DarktableVsRawtherapee written at 12:25:58; Add Comment
Darktable versus Rawtherapee
When I wrote my entry on Linux RAW processors I said that Rawtherapee was a better choice than darktable. I have to take that back because it turns out my quick tests weren't a good representation of using either program for real.
I formed my initial views after test-processing just a couple of photos with each program. Now that I've used both to process batches of photos for real (and in one case I've run the same batch through both), I've had to change my opinion. It turns out that darktable is what you want to use, not Rawtherapee. For all of darktable's irritations, it works better. I summarized the main reasons why in a tweet:
(I've since become more acclimatized (or numb) to darktable's interface issues.)
The first issue is that Rawtherapee turns out to be relatively terrible for sorting through a bunch of photos and figuring out which ones are worthwhile. I could do it, but it took too long and was a pain in the rear in all sorts of ways because Rawtherapee has fumbled multiple aspects of doing this efficiently. Darktable is not great at this but in practice I can go through a bunch of photos much quicker and more efficiently with it. Since this is a major part of my daily workflow, this matters a lot to me.
(For example, Rawtherapee has absolutely and utterly terrible downsizing of thumbnails in its directory overview, to the point where they are basically useless for telling you anything about the quality of the photos. Think of the most crude and jagged downsizing you've seen; that's Rawtherapee.)
The other part is that I get better processed photos with darktable, in that I like how they look and it's (much) easier to produce what I think of as good looking photos. Again, darktable is not perfect and there are some things that Rawtherapee unquestionably does better, but darktable wins overall for me. I find it very hard to argue with clearly better results, especially when I can get them surprisingly rapidly and easily.
Now I'm going to say something that may make people especially unhappy, because there's a third advantage to darktable. Namely, it's under much more active development than Rawtherapee (I track the source repositories for both and darktable sees multiple commits a day whereas Rawtherapee moves much slower). I know that development activity doesn't necessarily equal quality, but both programs are highly imperfect right now so the one that's under much more active development is much more likely to improve into something good (or at least have your favorite irritation fixed).
(Note that with either program you want to be using the latest version compiled from the project's source repository. Both are under active development and improvement and yes, it really makes a difference. Probably not as much a difference as in my initial tests (where the then-current release versions produced bad output), but you'll find that both are better experiences.)
(As before, you should pay attention to the publication date of this entry if you're coming here through a web search. It's quite possible that things will be different in a year or two. I certainly hope that Rawtherapee improves substantially over time and at least some of its issues should be relatively fixable.)
Sidebar: what happened to make me discover this
I didn't set out to try out both on a batch of real photos; instead, I set out to process a batch with Rawtherapee because I thought it was the program for me. After slogging through the whole process and getting a trio of processed photos that I wasn't really enthused with, I decided to re-run the same batch through darktable just to see. Much to my surprise I was able to do so much faster and I was uniformly much happier with the results, to the point where I immediately replaced all of the Rawtherapee versions I'd uploaded to Flickr with the darktable versions.
(The extra speed with darktable didn't come because I immediately zeroed in on the 'best' photos and only dealt with them. I reconsidered all of the batch from scratch in darktable, although I wasn't surprised to wind up with the same set of selects.)
SlingbagWhyNot written at 00:06:04; Add Comment
Why I have a camera slingbag but you probably shouldn't
Camera slingbags are inherently a compromise. Backpacks (and some belt systems and the like) provide better support, while shoulder bags and belt systems provide faster access to gear. This compromise nature is why I think you probably shouldn't get a slingbag since you can do better on either aspect and in the long run I think the compromises inherent in a slingbag will prove irritating.
(Especially I would not get a big slingbag because slingbags just don't provide enough support for carrying a relatively heavy load.)
Why I have a slingbag, and specifically why I have a Lowepro AW-series slingbag, is that I am an impatient bicyclist. As a bicyclist I need to carry my camera in some way that keeps it both stable and out of the way; this rules out both belt systems and anything like a plain shoulder bag. As an impatient bicyclist I want my camera to be relatively quickly accessible so there is not a big time-consuming production involved in stopping to take a picture; this rules out backpacks. So I'm left with the Lowepro slingbag; it's stable enough to stay in place even with relatively aggressive bicycling and being able to just unhook the stabilization strap and sling the bag around keeps the camera accessible enough to make me happy when I stop to take pictures. I live with the relative lack of support (which I can definitely feel on long days with relatively heavy loads) and the relative lack of fast access because I need the particular combination in the middle.
(Why the Lowepro specifically? Because it has a second stabilization strap that holds the slingbag firmly in place when it's clipped on to the main strap. I've been unable to find any other slingbag with such a stabilization strap, although I haven't looked everywhere.)
