- The D300 has Liveview, so you can see the motive on the LCD screen before taking a photo. The function is somewhat clunky compared to compact cameras, but there are situations where it is indispensible.
- The D300 has easy access to standard configurations, like changing ISO or image size and quality.
- The D300 has bracketing, which means that the camera can take several pictures in a row with slightly different configurations. This is very useful for HDR.
- The D300 has an auto focus motor, so lenses without auto focus motor still work without manual adjustments.
- The D300 has higher ISO and much better noise control in low light situations.
- The D300 has slightly more pixels than current low end Nikon DSLRs.
- The D300 has more 51 possible focus points, so the focus point can be virtually anywhere in the picture. Low end cameras have much fewer points - sometimes just 3.
- The D300 has a faster motor, so it can take 6 photos per second, while a low end camera may only take half of that. The high speed is very useful for photos of moving objects like birds, acrobats and Formula 1 cars.
Sunday, July 27, 2008
About D300
D300 is a "mid range" DSLR from Nikon. Here are some of the features that makes it stand out against low range DSLRs, or at least compared to the D40X.
Solving the Low Light Problem
Most of us occasionally end up in situations where there is too little light for a good shot. There are several more or less obvious solutions.
Flash. I have not got much successful experience of flashes, which I find often end up too hard and artificial. Besides they do not work in long distance situations, like public evening football matches or Peking Opera.
Aperture. Increase the aperture (lower the F-value), and more light falls on the image sensor.
Shutter speed. Increase the shutter speed, and more light falls on the image sensor.
ISO. Increase the ISO value, and the image sensor becomes more light sensitive and can handle low light. At the same time noise increases in the picture. How high ISO values one can use with success depends much on the camera.
And then my favourite solution:
Change lens. It may not be intuitive to talk about "fast" or "slow" lenses. A lens is mostly fairly static glass, after all. However, some lenses allow for bigger aperture than others. That means that they work better in low light situations. Even in normal light, you can increase the shutter speed more, so it is easier to capture, for example, birds in flight.
My "fast" lens is a AF Nikkor 50mm f/1.8D. It is small enough to fit in my pocket. It weighs just 155g compared to the 560g of my AF-S DX VR Zoom-Nikkor 18-200mm lens. It cost not much more than 150 euro. And it is much faster than the 18-200mm lens, which has a maximum aperture of just f/3.5.
The 50mm f/1.8D is not a DX lens, which means that the equivalent picture angle for most digital cameras is 75mm.
The 50mm f/1.8D has no zoom, but that is actually often a blessing. As I know I cannot change the zoom, I concentrate more on getting the other values right when in a hurry.
Luckily, 75 mm is more or less my favourite angle. I often end up there around even with the 18-200 lens.
The 50mm f/1.8D has no auto focus, when used on Nikon's low end DSLRs (D40, D40x or D60). That is not always that bad. It is sometimes easier to manually adjust the focus than to select the right focus points. Besides, manual focus is what our grand-parents used, and it worked fine for them.
With all other current Nikon DSLRs (including my D300) the auto focus should work.
Some review of the 50mm f/1.8D, claimed that it provides "super sharpness". That is a slight exaggeration, but the lens is more than adequate in most situations. I tested it on a tripod against my 18-200 zoom and the low end AF-S DX Zoom-Nikkor 18-55mm that came bundled with my D40X. I applied each of the lenses to my D300 and shot the same section of my bookshelf at maximum and minimum aperture. The low end 18-55 actually did slightly better than the 50mm f/1.8D. However, the difference was very small. In a handheld test, the 50mm f/1.8D of course was much sharper than the other two, as it allows for much bigger aperture and therefore quicker shutter speed.
Flash. I have not got much successful experience of flashes, which I find often end up too hard and artificial. Besides they do not work in long distance situations, like public evening football matches or Peking Opera.
Aperture. Increase the aperture (lower the F-value), and more light falls on the image sensor.
Shutter speed. Increase the shutter speed, and more light falls on the image sensor.
