Pentax wireless flash experiment


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sbc

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Jun 27, 2005
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#1
This is for people who shoot events and find that the Pentax flash is not strong enough.

In those film days, the most popular flashes among wedding photographers are the Metz 45and 60. Those have a GN of 45 and 60 @35mm respectively.

My all time favorite flash is the Sunpak Auto 555 with a GN of 45 @35mm. More importantly it has a recycle time of 3 sec using AA and 1 sec using TR power pack (6 C). Nothing that I know of comes close to this performance. Unfortunately, they don't support Pentax AF, let alone P-TTL.

The strongest current Pentax flash 540FGZ has only a GN of 39 @35mm. When shooting a group photo using bounce flash, it may not be powerful enough. Also the recycle time is about 6 sec at full discharge; way too slow. The TR 3 power pack shortens it to 4.5 sec but still not so good.

So I am left with this few options.

1. Get a Metz 45CL4 Digital at about >$1k.

2. Get the latest Metz 76 MZ5 at >$2k (ouch!)

3. Get the TR3 power pack to shorten the recycle time

4. Get 2 Pentax flashes at < $1k

My solution is to utilise the wireless capablility of the Pentax flashes to combine the output of 2 flashes. Using a 540 and a 360, I get a total GN of 46 @35mm. And because of the more powerful output, the flashes do not have to discharge at full power all the time. This will in turn cut down on the recycling time.

The added benefit is that should 1 flash dies (it happened before), you have a backup on hand.

This picture is shot with a phone camera.
 

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sbc

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#3
Good news for flash newbies who wants to try wireless flashes. (Please ignore this post if you know this already ;))

The Pentax wireless system can support more than 2 flashes.
This mean you could use the RTF to control 2 external flashes. Not only that, there are some functions available that are not stated in the manual.

This is what I found (with 2 external flashes, that is all I have).

1. You can set both external flashes as slave and the RTF as Master or Controller (as mentioned).

2. You can use the contrast ratio setting on each flash. The possible settings are 1/1, 2/3, 1/2, 1/3.

3. If you don't like to mess with that, you can use the Exp comp to set the contrast. The possible settings are -3 to +1 stop.

4. Or if you are really into precise control, switch to manual (M) mode and use the power ratio control. Settings are full to 1/64. Of course you will need a flash meter to measure the output and set the aperture.

If you buy 2 tabletop tripods and 2 hotshoe to tripod adapters, you can have a very portable macro studio lighting set up. Add a light tent and you are complete!
 

sbc

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#6
54AF-1 is GN 54 and 58AF-1 is 58.

The 54-AF-1 is same distance as our 540AFGZ or there is a Metz 76 MZ-5 which is GN of 76
54AF-1 is 54 at 105mm, Pentax 540FGZ is 54 at 85mm. If you want to compare power, please do so at the same angle setting. The Metz is about 35@ 35mm. The Pentax is 39@35mm.

It is the same for the rest of the flashes. THe Metz 76 is ONLY 45 @35mm.

Note that the focal length of 35mm is for FF and film. For APC-C it is 24mm.
 

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felixcat8888

Senior Member
May 8, 2005
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#7
54AF-1 is 54 at 105mm, Pentax 540FGZ is 54 at 85mm. If you want to compare power, please do so at the same angle setting. The Metz is about 35@ 35mm. The Pentax is 39@35mm.

It is the same for the rest of the flashes. THe Metz 76 is ONLY 45 @35mm.

Note that the focal length of 35mm is for FF and film. For APC-C it is 24mm.
THanks for teh clarification. Now i see why.
 

sbc

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#8
No problem :D. It can get tricky at times. These manufacturers like to play around with specs to make their product looks good. Many are caught unaware.
 

sbc

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#9
Did a quick shoot for posting on ebay. Nothing fancy, just a 540FGZ on table tripod controlled by RTF. I am spoilt by studio modelling light so it was kind of a hit and miss thing because I can't see the 'quality' of light. Had to depend on the LCD for review.

Flash was set to manual output (M) because P-TTL tend to underexpose. Reading taken with a Sekonic L-358.

K20D+DFA100+540FGZ+white plastic diffuser. F11, 1/125.
 

sbc

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#10
Taken with a 540FGZ on the left and a 360FGZ on the right. Both lights softened with white plastic cards. White paper reflector on the front left. This time I use P-TTL. I have to add +1 expo comp because of the infamous P-TTL underexposure when there is a bright object.

 

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sbc

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#11
Went back to manual with this one. More consistant than trying to predict what P-TTL is going to do. 540FGZ at top, 360FGZ at right, with white reflector at front left.

 

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