The nuts and bolts of off-camera flash

Just to make it easier for reference, I’m collecting all 4 parts of this piece together into one post before they get lost in the black pit of the “blog archive”!

PART 1 – Intro/basics

PART 2 – Manual flash

PART 3 – TTL wireless

PART 4 – Syncing/sync speed

So there you have it!  all the nitty gritty of off camera flash in one convenient package for your bookmarking convenience 🙂

The Nuts and Bolts of off-camer flash – part 4, miscellaneous topics

Note: this is the final part of a 4 part series –
PART 1 – basics

PART 2 – manual flash

PART 3 – TTL wireless

Let’s talk about sync speed.
Sync speed is probably the most misunderstood topic for folks starting out with off-camera lighting, and for good reason.  There is a ton of seemingly contradictory information out there, misinformation, disinformation and downright wrong information… but really it’s not all that complicated, so let’s break it down.   First off to understand “sync speed” we must first understand how an SLR shutter works.  SLRs (whether digital or film) all (generally) use a type of shutter known as a “focal plane” shutter –

Obviously the job of a shutter is to expose your film or sensor for a prescribed period of time (usually less than a second).  The way a focal plane shutter work is by using 2 “curtains” that travel across the film plane.  The first (or “leading”) curtain starts by moving outward, exposing the film plane, and when it is done the “trailing” curtain follows it closing off the exposure.  Now what happens when the shutter speed gets faster than a certain point is that the 2nd curtain starts its travel before the first curtain has cleared the film plane.  In other words, the film/sensor is *never completely exposed* as a whole.   As the exposure get faster and faster, there is an increasingly narrow “slit” created by the two curtains that kind of “paints” itself across the film.  While this poses no problem for a shot using a continuous light source, for flash this is quite problematic.  Since normally the actual duration of the flash burst is much faster than the actual exposure, if one of the curtains is in front of the film plane when the flash “pops” it will partially block the light, yeilding the dreaded “black bars” across part of the image.

(Ben Mathis of the Lighting-Practice blog has a great animation of this here)

So in essence when you talk about “sync speed” this is what you are referring to – the maximum shutter speed at which the film is completely exposed at a point of the exposure.

Now if you think abou thtis process, it is a actually a hard physical limit.  There is physically *no way* to change how the shutter curtains operate, or the maximum speed at which they are fully open.  In other words, when folks throw around the term “cheating” or “hacking” the sync speed, it actually has *nothing to do* with the physical x-sync per-se, which is a common point of confusion.  What they are talking about is actually different ways of manipulating the flash burst to “work around” they shutter limitation.

*of course having said that*, let me first point out the exception to the rule 🙂

Invariably, during any sync speed discussion, someone will inevitably chime in with “you must be wrong since I normally at up to 1/2000 or so all the time with flash”.    They are, in fact, correct but it is a special case – they are generally using a Nikon D70/D40 when they report this.   There is a unique feature on some Nikon DSLRs (and a few other cameras), which is that they actually don’t use a purely mechanical focal plane shutter – they use what is called a “hybrid” Electronic/mechanical shutter.   This works similarly to a regular focal plane shutter, in that there are the normal first and second curtain, however after a certain point (usually 1/60th) any exposure faster than that does *not* precipitate an increase in the physical shutter speed – the curtains still open/close at 1/60th, however the camera merely “grabs” a smaller and smaller “slice” of the exposure recorded by the CCD.  In other words, even at 1/2000, the shutter is still opening for 1/60th, and then a tiny slice of that exposure is recorded.  The practical ramifications of this is that in essence the shutter is *always*  fully open for the eposure (for all practical purposes) – you never have to worry about the curtains blocking the flash.
Now for those of us who don’t have one of these cameras, we need a different method if we want to use flash with shutter speeds higher than the sync.