ISO. Increase the ISO value, and the image sensor becomes more light sensitive and can handle low light. At the same time noise increases in the picture. How high ISO values one can use with success depends much on the camera.
And then my favourite solution:
Change lens. It may not be intuitive to talk about "fast" or "slow" lenses. A lens is mostly fairly static glass, after all. However, some lenses allow for bigger aperture than others. That means that they work better in low light situations. Even in normal light, you can increase the shutter speed more, so it is easier to capture, for example, birds in flight.
My "fast" lens is a AF Nikkor 50mm f/1.8D. It is small enough to fit in my pocket. It weighs just 155g compared to the 560g of my AF-S DX VR Zoom-Nikkor 18-200mm lens. It cost not much more than 150 euro. And it is much faster than the 18-200mm lens, which has a maximum aperture of just f/3.5.
The 50mm f/1.8D is not a DX lens, which means that the equivalent picture angle for most digital cameras is 75mm.
The 50mm f/1.8D has no zoom, but that is actually often a blessing. As I know I cannot change the zoom, I concentrate more on getting the other values right when in a hurry.
Luckily, 75 mm is more or less my favourite angle. I often end up there around even with the 18-200 lens.
The 50mm f/1.8D has no auto focus, when used on Nikon's low end DSLRs (D40, D40x or D60). That is not always that bad. It is sometimes easier to manually adjust the focus than to select the right focus points. Besides, manual focus is what our grand-parents used, and it worked fine for them.
With all other current Nikon DSLRs (including my D300) the auto focus should work.
Some review of the 50mm f/1.8D, claimed that it provides "super sharpness". That is a slight exaggeration, but the lens is more than adequate in most situations. I tested it on a tripod against my 18-200 zoom and the low end AF-S DX Zoom-Nikkor 18-55mm that came bundled with my D40X. I applied each of the lenses to my D300 and shot the same section of my bookshelf at maximum and minimum aperture. The low end 18-55 actually did slightly better than the 50mm f/1.8D. However, the difference was very small. In a handheld test, the 50mm f/1.8D of course was much sharper than the other two, as it allows for much bigger aperture and therefore quicker shutter speed.
Saturday, July 12, 2008
What's the JPEG compression level?
When you save a file as jpeg you usually get an option to choose the compression or quality level. To know which level to choose you have one single reliable source: your own experience.
I did some experiments with a 2 Megabyte tiff file and measured the size when exported from different applications. The sizes varied widely between each application. Note that the only thing that can be measured absolutely is the file size - not the file quality. Quality can vary even more. The test was done with one single file. Other files may show very different behaviour.
Aperture and Photoshop have a scale from 0 to 12. An Aperture 12 jpeg was bigger than Photoshop 12. On the other hand, Aperture 0 was smaller than Photoshop 0, so Aperture's spread was wider.
Photoshop has a "Save for web..." option that increases the compatibility of the files. Here, the scale confusingly goes from 0 to 100. Both of those values are smaller than the corresponding files that result from "Save as..." in Photoshop with the settings 0 and 12.
Capture NX also goes from 0 to 100. It's 0 value is unusable, but Photoshop's 0 quality files, which are smaller, might work in some low requirement circumstances.
The gimp also goes from 0 to 100. It's 0 value quality looks like a bad computer game for a character based DOS program from the 1980ies, but it also is the smallest of them all.
All high quality jpegs look decent of course.
Numbers
Highest quality jpegs in each application: Aperture (1.1 M), Preview (1.1 M), Photoshop (912 k), Photoshop saved for web (780 k), Capture NX (712 k), gimp (644 k).
Lowest quality jpegs in each application: gimp (12 k), Photoshop saved for web (48 k), Capture NX (60 k), Preview (72 k), Aperture (76 k), Photoshop (88 k).
