pieces exactly the length of an AA-size battery minus the positive contact protrusion. These will be the four fake batteries inserted into the flash in place of the real batteries.

The next step is to solder the wire to the battery holder. Many holders have wire leads already attached to prevent the soft plastic holder from being damaged by hot soldering. If you're good at soldering quickly, I recommend snipping these leads and soldering your wire directly to the holder. Otherwise, solder your wire to the existing leads and cover the bare wire with electrical tape.

Next, snip the other end of the wire to the preferred length. For example, if the case purchased is designed to clip to your belt, measure a length of wire from your waist to your eyes (allow an additional extra foot or so for play).

Now solder the other end of each wire lead to one of the two screws. So the screw will sit flush when screwed into the wooden dowel, it is important to keep this soldering as flush as possible with the underside of the screw head.

You're just about finished now. Drill a small hole centered into the end of your four fake batteries and attach the four screws. At this point, each of your four fake batteries, with the screw protrusions, should be roughly the overall length of a typical AA-size battery, including the positive contact protrusion.

One of your fake batteries will be the positive and the other the negative when inserted into the flash (the other two fake batteries have no electrical connections). Look at the battery holder to see which lead is the negative and which is the positive. Trace the leads to your fake batteries and mark each one with this information (+ and -).

Next, insert the fake batteries into the flash unit temporarily and look where the power cord can exit the flash unit's battery compartment. You'll need to drill a small hole along the edge (note "edge" here) of the battery door at this point to allow that power cord to exit. The wire from the fake batteries will ultimately be fed through this hole during use.

Finally, insert your batteries into the holder, your holder into the case, and fake batteries into the flash unit. You may want to wrap the wire once around the holder inside the case to act as a strain relief. Now, unless you inserted the fake batteries backwards, your flash should start up and function normally. The only difference is the flash should now operate much longer between battery charges, with much faster recycling times.

There is also one other issue to consider here. Voltage does impact flash recycling times. Rechargeable batteries are rated at 1.2-volts, while non-rechargeable batteries are rated at 1.5-volts. The flash will recycle quicker with that 1.5-volts. As such, if flash recycling times are important, you may want to consider non-rechargeable batteries. The C-size or D-size non-rechargeable batteries will provide power for many flashes (far more than AA-size batteries), so this is still a reasonably economical solution. Another option is to keep an eye out for the higher voltage (1.5 to 1.7-volt) rechargeable batteries just now being announced by several battery manufacturers (coming soon, but not available yet).

That's it. Enjoy your new battery pack and improved flash performance.

stewart

Copyright ©2007, Stewart, Stewart Photography. All Rights Reserved.

RiceHigh · 07-20-2007, 01:21 AM

Originally posted by Anthony12

Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster?

Put your flashgun in Manual L (low power) mode and turn up ISO then you can get faster and more continuous flash bursts.

Of course, you need to calculate and experience the exposure by doing so. Read on the chart on the LCD panel for this as a start.

**Lowell Goudge** · 07-20-2007, 02:10 PM

Originally posted by Anthony12

Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster?

Look for a flash that comes with an external (HV usually) power feed. Cycle time is almost zero. Years ago I bought a sunpak AF3000 Auto Zoom flash that could be plugged in and it could operate in burst mode continually.

I think some of the newer pentax flashes also have this feature.

Entropy · 07-20-2007, 02:17 PM

Stewart, one comment to make that I don't think was in your post:

Keep in mind that a lot of C and D rechargeables are not really Cs or Ds - They're AAs inside a C or D shell. You can tell in the following ways:

No published capacity rating, or published capacity ratings not much higher than AAs
They don't feel MUCH heavier than AAs when you pick them up

Also, due to cell construction differences, Cs and Ds may not have quite the dramatic improvement in current delivery capability (i.e. how fast they'll cycle the flash) compared to their improvement in capacity (how many flashes they'll give before dying). If current delivery capability is the main concern, a 4-series-2-parallel arrangement of 8 AAs may work better.

Of course at some point the flash's charging circuitry itself becomes a limit. I think with an external HV pack it's around 1.5 seconds for the 540, with an external low-voltage pack and dummy batteries I don't know, I believe' it's 4-6 seconds with internal AAs for a full power pop.