The first, and most common is known as HSS (High Speed Sync), sometimes also referred to as “focal plane sync” (FP sync).  Remember that at speeds higher than the max sync speed, the shutter curtains are essentially creating a “slit” that travels across the film plane.  In HSS, the flash will “strobe”, firing a series of superfast bursts (instead of one single burst) that are timed to match up with the shutter movement, ensuring that the whole frame is exposed uniformly as the “shutter slit” passes across each part.  HSS works great, although there are 2 major downsides.

1) it is proprietary – because the flash needs to “talk” to the camera in order to ensure that it’s pulses are timed properly with the shutter movement, HSS is limited to the manufacturers TTL capable flash units, so manual flashes and studio strobes are out :-).  This also means that triggering solutions like cables/pocketwizards/any manual triggering will *not* work (remember they only provide a “dumb” fire signal, no communication which is needed for HSS).  This means you are limited to using the manufacturers wireless ttl triggering if you want HSS off camera (and Radiopoppers potentially) with the associated drawbacks)

2) because the flash has to fire a bunch of little “pulses” across the entire exposure from a single charge of the capacitor (as opposed to one big burst), the flash output is *drastically* decreased.  HSS really eats the output of your flash (hence Dave Hobby & Joe McNally’s desert shoot using *7* SB800s 🙂

That being said, if you are using system flashes with something like radiopoppers (or in an indoor/studio situation) HSS is probably the easiest way to sync past the max sync speed of your camera.

Another (and much less optimal) method actually involves turning the flash into a conitnuous light source!!

Consider:  even though the flash may seem to be an instantaneous burst, it still takes time for the burst to occur.  (this depends on the flash and the power, but often in the range of 1/4000-1/7000 second) that is the time that the flash is physically “on” putting out light.  Now consider if your shutter speed is faster than that, the sensor “sees” the flash output for its entire exposure!  in essence the flash has become a continuous light source as far as the camera is conernced.  Now this isn’t a particularly flexible solution (requires very specific parameters from both camera and flash in order to work), however in the right circumstances in a pinch it will do…  (one thing to remember if you are doing this as that as a “continuous light” the flash contribution to the exposure is now affected by shutter speed just as ambient is!)

I personally shoot with a Canon 5d which has a max sync of 1/200. for faster, I generally use HSS with radiopoppers, or in a pinch the Canon G9 has a hybrid electro-mechanical shutter as described above (similar to the D70/D40) which allows syncing up to 1/2000 or 1/2500 pretty reliably.   Between those 2 methods, I cover all my bases pretty well.

Anyway, that about wraps it up for “the nuts and bolts of off-camera flash”.  I hope this series has been informative, and I may add/refine/clarify it as time goes on 🙂

-Ed Z

the 15 second DIY adjustable snoot!

So I’ve done the cardboard snoot thing.  It’s cheap.  It works.  but I find they don’t last too long trashing around in a camera bag.   I really like the idea of a flexible snoot like the Honl speedsnoot, so I figured I’d try to make my own…

A quick trip down to Perl (art supply store) yielded the required materials.  2 9″x12″ sheets of “foamies” craft foam (it’s a thin, neoprene like foam material – flexible yet rigid enough to hold it’s shape) one white, one black and 4′ of velcro “wrap” (the velcro that has hooks on one side and loops on the other, so it can stick to itself if you wrap it around something)  The neat thing about the foamies sheets is that you can get them either plain or with one side covered in adhesive.   I opted for a plain black and an adhesive-backed white sheet.

total cost for materials: about $5 (the velcro was $3 and I think the foamies sheets were .59 each)

Once at home, I simply peeled the backing off the white adhesive side, and laid the black sheet on top.  Pressing firmly secured the 2 together.  They can bend and flex together without wrinkling or buckling.

I then cut 2 velcro wraps long enough to wrap around the flash head and secure it tightly.

TaDa!  instant snoot – total time to construct: about 15-30 seconds 🙂

the best part about this snoot is that it is adjustable.  For a normal throw, wrap it into a cylinder shape, and secure each end with a wrap.   If you want a tighter throw, wrap it into a cone shape.  You can get a very tight dot of light this way.

