Sunday, February 21, 2010

CF Cards for the 7D

One of the claims to fame of the Canon 7D is its burst speed of 8 frames per second.  One frequently asked question is "Which memory card should I buy?.  Burst speed is often associated with the speed of the memory.  I rounded up a small assortment of SanDisk cards and did a very quick test.

Canon recommends a UDMA compatible card.  Of the four cards tested, only my old 2GB Ultra II was not a UDMA card.  For video, Canon recommends a read/write speed of at least 8 MB/sec.  The old Ultra II is listed at 15 MB/sec, the Extreme IV as 45 MB/sec and the "Extreme" (no suffix) is 60 MB/sec. 

Rob Galbraith has researched, tested and published data for the performance of many memory cards.  I wanted to see for myself.  My normal practice is to shoot in RAW+JPEG mode with the JPEG at the smallest size.  I set the 7D for ISO 400, manual exposure, manual focus, IS turned on.  Each memory card was freshly formatted in the 7D.  My subject was the XNote Timer that I'd used previous to estimate G9 shutter lag.

I simply pushed the shutter button and held it down until more than 30 shots had been fired.  Of course, I never shoot this way but I wanted to see what would happen.

All the cards performed the same for the first eight shots.  That is, no matter which one of the cards was used, the 7D cranked out eight shots in about 0.9 seconds.  Apparently, these eight RAW+JPEG fill up the internal (buffer) memory of the 7D.   After those first eight shots, shooting rate changes.

With the Ultra II, the 7D required 21.7 seconds to fire off 30 shots; that is, 0.9 seconds for the first eight shots then 20.8 seconds for an additional 22 shots. 

The 60MB/sec Extreme(s) and Extreme IV all performed the same as far as I could tell.  With any of those cards, the 7D required 7.7 seconds to get off 30 shots; that is, the first eight shots required 0.9 seconds and the next 22 shots required 6.8 seconds.  The timing was not uniform between shots.  Two shots would be roughly 0.15 seconds apart followed by roughly a half second delay and then another two shots 0.15 seconds apart, etc., etc.

In practice, I've had a few impatient delays with the Ultra II in the 7D but not with the Extreme IV.  I can't speak to any quality or ruggedness differences between the Extreme IV and the Extreme (no suffix).  I've never had a problem with a SanDisk card.  The Extreme (no suffix) are less expensive than the Extreme IV so, for now, that's my card.

Tuesday, February 16, 2010

HD Video and the DSLR

I fully expected the Canon G11 to have HD Video and still can hardly believe that it does not.  Whatever the marketing or technical reasons for Canon's not including HD Video in the G11, the 7D has it and I bought the 7D instead (that should show them!).  I had and still have great plans for learning HD Video with my 7D but, so far, have done very little of it.  At least part of my hesitation is the very large learning curve in front of me 

I've recently found a "book" that should help:  "Mastering HD Video with Your DSLR" by Helmut Kraus and Uwe Steinmueller.   This is a 40MB downloadable E-Book in pdf format; it costs $29.95 and seems well worth the price to me.  Even though I'm only part way through the book I'm enthusiatic enough to recommend it to others.

One surprise though:  No video in the E-Book!  I've never seen video in a pdf file but I'll bet it is coming -- if not already available.

Sunday, February 14, 2010

YN460-II with 7D

I'm still pleased with the simple and inexpensive YN460-II flash described previously. Sure, all it does is flash when told to do so and its flash power must be set manually; that is, no automatic flash exposure at all. But the YN460-II does these basic things well. Also noted previously, the YN460-II works with the Canon 7D camera even when the 7D popup flash is set for ETTL mode provided the YN460-II is set in its own "S2" mode. Again, "works" means only that the YN460-II fires with the appropriate timing -- its flash power is not set by the 7D flash controls.

After a few days of tinkering, I suddenly wondered "What if the YN460-II actually interfered with the 7D popup flash?" To test my loss of faith, I set up a simple scene with the faithful Woof-Woof and fired off several shots at varying conditions. First, the base case using only the 7D popup flash is shown below. The 7D was set for ISO 200 using manual exposure and 1/250 second at f5.6. The 7D was set to ETTL mode using the internal flash only and without flash compensation. Using the Canon 15-85mm lens at mid-zoom, I was perhaps nine feet away from Woof-Woof. The white balance was set for "flash" in Adobe Camera Raw.