**jfdavis58** · 07-20-2007, 03:05 PM

Originally posted by Anthony12

Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster?

There is a notably large pile of rubbish and some extremely dangerous suggestions in this thread!

Neither the 360 nor the 540 flash units multi-burst as you seem to desire. Nor will they recycle faster with bigger batteries--they may recycle more consistently, but the overheating will present a significant risk of actual fire and the possibility of small nasty explosion. Aside from the daft physics presented such external battery hacks void any warranty.

The 540 does have an external battery pack/charger specific to the unit. It's for extended shooting at the normal rate and specifically warns (repeatedly) about popping too fast--damn those pesky manuals. It doesn't significantly alter the recycle rate which is circuitry protected to about 4.5 seconds. This pack charges the main flash capacitor directly-hence the proprietary plug; and it generates a hair-curling 330-360 volt discharge that can be delightfully painful-ONCE!

The 500 flash from film era cameras: PZ/ZX, DOES do a multiburst pop--up to nine. It's questionable as to full compatibility with the current digital line-up of Pentax cameras. The 500 also has an external battery pack/charger-same high voltage warning as implied above. It also has the recycle warnings but actually DOES decrease recharge times to about 1 second -vs- a normal in-unit quad array of AA's taking about 6 seconds.

Few if any studio strobe will perform a multi burst pop; they actually work at the other end of the physics.

If what you really want is just very fast flash capability, the only way to safely obtain such rapid recycling is to use very high capacity strobes at the very low-power end of their ability--you may still run into overheating problems with a large number of pops in a short time. Several of the suggestions above suggest such a situation for the smaller 360/540 flashes of which you made initial inquiry. Indeed, a fair suggestion, included in the manuals for both units--up to a point. That heat thing again!

Entropy · 07-20-2007, 08:28 PM

It's a known fact that many flash units charge faster when using batteries with lower internal resistance (i.e. higher current delivery capability) than AAs. It's not "fake physics", it's real battery physics. Cs and Ds have lower internal resistance than AAs. As stewart_photo mentioned, it's an old hack that goes back years. It's the same reason cycle times are slightly lower with NiMHs than alkalines despite the lower voltage (1.2v per cell for NiMH vs. 1.5 for alkaline) - while the nominal voltage of the alkalines is somewhat higher, their internal resistance is MUCH higher and so their power delivery is compromised.

Yes, there are also internal circuitry limitations, which is why even with an ideal zero-impedance voltage source, the charging circuitry itself will limit you. Modern charging circuits (Such as the Linear Technologies LT3420) are designed with specific safety limits to prevent burning themselves out, which is why you'll likely never see full-power cycle times below 2-3 seconds with a battery-powered flashgun, but you can still get some improvement at least.

You're somewhat right about heat - Constantly popping full-power pops at a high rate would be a very bad idea, but a small (4-5) pops with a 2 second cycle time (as compared to 4-5 seconds) would be safe.

RiceHigh · 07-20-2007, 08:56 PM

The physics you mentioned are true. But too low the internal battery resistance might damage the flash units, by having too large the current than the design would tolerate. This is the reason why in old days some flash units did not allow the use of NiCd or even NiMH.

Originally posted by Entropy

It's a known fact that many flash units charge faster when using batteries with lower internal resistance (i.e. higher current delivery capability) than AAs. It's not "fake physics", it's real battery physics. Cs and Ds have lower internal resistance than AAs. As stewart_photo mentioned, it's an old hack that goes back years. It's the same reason cycle times are slightly lower with NiMHs than alkalines despite the lower voltage (1.2v per cell for NiMH vs. 1.5 for alkaline) - while the nominal voltage of the alkalines is somewhat higher, their internal resistance is MUCH higher and so their power delivery is compromised.

Yes, there are also internal circuitry limitations, which is why even with an ideal zero-impedance voltage source, the charging circuitry itself will limit you. Modern charging circuits (Such as the Linear Technologies LT3420) are designed with specific safety limits to prevent burning themselves out, which is why you'll likely never see full-power cycle times below 2-3 seconds with a battery-powered flashgun, but you can still get some improvement at least.

You're somewhat right about heat - Constantly popping full-power pops at a high rate would be a very bad idea, but a small (4-5) pops with a 2 second cycle time (as compared to 4-5 seconds) would be safe.