PS: in some ways I'd be better served by a handlebar bag that was big enough for my camera (and lens), padded enough so I could trust it to not rattle the camera too much, and detachable so I could take it with me when I get off the bike. Unfortunately you really want drop handlebars to create the cable-free space for such a relatively large handlebar bag and, well, I don't have them on my current bike.
(Update: it turns out that I'm wrong about the Lowepro being the only slingbag with a stabilization strap; they're actually reasonably common if you look around and read specifications in detail. Due to not having seen or played with any of the alternatives in person, I have no opinions on the relative merits of my Lowepro versus the alternatives.)
LinuxRAWProcessors written at 23:01:15; Add Comment
A brief, opinionated summary of Linux RAW processing options
For reasons that don't fit in the margins of this entry, I've been looking at and doing brief tests with a bunch of Linux RAW processing programs lately. Rather than have all of this fall out of my mind in a bit, here's my views written down.
(If you're coming here through a web search you should pay attention to the publication date of this entry. The information here will probably be out of date in six months and will definitely be out of date in a year or two. I'll put in a link to any future updates I make.)
Update (April 16 2013): I now recommend darktable over Rawtherapee. See DarktableVsRawtherapee.
As a starting point I will note that I do not want a program to do catalog management for me. I have my own system for that and I've got no interest in shoveling all of my photographs into some opaque black box. What I want out of a RAW processing program is processing a directory of RAW files and generating output; I will take it from there, thanks.
While this is every current Linux RAW processor that I know about, I probably don't know about them all. Please feel free to mention any that I've missed in the comments.
(Explicitly not considered: using Wine or some other Windows virtualization method to run various Windows software options.)
Sidebar: Macs and Windows are better for this
I'm going to say it straight up: the overall quality of the RAW processing software you can get on Macs and Windows clearly exceeds any of these Linux options. The closest that Linux can come is AfterShot Pro, and that is somewhere around third tier software in the Mac and Windows worlds. If good, high quality photo processing is a significant priority for you, you should not be doing it on Linux.
(My vague impression is that Macs are currently a somewhat better choice than Windows for reasons that do not fit in the margins of this sidebar.)
I don't process my photos on Linux because it's a good idea; I do it because I'm welded to Linux for other reasons and I'm not yet at the point where I'm willing to buy a second system (it'd be a Mac) and find the space for it. If I was more committed to my photography, this would be one of the things that would change.
UsingExposureLock written at 01:01:09; Add Comment
Using automatic exposure locking
Back in 2008 when I set up my D90 and wrote down my settings, I said this about the AE-L button:
Boy, I was kind of innocent back then. Nowadays I have learned what autoexposure locking is for the hard way and I use it reasonably frequently. The simple way to put it is that locking the exposure is the quick way to deal with the importance of watching your exposure from shot to shot.
If you're not in full manual mode, the camera can change the metering during a sequence of photographs; it can do this even if all you're doing is changing the exposure compensation. Locking the exposure with AE-L counteracts this, giving you a stable exposure that you can make consistent adjustments to. Otherwise your attempts to adjust the exposure to get the picture right can be happening on top of quicksand, so that you dial in some negative exposure compensation to correct things but then the camera decides to expose more so in the end your exposure winds up just the same. This is both pointless and frustrating when it happens (and very puzzling if you don't notice the exposure shifting on you; here you are adding exposure compensation yet nothing is happening, or the wrong thing is happening).
I've repeatedly stubbed my toe on this so these days I've learned that if I'm taking a sequence of pictures of the same thing the first thing I should do is hit the AE-L button, especially if I'm just working to get the exposure right. Otherwise, even if I'm just lowering the camera to look at the histogram after I've taken a picture the composition can be just different enough when I bring it back up to my eye that the Nikon matrix metering changes the base exposure.
I maintain that my choice of 'tap to hold' is absolutely the right option for this on Nikon cameras, at least for what I want to use AE-L for. It would be very hard to have to keep one finger on the AE-L button all the time, even when I'm doing things like checking the histogram for specific areas of the picture.
HowLongMetering written at 21:23:03; Add Comment
How long an exposure can my camera meter?
A friend and I were talking about long exposure photography today, which brought up the issue of determining how long an exposure you needed. Like most DSLRs, my Nikon D90 will only automatically expose out to 30 seconds; if you need a longer exposure than that, you have to time it by hand in Bulb mode.
(In my opinion this is a pointless limitation, probably reflexively carried forward from the days when there was only so much space on a physical shutter speed dial. Since cameras are computers these days, you could even limit automatic exposures to no more than 30 seconds while still letting the camera count the time for longer manual exposures.)
But that's just how long an automatic exposure the camera will do, not the limit of what it will meter for you. If the exposure is at the 30 second limit and the viewfinder is still reading 1 EV of underexposure, you can fix that with an exposure that has 1 EV more time, ie a 60 second bulb exposure. So how long an exposure can I actually meter with my camera?
