Messages

376

Lenses / Re: How low will it go? (50L)

« on: February 19, 2013, 06:45:33 PM »

If $100 means so much to you that you'll hold off for months to buy this lens, then this lens most emphatically isn't for you.

The 50 f/1.4 is a superlative lens that even generally outperforms the L. For double your money you get an extra fraction of a stop and "superior build quality." Big whoop. It has got to be the worst bang-for-the-buck in the Canon lineup.

If you really need that extra fraction of a stop, then you're making enough money off your photography that you're not sweating over $100. If it's build quality that you're interested in, put the extra $800 into a bank account. After several years of heavy use when the f/1.4 finally breaks, toss it and use the money you set aside to buy a second one. You'll still come out ahead.

In short, this lens is for people for whom $1500 is chump change. If your reaction at discovering that your car needed $1500 of repairs would be anything beyond mild annoyance, don't buy this lens.

(If you do have that kind of money, sure, go for it. Why not?)

Cheers,

b&

377

Lenses / Re: lens question for the math geniouses

« on: February 19, 2013, 06:11:43 PM »

Perhaps the most intuitive, understandable explanation I've ever heard... This is tremendously helpful. Thanks!

You're welcome. Glad to help. I don't remember where I first encountered it, but the idea if not the source obviously made an impression....

b&

378

EOS Bodies - For Stills / Re: Better Dynamic Range in a Camera

« on: February 19, 2013, 01:17:36 PM »

When I look at a scene I often can see the bright and the dark and not lose detail in the bright or the dark.
When I take a photo of the scene depending on where it's metering it might make a photo too bright or too dark (losing detail in either case). It might also (if I meter correctly) do a kind of average where I lose some detail in the bright and some detail in the dark.
The dark bit I might dodge and the light bit I might burn (or use a lightroom filter).
Could a sensor have dark but retain all the detail (ie it's not black unless it  is black) and bright light but also retain all the detail (it's bright but not completely white)?

Let's put some numbers to the question to help things along.

We'll start with a carefully controlled environment -- a viewing booth with a standard D50 illuminant. That would be a full-spectrum daylight-balanced light source that's reasonably bright at the print. A light trap (a hollow black-lined box with a small hole at the top) would be 0. A piece of Teflon thread tape would be 100 (or close enough as makes no difference. A piece of high-quality fine art paper would be just barely discernibly darker, around 98 or 99. The darkest you could print on that paper would range from 10 or so to 20 or so, depending on the actual paper and printer.

That's basically what the L* value represents in the Lab color space -- except, of course, the definition is more precise than what I just gave.

Unlike RGB color spaces, the Lab space is open-ended. Most real-world scenes contain images with considerably more than an L* value of 100.

For example, right next to this standard light booth, let's place another one with the print raised so it's closer to the light source. It's the same piece of paper as the one in the standard booth, but it's now more brightly lit and so, to the observer, has an L* of more than 100. How much more depends on how much closer the paper is to the source, but let's pick an arbitrary number and say it has an L* of 150.

You're standing there with your high dynamic range camera and you take a picture of this very scene. Not a problem -- the camera captures it just fine.

But now what're you going to do with that file?

If you want to make a print, the stuff in the standard viewing booth is no trouble; with the proper workflow, within certain limits, your print can look identical. The picture of the bare paper gets no ink in your print, either, and the other parts get the same ink as in the original.

But how are you going to make the image of the paper in the non-standard booth be brighter than the paper in your print? That is, with a paper that has an appearance of L*=99 in standard viewing conditions, how are you going to make an image of something that has an appearance of L*=150, and still show the image in standard viewing conditions?

There are a few possibilities.

You could compress the captured dynamic range. The image of the paper in the brighter booth would get printed as L*=99 (you have no other choice), and everything else gets similarly scaled by 2/3. The image of the paper in the standard booth gets printed as L*=66, which is roughly Zone VI.

