Category Archives: Photography

Additional power for Strobes

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The 4 AA batteries that all flashes take is enough for most uses, but if the flash is not easily accessible, or batteries die too quickly then AA batteries are not a good option any more. I’ve been thinking about how to extend the power supply of flashes.

My solution is to use Li-Ion batteries, with a DC-DC converter. I’ve identified several DC-DC converters that may work.

The big question is how much power does the flash draw when recycling after a flash? On 1/4 power, a SB800 will get about 1500 shots on a 2000mAh battery set. (source) It took 30min for the batteries to reach 1400 shots (and dies at just shy of 1600 shots), so that averages out to about 1 Amp continuous draw out of the batteries for 1/2 hour.

At full power, on a Canon 430EX II, the power draw peaks at 9Amps, then 6Amps after 1 sec, and 3Amps after 2 sec. (source post #15)

For a reasonable price ($12ish) a 5V, 5A DC-DC converter like this one or this one would probably work. The max input voltage is only 14V, so realistically only a 3S Li-Ion battery would work. That’s already twice the voltage of 4 AA batteries.

A bit more power to 10A at 5v can be had for about $18 in this module, or this one.

For higher input voltage range (9-28V) something like this can be used with the limitation that only 2A can be drawn. This one also costs about $24.

Of course there is an option for high input voltage (18-36v) and high output current (40W, so at 5A, that’s 8A) but it also costs $87 in this module. Out of my price range.

I think the best option is to have the max available current any time I need it, even though I may not shoot at full power very often. It also means the re-charge rate is maintained at the same level for a much longer period of time.

A 5000mAh 11.1v (3s) Li-Ion battery from HobbyKing costs about $25. This battery should have more then four times the capacity of 4 AA at 2000mAh.

Is it worth it for the extra complexity? I don’t know.

UPDATE:

Found a DC-DC converter (LMZ12008TZ) for a reasonable price that can handle 6A at anywhere from 0.8V to 6V output. The input voltage is 6V to 20V so a 5s battery would work. The digikey price is $22 ish and it requires very few external parts.

AF Assist tool v3.0 – more testing

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I tried out the 540ez lens with both the LED that came with the assembly as well as the LED I bought from digikey. The digikey LED was brighter then the led that came with the 540ez lens. Brightness was judged with the LED installed in the housing, and the projected pattern was the object of judgment.

However, when it came to what the camera saw, it was a different story. At 40ft (the length of my basement; can’t go any longer indoors) the camera was pointed at a blank wall, and all the lights were turned off. The LED that came with the 540ez lens assembly was able to get a focus confirmation out of my 40D whereas installing the Digikey LED in the same lens assembly, did not provide AF confirmation. This was very interesting because the same contrast producing pattern was projected, and even though to the human eye (my eye) the digikey LED seemed brighter, the camera saw something else. At 40ft, I was could not visually  see the pattern projected by the 540ez led (yet focus was confirmed by the camera). With the Digikey LED, I could see the projected pattern (just barely) but the camera was not able to use that information to focus.

The Digikey LED is of 66onm wavelength. I can only guess that the led that came with the 540ez flash is higher then that (nearer to infrared).

I also tested a few other flashes to see if I could achieve AF confirmation on the same blank wall in total darkness, 40ft away.

Canon 420ex – AF confirmation achieved (pattern just visible 40ft away)
Nissin Di622 mark II – AF confirmation achieved (pattern not visible 40ft away)
Younguo ST-E2 – AF confirmation achieved (pattern clearly visible 40ft away)

Looking at the flash quoted AF assist distance I compiled for a few flashes seems to be understated?

The Plan:

Near-infrared is starts at 780nm and goes up from there. So I’ll have to find some LEDs that are between high 600nm and 800nm
OR
Find some brighter deep red LEDs.

UPDATE:

For the next version of the autofocus tool I’m currently working on I need to test several wavelengths of IR light .
3 x IR LED 770nm (p/n: 15P2280)
3 x IR LED 830nm (p/n: 93K0966)
3 x IR LED 850nm (p/n: 97M1058)

AF assist tool v3.0 – testing

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So I got some parts from DigiKey today; enough to  do some more testing. Took out the ebay purchase I’ve had for a few weeks, and got to work.
I picked up this AF assist lens from a Canon 540EZ flash, complete with LEDs.

CANON AF LED UNIT SPEEDLITE 540EZ FLASH NEW

I hooked up an LED to the 540EZ AF lens along with a resistor (200 ohm) and a 9v battery.

This is what I got in terms of a pattern. Shot on the left was from 7.5ft, then 15ft, then 30ft. At 30ft, I could barely, just barely make out the pattern on the flat white door onto which I was projecting the pattern.

The camera exposure was:  ISO:3200, aparture: f1.4, exposure: 1/40

Again I must stress, there was VERY little light on that door from 30ft away, however the AF sensor on the camera locked in an instant. Maybe took a fraction of a second longer then from the 15ft distance, but it was hard to say.

I can hardly believe that such little amount of light can produce such a focus lock on a flat color (white) door in total darkness.

I took out my 420EX flash and fired the AF assist light (was not able to capture it since the flash was on the camera, and the light goes off once AF is achieved) and the light is much brighter. Maybe 1-2 stops brighter from 30ft. Maybe I need to use a lower value resistor to get more power out of the LED that came with the 540ez lens, or just replace it with a brighter LED.