Lowest quality jpeg in Photoshop
Lowest quality jpeg in the gimp
I did some experiments with a 2 Megabyte tiff file and measured the size when exported from different applications. The sizes varied widely between each application. Note that the only thing that can be measured absolutely is the file size - not the file quality. Quality can vary even more. The test was done with one single file. Other files may show very different behaviour.
Aperture and Photoshop have a scale from 0 to 12. An Aperture 12 jpeg was bigger than Photoshop 12. On the other hand, Aperture 0 was smaller than Photoshop 0, so Aperture's spread was wider.
Photoshop has a "Save for web..." option that increases the compatibility of the files. Here, the scale confusingly goes from 0 to 100. Both of those values are smaller than the corresponding files that result from "Save as..." in Photoshop with the settings 0 and 12.
Capture NX also goes from 0 to 100. It's 0 value is unusable, but Photoshop's 0 quality files, which are smaller, might work in some low requirement circumstances.
The gimp also goes from 0 to 100. It's 0 value quality looks like a bad computer game for a character based DOS program from the 1980ies, but it also is the smallest of them all.
All high quality jpegs look decent of course.
Numbers
Highest quality jpegs in each application: Aperture (1.1 M), Preview (1.1 M), Photoshop (912 k), Photoshop saved for web (780 k), Capture NX (712 k), gimp (644 k).
Lowest quality jpegs in each application: gimp (12 k), Photoshop saved for web (48 k), Capture NX (60 k), Preview (72 k), Aperture (76 k), Photoshop (88 k).
Lowest quality jpeg in Photoshop
Lowest quality jpeg in the gimp
Resizing JPEG, TIFF and PSD in Mac OS X
To resize pictures it is usually safest to use an application like Photoshop or the gimp to do it, to keep control of what is happening.
However, in Mac OS X 10.5 (Leopard) one can also automatise resizing directly without any additional applications. The blog PagesFAQ describes how to do it with AppleScript or Automator.
However, in Mac OS X 10.5 (Leopard) one can also automatise resizing directly without any additional applications. The blog PagesFAQ describes how to do it with AppleScript or Automator.
Friday, July 11, 2008
How much ... do I need?
Every now and then a question is asked with the pattern "How much of X do I need?": "How many pixels do I need?" or "How much zoom do I need?" or "How much ISO do I need?" There is only one valid answer to those questions. It is: "That depends".
There is basically no upper limit to what we could do, if we got a little more of everything.
Hasselblad just introduced a 50 million pixel camera. That is probably about 5 times as much as on any camera you ever held in your hands. Clearly you do not need that much to take a recognisable picture of auntie Kate. But equally clearly there are situation where you might want to crop down a picture to a level of detail, where you could use all those pixels. And if you had such a camera and you could take a highly detailed photo of Manhattan from the Empire State building, you would probably do it, and perhaps even print it out in large format and put it on your wall.
Nikon's D3 has ISO 6400. You would never use that if all the pictures you were taking were sunny beach pictures on the Seychelles. However, if you had it, you could take a lot of pictures you otherwise cannot take, like in badly lit streets late in the evening. Even on the Seychelles.
The weight in grams of your SLR may not feel disturbing. But if you are going on a long hike over several days, you usually want everything as light as possible. In the end you may select a simple pocket camera or just a phone camera, as carrying a sufficient amount of water into the dessert is more vital than a top notch camera.
The number of frames per second, the zoom factor, sensor size, there are always situations where you could use a little more.
That does not mean that it is worth the cost, of course. And even if it is worth the cost for your rich neighbour, it does not mean that it is worth the cost for you.
If someone says "I have all the... I want; I really do not want more," then there is a fairly good chance s/he lacks imagination. On the other hand if someone says "I absolutely need..." then there is a fairly good chance that he lacks the ability to adjust to reality and the size of his/her wallet.
There is basically no upper limit to what we could do, if we got a little more of everything.
Hasselblad just introduced a 50 million pixel camera. That is probably about 5 times as much as on any camera you ever held in your hands. Clearly you do not need that much to take a recognisable picture of auntie Kate. But equally clearly there are situation where you might want to crop down a picture to a level of detail, where you could use all those pixels. And if you had such a camera and you could take a highly detailed photo of Manhattan from the Empire State building, you would probably do it, and perhaps even print it out in large format and put it on your wall.
