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Digital Cameras

In May I gave a talk for LUV about the basics of creating video on Linux. As part of the research for that I investigated which cameras were good for such use. I determined that 720p was a good enough resolution, as nothing that does 1080p was affordable and 1080i is lower quality. One thing to note is that 854*480 and 850*480 are both common resolutions for mobile phones and either of those resolutions can be scaled up to full screen on a 1920*1080 monitor without looking too blocky. So it seems that anything that’s at least 850*480 will be adequate by today’s standards. Of course as Dell is selling a 27 inch monitor that can do 2560*1440 resolution for a mere $899 in the near future 720p will be the minimum that’s usable.

Cheap Digital Video Cameras

The cameras I suggested at the time of my talk (based on what was on offer in Melbourne stores) were the Panasonic Lumix DMC-S3 which has 4*optical zoom for $148 from Dick Smith [1] and the Olympus MJU 5010 which has 5*optical zoom camera for $168 (which is now $128) from Dick Smith [2]. Both of them are compact cameras that do 720p video. They are fairly cheap cameras but at the time I couldn’t find anything on offer that had significantly better specs for video without being unreasonably expensive (more than $600).

Update: In the comments Chris Samuel pointed out that Kogan has a FullHD digital video camera for $289 [13]. That’s a very tempting offer.

More Expensive Digital Video Cameras

Teds Cameras has a good range of Digital Video Cameras (including wearable cameras, and cameras that are designed to be attached to a helmet, surfboard, or car) [3]. These are specifically designed as video cameras rather than having the video function be an afterthought.

Ted sells the Sony Handycam HDR-CX110 which does 1080p video, 3MP photos, and 25* optical zoom for $450 [4].

They also sell the pistol-style Panasonic HX-WA10 which is waterproof to 3M, does 1080p video, 11MP pictures, and 5* optical zoom for $500 [5].

For my use I can’t justify the extra expense of the digital video cameras (as opposed to digital cameras that can take video), I don’t think that they offer enough. So a cheap $128 Olympus MJU 5010 is what I will probably get if I buy a device for making video. I can afford to replace a $128 camera in a year or two but a device that costs $500 or more needs to last a bit longer. I expect that in a year or two I will be able to buy something that does 1080p for $200.

Features to look for in Great Digital Cameras

The other option when buying a camera is to buy something that is designed to be a great camera. It seems that RAW file capture [6] is a requirement for good photography. RAW files don’t just contain uncompressed data (which is what I previously thought) but they have raw sensor data which may not even be in a cartesian grid. There is some processing of the data that can be best done with raw sensor data (which may be in a hexagonal array) and which can’t be done properly once it’s been converted to a cartesian array of pixels. Image Magick can convert RAW files to JPEG or TIFF. I haven’t yet investigated the options on Linux for processing a RAW file in any way other than just generating a JPEG. A client has several TB of RAW files and has found Image Magick to be suitable for converting them so it should do.

The next issue is the F number [7]. A brief summary of the F number is that it determines the inverse-square of the amount of light that gets to the CCD which determines the possible shutter speed. For example a camera set to F1 would have a 4* faster shutter speed than a camera set to F2. The F rating of a camera (or lens for interchangeable lens cameras) is a range on many good cameras (or lenses for detachable lens cameras), if you want to take long exposure shots then you increase the F number proportionally. A casual scan of some web sites indicates that anything less than F3 is good, approaching F1 is excellent, and less than F1 is rare. But you don’t want to only use low F numbers, having a higher F number gives a larger Depth of Field, that means that the distance between the nearest and furthest objects that appear to be in focus is greater. So increasing the F number and using a flash can result in more things being in focus than using a low F number without a flash.

Another important issue is the focal length, cheap cameras are advertised as having a certain “optical zoom” which apparently isn’t quite how things work. The magnification apparently varies depending on the distance to the object. Expensive cameras/lenses are specified with the range of focal lengths which can be used to calculate the possible magnification. According to DPReview.com Optical zoom = maximum focal length / minimum focal length, so a 28mm-280mm lens would be “10* optical zoom” [8]. Finally it seems to be that the specified focal length of cameras is usually in “35mm” equivalent. So a lens described as “280mm” won’t be 28cm long, it will be some fraction of that based on the size of the CCD as a proportion of the 35mm film standard (which is 36*24mm for the image/CCD size).

