Paul C. Buff, Inc. Technical Forum

Latest lame and incorrect post by the same hater. Since I can't defend this sort of misinformation libel at FM, I'll respond here:

Kenski claims to be an electronics expert, yet doesn't know what he's talking about.

Actual fact is, as I said before, virtually every mono light and power pack system currently on the market employs voltage doublers (actually quadruplers) and voltage regulation, and no isolation or step up transformers . . . just like AB, WL, Zeus and Einstein. The list includes, to the best of my knowledge, all Elinchrom models, Hensel, Dynalite, Profoto, Broncolor, Photogenic and virtually everything else. Most use the same basic circuit design and power control methods as I first introduced in 1986 WL Ultra. All but Broncolor Grafit/Scoro employ the same analog voltage control of flashpower, replete with the same characteristic color vs power shift. Most have simply added digital interface to the still-analog power control circuitry. A few use analog voltage control plus capacitor switching such as we use in WLX1600/3200 and Zeus.

BTW, if you think I am stooping low to call Fred Miranda Fred Morondo, this is tit for tat for his first ignorant or purposeful reference to me as "Paul C. Bluff" instead of my actual name in his "boot me off" post. To be blunt, I'm not Bluffing here and IMHO Mr. Miranda is indeed moronic in his actions, as are a dozen or two of his favored hate mongers.


kenski http://www.fredmiranda.com/forum/topic/1004585/0

p.1 #25 · Help me with my transition from AlienBees to ??
By the way, that is a pretty good website but it is talking about its lack of a step up transformer, not isolation which by using voltage doublers explains why their is a lack of consistancy in light output with a Alien Bee. Without the use of isolation and voltage regulators, which I do not see any in those pictures since this IS an analog setup, the use of a cascading multiplier will own amplify the signal that is present. The "CONTROL" of the light output is really nothing more than a variable RC filter so it doesn't care WHAT the signal is coming in.

BTW, electronics aren't a hobby or a side job for me. This is what I have done for 14 years now as my real job.

wow. I 've been a EE for 30 years now, and to me it sounds like kenski is speaking half-gibberish.... There are some things that sound like "truthiness" (Colbert!) but even allowing that he knows/understands more than he lets on, he is still stating this as if only ABs do it this way.

I hate to take it to this level, but isn't FM putting himself in some legal peril by allowing libelous or untrue statements about Buff products on his web site without allowing you to correct the inaccurate information. Couldn't you just send Fred and your lawyer a rebuttal and takedown notice every time this idiot spouts off? Eventually it would lead to the haters getting banned because obviously FM doesn't have any time for moderating his forums.

Here's the latest from "electronics expert" Kenski. And here is my breakdown. Obviously this guy works in a really really old factory of some sort and has no idea of modern electronics

First, there is no such device as a "variable transistor", unless you are referring to a Varistor . . . which is not a transistor at all . . . it's a surge protector and has nothing to with with flash control circuitry.

He talks about "solid state conversion". Solid state defines the transition from tubes to transistors that occurred in the 1950s.

He mentions he works on 40's technology and getting a solid state conversion and still uses a few tubes. This says he replaced some 40's tube circuits with 50's transistor circuits. Uhh duu, transistor technology was primarily replaced by Integrated Circuits in the 60's and 70's.

The core of essentially all current electronics is based on ICs, both analog and digital. In the past ten years, more and more equipment augments the analog and digital ICs with microprocessors, primarily as a user input interface that typically has little to no effect on the actual circuit function. So a $900 RX600 is essentially a $360 AB1600 that reads out the same parameters in numerical form rather than dial position.

Yes, you can resolve an f stop setting in finer increments with a numerical display and that's the total difference. There are several high end flash units including AB/WL whose interface remains mechanical control of precision IC circuitry, replete with accurate voltage regulators, Thyristors, Opto Isolators, etc . . . functional and electronic equivalents of AB and WL, and many customers that prefer the mechanical methods.

An important point here: Because a digital display says "61MPH" doesn't mean it's accurate. I drive with a digital speedometer, a GPS tracking speedometer, and an analog dial speedometer. The two digital readout speedometers typically display about a 4MPH difference, with the dial speedometer indicating about half way between the two.. So is it 61MPH, 63MPH or 65MPH? I also wear a Timex analog watch because it's easier to use and just as accurate as the overly complex digital watches I used to wear.

A final subject: Broncolor High end pack and heads systems, Einstein and most speedlights have advanced beyond the variable-voltage power control (Circa WL Ultra 1986) used in almost every current mono flash regardless of price. IGBT control requires extremely precise calculations of IGBT Gate shutoff timing and voltages applied to the flash capacitors, and thus demands using microprocessors. Additionally, the Cyber Commander radio remote control/display further demands extensive uP circuitry and programmable digital interface.

Any advanced engineer (or user) can immediately identify the Einstein/Cyber Commander system as being years ahead any studio flash on the market, at any price, in performance, function and precision and ergonomics.

IMHO, Kenski is living in the 50's and has a highly inflated opinion of his knowledge. If FM readers want this sort on ignorance I guess Fred is right . . . I don't belong there . . . he has too many friends in low places to deserve my presence.

Anyone else who actually knows what they're talking about want to weigh in on this?



http://www.fredmiranda.com/forum/topic/ ... astmessage

Most of the higher ends use variable transistors and regulators in the control section for accurate control of the output.

Yeah well the equipment I work on is 40's technology and I actually use a few tubes still. We did get a solid state conversion for part of the tube assembly and let me tell you how noisy our wave guides were AFTER we converted to Solid State. We had to replace almost every gasket seal down the line and couldn't believe how the tubes just didn't care. You should see the mainframe computer I have to deal with. Ughhh....