Nikon's D3 has ISO 6400. You would never use that if all the pictures you were taking were sunny beach pictures on the Seychelles. However, if you had it, you could take a lot of pictures you otherwise cannot take, like in badly lit streets late in the evening. Even on the Seychelles.
The weight in grams of your SLR may not feel disturbing. But if you are going on a long hike over several days, you usually want everything as light as possible. In the end you may select a simple pocket camera or just a phone camera, as carrying a sufficient amount of water into the dessert is more vital than a top notch camera.
The number of frames per second, the zoom factor, sensor size, there are always situations where you could use a little more.
That does not mean that it is worth the cost, of course. And even if it is worth the cost for your rich neighbour, it does not mean that it is worth the cost for you.
If someone says "I have all the... I want; I really do not want more," then there is a fairly good chance s/he lacks imagination. On the other hand if someone says "I absolutely need..." then there is a fairly good chance that he lacks the ability to adjust to reality and the size of his/her wallet.
Monday, June 30, 2008
Taking pictures for HDR
To work with HDR one needs pictures that are almost identical. Each pixel needs to match, even though their values may be different.
To achieve this one needs a) a tripod, b) a good camera.
I have not figured out if this is possible with my D40X, so the following just describes how to do it with my D300.
The task is to take a series of pictures of exactly the same motive but with varying exposure - bracketing. The D300 has different kinds of bracketing, but here we talk just about exposure bracketing.
Values to the right of "Off" increase the number of frames on both sides of the current setting. Check the LCD screen to visualise the settings.
The lower button next to the lens is called "Fn button" in the manual.
To launch the shooting of images
The number of images entered in the Interval timer shooting panel does not matter. What matters is what you selected with the Fn button and the command dials. Neither does it matter what start time you enter, unless you really use the start time option. "Now" means "in three seconds".
Self-Timer mode and the time set for it in Custom setting C3 is not used. It even prevents the Interval timer shooting from working.
Do not bother with the camera setting "Multiple exposure". That is just a setting to make one picture of several shots inside the camera - something we do not intend to do now.
(The explanation above may not be simple, but the usability in this particular area is confusing and incomprehensible without several trials and errors. Try and err. You may soon understand it.)
To achieve this one needs a) a tripod, b) a good camera.
I have not figured out if this is possible with my D40X, so the following just describes how to do it with my D300.
The task is to take a series of pictures of exactly the same motive but with varying exposure - bracketing. The D300 has different kinds of bracketing, but here we talk just about exposure bracketing.
- Make sure the Custom Setting e5 in the camera is set to "AE only".
- Press the lower button next to the lens and turn the small command dial (away from you on the camera) to select the bracketing exposure increment. Possible values are 0.3, 0.7 and 1. Check the LCD display to see the values.
- Press the lower button next to the lens and turn the main command dial (closest to you) to select the number of shots in the bracketing sequence.
Values to the right of "Off" increase the number of frames on both sides of the current setting. Check the LCD screen to visualise the settings.
The lower button next to the lens is called "Fn button" in the manual.To launch the shooting of images
- Attach the camera to a tripod.
- Go to the Shooting menu > Interval timer shooting > right arrow (to enter the Interval shooting panel).
- Highlight Now and press left arrow. (Not right arrow, unless you have modifications to make.)
- Press up arrow to highlight "On".
- Press "OK".
The number of images entered in the Interval timer shooting panel does not matter. What matters is what you selected with the Fn button and the command dials. Neither does it matter what start time you enter, unless you really use the start time option. "Now" means "in three seconds".
Self-Timer mode and the time set for it in Custom setting C3 is not used. It even prevents the Interval timer shooting from working.
Do not bother with the camera setting "Multiple exposure". That is just a setting to make one picture of several shots inside the camera - something we do not intend to do now.