Entropy · 07-21-2007, 08:49 AM

True. Most modern flashes are now using specialized photoflash charge controller ICs like the Linear Technologies one that I mentioned - these have built in current limiters. Usually the current limiter is set above what 4xAAs can produce, so using batteries with lower internal resistance will give some benefit.

Still, as I mentioned above, subsecond full-power cycle times are impossible except maybe with super high-end studio units.

07-17-2007, 10:31 AM	#1
Anthony12 Inactive Account Join Date: Feb 2007 Location: Ottawa Posts: 3	Flash Compatability with K10D Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster?

07-17-2007, 10:22 PM	#8
stewart_photo Veteran Member Join Date: Apr 2007 Location: Heidelberg, Germany Posts: 1,864	Homebrew Battery Pack for Flash Units Without an External Battery Pack Option. Originally posted by Anthony12 (snip) I love the camera but a little disappointed in the flash cycle. (snip) Okay, how good are you at basic hand tools and soldering, Anthony? There is an easy way to dramatically shorten recycle times - build an external battery pack. Since photographers have been doing this for decades, it's not exactly a new idea. I've done this with several of my external flash units in the past. Anyway, this is an easy afternoon project, requiring only basic tools and a touch of soldering. Please read and re-read these entire instructions before proceeding. The general idea is to use larger batteries in the external battery pack. Most AA-size batteries top out at about 3200mAh. However, C-size rechargeable batteries are commercially available in capacities up to 5500mAh, while some D-size rechargeable batteries are rated at over 12000mAh. All standard sized batteries, AAA through D-size, are 1.2-volts. As such, voltage is not an issue here. What we're interested in is the capacity of the battery - how long it will hold a charge (rated in mAh). If one is interested in the longest battery life, the D-size batteries are the obvious choice. However, the C-size batteries are smaller and lighter in weight. Which one is entirely up to you (see below for more about rechargeable versus non-rechargeable). Once you've made that choice, the next step is to purchase the parts for the external battery pack. Here is what you'll need... - 1x C-size or D-size 4-battery holder (available at most electronics stores, such as Radio Shack) - 4x rechargeable or non-rechargeable batteries (C-size or D-size, again your choice)(if you select rechargables, you may also want to pick up a charger at the same time) - 1x round wooden dowel exactly the width of an AA-size battery (available at hardware store - take a battery with you to check size) - 4x round-head wood screws - 1x thin, small-guage, two lead, wire (length your preference - see below)(available at electronics stores, including Radio Shack) - 1x case for battery holder (one of the small camera cases available at most stores is a good choice) All of this, minus the batteries and charger, should cost less than $20. The cost of the batteries and charger varies greatly depending on brand, capacity, and so on. You'll also need some basic tools... - 1x Screwdriver - 1x soldering iron - 1x very fine cut saw - 1x drill (with bit properly sized for screw threads) To build the battery pack, start by cutting the wooden dowels. You'll need four pieces exactly the length of an AA-size battery minus the positive contact protrusion. These will be the four fake batteries inserted into the flash in place of the real batteries. The next step is to solder the wire to the battery holder. Many holders have wire leads already attached to prevent the soft plastic holder from being damaged by hot soldering. If you're good at soldering quickly, I recommend snipping these leads and soldering your wire directly to the holder. Otherwise, solder your wire to the existing leads and cover the bare wire with electrical tape. Next, snip the other end of the wire to the preferred length. For example, if the case purchased is designed to clip to your belt, measure a length of wire from your waist to your eyes (allow an additional extra foot or so for play). Now solder the other end of each wire lead to one of the two screws. So the screw will sit flush when screwed into the wooden dowel, it is important to keep this soldering as flush as possible with the underside of the screw head. You're just about finished now. Drill a small hole centered into the end of your four fake batteries and attach the four screws. At this point, each of your four fake batteries, with the screw protrusions, should be roughly the overall length of a typical AA-size battery, including the positive contact protrusion. One of your fake batteries will be the positive and the other the negative when inserted into the flash (the other two fake batteries have no electrical connections). Look at the battery holder to see which lead is the negative and which is the positive. Trace the leads to your fake batteries and mark each one with this information (+ and -). Next, insert the fake batteries into the flash unit temporarily and look where the power cord can exit the flash unit's battery compartment. You'll need to drill a small hole along the edge (note "edge" here) of the battery door at this point to allow that power cord to exit. The wire from the fake batteries will ultimately be fed through this hole during use. Finally, insert your batteries into the holder, your holder into the case, and fake batteries into the flash unit. You may want to wrap the wire once around the holder inside the case to act as a strain relief. Now, unless you inserted the fake batteries backwards, your flash should start up and function normally. The only difference is the flash should now operate much longer between battery charges, with much faster recycling times. There is also one other issue to consider here. Voltage does impact flash recycling times. Rechargeable batteries are rated at 1.2-volts, while non-rechargeable batteries are rated at 1.5-volts. The flash will recycle quicker with that 1.5-volts. As such, if flash recycling times are important, you may want to consider non-rechargeable batteries. The C-size or D-size non-rechargeable batteries will provide power for many flashes (far more than AA-size batteries), so this is still a reasonably economical solution. Another option is to keep an eye out for the higher voltage (1.5 to 1.7-volt) rechargeable batteries just now being announced by several battery manufacturers (coming soon, but not available yet). That's it. Enjoy your new battery pack and improved flash performance. stewart Copyright ©2007, Stewart, Stewart Photography. All Rights Reserved. Last edited by stewart_photo; 07-18-2007 at 12:38 AM. Reason: spelling corrections