You could be more gentle in your compression. You could print the paper in the brighter booth at L*=99, print the paper in the standard booth at L*=90, and thus make the standard booth look very close to as it was but everything in the brighter booth would look very washed out.

You could go ahead even further and clip everything in the brighter booth that happened to wind up brighter than L*=99.

You could do some masking and render each booth to a normalized version, such that the white paper in the standard booth got rendered as L*=99 and the white paper in the bright booth also got rendered as L*=99...but what're you going to do in the space between the booths? And you're now left with the two booths looking the same when they were significantly different to your eye.

One obvious solution would be to not make a print of the scene but rather to show the scene on an illuminated display. Let's say that this display can go from L*=5 to L*=200. Now, there's no problem showing the full scene that originally went as high as L*=150. But now you might have a different problem...the viewer's eyes might be adapted to thinking that L*=200 is "full bright," and the L*=150 parts of the scene in the original give the appearance of being less bright than they actually were. You then might be tempted to scale everything the opposite direction, to make L*=150 map to L*=200...but now either you also have to raise the blacks and make them washed out, or you wind up stretching the dynamic range overall and creating more contrast than there originally was.

Now, instead of simply two viewing booths with slightly different light levels, imagine you're also including the lightbulb itself in your scene. That may well be L*=1000; how are you going to reproduce that?

So, sorry, hate to break it to all y'all, but we're never going to stop having problems with dynamic range in photography.

Indeed, it's the exact same problem as artists everywhere have always faced...and that's why artists are always talking about the light, why there exists such things as good light and bad light.

It's all about the light. It always has been, and it always will be.

Cheers,

b&

379

Lenses / Re: lens question for the math geniouses

« on: February 19, 2013, 10:44:32 AM »

There's an easy way for a photographer to get a mental grasp on the meaning of focal length.

Take a sheet of cardboard and cut a hole in it the same size as your camera's sensor (or film or whatever). Hold it 50mm away from your eye, and you'll see exactly the same field of view as your camera captures with a 50mm lens. Hold it 24mm away and you see what you would with a 24mm lens. Hold it 50mm away but with a hole cut for a different format and you now see what that other format sees with a 50mm lens.

50mm is about two inches. Space your fingers about an inch and a half apart and hold them about two inches away, and you see what a 135 format ("full frame") camera sees with a 50mm lens. Hold your hand in the same spot but bring your fingers closer, to about an inch apart, and you now see what an APS-C camera does with a 50mm lens. Hold a sheet of paper two inches from your eye and what it covers is what a large format camera sees with a 50mm lens. Hold your little finger two inches from your eye and what the tip covers is what a P&S camera sees with a 50mm lens.

...and now you should understand all you as a photographer need to know about focal length and image format.

For bonus points, imagine a spot midway between your fingers and your eye where the light gets focussed through. That spot is the size of the focal length divided by the aperture. For f/2, it's half the size; for f/4, it's a quarter the size, and so on. Hold your fingers two inches away an inch and a half apart and imagine a 3/4" hole between; that's 50mm f/2. Keep your fingers an inch and a half apart but move them four inches away, but the spot stays at 3/4"; that's 100mm f/4.

Cheers,

b&

380

Lenses / Re: lens question for the math geniouses

« on: February 19, 2013, 10:29:07 AM »

All else held constant, the larger the format the shallower the depth of field.

That depends on what "all else" is. Assuming you mean the same optics, then
if AOV is constant then yes - if it is distance to subject then no (cropping i.e. "changing the format" ) does not
affect DOF.

Br,
Thomas

Yes, of course. Focal length must be matched to the angle of view for the format. A 50mm lens is a normal lens on 135, but it's a full-circle fisheye on 8"x10" and a supertelephoto on a P&S.

The only reason there's ever any confusion on this subject is because we happen to be at an unusual point in history when it's common to mount the same physical lens to two different formats. But that same 50mm normal lens on 135 is really a short telephoto on APS-C. "All else held constant" between 135 and APS-C would mean swapping the 50 for a 35.