I then tried the 7D with the YN460-II in several positions using bounce and direct flash at varying power levels. Not much to report here except that the 7D flash obviously does not know or care about the YN460-II. The 7D fires its preflash (which the YN460-II ignores), computes the "correct" flash exposure without regard to the YN460-II and then fires away -- joined this time by the YN460-II. In other words, the 7D flash does not instantaneously change its mind when the YN460-II fires.

To get the shot below, the YN460-II was placed a little behind Woof-Woof and aimed directly at him. The YN460-II was set to 1/32 power; the 7D internal flash was in ETTL mode and set at -3 flash compensation. White balance was set in ACR at the "flash" setting.

Throwing a simple second flash into the mix certainly can add a new dimension to a shot!

Saturday, February 6, 2010

Yongnuo Speedlite YN460-II


In the end, I couldn’t resist ordering the YN460-II even though my arsenal of flashes is (mostly) built around the Nikon SB series. In a previous post, I wrote about replacing the foot of a damaged SB-24. I actually did not expect to win that damaged SB-24 and had, in fact, ordered the YN460-II just two days prior. Fifteen days later, the YN460-II arrived in a plain brown wrapper, shipped via airmail from Hong Kong.

The YN460-II is a simple and inexpensive flash unit that is an upgrade of the (what else) YN460. The upgrade consists of more power (claims Guide Number of 53 instead of 33), faster recycling and fine tuning for the flash power. The flash head has both tilt and swivel. The YN460-II has two operating modes: manual flash and optical slave flash. In either operating mode, the YN460-II flash power must be set manually.

Here are my first thoughts and impressions.

My first concern was the packaging. Although the shipping envelope was lightly padded, the YN460-II box was simply placed inside it without additional padding. There was no padding inside the box although the flash was inside a plastic bag which was inside a nice black cloth bag. In spite of my concerns, all parts arrived in good condition.


The YN460-II is a nice looking flash with a better quality appearance that I expected. The tilt/swivel head position is held by friction; that is, just grab it and turn/tilt – no release buttons to push. This is fine for now but I wonder if it will become sloppy loose with much use.

I dropped a set of PowerEx NiMh rechargeables into the YN460-II and pressed the ON button. Nothing. Press again – nothing again. Did I get a bad flash? A quick glance at the instructions confirmed that I was indeed pushing the ON/OFF button but should have been holding it down for 2 seconds. Duh. Firing a few quick pops manually, the YN460-II took about 8 seconds to recycle to full power; the SB-28 from which I robbed the batteries took about 9 seconds. (Time to recharge?) Recycling was near instantaneous at minimum power setting. (A fresh set of PowerEx reduced the recycle time to less than 5 seconds.)


Changing the flash power is easy and very visual: Press the Power +/- button and watch the lights change. However, the button must be pressed for each step change. Same for changing modes: Press the Mode button and watch the lights change. When the YN460-II is turned on, the mode is set to manual and the flash power is set to the minimum; it does not remember the previous settings.

In contrast to the simplicity of setting flash power, “fine-tuning” was not so simple. Well, I could follow the instructions but the flash power output level lights do not remain as set so I had no confidence in what I’d done. The procedure is to press and hold the MODE and PILOT buttons until the middle light blinks then use the +/- button to fine tune. This seems OK except that the output level lights soon revert to the non-fine tuned display. Pressing MODE and PILOT again shows the fine-tuned setting. I quickly resolved not to use the fine tuning feature (for now anyway). Illustrated is 1 stop down from maximum (i.e., would be half power) but then 2 clicks farther down using "fine tuning".

Somewhat skeptically checking the YN460-II in optical slave mode, I found that it works very well with my Canon G9. In fact, the YN460-II was triggered by the G9 flash in both the S1 and S2 settings when the G9 was in P mode. With the G9 in manual mode (no pre-flash emitted), the YN460-II was triggered only in its S1 mode. Even more surprising, these quick tests were shot at 1/500 second! I was impressed. With my 7D, the YN460-II also worked in both S1 and S2 modes when the 7D was set for ETTL; however, at 1/200 second and faster, S2 is necessary. In a dimly lit room, triggering is easily possible at a distance of some 20 feet. The obvious conclusion is to use S1 for pure manual flash and S2 for triggering with ETTL -- as advertised.

