TR3 battery pack for Pentax flash


amoringello

Link Posted 13/06/2008 - 16:34
Anyone use the external battery pack for the Pentax flashes? Does it help with recycle speed of the flash?

I've been asked to shoot an event but hate to be forced to wait six seconds between shots. It is likely that I will need full power most of the time - more likely high speed sync -- lower output but full charge used nonetheless.

Alternatively, anyone know of DIY hacks or other methods (cheaper then $300+ for the TR3) that will pump more power to the flash?

MattMatic

Link Posted 13/06/2008 - 16:48
AFAIK, the external AF540 power pack houses a set of C-size cells to give longer life... not faster recharge

Running at full power all the time isn't good. Can you crank the ISO higher and effectively increase the guide number? (That's what I do all the time!)

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

gartmore

Link Posted 13/06/2008 - 16:59
Funnily enough I was looking at them on the web this morning and I'm sure that SRS claim that there is a significant decrease in recycling times.
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -

amoringello

Link Posted 13/06/2008 - 17:09
Hmm, too bad.
I'm looking to knock down/balance the ambient light a bit so I believe I'm limited to shutter speed to do that.
Maybe I'll practice some more with lower power considerations.
If I can work at half power that might be OK, not great but better than nothing.

I supposed I could always rig up a pair or half a dozen flashes on some sort of rig. Now that would be cool! maybe not...

gartmore

Link Posted 13/06/2008 - 18:53
gartmore wrote:
Funnily enough I was looking at them on the web this morning and I'm sure that SRS claim that there is a significant decrease in recycling times.

Are we talking at cross purposes here? 'decrease' = faster!

Ken
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -

Bob and his Pentax

Link Posted 18/06/2008 - 14:10
Yes I have the TR3 battery pack.

You will see in your AF540 manual that it says that you must still have batteries in your flash (i.e. 4xAA) in order to use the flash with the TR3 fitted. The flash still uses the power from the internal batteries to supply its low voltage needs (screen, IR beam, focal length adjust ment etc) when the TR3 is fitted.

There are also 2 settings that can be set on the flash gun to determine where it getts its high voltage power from when the TR3 is used It can take its high voltage either from the external battries only or the from the internal + external battries.

When external only high voltage is selected the recycle time (from full discharge) is the same as without the battry pack attached that is about 6 seconds.

The AF540 manaul does say that if both iternal and external high voltage is used then recycle time is reduced. I haven't tried that so I cannot confirm.

I was hoping that (like the battry pack for the old AF400T flash gun) the battery pack would completely replace the internal batteries - but its only got 2 terminals in the connector so its clear that only high voltage is supplied. There fore I've chosen to prolong internal battery life by using exernal high voltage only setting (hence I don't know recycle time for internal + external high voltage setting).

I recently (before I had the battery pack) got about 100 flashes in an evening from 4xAA battries before needing to change them. So using the external battery pack should give most people confidence that they will be able to get many more than that.

Theres also a decision of what spare batteries you carry - I carry no spare C cells for the TR3 but 2 spare sets of chargeable AAs for the AF540 knowing that if the TR3 goes flat I've still got spare power to use the AF540 without the TR3 for another 200 flashes, which I think should be adequate for my needs.

good luck
Bob
Good luck

Bob

Pentax user since 1978, Digital since 1997.
Kit includes: K-7, K20D, K10D, *istDS, full set DA* lens, etc

amoringello

Link Posted 18/06/2008 - 14:27
Thanks a lot for the info. I was really hoping the battery pack would give a significant decrease in recycle time. I would doubt adding the AA to the TR3 would do much, but I would be interested in how fast recycle time is if you should try that setting.

MattMatic

Link Posted 18/06/2008 - 14:27
Quote:
...but its only got 2 terminals in the connector so its clear that only high voltage is supplied.

My guess is that the TR3 supplies low voltage to the flash - otherwise the recharge time could be a lot shorter
.
It also explains why when using both sets of batteries the recycle time should be lower - it's putting them in parallel so more current can be drawn. I would suspect it would halve the time.

Given the safety issues of have HV on a small connector, and the difficulties of getting worldwide safety approval, I wouldn't be at all surprised if that's why they chose a LV route

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

Bob and his Pentax

Link Posted 18/06/2008 - 18:26
Hi Matt,

I was basing my oppinion on the following

The battery pack for my AF400T has 3 connectors, powers flash gun without batteries in flash, and the manual states that it delivers 550volts to the flash gun.

In the TR3 battry pack there is a capacitor which charges up during which you can hear the whine and a light that comes on when ready even if its not connected to the AF540 - I take this as a VERY firm indication that the voltage coming out of the TR3 is more (even a lot more) than the 9V supplied from the battery. The TR3 battery pack is more than a holder for the battries.

Also I infere from the AF540 settings which permit turning off of the internal battery contribution to the flash that only high voltage is supplied. - It may well be that the voltage suppied is not the full amount that goes through the flash tube but I think we can be sure that its more than 9V. It may well be that the TR3 does 'stage 1' boosting and it's input bypasses 'stage 1' in the flash.