Cheers,

b&

381

EOS Bodies - For Stills / Re: Better Dynamic Range in a Camera

« on: February 19, 2013, 10:10:04 AM »

Is this what you feel at the edge of the grand canyon on a partially cloudy day? "Ouch, too much dynamic range"?

Yes, exactly. Why else do you think people squint, shade their eyes with their hands, or wear sunglasses or hats?

Where I am sitting right now, I can watch a bright snowy landscape out of my windows, or peek at my interior in the shade.

And I'll bet that you're squinting at the snow, and, after a bit of squinting, you can't see a bloody thing around you inside. Or else the glass is tinted.

There are certainly times when the point of art is to make people uncomfortable, but those are exceptions. And, even then, the discomfort is almost always toned down or somehow simulated or made distant. Very few people would be interested in a sunset photograph of a beautiful scene that made them squint and shade their eyes, as much as they might enjoy being in the actual setting where the photograph was made, painfully bright light and all.

Cheers,

b&

382

Lenses / Re: lens question for the math geniouses

« on: February 19, 2013, 10:01:04 AM »

All else held constant, the larger the format the shallower the depth of field.

All else held constant, the larger the physical aperture the shallower the depth of field.  (A 100mm f/2 lens has the same 50mm physical aperture as a 50mm f/1.0 or a 200mm f/4.)

All else held constant, the greater the distance between subject and background the more the background will be blurred resulting in a perceived (but not actual) increase in the depth of field.

All else held constant, the closer the subject the more out-of-focus distant objects become.

So, to create an image with the shallowest (perceived) depth of field, you'd use the largest possible format with the largest possible physical aperture at minimum focus distance with the background as far away as possible.

In practice, even an 85 f/1.2 on 135 format ("full frame") is overkill. Your subject's pupil will be in focus but the iris won't -- and, even then, of course, only in the one eye; the other will be a blur.

...and then, of course, you can use the Scheimpflug principle to angle the focal plane....

Cheers,

b&

383

Lenses / Re: 180 3.5 as a PORTRAIT LENS

« on: February 19, 2013, 09:42:25 AM »

Any out door longer shots with this lens, (daylight people shots full body etc...)

This lens isn't meant for full-body portraiture. You're looking at something like 50' working distance for a full body shot. If you're serious about full-body telephoto outdoor portraiture, what you really want is a 70-200...and a walkie-talkie to tell your assistant how to direct the model.

Classic portraiture is done with a set of lenses from a fixed distance of eight to ten feet. You'd do the really big group shot with the 24, the full body standing portrait with the 35, the sitting portrait with the 50, the waist-up shot with the 85, and the head-and-shoulders passport shot with the 135. And it's no coincidence that a standard zoom covers all of that range except for the extremes. There are (of course!) good reasons to break those rules, but it would be prudent to follow them until you understand both why those rules exist and what you'll gain (and lose) by breaking them.

Cheers,

b&

384

EOS Bodies - For Stills / Re: Better Dynamic Range in a Camera

« on: February 19, 2013, 09:21:19 AM »

If we are able to _reproduce_ those 24 stops, my guess is that it will look amazing.

Quite the opposite -- it would be painful.

Monitors today are already at the practical limits of dynamic range. That is, some of them you can make too bright to comfortably look at in a typical indoor environment.

If I were to accurately reproduce the dynamic range in that shot of the Canyon, you'd go just as blind from trying to look at the picture of the Sun as you would from looking at the real Sun. I simulated that by making the Sun and the surrounding sky be low contrast near paper white, difficult to make out -- because it was. In reality, though, there was far more dynamic separation between the ring of fire of the eclipsed Sun and the immediately adjacent sky than there would be with a Klieg light projecting from a coal mine.

Cheers,

b&

385

Lenses / Re: 180 3.5 as a PORTRAIT LENS

« on: February 18, 2013, 06:52:40 PM »

The 180 makes a superlative long portrait lens.