Another added benifit is that it can be used as a bounce card – simple wrap one end around the flash head pointing up, and leave the other end free.  presto bounce card.

For five dollars and a minute of work, this is something that will have a permanent place in my camera bag!

quick and dirty seamless backdrop for small subjects…

Just a quick tip if you do a lot of product/small object shots and want them on a seamless background.  Instead of rolling out a whole huge backdrop, just use a piece of matboard.  If you do your own matting/framing, you’ve probably got some on hand.  It comes in nice 30″x40″ sheets, and it is rigid enough to stay in place on it’s own when propped against a vertical surface like a wall or chair pushed up agains a table.  It gives a nice smooth curve under it’s own weight, and provides a non-wrinkly insta-seamless-backdrop.  and when you are done, you can mat your pictures with it 🙂

Quick tip – keep track of your charged/uncharged batteries!

If you are like me, you probably have a *lot* of batteries.  Particularly on location with a couple of strobes.  You’ve got a bucket full of AAs, and maybe 3 or 4 batteries for your SLR.  All well and good up until you start changing batteries in the field.  Maybe it’s just me, but once I start swapping batteries, when I get home it they are generally all jumbled up and I have no idea which are still charged, which are dead and which may have been partially used, but still need a “top off”.   To solve this I came up with a rather simple solution – when I charge my batteries, as they are charged I put a rubber band around them.  This serves two purposes – 1) it keeps each set of AAs together in a nice neat group of 4, but more importantly it “marks” them.  Since I obviously have to take the rubber band off before using the battery, at the end of the day, I know that any battery with no band has at least been used, and the ones still banded are fresh.  Then I simply charge the loose ones and re-band them.  Works with both AAs and SLR batteries, quick and easy.

The G9 as a location scouting tool

Did some location scouting yesterday, and I figured I’d share one of my little tips for scouting for shoots.

Now, normally when scouting, you go around and when you find a potentially good spot for a shot you fire off some frames

However, I like to use my G9 for scouting – not only because it is light and compact (I toss the g9, a sync cord and strobe in a little shoulderbag, and it weighs a few oz.) but for the *movie mode*

In addition to my reference shots when I find a good spot, I will flip it into video mode, and pan around the area – recording all the angles/light in the area – as well as speaking some “notes” about my ideas for the shoot. That way when I get home, I not only have my still images of the locations, but a bunch of little video clips showing all the angles, with narration along the lines of “corner of x street… light coming from the west… will place model in front of the tree/car/whatever… with a reflector to the left and single strobe to the right”

or something like that 🙂

This way I remember *excatly* what I was thinking at the time for the shot/setup.

Anyway, hope it’s a useful tip – it doesn’t have to be with the G9 either, any pocket cam with a video mode will make a nice companion to your SLR when scouting locations! (though with the G9, I find I hardly need the SLR backup)

Dodge and Burn – Lightroom 2 beta vs Aperture 2.1

Preface: this is a “sequel” to my previous article on the new dodge and burn plugin in Aperture, so it’s best to read that one first!

Here’s a quick rundown of my experiences with the new dodge and burn tools in the Lightroom 2 beta, and how they stack up to the same in Aperture 2.1. After a weekend of working with both tools, I’m still of very mixed feelings:

there are a few things I *really like* about Lightroom’s implementation, but in a lot of ways I feel they fall short. I used the same image as I did with my Aperture article for ease of comparison. Once again, here’s the original image:

Now Lightroom and aperture seem to approach the whole “brush based tools” paradigm in a very different way. Here’s the basic interface panel for the new tools in Lightroom 2 beta develop module:

Clicking the little “brush” looking icon brings up this dialogue. You’ll see the adjustment you want (exposure, which is essentially dodge and burn together depending on if you set a positive or negative value for the tool) and the standard size/feather/flow for the brush.

Note that as far as I can tell there is no kind of pressure sensitivity control when using a pen tablet as with aperture. You have 2 brush “presets” A and B and can switch between them. I usually keep one as a soft brush and one as a hard brush.