Next up was to test the YN460-II with my Cactus wireless triggers. The only way to connect to the YN460-II is through the hot shoe. This is OK with me because my Cactus units are more reliable when connected via the hot shoe. The YN460-II worked fine with my Cactus wireless triggers and could be triggered at 1/640 second using the Canon G9.

Finally, I compared the flash power of the YN460-II to some other flashes. I did this by shooting the flashes directly mounted on my Canon G9 camera in full manual mode. Just firing shots across a dimly lit room, it seems to me that the YN460-II is not as powerful as the Canon 580EX but is similar to the Nikon SB-28 and more powerful than the SB-24. In fact, the relative power of all those flashes seems to be about as listed in my post on guide numbers. I also noticed that the YN460-II seems a bit “cool” in color cast, especially in comparison to the Canon 580EX (which seems a bit warm).

All in all, my YN460-II works and seems to work as advertised. I’m pretty happy with this one – in fact, am thinking about getting another one.


Thursday, February 4, 2010

Guide Number

The guide number of a flash provides a simple means for comparing flash power and for estimating the necessary f-stop for proper exposure when using flash. Strangely, I’ve not previously posted about guide numbers, so here goes.

Divide the guide number by the distance to the subject to get the f-stop.

Is that it? How could this possibly work? Imagine setting up a totally manual single flash such that the exposure is correct; the guide number is then defined as
GN= distance x camera f-stop

If the distance is in meters, then the GN is expressed in meters. If the distance is in feet, then the GN is expressed in feet. (To convert a GN given in meters to a GN given in feet, multiply the meters GN x 3.28) .


To further complicate matters, the guide number changes with film/sensor ISO speed. The convention is that ISO 100 is a convenient reference point. If you know the guide number at ISO 100 then the guide number at ISO 400 is 2x the GN at ISO 100 (that is, the square root of the ratio).


Here are some examples of guide numbers:

Canon G9 built-in flash: GN = (about) 3 m; not specifically provided
Canon 7D built-in flash: GN= 12 m
Canon 580EX: GN=58 m
Canon 420EX: GN = 42m
Canon 220EX: GN = 22 m
Nikon SB-28: GN = 50 m
Nikon SB-24: GN = 36 m
Yongnuo 460-II: GN = 53 m


Notice that the Canon flash model number is the guide number followed by a zero. For flashes with zoom capability, the manufacturers usually provide the guide number at maximum zoom (probably because this is a larger number). Sometimes tables of guide numbers are provided at various zoom and ISO settings.


Here's an example of the guide number in use. Suppose that your flash has GN=40 m, your camera is set for ISO 100 and the flash is 5 meters from the subject. Divide 40 by 5 to get 8 – this is the correct f-stop for your camera (i.e., set f8 on the camera).


The guide number is best used as a first approximation and actual results vary considerably with the location, flash orientation, bounced light, etc., etc.


Wikipedia and the Strobist have more detailed information on guide numbers.



Tuesday, February 2, 2010

SB-24 Foot Replacement


As noted in other postings, I frequently use Nikon flashes, especially the SB-28 and SB-24, with my Canon G9. The SB-28 and SB-24 are particularly useful with my Cactus wireless trigger (works with my G9, 20D and 7D) and sometimes a used SB-24 is available at a low price. I just bought another used SB-24 that had a broken foot but was otherwise working. I then bought a replacement foot, installed it and now have another working SB-24 flash. Here’s how I replaced the foot.

But first, the cowardly disclaimer: These are not instructions. I’m just writing about what I did. Proceed at your own risk. I’m not responsible for damage or injury.

First I checked the old and damaged SB-24 to see if it worked at all; it did. I then triggered the flash and immediately turned it off and removed the batteries. While replacing the foot, I tried not to touch the various wires and contacts but, of course, did touch them; however, no shocks, no sparks. You may not be so lucky -- I don't know.

The replacement process is basically to remove four exterior screws and then three interior screws to separate the component parts. The locking ring must be removed from the old foot and placed on the new foot.

Here's the old foot and the new foot with the locking ring from the old foot.

It took a bit of patience and trial and error to get the contact pins aligned with the new foot. I finally realized that the pins were not sliding smoothly in the holes of the new foot. Taking a round screwdriver, I reamed and cleaned the holes and the contact pins then slid into place easily.

Even though this setup is very ungainly, it demonstrates that the new foot has saved the old SB-24 from the scrapheap and provided me with an inexpensive third SB-24.