Since every EV is a doubling of the exposure time, 8 EV of exposure past 30 seconds is 128 minutes; call it a two hour exposure. If this isn't enough, I can start pulling the viewfinder meter back by metering with a high ISO but actually photographing with a low ISO. My camera has a base ISO of 200 and is easily raised to ISO 3200, giving me another 4 EV of metering range (a total of 12 EV); that takes me to an exposure duration of over 30 hours.
So the real answer here is that my camera battery is going to die long before I get to an exposure that I can't meter. (Probably the sensor would overheat from continuous use, too.)
(In theory the D90's meter is only specified to work down to -1 LV. In practice this isn't even moonlight and I've metered without problems in much darker conditions.)
PS: since I'm unlikely to sit still for a one hour exposure, much less a two hour one, I don't even need to change the exposure compensation step size. My normal settings still give me 7 EV of exposure past 30 seconds, which is already just over an hour. Mind you, using 1/2 EV steps makes the eventual time calculations somewhat easier.
WatchYourExposure written at 13:11:18; Add Comment
The importance of watching your exposure
One of the things I've learned over the time that I've been doing photography is the importance of watching my exposure. Not in the usual sense of noticing when the camera is putting you at a too low or absurdly high shutter speed (or ISO, or aperture), although that's important too. What I mean is watching your exposure from shot to shot.
Modern cameras in matrix or evaluative metering can and do change how they decide to expose a scene depending on just how it looks to them, regardless of whether or not the actual light has changed. Or in other words, if you change your composition the camera can change to a bad exposure. If your first photograph of a mixed scene with the clear sky visible has the sky correctly exposed at 1/200th at f/11 at ISO 200, you then recompose to show more of the shadowed ground, and the camera suddenly wants to be at 1/100th at f/8 at ISO 200, you are probably going to completely blow out the sky if you just automatically click the shutter.
(As they say, I've been there and done that.)
The same thing is true in more extended circumstances. If you're strolling along a path in a park taking pictures of different things, your exposure often should be fairly constant regardless of how much of the sky or sunlit ground is visible in each photograph. And if the camera's metering seems very off, you probably have a choice you need to make; you can let the camera more or less expose for the darker areas you're looking at (and accept that the bright areas may well blow out), expose for the sky or other bright area and live with the darker areas (possibly doing tricks in postprocessing), or add fill flash or the like. Or decide that there's too much contrast in the picture and you can't get a decent version of what your eyes are seeing.
This is why I say you want to watch your shot to shot exposure; you want to realize that the 1/100th at f/8 at ISO 200 exposure has to be wrong before you click the shutter. Even if you routinely check your histograms after taking a photograph, getting a good exposure to start with will save you the aggravation of immediately re-taking a shot (and trying to narrow in on the right exposure).
(Some people will say that the answer is clearly to use manual mode and maybe center-weighted or spot metering. Both are too much work for me and tend to blow up in my face in their own ways; in practice it's easier for me to watch shot to shot exposure and correct the metering with exposure compensation when necessary.)
ETTRIssueDemo written at 13:19:11; Add Comment
Link: A demonstration of an issue with ETTR
This link requires a bit of explanation (if only so that I can remember it later). The person I'm linking to took a standard colour checker test target and took a properly exposed shot then a series at increasing positive exposure compensations (ie, exposing to the right), postprocessed all of the overexposed photos to correctly expose them again, and then cropped strips of the colour targets and stacked the same strips from each exposure. The goal is to clearly see any colour shifts caused by ETTR.
(As he notes, some are deliberately overexposed, going beyond what you should theoretically do with ETTR. Of course they do represent what happens if you accidentally overexpose in the course of trying to do ETTR.)
Part of what I like about this is that it's an experiment that anyone can do (if you have a colour checker test target). Your camera and processing system may well give you different results than his, but either way you'll have learned something interesting.
PS: obviously you should do this test with the camera on a tripod and locked at a single ISO, unless you also want to test the effects of ISO on colour shifts. Although that too may be a useful test, depending on how you're thinking of using ETTR.
PhotoWorkflow written at 01:02:59; Add Comment
My current photo processing workflow (as of June 2010)
I have some spare time today for once, since I already wrote today's techblog entry, so I feel like tackling this one just because.
To start with, a note. My workflow is strongly influenced by two things. First, I'm a Linux user, which means a limited choices for software and tools (and a bunch of scripting, because I'm comfortable with that). Second, it's strongly oriented around my Project 365 work, with an inevitable time-based focus on how I organize and approach things.