From http://www.fredmiranda.com/forum/topic/ ... astmessage
Kenyee: This is also probably why the variator dial (fancy name for varistor in an RC circuit) on Speedo packs is limited to 1/4 range (IIRC).

kgphotography: I'm still putting the Einsteins through their paces, and so far so good. Perfect light to have "on the way to something better" sometime in the future.

Rustrybag: NOTE: I've also seen color shift from 'shot to shot' with my AB400 when shooting faster sequences than full recycle time requires. IIRC ... PCB's design will let you shoot before full recycle is achieved (i..e. imperfect light is better than 'no light, missed the shot' philosophy)

Comments from Paul Buff:

Kenyee . . . 1. What is referred to incorrectly here as a "Varistor" is properly called a potentiometer. 2. As for "RC Circuits controlling power" . . . . simply wrong. The charging and voltage regulating circuits in virtually all mono lights and packs are capacitive voltage multipliers. There are no RC circuits in any of them.

Rustybag: Most stories of AB inconsistency are, as you say, caused by shooting before recycle is complete. We allow this purposefully on the assumption that shooters that exceed the recycle rate would prefer post-salvageable shots to the blank frames that result from lights that don't allow firing before complete recycle.

kgphotography: On the way to what? The only lights that come even close to the power range, color consistency over power range and flash durations of Einstein are Broncolor, Grafit and Scoro pack and head systems in the $10,000+ range, and they don't quite equal Einstein performance. These lights are not on the below chart because they aren't apple to apples. Please see chart at http://www.paulcbuff.com/pcb2009/einstein.html and http://www.paulcbuff.com/pcb2009/e640detail.html

Note the characteristic shift in color and flash duration in all non-IGBT monolights from the cheapest Chinese imports to the most expensive Euro lights. Also notice the most expensive (Profoto) is the worst of all.

[color=#FF0000]From http://www.fredmiranda.com/forum/topic/ ... astmessage
mill4570 wrote:
The larger modifiers also require more power from the light system.
Richard K.

Why is that? I have only tried 5' octa as my max size and don't understand why bigger size requires more power. Now if you mean bigger size further from subject and that in turn requiring more power I understand.

Answer: Bigger modifiers don't require more power than small ones . . . misconception. This only applies to a big modifier when placed close to the subject when the modifier approaches the subject size. This is inverse square law behavior - when light from the perimeter has to travel farther to reach the subject than light from the center.

Of course, any modifier with diffusion material on the front decreases on-axis light, over a focused reflector, because it widens the beam and spreads the light over a wider area. Physics 101.

At a distance, a 10' soft box will provide the same amount of light as a 2' softbox.

Silver 86" PLM proves this since it's a very large focusing reflector designed for very high focusing without undesired wasted spill.

Paul. I miss having your feedback over at FM. Unfortunately that's the site I visit and refresh most often. If there were a site with more activity and useful information I'd change. I was surprised to see Fred take the course of action he did and didn't think it was warranted.

http://www.fredmiranda.com/forum/topic/ ... /0#9552465

there's my little bit of support for you.

Thanks. And thanks Tetrode for your post on FM. Here's the hater response (I think we're getting under the skin of FM haters group . . . they and Fred asked for it.)

From http://www.fredmiranda.com/forum/topic/ ... astmessage
tetrode wrote:
Lovely shot, Alex. I always look forward to your next "how this shot was made" blog entry.

On that "other" subject, I would just direct readers to:

viewtopic.php?f=8&t=1386&start=10#p8980

viewtopic.php?f=8&t=1386&start=10#p8995

viewtopic.php?f=8&t=1386&start=20#p9059

These posts speak for themselves and make it very clear why things have taken the turn they have.

Dave F.

Jeez guy...do you have to troll everything Buff. Even post-mortem? Read the post directly above yours. (jdben622)

Thanks for the correction Paul.
I hated analog circuit design way back :-)
I don't even remember voltage multiplers:
http://en.wikipedia.org/wiki/Voltage_multiplier
I always thought that strobes/packs used resistors to decrease voltage, so thanks for the pointer.

Way old power packs like early Speedotrons used a step up transformer to get 900V on the flash capacitors. Problem is, you can't charge big capacitors without limiting the current flow, so a series resistor was used to limit the surge current so the thing doesn't draw hundreds of amps and blow all the fuses on the block.

But, according to physics of power transfer, the resistor becomes the "source resistance" and the capacitors become the "load impedance". In this approach, the power dissipated in the process is divided between the source and load impedance. In a "power matched system" 50% of the power appears as heat in the resistor and 50% makes it to the flash capacitors. Thus, in an 800WS system fired once per second, you need an 800W limiting resistor (bigger than a breadbox and hotter than a firecracker) and you only get 50% efficiency.

A bit abbreviated, but capacitor multipliers achieve the same result, with only about 5% of the power appearing in the multiplier capacitors and 95% going to the flash caps. Thus, 95% efficiency and little internal heat, smaller package. That's why they are pretty much universally used. But multiplier circuits do require sine wave inputs to operate properly - thus pure sine inverters.

More "modern" switching power supplies are an alternative, but are really difficult to configure for high power flash, very expensive, produce enormous EMI, and also don't play well with sine or modified sine inverters.

I tried for switching power supply originally in Einstein, but the best power supply consultants I could hire couldn't make it work nearly as well as the capacitive multiplier circuits I finally designed and settled on.