Another interesting feature is the “auto mask” which essentially tries to keep the adjustment you are painting within the boundaries of the area you are working in (by finding the edges and containing it within them). This seems to work fairly well on some images (that have clearly defined areas/regions, like burning the sky against a building for example) and not so well on others. Still a neat addition.

Now here we come to a fundamental difference between the Lightroom and Aperture implementations. While Aperture essentially has a “layer” for each adjustment (dodge, burn, saturation etc…) which you paint into, Lightroom uses discreet “point based regions” for each adjustment. To clarify: in Lightroom every time you make a “new” adjustment it creates a “point” which is a little white dot around which that brush stroke adjustment is based. This is essentially the anchor for the adjustment region, and you simply paint on the adjustment you want.

You can also switch to the erase brush with the same controls (feather, softness etc…) or simply toggle it by holding the option key (alt on windows I believe)

The interesting this is that once painting, each “pinned” region becomes just another adjustment on the image and can be changed/refined after the fact, by selecting “edit” and editing the adjustment – you can adjust the amount of exposure (dodge/burn) etc…

Now the annoying thing (to me at least) is the fact that there is no way of toggling the “overlay” of the brushed/adjusted area the way there is in aperture. When you hover over on the the “pins” it comes up with the area highlighted, but only while you are hovering over it. Sometimes you really want to be able to fine tune the edges of your adjustment area, and it is difficult to do this without having an overlay view. Hopefully this is something that will be implemented by the final release. I also wish they would make the overlay a color rather than just a translucent grey/white as sometimes it is difficult to see when brushing an effect onto a bright/white area.

As opposed to the Aperture paradigm of having a single adjustment layer with various intensities, here you are more likely to make multiple overlapping “point” regions, and adjust them individually after the fact. Unfortunately what I found was that this lead to a lot of “guesswork” for example when you want to lighten an area, first you have to guess how much exposure should be applied, then brush it in, then further refine it by adjusting the level, then if a “sub-area” need to be lightened/darkened more you have to create a new overlapping point region and again guess how much exposure is needed and adjust from there.

I give the win to Aperture’s implementation for ease of use and intuitiveness, but I can see the potential in having independently adjustable brush-edit regions.

Now after complaining about the implementation of the tool, I would like to point out the one incredibly awesome feature of Lightroom’s adjustments, that by itself may even be significant enough to swing the decision in it’s favor despite my favor for Aperture’s implementation:

that is the inclusion of the edits in the adjustment history for the image.

As mentioned before, Aperture creates a separate .tiff file from your master .raw when you invoke the burn and dodge tools. While not a huge drawback (it’s no different than roundtripping it to Photoshop for example) it adds a layer of complexity, as you are now essentially adjusting 2 images.

Lightroom on the other hand, makes the adjustments exactly the same as any of it’s other adjustments – meaning they they apply to the raw file, and are included in the history. Being able to step back and forth through the edit states of an image is just a fantastically useful feature, and a huge point in Lightroom’s favor.

In conclusion after using both tools for a short time now, I am really torn. I like apertures implementation overall better – it feels more natural and almost “painterly. I can definitely appreciate the approach of Lightroom’s implementation, but to me it isn’t quite “there” yet – there are a few annoying little details that make it less useful overall – the overlay is rather useless, with no toggling option and there really should be some kind of pressure sensitivity. It would also be nice to be able to label the “pins” to easily remember which pin went to which adjustment. I also really miss brush based blur and sharpening (both of which Aperture has).

Nonetheless, Lightroom gets big points for incorporating the brush tools into it’s standard workflow and history panel. This is simply an amazing feature which cannot be overlooked. If Lightroom can fix/improve the issues with the masking/overlay transparencies by the final release, it may still win out over Aperture. For now I reserve judgment – I will play with both and wait for the Lightroom final release 🙂


Aperture 2.1 dodge and burn module – a quick tutorial and review.

Aperture 2.1.