Note that it is on the long side for a portrait lens, best suited for head shots (with similar framing to a passport photo). Once I clear myself out of a pile of other priorities, I expect to do a fair amount of work with it doing exactly that type of shot for starving musicians and actors.

Motion blur will depend on shutter speed, of course. But 1/250 @ f/8 gives you everywhere from ISO 50 in midday snow to ISO 800 at sunset, so you shouldn't have any problems there. It's perfect in the studio, where flash will take care of any movement.

The only thing you're not going to do with the lens is create razor-thin depth of field shots, though you can still get fairly thin with unidentifiable backgrounds. But f/8 is just about perfect with this lens...the whole face is in focus, and the hair at the back of the head is just a bit soft.

I'm attaching a few portraits I've taken with this lens. Eric, the clarinetist, still raves about this shot, saying it's the only picture of himself he's seen that he likes.

Cheers,

b&

386

EOS Bodies - For Stills / Re: Better Dynamic Range in a Camera

« on: February 18, 2013, 05:54:18 PM »

I'm suppose I'm missing what's missing to get a photograph to have all the dynamic ranges I see with my eyes.
Is it impossible to translate it to a photograph?

"It depends."

If the scene itself has a large enough dynamic range -- such as the eclipse over the Grand Canyon I linked to in my previous post -- then, yes, it's basically impossible to translate it into a photograph. There's only so much difference between paper white and the darkest ink you can lay down, and that's nowhere near the difference between the Sun and the shadows at the bottom of the Grand Canyon. Not even remotely close. And, though there is often a greater difference between maximum white and maximum black on a computer display than there is in a print, it's not all that much more.

So, what you have to do is, ideally, reduce the dynamic range of the scene itself. With landscapes, that happens naturally during the "golden hour." With other types of photography, you do this by adding light (with flash or reflectors) to the dark parts and removing light (with shades and scrims) from the bright parts. Doing so isn't merely a skill, it's what photography is actually all about. The camera parts are secondary; controlling the light is what your job is.

In scenes with a greater dynamic range than you can display and / or capture with a single exposure, you're left with compromises.

At the capture end, you can often use a graduated neutral density filter, but if your subject is relatively static, you can do much better with multiple exposures. You can mimic a GND with a layer mask and the gradient tool, or do better with a layer mask and a large, soft brush, or you can go the tonemapped HDR route (which I personally find distasteful but some like). Or you can do a linear HDR development with Photoshop and load the resulting 32-bit TIFF back into Camera RAW and use its tools (fill light, highlight recovery, etc.) to tame the dynamic range rather effectively.

In cases when you have a single capture with more dynamic range than you can print, you're basically doing the same thing. You can develop twice (or more) and mask the two developments together as you would multiple exposures, or you can use any of the (sadly) popular single-image HDR tonemapping tools, or you can again play with the sliders in ACR.

Mostly, though, what you really need to do is experiment. A lot....

Cheers,

b&

387

EOS Bodies - For Stills / Re: Better Dynamic Range in a Camera

« on: February 18, 2013, 05:12:27 PM »

For scenes with good light, there isn't a camera on the market that has insufficient dynamic range. In most situations where you might wish your camera had more dynamic range, the proper solution is almost always to fix the light. Generally, fixing the light for landscape photography means waiting for the magic hour. With most other types of photography, it means properly using flash and / or other light modifiers.

Sometimes, but rarely, the whole point of the exercise is to capture some sort of setting with extremes of light. Such light is not attractive in and of itself, and it is the harshness of the light which one is capturing. In those cases, the scene as you look at it will have lots of areas of reduced contrast, including shadows and highlights where you cannot discern details. Somebody mentioned the cave entrance at noon; in the real world, it would be a black hole, and the puffy clouds overhead would be too painful to look at to see detail. If you're shooting that scene, it's presumably because you want to capture the feeling of looking into a bottomless abyss while in the harsh light of day, and you'd expect the print to have a similar lack of detail in the cave and clouds. If, instead, you really do want to capture the detail in both, you should wait until sunset when the last rays of the Sun gently light up the inside of the cave, at which time that light will be well balanced with the colorful clouds. Or you should be painting the scene as you imagine it rather than trying to photograph it as it isn't.