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07-17-2007, 02:37 PM	#2
stewart_photo Veteran Member Join Date: Apr 2007 Location: Heidelberg, Germany Posts: 1,864	This is fairly typical behavior for multiple exposures using a flash (any flash). To speed up the recycling time, prevent the flash from using so much power on any one image by reducing the area covered and reducing the distance to the subject. Overall, the multi-exposure mode works best with portraits of individuals, for example, located only a few feet from the camera (closer to the minimum flash range rather than the maximum). Of course, another option is simply waiting for the flash to recycle normally, however long it takes. After all, you're not that big of a hurry, are you? stewart

07-17-2007, 02:59 PM	#3
Anthony12 Inactive Account Join Date: Feb 2007 Location: Ottawa Posts: 3 Original Poster	Thanks...is there a multiple exposure mode on the 360? As far as being in a hurry I like to take multiple shots and would like a flash to keep up with the shoot.. Sincerely Anthony12

07-17-2007, 03:41 PM	#4
stewart_photo Veteran Member Join Date: Apr 2007 Location: Heidelberg, Germany Posts: 1,864	Okay, the terminology you're using is a bit confusing. Perhaps you're talking about stroboscopic flash - multiple bursts in rapid succession to capture movement and so on. This is not the same as multiple exposure, which is primarily handled by the camera (my previous message talked about that). As far as I know, the Pentax AF-360 FGZ does not have a dedicated mode (burst mode - not the same as the 10 strobes/Sec modeling function) for stroboscopic flash. However, you can achieve very similar results by opening the shutter on B, quickly firing the flash the appropriate number of times with the flash test button, and then closing the shutter. You can also use a longer timed exposure. By the way, normal multiple exposures can be made roughly the same way as well. Use the variable power option of the AF-360 to reduce the potential for overexposure and shorten recycling times. Of course, the chance of overexposure is greatly reduced if you use a dark background since dark-field multiples don't add exposure in layers. Each shot against a black background, for example, would be made at normal exposure with little or no compensation. stewart Last edited by stewart_photo; 07-17-2007 at 04:17 PM. Reason: clarification and spelling

07-17-2007, 04:20 PM	#5
Peacekeeper Senior Member Join Date: Jul 2007 Location: Back at work :( Photos: Gallery Posts: 168	Anthony If you are talking about having the camera in Continuous Mode and taking 3 shots per sec with a K10D and having the flash keep up. Then Yes it can do that, but within reason. As Stewart said, the limiting factor is the flash recycle time. Depending on how much of the capacitor was discharged to effect the flash will depend on how long it takes the battery to recharge the capacitor again. If you are able to set the camera to wide aperture, high ISO, slower shutter speeds, effectively almost ambient light metered shooting, then the flash is hardly discharging at all and can fire continuously with each shot. Just be careful of overheating the flash strobe with too many continuous flashes, you can damage your flash. I have seen one where the flash's lens face actually started to go dark and melt inside. I have used my Pentax and Sigma flashes in continuous mode shooting. I was able to shoot without the flash but chose to use it so I could up my shutter speed a couple of stops. Paparazzi style flash photography Blind them and machine-gun them hehe Hope this helps answer your question.