Update: In the comments Aigars Mahinovs said: Don’t bother too much with the zoom. The view of a normal person is equivalent to 50mm lens (in 35mm film equivalent). Anything under 24mm is for landscapes and buildings – it is for sights where you would actually have to move your head to take in the view. Zooms are rarely useful. Something in 85-100mm range is perfectly fine to capture a bird or a person some distance away or some interesting piece of landscape, but anything more and you are in the range of silly stuff for capturing portraits of football players from the stands or for paparazzi photos. And the more zoom is in the lens the crappier the lens optics will be (or more expensive, or both) that is why the best optics are prime lenses with no zoom at all and just one specific optical length each. For example almost all my Debconf photos of the last two years are taken with one lens – Canon 35mm f/2.0 (a 50mm equivalent on my camera) and only the group shots are taken with a lens that is equivalent to 85mm.

So I guess if I was going to get an interchangeable lens camera then I could get fixed focus lenses for things that are close and far away and one with a small zoom range for random other stuff. Of course that would get me way outside my budget unless I got some good deals on the second hand market. Also having a camera that can fit into a pocket is a real benefit, and the ability to rapidly get a camera out and take a picture is important!

A final item is the so-called ISO Number which specifies how fast the film is. A higher number means that a photograph can be taken with less light but that the quality will generally be lower. It seems that you have a trade-off between a low F number (and therefore low Depth of Field), good lighting (maybe a flash), a long exposure time (blurry if the subject or camera isn’t still) and a grainy picture from a high ISO number.

Comparing Almost-Affordable Great Digital Cameras

I visited Michaels camera store in Melbourne [9] and asked for advice about affordable cameras that support RAW capture (every DSLR does but I don’t want to pay for a DSLR). The first option they suggested was the Samsung EX1 that does 10MP, F1.8-F2.4 with a 24-72mm equivalent focal range (3* optical zoom), and 640*480 video [10] for $399.

The next was a Nikon P7000 that does 10MP, F2.8-5.6 with 7* optical zoom (28-200mm equivalent), and 720p video [11] for $599.

The final option they had was the Canon G12 that does 10MP, F2.8-4.5 with 5* optical zoom (28-140mm equivalent), and 720p video [12] for $599.

3* optical zoom isn’t really enough, and $599 is a bit too much for me, so it seems that RAW format might not be an option at this time.

Conclusion

I can’t get what I want for great photography at this time, there seems to be nothing that meets my minimum desired feature set and costs less than $550. A client who’s a professional photographer is going to lend me an old DSLR that he has hanging around for some photography I want to do on the weekend.

I am also considering buying a Olympus MJU 5010 for making videos and general photography, it’s better than anything else I own at this time and $128 is no big deal.

Please let me know if I made any errors (as opposed to gross simplifications) in the above summary of the technical issues, also let me know if there are other things to consider. I will eventually buy a camera that can capture RAW images.

14 comments to Digital Cameras

  • Screwtape

    Yes, yes many great oversimplifications, but you’re generally pretty right.

    The only corrections I would have are:

    – Every raw file (not “RAW”, it’s an adjective, not an acronym) you’re ever likely to meet is in a cartesian grid; the thing that makes raw files difficult to process is that they don’t record an (R,G,B) tuple for each pixel; each pixel measures R *or* G *or* B (see “Bayer Filter”). Interpolating the missing values without obvious artifacts can be very difficult.

    – The simplest way to process a raw file is with the “dcraw” command-line tool. There’s a lot of prettier GUI tools that let you tweak the output; the most popular on Linux is UFRaw, but RawTherapee, and DarkTable are getting popular.

    – The whole point of raw files is that a trained human can make better photo-specific decisions than the generally optimal decisions made by the camera’s firmware (and indirectly by the engineers who designed it). There’s not much point using raw to avoid the camera’s default settings if you’re just going to use the default settings of dcraw or ImageMagick (or whatever). If you’re not planning to spend ten minutes to half an hour tweaking the conversion parameters of each photo, taking photos in raw format is just wasting your time.

    One last thing: there’s a third-party firmware implementation (GPL’d) for many Canon compact cameras called CHDK, which adds many features not supported by the original firmware. It may be worth limiting your search to Canon cameras, just so you have the option of using CHDK.