On some days, I'm selecting images for more than just my Flickr uploads; the most common case is that I am also selecting for TBN's website. In these cases I generally repeat the last three stages for each separate reason, sometimes entirely independently and sometimes interleaved (where as I look at each image, I decide both if it's good for Flickr and if it's good for TBN).
(Note that I have two completely separate photo archive areas, one for
the master directories, and one general photo archive area for all of
the pictures that I've selected for various things. The second area has
subdirectories for the thing, like
As a Linux user, my strong impression is that Bibble 5 is about my only good choice for processing anything more than a few photographs in raw format. There are some free programs that will process individual raw format pictures, generally not really very well or fast, but I haven't found one that does a decent and acceptably fast job at browsing through them so I can make my selects.
(At this point I am nowhere near willing to either give up Linux or to get a second computer just to do photo processing.)
I could simplify a bunch of this workflow if I could bring myself to trust Bibble 5's 'catalog' asset management features. I would probably use multiple catalogs, with one for my master archive and then one for each reason I pick out photographs (a Flickr one, a TBN one, etc), and switch to formatting the card every time I copied the pictures off it (even though this makes me nervous; leaving the pictures on the card is vaguely reassuring just in case something disastrous happens on the computer). However, this would mean giving up the principle that nothing except my own scripts gets to go anywhere near the master archives.
(I'm a sysadmin. No, I don't trust your program.)
With a more complicated copying scheme I could change my master archives
over to a date-based directory structure while still not reformatting
cards immediately. I would have to
Sidebar: looking back at the history of this
A lot of the dance around my master directories is because when I
started out, I was planning to burn each master directory to DVD when it
was 'done' as a backup archive; this is also why I got a 4GB SD card,
because it went well with wanting roughly DVD-sized chunks of work.
I never actually implemented this plan; my backups are instead just
(Don't panic, my machine has mirrored drives to start with.)
It's interesting and a bit depressing to see how pervasively this never implemented backup plan has shaped the rest of my workflow.
Back when I was using Bibble 4, my theoretical workflow was to use the staging area only to make my selects, then have Bibble 4 copy the selects to the per-day P365 archive area, re-point Bibble 4 to it, and process them there. This never entirely worked; every so often I would have to do most of the processing before deciding whether something was a select or not, and every so often I would get pulled into processing an image before pausing to copy it.
When the Bibble 5 beta came out, it forced my hand by not supporting directory based file copying (it could only copy files around inside its asset-management catalogs). If I was copying the files outside of Bibble 5 anyways, it was much easier to do all of the processing in one directory instead of theoretically splitting it across two separate ones.
NikonManualAutoIso written at 21:59:10; Add Comment
The Nikon DSLR trick with Auto ISO and Manual mode
Nikon DSLRs have a reasonably smart automatic ISO mode, where you set your minimum shutter speed and maximum ISO and when the camera has hit the minimum shutter speed it starts raising the ISO. They are also famous (or infamous in some quarters) for not turning off Auto ISO if you go into Manual mode, contrary to what you might expect.
(What happens in this semi-Manual mode is that the camera works out its idea of the correct exposure and then attempts to get there purely by changing the ISO.)
I actually sort of like this, because it enables a trick: it essentially turns Manual mode into a combined Aperture+Shutter priority mode, and in turn what this does is give you a convenient way to vary auto ISO's minimum shutter speed as conditions change:
(Life would be somewhat simpler if Auto ISO also let us pick a minimum aperture; even though I can shoot a 50mm f/1.8 wide open, I often don't want to and I'd rather raise the ISO a bit and be at, say, f/2.8.)
Using Manual mode this way means that you really want to be able to control exposure compensation, and in turn this probably makes this trick unusable on bodies with only a single control wheel (where you lose access to exposure compensation in M mode).
The one thing that I really have to remember when doing this is to pay attention to the ISO and to the exposure meter, because the camera can overexpose if you push it. Generally if I'm doing this I want the ISO to always be above base ISO; the ISO going to base ISO when I'm at a comfortable shutter speed is a sign that I should switch to another exposure mode, because M mode probably isn't getting me anything useful.
MovingBicycles written at 02:48:26; Add Comment
The problem with taking pictures of people bicycling
(Well, one of them.)
There are three shutter speeds for taking pictures of moving bicycles:
The 'just right' shutter speed is a narrow zone and varies quite significantly depending on how fast the rider is going. (And it goes quite high; I believe I've seen visible motion blur in shots at 1/250th, and the bicyclist wasn't going particularly fast.)
So far my best results have come from cheating, in the form of panning with the bicyclist at 'lower' shutter speeds (lower being relative here). But this has its own problems; it's okay for shots of just the bicyclist, but it's not good for 'rider in context' shots, since the context is blurred.
(And you have to carefully match your panning speed to the bicyclist's speed in order to keep them sharp, which I am not yet all that good at.)
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