07-17-2007, 04:32 PM	#6
Anthony12 Inactive Account Join Date: Feb 2007 Location: Ottawa Posts: 3 Original Poster	Yes ...thanks and sorry.....I am talkining about stroboscopic........I will try a few shoots as you suggest and see what happens. I love the camera but a little disappointed in the flash cycle. Thanks again

07-17-2007, 06:10 PM	#7
Entropy Veteran Member Join Date: Jun 2007 Location: Owego, NY Posts: 976	Almost no battery-powered flashes (actually, likely none if you define "battery powered" as 4 AAs and exclude specialty external battery packs) can come even come close to 3 shots per second at full power. If you need sub-second full-power recycle times, you will need an AC strobe. I think the best the AF540FGZ can do is around 1.5 seconds for a full power pop with an external high voltage battery pack. 3-5 seconds on AAs. (This is a fundamental limitation of the batteries themselves, which is why the external pack which uses a large number of Cs or Ds is much faster.) If you ABSOLUTELY need consistent fast recycle times, put it in manual mode and dial down the power output. Either that or go buy a line-powered studio strobe.

07-20-2007, 01:21 AM	#9
RiceHigh Veteran Member Join Date: Nov 2006 Location: Hong Kong Posts: 1,934	Originally posted by Anthony12 Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster? Put your flashgun in Manual L (low power) mode and turn up ISO then you can get faster and more continuous flash bursts. Of course, you need to calculate and experience the exposure by doing so. Read on the chart on the LCD panel for this as a start.

07-20-2007, 02:10 PM	#10
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by Anthony12 Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster? Look for a flash that comes with an external (HV usually) power feed. Cycle time is almost zero. Years ago I bought a sunpak AF3000 Auto Zoom flash that could be plugged in and it could operate in burst mode continually. I think some of the newer pentax flashes also have this feature.

07-20-2007, 02:17 PM	#11
Entropy Veteran Member Join Date: Jun 2007 Location: Owego, NY Posts: 976	Stewart, one comment to make that I don't think was in your post: Keep in mind that a lot of C and D rechargeables are not really Cs or Ds - They're AAs inside a C or D shell. You can tell in the following ways: No published capacity rating, or published capacity ratings not much higher than AAs They don't feel MUCH heavier than AAs when you pick them up Also, due to cell construction differences, Cs and Ds may not have quite the dramatic improvement in current delivery capability (i.e. how fast they'll cycle the flash) compared to their improvement in capacity (how many flashes they'll give before dying). If current delivery capability is the main concern, a 4-series-2-parallel arrangement of 8 AAs may work better. Of course at some point the flash's charging circuitry itself becomes a limit. I think with an external HV pack it's around 1.5 seconds for the 540, with an external low-voltage pack and dummy batteries I don't know, I believe' it's 4-6 seconds with internal AAs for a full power pop.