The external battery pack is 9V (6xC cell) and the internal battery pack is 6V (4xAA cell) Which would also suggest that the power is introduced from the TR3 into the AF540 at some point in the step up process there isn't a 50% disparity in voltages. But I think you have far more knowledge of electronics than my rusty30+ year old engineering degree provides so I would be happy if you could prove me wrong...

I'm not sure about your safety argument either as I'm told its the amps that do the damage in an electric shock not the volts. There seems to be no problem with car manufactures using 20,000V in the HT of a car and the connector on the TR3 is better shielded than the connectors of the HT leads on a car. I've had 20,000V from the HT of a car and it was far less uncomfortable than 50V from a phone line or 240V from the mains.
[Please don't read that as if I'm encouraging anyone to experiment with recieving electric shocks]

I might try measuring the voltage from the TR3 latter when I'm home as I think my multimeter goes up to 1,000V DC but I'll have my fire extinguisher ready if I do it!

Good luck

Bob
Good luck

Bob

Pentax user since 1978, Digital since 1997.
Kit includes: K-7, K20D, K10D, *istDS, full set DA* lens, etc

Bob and his Pentax

Link Posted 18/06/2008 - 20:10
OK home from work, found multi-meter which does go up to 1000V DC,
got TR3 out only to find it says on the side where the output lead plugs in 330 Volts DC. (Multi meter measured 321V)

So yes TR3 does output high(ish) voltage.

I also measured the recycle times (from pressing test button to test light coming on again).

Internal batteries 8 sec
External batteries 8 sec
Internal + external batteries 4 sec

good luck

Bob
Good luck

Bob

Pentax user since 1978, Digital since 1997.
Kit includes: K-7, K20D, K10D, *istDS, full set DA* lens, etc

MattMatic

Link Posted 18/06/2008 - 20:53
I stand corrected

Excellent news then...
Thanks!
Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

Unlocker

Link Posted 18/06/2008 - 23:10
Not sure if I am going off topic or not here, but feel it's worth mentioning anyway, but maybe a change of flashgun might help?

With fresh AA batteries my Metz 58 recharges from a full discharge in approx 3 secs, which admittedly does go down as the batteries are running out, but is still half the time of that just quoted here for the 540.

Also the dedicated power pack recharges in 2.5 secs, and depending on which type of AA battery you use, according to the spec sheet http://www.metzflash.co.uk/pdffiles/Tech58%20AF-1%20digital.pdf you can get over 300 shots per set!

Not wishing to start any arguments here of course, maybe time for Pentax to bring out a better flash gun?

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MattMatic

Link Posted 19/06/2008 - 06:36
Just an added thought -

Good NiMH AA batteries will give a faster recycle time. Freshly charged From memory, Hybrio batteries in my AF540 recycle in about 4 seconds.

But... and here's the warning... if you are fully discharging the flash on every shot, then you're asking for trouble! If you run anything at the limit, how do you know whether it actually needed more power for the shot? Of course, you don't, and you risk underexposure!

The AF540 is a fine piece of kit - better than the AF360 - and I have absolutely no problems or issues with it at all (But then I always balance ISO/Aperture and sometimes shutter speed to ensure I'm well under a full discharge).

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

nathanever82

Link Posted 20/06/2008 - 00:11
Hello there!

I've been reading this post with great interest, as I am doing quite a lot of work that necessitates a flash, and as I wrote in another post, I struggle quite a lot with recharge times and battery exchange....

So... Matt... as I am trying to learn as much as I can to maximise the use of the flash (360) I believe that i am correct in switching immediately from P-ttl, to A or M. I have only done this rarely, as a trial and not during an event - in order not to have problems with the shoot.

What are the settings you would suggest to maximise use?
ISO / Aperture / time / should I simply use the flash in A and set the parameters of the shot? and then only use fill-in? What if the light condition is very low, and this becomes impossible?

PLease enlighten me!

Cheers
Nathan
'Between the lights there is always a shadow'

www.nathanservi.com & PPG

MattMatic

Link Posted 20/06/2008 - 17:10
Hi Nathan,
The BEST way to get absolute control is as follows:
* Put the camera in "M" mode
* Put the Flash in P-TTL
* I set the aperture, press the Green Button to get the correct shutter speed
* Then increase the shutter speed until the metering shows around 1 stop under (ie -1Ev)
* Shoot

If the shutter speed is too low, hold down the OK button and adjust the ISO.
I've also been experimenting using a home made bounce card (out of a piece of white "Funky Foam" - as illustrated on www.abetterbouncecard.com The combination of bounce, reflected light & the M+P-TTL makes a great shot!


Other modes I've used are: Av with ISO mapped to the front wheel. You need to set the Av & ISO without the flashgun on first - to get a feel for the ambient light. Then lower the ISO by a stop or so and use P-TTL flash.

If it's portraiture, then I use M on camera, and M on flash (set at 1/8 as a starting point).

There's more info on the sticky post about P-TTL flash
Hope that helps!
Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
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