The most challenging HDR shot I've ever done is here:

http://www.canonrumors.com/forum/index.php?topic=12617.0

And that really is very much what the scene looked like as you stood there. Yes, I could have gone all painterly and created something surreal and tonemapped that showed details that you couldn't see, but then it wouldn't look like what the scene actually looked like. You really could only just barely pick out the details in the shadowed parts of the Canyon, and, though glasses, the Sun still looked small and bright with a hole in it but lots of glare surrounding it. And the layers of the Canyon receding into the distance really did almost blend into the horizon, and the foreground really was that bright and contrasty.

If I wanted a painterly photograph of the Canyon, I wouldn't have shot into the Sun during an annular eclipse; I'd have camped out during thunderstorm season and hoped / waited for a day with a good sunset -- and I'd have been on the North Rim, not the South. I'd still have bracketed the exposure and still might have wound up blending a couple of them together, but the final image would largely have looked like the straight-out-of-the-camera middle exposure. If I did blend exposures, it'd most likely just be a simple pair separated by only a couple stops with a gradient blend, simulating a graduated neutral density filter.

About the only times I can think of when more single-shot dynamic range is of any significance is for digital fill flash for event photography in bad light. But, even then, either you're doing journalistic-style photography and you should be representing the scene as it is, or you're doing dynamic portrait photography (such as for a wedding) and you're being paid to make the light what it needs to be. In other words, either you should be letting the whites blow and crushing the blacks, or we're right back to fixing the light.

Really, when it comes right down to it, an extra two stops of dynamic range is nothing more than a single file that's the same as a +/- 1 stop bracket already composited together. Big whoop. Saves me the least important step in the creative process.

Cheers,

b&

388

Lenses / Re: Are you using a filter on your 40mm

« on: February 17, 2013, 08:28:25 AM »

A filter? On the Shorty McForty? For protection? Seriously?

The front element isn't merely recessed, it's smaller than my thumbprint. And I have small hands.

If this lens needs protection, then so does the viewfinder. How many of all y'all have viewfinder covers?

Cheers,

b&

389

Technical Support / Re: at what shutter speed you turn IS off?

« on: February 16, 2013, 07:22:47 PM »

IS needs processing power.

That processing is done entirely by the lens, not by the camera. That's why IS works the same on any EF mount body, from film through the 1DX. It's also why upgrading bodies doesn't enable new IS modes and better IS performance on old lenses.

So, yeah. I would entirely expect IS to improve autofocus performance. And I'd be astounded if IS degraded AF performance, though I could easily imagine situations where whatever improvement it might make would be negligible.

Cheers,

b&

390

Software & Accessories / Re: BlackRapid & Kirk clamp hook-up

« on: February 16, 2013, 06:05:48 PM »

At least with the 5DIII, the RSS L-bracket actually makes the grip more comfortable than without the bracket. Attach one of the little clamps to the side part of the bracket, and you've got the perfect setup -- comfortable in either orientation without anything getting in your way, yet entirely secure.

Going the other direction, pop off the grip (and you can leave the bracket attached to the grip when you do so), screw the BR wrist strap into the tripod mount, and slap on the Shorty McForty, and you've got the ultimate (slightly oversized) P&S.

It's actually kinda scary how versatile the 5DIII is. There are a few cameras that do certain things slightly (but not much) better, but there literally isn't anything it doesn't do well. And pick anything that one of those other cameras beats the 5DIII at and there'll be something else that the 5DIII beats it at. That even carries through to the 1DX -- the 5DIII has silent shooting and can do small and diminutive (no grip + Shorty McForty), and nothing other than the 1DX (and 1DIV?) beat the 5DIII at action.

Totally off-topic, but I do believe that the 5DIII may be the single best camera ever made.

Cheers,

b&