07-20-2007, 03:05 PM	#12
jfdavis58 Site Supporter Join Date: Nov 2006 Location: 13 S 0357397-3884316 Photos: Gallery Posts: 887	Originally posted by Anthony12 Does anyone use the Pentax AF360? I find there is no way to use it in multi shoot mode....does it take a long time to recycle? Is there a better flash that is more compatable and cycle faster? There is a notably large pile of rubbish and some extremely dangerous suggestions in this thread! Neither the 360 nor the 540 flash units multi-burst as you seem to desire. Nor will they recycle faster with bigger batteries--they may recycle more consistently, but the overheating will present a significant risk of actual fire and the possibility of small nasty explosion. Aside from the daft physics presented such external battery hacks void any warranty. The 540 does have an external battery pack/charger specific to the unit. It's for extended shooting at the normal rate and specifically warns (repeatedly) about popping too fast--damn those pesky manuals. It doesn't significantly alter the recycle rate which is circuitry protected to about 4.5 seconds. This pack charges the main flash capacitor directly-hence the proprietary plug; and it generates a hair-curling 330-360 volt discharge that can be delightfully painful-ONCE! The 500 flash from film era cameras: PZ/ZX, DOES do a multiburst pop--up to nine. It's questionable as to full compatibility with the current digital line-up of Pentax cameras. The 500 also has an external battery pack/charger-same high voltage warning as implied above. It also has the recycle warnings but actually DOES decrease recharge times to about 1 second -vs- a normal in-unit quad array of AA's taking about 6 seconds. Few if any studio strobe will perform a multi burst pop; they actually work at the other end of the physics. If what you really want is just very fast flash capability, the only way to safely obtain such rapid recycling is to use very high capacity strobes at the very low-power end of their ability--you may still run into overheating problems with a large number of pops in a short time. Several of the suggestions above suggest such a situation for the smaller 360/540 flashes of which you made initial inquiry. Indeed, a fair suggestion, included in the manuals for both units--up to a point. That heat thing again!

07-20-2007, 08:28 PM	#13
Entropy Veteran Member Join Date: Jun 2007 Location: Owego, NY Posts: 976	It's a known fact that many flash units charge faster when using batteries with lower internal resistance (i.e. higher current delivery capability) than AAs. It's not "fake physics", it's real battery physics. Cs and Ds have lower internal resistance than AAs. As stewart_photo mentioned, it's an old hack that goes back years. It's the same reason cycle times are slightly lower with NiMHs than alkalines despite the lower voltage (1.2v per cell for NiMH vs. 1.5 for alkaline) - while the nominal voltage of the alkalines is somewhat higher, their internal resistance is MUCH higher and so their power delivery is compromised. Yes, there are also internal circuitry limitations, which is why even with an ideal zero-impedance voltage source, the charging circuitry itself will limit you. Modern charging circuits (Such as the Linear Technologies LT3420) are designed with specific safety limits to prevent burning themselves out, which is why you'll likely never see full-power cycle times below 2-3 seconds with a battery-powered flashgun, but you can still get some improvement at least. You're somewhat right about heat - Constantly popping full-power pops at a high rate would be a very bad idea, but a small (4-5) pops with a 2 second cycle time (as compared to 4-5 seconds) would be safe.

07-20-2007, 08:56 PM	#14
RiceHigh Veteran Member Join Date: Nov 2006 Location: Hong Kong Posts: 1,934	The physics you mentioned are true. But too low the internal battery resistance might damage the flash units, by having too large the current than the design would tolerate. This is the reason why in old days some flash units did not allow the use of NiCd or even NiMH. Originally posted by Entropy It's a known fact that many flash units charge faster when using batteries with lower internal resistance (i.e. higher current delivery capability) than AAs. It's not "fake physics", it's real battery physics. Cs and Ds have lower internal resistance than AAs. As stewart_photo mentioned, it's an old hack that goes back years. It's the same reason cycle times are slightly lower with NiMHs than alkalines despite the lower voltage (1.2v per cell for NiMH vs. 1.5 for alkaline) - while the nominal voltage of the alkalines is somewhat higher, their internal resistance is MUCH higher and so their power delivery is compromised. Yes, there are also internal circuitry limitations, which is why even with an ideal zero-impedance voltage source, the charging circuitry itself will limit you. Modern charging circuits (Such as the Linear Technologies LT3420) are designed with specific safety limits to prevent burning themselves out, which is why you'll likely never see full-power cycle times below 2-3 seconds with a battery-powered flashgun, but you can still get some improvement at least. You're somewhat right about heat - Constantly popping full-power pops at a high rate would be a very bad idea, but a small (4-5) pops with a 2 second cycle time (as compared to 4-5 seconds) would be safe.

07-21-2007, 08:49 AM	#15
Entropy Veteran Member Join Date: Jun 2007 Location: Owego, NY Posts: 976	True. Most modern flashes are now using specialized photoflash charge controller ICs like the Linear Technologies one that I mentioned - these have built in current limiters. Usually the current limiter is set above what 4xAAs can produce, so using batteries with lower internal resistance will give some benefit. Still, as I mentioned above, subsecond full-power cycle times are impossible except maybe with super high-end studio units.