(The explanation above may not be simple, but the usability in this particular area is confusing and incomprehensible without several trials and errors. Try and err. You may soon understand it.)
HDR with the gimp
Basic HDR can be handled in for example the gimp.
We start off with this image:
The areas where the leaves are in the shadow are underexposed, so no details are visible. The sand in the foreground is overexposed, so hardly any details are visible. It would be very difficult to find a setting where the camera captured everything correctly.
Luckily two other pictures were taken at the same time. One was had a longer shutter speed, so it is even more overexposed:
The other picture had a shorter shutter speed, so it was more underexposed:
The trick is to use the good parts of the overexposed pictures and the good ones from the underexposed picture and put them together with the good bits of the original picture.
1. Open all three pictures in the gimp.
2. Copy the underexposed picture, and paste it as a new layer on top of the original. (Click on the underexposed picture > ctrl+A > ctrl+C > click on original > ctrl-L to display the layers > click on the New layer icon.)
3. Copy the overexposed picture, and paste it as a new layer on top of the original. (Click on the overexposed picture > ctrl+A > ctrl+C > click on original > display the layers > click on the New layer icon.)
4. Save the original image in a new xcf file, in case something goes wrong.
In the image above I have also renamed the two pasted layers.
We now want to hide the overexposed areas of the overexposed picture. To do this we use a layer mask.
5. Highlight the overexposed layer.
6. Go to the menu Layer > Mask > Add Layer Mask.
7. Select "Grayscale copy of layer" and "Invert mask".
We now want to hide the underexposed areas of the underexposed picture with another layer mask.
8. Highlight the underexposed layer.
9. Go to the menu Layer > Mask > Add Layer Mask.
10. Select "Grayscale copy of layer" but not "Invert mask".
We now have a picture where the sand no longer is overexposed and the leaves no longer are underexposed.
To change it further, we can apply curves to the layer masks, to fine tune which parts of the picture are hidden by the layer.
11. Click on a layer mask.
12. Menu Colors > curves.
Of course other changes, like increasing saturation can also be applied.
We start off with this image:
The areas where the leaves are in the shadow are underexposed, so no details are visible. The sand in the foreground is overexposed, so hardly any details are visible. It would be very difficult to find a setting where the camera captured everything correctly.
Luckily two other pictures were taken at the same time. One was had a longer shutter speed, so it is even more overexposed:
The other picture had a shorter shutter speed, so it was more underexposed:
The trick is to use the good parts of the overexposed pictures and the good ones from the underexposed picture and put them together with the good bits of the original picture.
1. Open all three pictures in the gimp.
2. Copy the underexposed picture, and paste it as a new layer on top of the original. (Click on the underexposed picture > ctrl+A > ctrl+C > click on original > ctrl-L to display the layers > click on the New layer icon.)
3. Copy the overexposed picture, and paste it as a new layer on top of the original. (Click on the overexposed picture > ctrl+A > ctrl+C > click on original > display the layers > click on the New layer icon.)
4. Save the original image in a new xcf file, in case something goes wrong.
In the image above I have also renamed the two pasted layers.
We now want to hide the overexposed areas of the overexposed picture. To do this we use a layer mask.
5. Highlight the overexposed layer.
6. Go to the menu Layer > Mask > Add Layer Mask.
7. Select "Grayscale copy of layer" and "Invert mask".
We now want to hide the underexposed areas of the underexposed picture with another layer mask.
8. Highlight the underexposed layer.
9. Go to the menu Layer > Mask > Add Layer Mask.
10. Select "Grayscale copy of layer" but not "Invert mask".
We now have a picture where the sand no longer is overexposed and the leaves no longer are underexposed.
To change it further, we can apply curves to the layer masks, to fine tune which parts of the picture are hidden by the layer.
11. Click on a layer mask.
12. Menu Colors > curves.
Of course other changes, like increasing saturation can also be applied.
HDR? What is that?
HDR or High Dynamic Range, is a way to get more into a picture than the camera can capture in one shot.