  • Brendan Scott

    Additions:
    * RAW is only useful if you’re planning on spending a non-trivial amount of time tweaking the photo after you’ve taken it. Not everyone wants to do this. So, if that’s not you, then don’t look for RAW support. (+1 to screwtape’s comments on RAW)
    * colour reproduction – better cameras have more faithful colour reproduction than el cheapos (this gap is probably closing). This is one of the things which distinguishes phone cameras from others. On paper phone cameras have great specs. The reality is usually different because of their colour reproduction (and lag – below).
    * smaller cameras with smaller lenses have greater depth of field, so you will have more limited scope for isolating a subject with such a camera. Lower F + faster shutter = same exposure + stop moving subjects. Lower F + same shutter = increase exposure + resolve darker objects/blow highlights. Lower F = less depth of field => isolate subject from background (background will be blurred if it is far enough away). High F is for landscape/architecture/macro work. Low F for people/other stuff which has an object that you want the viewer to notice.
    * lag – a big deal with a lot of cameras is the time between pressing the button and the shutter firing. If it’s not instantaneous (ie try it in the shop) I promise it will cause you grief.

    Cheers

    Brendan

  • Brendan Scott

    PS: buy a $100 digital compact camera to learn how it is limiting what you want to do. Lots of people do great stuff on digital compacts. You may find it is a good overall fit. Ironically, once you get into your camera you will realise that the most important thing that makes a photo is the light…

  • etbe

    Screwtape: Wikipedia mentions hexagonal grids in raw files but doesn’t say how common they are.

    I agree that using a raw file could be considered a waste of time. But then I thought that saving original JPEG files of pictures I took 10+ years ago was a waste of disk space and that turned out to be a big mistake.

    For pictures that I publish under a CC license (which is most of them) I would like to publish the raw format as well and users do what they wish. If some random person on the net decides that a picture which seemed unimportant to me deserves the extra effort in raw processing then I’m happy to let them do it.

    Finally merely cropping a JPEG loses quality. If I start from a raw file for cropping or a 60MB JPEG output from Image Magick then it should give a better result than starting from a 5MB file that the camera produces. One of my clients runs a bunch of Nikon DSLR cameras that produce 10MB raw (nef) files which get converted to 60MB JPEG files.

    I read about CHDK on Wikipedia, I’m a little hesitant to use it though. I’m happy to fool around with PCs where I can reinstall the OS easily if required. But messing with smart-phones, routers, cameras, etc is a little more risky and requires more knowledge.

    http://en.wikipedia.org/wiki/Chromatic_aberration

    Brendan: Apparently processing of raw files can reduce chromatic aberration.

    I wonder if we need a CCD size/F number metric. It seems that mobile phones will look good by F number because they have a short focal distance and a tiny CCD. The shutter time is appalling, I’ve been thinking of benchmarking some of my phones on the basis of time taken to get it out of my pocket and take a picture and time taken to take one picture.

    http://etbe.coker.com.au/2010/11/23/first-digital-camera/

    At the above URL I suggested that people start with a cheap camera. I didn’t repeat that advice in this post because you can get some quite decent cameras for not much more than $100 and my initial focus was on video cameras.

  • Aigars Mahinovs

    1. RAW is indeed useless unless you take a lot of time to work with it, and even then the benefits are very marginal. I can take and process 3-4 JPEG phots in the same time that it would take me to take and process 1 RAW photo. So for all my photo work I only shoot in JPEGs. Obsessing with RAW files is like ceramic brakes on a car – yeah, they are a good thing, but pretty useless if you have bald tires, and old 80hp engine and only drive for you 20 minute commute every day.

    2. Photo cameras are horrible at video. Yes, they do 1080p/60, BUT you need to go very high in the price scale to: get long recording times, not eat the battery in less than an hour of filming, get reasonable compression and not fill a 16 Gb card in 30 minutes, get actual autofocuss without noise in the video while filming, get rid of the jelly effect (where moving objects have their tops moving faster than bottoms), … For some situations, a cheap FlipHD type camcorder can take better video than a good Canon dSLR.

    3. Take a look at Sony NEX series – hey are dSLRs, but they are small and quite cheap, especially if you buy the last years model from people upgrading to the stuff that just came out.

    4. Lenses with F up to 5.6 are perfectly fine for daylight photography, it is in the evening, night and badly lit indoor spaces where you need to look for either a flash or a faster f/2.8 of f/1.8 lens, but those are exponentially more expensive as the F number drops.

