Friday, September 25, 2009

The Big Brother AF 540 FGZ

In the previous session we went over the Pentax AF 360 FGZ settings in detail. This session we're going to piggy back on that and discuss what the bigger brother the AF 540 FGZ brings to the table.

The Pentax AF 530 FGZ has all the same capabilities its little brother. The layout and buttons are almost identical infact so much that we won't be discussing any of that in this session as we covered it in the last session. The difference in the buttons is purely cosmetic and boils down to the switch on the 360 for the Master/Controller/Slave is a button on the 540 that toggles between the 3 roles and the LIGHT, ZOOM and the READY/TEST buttons are a little different. While the 360's READY/TEST LED is behind a clear plastic lens and a lot brighter the 540's LED is behind a less transparent cover that diffuses and reduces the LED's brightness. Other cosmetic differences include the S button and wheel, where they are recessed on the 360 they protrude a little on the 540.

The main differences between the 2 flashes is what makes the 540 the bigger brother. First off is power. The 540 boasts a Guide Number (GN) of 54 to the 36 of the 360. So now you see where the manufactures came up with the model numbers for the 2 flashes. So what does a GN of 54 do that 36 can't? More distance to the subject with the same f-stop or at the same distance a smaller aperture (more DoF). But by how much? Well a GN of 54 over a 10m distance gives you an f-stop of 5.4 (f5.6) and a GN of 36 gives you an f-stop of 3.6 (f4) so just a bit over 1 stop more light. At f4 the 540 gives you approximately (54/4=13.5m - 36/4=9m) 4.5m more throwing distance or about (4.5m x 3.28) 14.76 extra feet.

The other big difference is the swivel head. While both flashes sport a tilt head, the 540 also swivels (left or right) which is great for bouncing light of walls for diffused sidelight. With the 360 if your want to rotate the camera 90 degrees for a portrait frame the tilt only head changes the angle the light will come from. With the 540 you can tilt/swivel the flash head to the same position that you had for the landscape shot and the light source hasn't changed. That's a big bonus (to me at least) to have the same light in both a wide horizontal shot and a close vertical shot especially if the photos will be viewed in the same setting or running in sequence. Also with the tilt/swivel head the 540 allows you to bounce light from a wall behind you for a large soft front light when front light is what you want. With the 360 you are limited to harsher front lighting that requires a separate diffuser to soften the light.

Some smaller differences between the two flashes are the 540 allows you to change the auto power off settings a little while the 360's auto power off settings are static.

So now you can see why even though the 360 is smaller than it's sibling I love it just as much. It has all the same features for the most part and is very functional in most situations warranting the use of a flash and as a companion to it's sibling it's 100% functional for a lot less money. If you are going to buy 2 or more flashes buy one 540 and the rest 360s unless you know you will need the extra stop of light from each flash for a particular lighting setup.

Here's what the flash ratios look like using a 360 and a 540.

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