“brush” based Dodge and Burn based tools.

The verdict?  Awesome.

After a weekend of playing with aperture’s new burn and dodge plugin, I remain as impressed with it as I was at first.  Quite frankly with this module and 1 or two more plugins, I may well never open photoshop again! (hyperbole, I’m sure).  So without further ado, a quick summary of how the tools work, and my experiences working with them.

First off – there has been some complaints that aperture creates a .tiff copy of your image when opening in dodge&burn (D&B) rather than working on the actual raw image.  The way I see it is that you would be doing that *anyway* if you were round-tripping to photoshop, so you are not losing anything – and you are gaining the ability to edit “in house”.

As a quick demo I took some screenshots from a shot I did for a local food magazine’s article about cheese.  Not the worlds greatest picture, but it illustrates the dodge/burn functionality well. Here’s the original image, straight out of camera (raw)

Note the heavy shadow on the grapes.  Yeah, I should have used another light for fill – sue me.

Now on to the plugin.  Unlike the standard image adjustments, the dodge and burn tool (the name is slightly misleading as it actually does more than just dodge and burn – it also allows saturation, sharpening and contrast brushes. Cool!) is invoked by selecting an image and going to image -> edit with->dodge and burn.  This opens the image in a popup window with the dodge and burn controls. If you’ve used photoshop, these controls will be immediately familiar – there is brush size, hardness and strength right up top.  By default, scrolling the mouse wheel increases/decreases the brush size, and pen pressure controls the effect strength.

Fantastic if you work with a tablet (and you should be!)  The control scheme is very natural and took no getting used to whatsoever.  You can hit “Z” to zoom to full size just as in the normal viewer, and holding spacebar “grabs” the image allowing you to scroll around it quickly in fullsize view, just like photoshop.  

With regards to the actual tools, they are divided into separate sections, selected from the dropdown menu on the left.

As a photoshop user, you might think of each tool as a separate layer with it’s own quickmask.  Click any tool to select it and start “painting on that layer”   I have selected dodge, to lighten up the shadows on the underside of the grapes, to make them “pop”  I select a large, soft brush and start with a relatively low effect strentgh (repeated passes will build up the strength of the effect so it’s good to start low to begin with).   I quickly paint over the grapes, and there is a noticable lightening of the shadows (amaizingly without bringing up much noise!) Now what’s really cool is that as you work, you can instantly swith between the normal image view where you can see the effect of the tool, and what apple calls “overlay” mode which actually shows you where you have paintined on the effect and the strength (kind of like quickmask in photoshop).  Clicking “O” toggles between the two modes.   I found this to be absolutely critical and gave a very fast and accurate tool to fine tune the area and strength of effect, allowing very precise control.   Note that you can still brush on the effect in overlay mode.  You can also switch back and forth between tools, each get’s it’s own “layer” to paint on, with it’s own overlay mode.  As you select each tool, you can turn the effect on and off to see the results by pressing “S” I found myself quickly going back and forth between tools, dodge/burn/saturation to tweak the images in various points.  And if you ever find that you’ve painted too much or in the wrong area, simply select the eraser tool, and erase the effect back.  The eraser works much the same way as the brushes, meaning it can have varying hardness and strength so that you can simply lighten an effect that was painted on too strong, or completely erase a mis-stroke.

Another tool worth mentioning is the “feather” brush.  This allows you to quickly blend the edge of an effect to make it more subtle.  I found this to work *very* well, and really allowed for some sophisticated effect blending to look totally natural.  To illustrate the feathering, I have brushed on an effect with a brush at 0% softness  and 100% effect strength, to give a completely hard-edged, stand out effect.  Now, I go over the edges with the feather brush, and they soften and smooth out, giving a much more natural transition.  Now that was just a dramatic example – when you feather a more normally applied effect, it works even better.  The results are subtle, but it really adds an edge to the image.

