Paul C. Buff, Inc. Technical Forum

I am a little confused / surprised about the guide numbers for the AB 800 (320WS) compared to the stated guide number for my old WL10,000 lights (250WS)

On the sticker on the back of my old WL10,000, it says that the guide number at ISO 100 at full power is 220.

On the Expected Output Chart for the current PCB products located here:

http://www.paulcbuff.com/output.php

It states that the expected guide number for a 320 - 330 Ws flash with a 7AB/R Silver Field Reflector is only 109.

Do the Wl10,000 have twice the guide number because their reflectors are twice as efficient / much more narrow than the 7AB/R Silver Field Reflector?

Or are the stickers on the old WL10,000 a bit optimistic?

Or am I missing something here?

I just want to make sure that if I get an AB800 I am getting a step up in power.

(BTW: I see that the AB800 gives off 14,000 LS but I haven't seen a rating in Lumen Seconds for the old WL10,000 series... just the Beam CPS rating of 10,000. Do we know the LS rating for the WL10,000 series? Alternatively, do we know what the BCPS of an AB800 with a 7AB/R Silver Field Reflector is?)

First, to be accurate, a doubling of a guide number would equate to a quadrupling of power (or efficiency). So a GN of 200 is four times as much light as a GN of 100.

The differences are due to a few reasons. First, the WL10000 reflector is a narrower beam, which will concentrate the light, thus making it brighter. Second, the environment in which the tests were done have changed. Earlier tests were done in an all white room, so reflection added to the overall exposure. Now, we use a slightly larger room, with +/- 18% gray walls. We also use different light meters, which likely give different results, as well as standards of descriptions have changed. Remember, the newest of these are almost 15 years old, and much has changed in the industry.

I will see if I can get hold of one and do a direct comparison, though it may take a while to get one scrounged up.

Thanks so much for attempting this.

In the meantime, I will try working it the other way: I will test out my WL10,000 at 10 feet and 5 feet from my subject and see whether the f/stop exposure readings I get are similar to the published Expected Output at 10 feet (ISO100) / Expected Output at 5 feet (ISO100) chart on the http://www.paulcbuff.com/output.php page.

Off the top of my head, f/11 and f/22 sound about what I was getting, so I am guessing the light output is nearly the same when using the 7AB/R Silver Field Reflector on an AB800

(Unfortunately, my Gossen Luma Pro F light meter - which is even older than my WL10,000 - seems to be wildly inaccurate.)

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Ok, One last difficult-to-answer question (and this is the gist of all my questions):

All in all, on a tight budget, a WL10,000 (or two) is still a pretty viable light even for outdoor daytime use when paired up with a Vagabond Mini Lithium, right?

I understand that the Alien Bees have more power control, shorter flash duration, internal fan, possible remote power adjustment, more available light modifiers, are lighter and smaller, but the WL10,000 will still get the job done, right???

I guess THAT is what I am really asking.

Thanks in advance.

Ok, at 10 feet, using our current metering methods, the WL10,000 metered at f/11'9. The B800 metered f/11 with the 7" reflector. The beam spread of the 10K is abut 60 degrees vs the 80 degree spread of the 7" reflector. When it is all evened out, the B800 is about .5f brighter than the 10K.

If you are using bare flash, then the 10K should be fine outdoors. In a softbox, up very close, you should probably be OK. However, you cannot add any reflectors to increase its efficiency, or change its characteristics while maintaining a higher output (like a beauty dish) like you can with the B800. Even the PLM's will not focus as effectively.

Thank you so much for taking the time to run the tests. I really appreciate them!!!

And I am REALLY impressed by your commitment to a product that was discontinued sometime during the last century. That is one reason why I would prefer to continue purchasing lighting from PCB instead of from other places.

(Just for comparison, I contacted a particular retailer of inexpensive chinese-made lights and their customer service acted like they were not interested in taking my business. Who needs that?!?!?!)

Ok, I am just thinking out loud here... no need to reply:

I could get the VML battery and use that outdoors with my two X WL10,000 and one x WL5,000 (a total of 650 WS - so I am guessing recycle time should be close to that of a single einstein at full power).

Then I could save up the $$$s for the AB1600 (or find some of the higher wattage White Lightning Ultras used for a reasonable amount).

Thanks again for the help. Much appreciated!!!

This brought up a curious point. Multiple lights can take longer to recycle than a single light at the same Ws setting. So, I did test and verified that 2-10K's and 1-5K will recycle in about 3.5s, or about the same as an E640, as you suggested. This was also with 120W worth of model lamps in the lights. This was necessary to see when the lights recycled, and we did not have lower wattages on hand. This likely lengthened the recycle time slightly.

You should not run the model lamps during normal usage.

Again, thank you SO MUCH for taking the time to test this out for me. I am (pleasantly) surprised that you were able to dig up three of the WL series lights for the test.

Again, thanks for all the help.

Again, thanks for the help.

I just placed my order for a Vagabond Mini Lithium (to use with my two WL10,000s and one WL5,000) last night, and a large part of my decision to buy it was because of your continued support of retired products.

Thanks again.