Either way, it looks like adding contrast is MUCH more effective then just adding light to help the AF sensor focus and the idea of using a flash AF assist lens is looking much more promising then the laser pointer idea.

The 540ez lens module is kind of bulky. I would prefer it to be a little slimmer. The AF assist lights in my 420ex is made of 2 side by side lenses which are a better size. Will need to scope out some of those lenses.

Pocket Wizard Flex system : now works with more flashes

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I had purchased a PW Flex TT1, 2 flex TT5s and an AC3 a while back and could not get my Sigma EF-500 DG Super or the Nissin Di622 MkII to adjust their power. The Canon 430EX I owned would work beautifully (Of course, it was on Pocket Wizard’s compatibility list).
The Sigma and Nissin flashes fire, but they always fire at full power, no matter what setting I chose on the AC3 or the camera FEC.

I had installed version 6 .00 of the Flex firmware a while back when it came out (a month ago or so) but never re-tested the Sigma and Nissis flashes. The compatibility list on the Pocket Wizard website had not changed.

I was preparing for a photo shoot and was testing all my gear, and I accidentally put the Nissis flash on a Flex TT5 unit. To my amazement, the flash power was adjusted! I was amazed!
I then quickly tested the Sigma flash, and it too worked. The power was adjusted as per the setting on the AC3 contreller. All of a sudden I have 2 more flashes that I can use on the TT5 units!

Horray!

If you have a Flex TT5 unit, and own either the Nissin or Sigma flashes I mentioned above, please test them and let me know if they work for you.
Just to mention it again this change has been in effect only since the firware 6.00 has been released for the Flex TT5/TT1 units.

UPDATE:
The Nissin works great; rock solid especially in manual mode. No HSS though, but they have their time and place.

As for the Sigma, I have some reservations. The shots fired are hit and miss. Some are proper exposure, some are not. There’s the occasional firing of the flash by itself. And the biggest gripe is that the pocket wizards fail to communicate with each other way too often. The dreaded red blinking light. I have not found a pattern as to why/how this happens. Maybe to much interference from the flash?
It’s too bad though, since these flashes are quite powerful and inexpensive.

Another Camera aid idea

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Shooting with a flash often needs an assistant to keep moving the flash around to track the moving subject, as the camera also moves to track the subject.

In some situations where an assistant is either not available or not practical. In these situations the flash is set in a location which would cover most subject locations, with a wide flash beam. Lots of flash power is wasted,  and it’s very inefficient.

What if the flash(s) could track the subject by themselves, always aiming the flash at the subject? Well, it may be possible using one of these Direction Finder tools.

The way it would work is that the flash (with a remote trigger) would be on a servo controlled gymbal, and the camera would paint the subject with a pulsed IR laser (pulsed so that the tracker only tracks the pulsed signal and not other continuous IR sources).

Kinetik4 photo book details

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I’ve decided on the details for the photo book. 81-120 pages seems reasonable. 35 bandsx2 pages per=70pages then 6-8 DJ pictures, + table of contents, + chapter(day) breaks (2 pages per)… certainly more then 80 pages, though less then 120.

8×10, Matte finish paper, 81-120 page.

7×7, Standard paper, 81-120 pages.

 

Links to refer to later:

Canadian photography law

Blurb books I came across that I liked:

MUSIC FROM THE BARRIERS | John Paul Gleason | Portfolios

 UPDATE: 10Aug2011

Up to about 113 pages in the book and that includes probably 6-8 empty pages. Expanded some band’s selection of photos so that there’s no more then 2 photos per page. Having 3 or 4 photos, shrinks the images down too much and since I have the pages to work with, keep the size as large as possible. The first page (with the artist’s title) used only one larger photo, and then subsequent pages get 2 photos per page.

Neurodance 2.8 shooting : thoughts

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Friday night (night before Neurodance) I was putting together my camera bag. Discovered that with the AC3 on the Pocketwizard TT1, I would not be able to use the Auto Focus assist tool that I made. Also, with the TT1 between the camera and the AF assist tool, the AF assist tool sits an inch higher then before. This throws off the alignment of the laser beam and the camera center AF point. Continue reading →

Photo Sorting Criteria

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To be consistent with myself, I’ll document the meaning and process I go through when sorting through images from a shoot.

0 star – images are brought in at no stars. (not kept)
1 star – technically good image. either sharp, or interesting (not kept)
2 star – image shows good emotional content or is visually interesting. would not be embarrased to show this image. keep to have a variety of images of same event. when choosing from several very similar images, one gets 3 stars, while the other stay at 2 stars (keeper)
3 star – image shows great emotional content or very visually interesting. these are images that I show. (keeper)
4 star – used in conjunction with 3 star, if finer granularity is needed. (keeper)
5 star – outstanding image. when having to choose only several images from a large set (keeper)

The most time consuming portion of the sorting is going from 0 stars to 1 star. At least in my current state of photographic competency, a lot of images get discarded due to out of focus result. This can result in moving only 1/10 (or less) of the images to 1 star, yet I still have to look through all the images. Each subsequent step is much easier as there are less images to look through.