    5. Don’t bother too much with the zoom. The view of a normal person is equivalent to 50mm lens (in 35mm film equivalent). Anything under 24mm is for landscapes and buildings – it is for sights where you would actually have to move your head to take in the view. Zooms are rarely useful. Something in 85-100mm range is perfectly fine to capture a bird or a person some distance away or some interesting piece of landscape, but anything more and you are in the range of silly stuff for capturing portraits of football players from the stands or for paparazzi photos. And the more zoom is in the lens the crappier the lens optics will be (or more expensive, or both) that is why the best optics are prime lenses with no zoom at all and just one specific optical length each. For example almost all my Debconf photos of the last two years are taken with one lens – Canon 35mm f/2.0 (a 50mm equivalent on my camera) and only the group shots are taken with a lens that is equivalent to 85mm.

  • etbe

    Aigars: I could write a shell script that copies all raw files from a camera and then runs two copies of “convert” at once so that both CPU cores are busy converting them to JPEG. The time taken for the conversion would probably be less than the time required to take my shoes off etc.

    Regarding cameras used for video, I have noted that some of them don’t support focus changes during the video, that’s a major lack. As for the vodcast specific devices doing better than a DSLR, that would surely only be in conditions of great lighting where the object isn’t far away. Admittedly that is pretty common for Youtube videos.

    http://www.sony.com.au/product/nex-5h
    http://en.wikipedia.org/wiki/Sony_NEX-5

    Thanks for the tip about the NEX, it sounds like great hardware. The RRP of $1649 is well out of my range though. Probably if I’m going to spend a moderate amount of money then I’ll consider a second hand DSLR. As I work for some professional photographers they may sell me one cheaply, and there are always advantages in using similar hardware to my clients. OTOH the smaller and lighter body of a mirrorless camera is a real benefit.

    As almost all my photography is done in the evening, at night, and indoors it seems that having a reasonably low F number (or one of those expensive diffuse flash devices) is important. Of the three cameras recommended at Michaels the cheapest had the lowest F number – but the smallest optical zoom range.

    Thanks a lot for the summary about focal length, this is really important!

    Chris: Thanks for that, it sounds like nice hardware.

  • Good overview.
    I bought my first digital camera in 1999 – a 1.3 megapixel Olympus Compact with no optical zoom with a maximum image resolution of 1280×960 pixels. I used it for about 6 years to document events and upload images to my website and to citizen journalism sites. A digital camera reduced the turnaround time and cost of publishing photos – with film cameras I had to get the film to a one hour photo lab, then back home to scan in, optimise and upload. It was a tedious and time consuming process. $1500 was the price for being an early adopter of entry level digital photography and online citizen photojournalism 12 years ago.

    Digital camera technology has come a long way since then. I went on to buy a series of Canon EOS DSLR cameras: 300D in 2005, then a 350D and most recently a 600D body for $900 early this year.

    I also bought in 2008 a small compact digital – a 7.2mp Sony Cybershot – which I use for quick stills and for short low res video (640×480 -up to 10 minutes). A reasonable compact camera for spur of the moment photography. Most digital compacts nowadays provide an adequate entry into still and video photography and allow you to experiment with post production through image and video editing software.

    If you decide you want more control over the photographic process, then you need to be prepared to spend more for an increased feature set and quality. Digital Single Lens Reflex (DSLR) cameras offer much better quality interchangeable lenses (high quality glass lenses can get very expensive but they do make a difference in photographic quality), faster response time (lag), and many more camera settings and much more control of manual camera features.

    For the last 6 years my photographic and video post production has been done on Linux using opensource graphic programs.

    I mostly photograph in jpeg image format, but if I am doing art, scientific or macro photography with my DSLR I’ll switch to using the raw format to give me more control over the image data. For these images I might spend significant time in post production. I use Rawstudio software, and then the Gimp for post processing.

    When I cover an event as a photojournalist, I can take a lot of photos so I work in jpeg. I do minimal basic post production in the Gimp. Usually it is to adjust the color levels slightly, often just to use auto adjust, and sometimes to crop the image. I then use Mapivi 0.9.7 – Martin’s Picture Viewer and Organizer – to add IPTC info (metadata information stored with the image) like description, keywords, copyright, author, contact details to all the images to be uploaded. Unfortunately the Gimp doesn’t support IPCT data in EXIF information, which is a real shame. I have to do the mapivi process after the Gimp processing.

    http://mapivi.sourceforge.net/mapivi.shtml

    Over a number of years I have used Hugin software to stitch together panorama images from 2 or more photos taken in series. This software has improved significantly recently providing much better end results for producing panoramas.