Unfeathered:

Feathered:

I found it quick and easy to switch between different effects, painting them on and erasing them, and quickly toggling overlay to view the progress.  Though not used in this image the sharpen and blur brushes can be used in much the same way in portrait/glamour retouching (although photoshop may still be required for some of the more sophisticated retouches of that sort!) And that’s about it! it’s rather simple, but I found it to be one of those “does exactly what it is supposed to do without a lot of extraneous junk” kind of things, which I really like.  Basic dodge and burn +brush based adjustment functionality, basic yet powerful controls. The image after a quick D&B: Now if you are a photoshop user, none of these features may seem like a big deal – “So what” you might say, I can already do all that in Photoshop”.  And you are right – none of the tools themselves are revolutionary, but the fact that you can now do it *not* in photoshop is quite intriguing.

The image after a quick D&B (no other adjustments)

Dodge and Burn functionality was something that I was honest surprised was *not* included with aperture or lightroom to begin with, as it is pretty fundamental to a lot of photograhic processing (at least for me coming from a wet printing background!)  It’s addition really takes the processing capabilites of aperture to the next level.  The fact that it is based on an open plugin architecture further leaves the door open for other modules and even more powerful processing capabilities.  It will certainly be exciting to see what comes down the pipeline in the next year or so!

POLL: how do you do b/w conversions.

So I love black & white photography.  Back in the old days, I don’t think I ever even shot a roll of color film (maybe a few slides here and there, but whatever…) 

Now while I’m one of those crazy folk who would love a dedicated black and white sensor in a dSLR, (resolution, no bayer filter etc…)  I’m realistic enough to realize it’s probably never going to happen, and really I’m ok with doing b/w conversions.  It has the added bonus of being more flexible than a straight up b/w image with regards to what you can get as the final output. 

The thing is, there are just *so many* ways to do it…lightroom, desaturation, color mixer, LAB color etc… I still haven’t decided on a favorite.   Usually I just convert in lightroom, use the channel mixer and then adjust contrast to taste.   But I’m always open to new techniques!  So I’m opening it up to y’all:

What’s your favorite method of b/w conversions in digital?  Post it here and I’ll give it a whirl! 

I take better pictures with primes.

As I mentioned in my previous article I am a devotee of the humble fixed focal length lens, AKA “prime”

As a predominantly fine art/street photographer, I have spent most of my photographic career not really “needing” zooms, but as I move more into the realm of commercial/assignment photography, I recently picked up a fast standard zoom (16-50/2.8) for when I need the flexibility over a prime.

so for the past few months while I play with my new toy, learning it particular quirks and characteristics my primes have sat on a shelf while my 16-50 has been attached to the camera.

And you know what? My pictures have gotten worse. Continue reading I take better pictures with primes.

Street Photography and Hyperfocal setting with the G9

As I mentioned in my previous article, I see the canon G9 as a excellent camera for “street photography” (at the risk of offending the leica-philes!). However, it still poses the same problem as any other digicam for street photography and that is LAG.

Luckily, the G9’s lag is not all that bad to begin with, and can be minimized a bit further. First off- the shutter lag is not bad at all, the predominant problem is the focus lag in low light (especially on the street where the AF assist lamp is not much use). Luckily this is one case where a small sensor actually *helps* us… since the small digicam sensor has such a large depth of field, it facilitates setting the hyperfocal distance (the focal point at which the DOF is from 1/2 the H.D. to infinity – eg if the hyperfocal distance is 10ft, then everything from 5ft to infinity will be in focus)
Continue reading Street Photography and Hyperfocal setting with the G9

super awesome flickr script happy funtime!

Digital Photography School has just posted a fantastic collection of flickr greasemonkey scripts by Martin Grommel.

If you are a flickr user at all (even just a browser), these will improve your user experience no end. I particularly like #1, #3 and #9

And if you aren’t using firefox with greasemonkey – what’s wrong with you? go get it! now!

(for the uninitiated, greasemonkey is a firefox extension that lets you run client-side scripts that customize the appearance and whatnot of webpages that you view as well as other stuff. Probably the single most useful firefox extension out there)