    My words of advice: Start cheap with a compact digital with a good range of features, experiment with post production and if the photography bug really bites then purchase an entry level DSLR as a second camera for more serious photographic work.

  • I always shoot in RAW, and the excellent rawtherapee (http://www.rawtherapee.com/) is used to convert to JPG.

    The benefits of using RAW are increased control over white-balance, exposure mistakes, and similar. Using RT you can easily mass-export to JPG with presets so that the review time is minimal.

  • Anonymous

    Very interested in the Dell monitor you mentioned, but I can’t find it for anywhere near that price. Mind providing a link?

  • harrytuttle

    “I read about CHDK on Wikipedia, I’m a little hesitant to use it though. I’m happy to fool around with PCs where I can reinstall the OS easily if required.”

    actually chdk gets loaded at every boot from the sd card, it doesn’t replace the original firmware, it’s more like a program that runs on top of it. it is a bit clunky to use, but being able to script the camera with lua is pretty cool, and for shooting raw it should get the job done. apparently there are some cameras supported in “beta” mode that can record video at 720p, don’t know about the zoom, might be worth investigating more. (or maybe not, i’m totally unqualified to give camera purchasing advice)

  • Brendan Scott

    PPS:
    +1 re zoom – use Sneaker Zoom. I went from using a zoom all the time to a 50mm prime and it had no noticeable impact on what I was doing.

    Shutter speed also affects motion blurring (different from lag). If the shutter is slow you need to stay v. still owise your photos will blur.

    Further on light – having the right light is what makes the shots, so the ability to accessorise with flash units will become important. The difference between the flash on my dslr (an 8 year old 10D) and on my phone (a 1 year old HTC Desire) is chalk and cheese (or great and rubbish). Depending on what you do though, you could use natural light + reflectors.

    If it’s for video make sure you get a sturdy tripod.

    1080p – I looked into this when I got a video recorder. I recall that there was some issue about 1080p and “real” 1080p. Can’t remember the details though, but a heads up.

    You also have to worry about being able to read/process the file format. Here’s what I said, although I was more concerned with the long term readability of the images:
    http://brendanscott.wordpress.com/2009/10/28/help-with-which-video-media-dead-camcorder/
    http://brendanscott.wordpress.com/2009/12/10/probably-buying-another-minidv-camcorder/

  • etbe

    Takver: I’ve got a 5MP Sony Cybershot from some time around 2005, I’ve been very happy with it. I really like the way you move a slide to turn it on. You can whip it out of your pocket and slide it open in one smooth motion. The down-side is that the slide on my camera isn’t firm enough and it slides open in my pocket leading to lens scratches. But for citizen journalism stuff the Cybershot is a good choice, it’s cheap enough that you can afford to lose it, fast to get out, and generally small and solid enough that it won’t break easily.

    http://en.wikipedia.org/wiki/Zapruder_film

    Citizen journalism ties in well with the need for raw files. You never know when a picture you take will become epic, Abraham Zapruder didn’t expect to create the most studied video in history…

    Theoretically mirrorless interchangeable lens cameras should give better quality pictures if all other things are equal. That said the best cameras all seem to be DSLRs, one of my clients has many DSLRs installed in boxes in places where humans can’t normally reach, the optical view-finder is never going to be used on those cameras – but he uses DSLRs because he wants the best pictures.

    http://en.wikipedia.org/wiki/Nikon_D7000

    What is “a lot of photos”? I’m currently borrowing a Nikon D7000, it’s raw files are 15M in size and the camera has an 8G CF card so it should be able to store about 500 pictures. I could easily buy a few spare 8G SD cards and keep them in my pocket. I really don’t think that running out of raw storage is going to be an issue.

    For my own use I would never get a DSLR, they are just too big. I might get one for my wife though.

    Anon: The price is on dell.com.au in Australian dollars. The US price might be greater as the US dollar isn’t worth as much as the Australian dollar.

    harrytuttle: OK, that makes it a lot more appealing. It’s a pity that phone vendors can’t do something similar.

    Brendan: Thanks for the suggestions, I’ve got a desktop tripod that is suitable for vodcasting, I’m not sure if I’ll get a regular tripod.

  • Anonymous

    etbe: Ah, that explains it; dell.com has it for USD$1099.