Let's take a metaphor to see the need for this. You sit at a sunny beach with almost white sand. Next to the beach is a dark cave, where you put your Perrier to keep it cool. You can look into the cave and see the water bottles. You can move your eyes and watch the sunlit sand next to it, and you will clearly see it - perhaps after having adjusted your eyes for a few seconds.
The camera, however, cannot be adjusted at the same time to capture both the cave and the sand. Everything has to go into the same picture.
With HDR one takes several pictures of the same motive with different settings. One then mixes them to cover a larger range of exposures than the camera was able to handle.
The result often looks unnatural and strange - sometimes natural and sometimes enchanting.
There are different programs in the market to handle HDR. To get a really good dedicated program, you need to pay quite a lot. However, some basic HDR can be done in Photoshop (which you already may have) or the gimp, which is free.
Wikipedia has more information of course.
Let's take a metaphor to see the need for this. You sit at a sunny beach with almost white sand. Next to the beach is a dark cave, where you put your Perrier to keep it cool. You can look into the cave and see the water bottles. You can move your eyes and watch the sunlit sand next to it, and you will clearly see it - perhaps after having adjusted your eyes for a few seconds.
The camera, however, cannot be adjusted at the same time to capture both the cave and the sand. Everything has to go into the same picture.
With HDR one takes several pictures of the same motive with different settings. One then mixes them to cover a larger range of exposures than the camera was able to handle.
The result often looks unnatural and strange - sometimes natural and sometimes enchanting.
There are different programs in the market to handle HDR. To get a really good dedicated program, you need to pay quite a lot. However, some basic HDR can be done in Photoshop (which you already may have) or the gimp, which is free.
Wikipedia has more information of course.
Friday, June 27, 2008
The Abbreviations
In the world of photography, like in most worlds, there are abbreviations people use assuming that everyone else knows them. Of course, we all saw each abbreviation for the first time at least once, and then we may probably were confused. These are some of the common ones.
ACR - Adobe Camera Raw.
ADC - Analogue to Digital Conversion.
ADL - Active D-Lighting.
AF - Auto Focus.
AF-S - Auto Focus lens with SWM.
AI - Automatic Indexing. Used to describe a lens technology from Nikon that was introduced in 1977.
CCD - Charge-Coupled Device - A type of camera light sensor. Not CMOS.
CMOS - Complementary metal–oxide–semiconductor. Not CCD.
CMYK - Cyan Magenta Yellow blacK. A colour space used mainly for printing.
CNX - Capture NX. Nikon's program to edit raw NEF files.
CR2 - Canon's current raw file format.
CRW - Canon's old raw file format.
DAM - Digital Asset Management. Storing, cataloguing and finding digital documents like digital images.
DNG - Digital NeGative. Adobe's attempt at a standardized raw file format.
DOF - Depth Of Field. A long or deep DOF means that objects both close to the camera and further away are sharp. A short DOF means that only objects at a particular distance are sharp, something that makes them stand out against the blurry background and foreground.
DPP - Digital Photo Professional. Canon's program to edit raw CR2 and CRW files.
DSLR - Digital SLR.
DX - Abbreviation for the digital format used by sensors in most Nikon SLR cameras and in DX lenses. Not FX.
DR - Dynamic Range.
ED - Extra-low Dispersion. Nikon's special glass to avoid chromatic aberration with tele lenses.
EV - Exposure Value.
EXIF - Exchangeable Image file Format.
fps - Frames per second. The number of images a camera can take per second.
f-stop - Predefined values for Focal number.
FX - Full size.
HDR - High Dynamic Range.
HSM - Hyper Sonic Motor. Sigma's name for an ultrasonic motor.
HUD - Head-Up Display.
IF - Internal Focusing.
IPTC - International Press Telecommunications Council.
IQ - Image Quality.
ISO - Hardly even an abbreviation but a setting to control how much light the camera will need to produce a picture that is not underexposed. High values mean that the camera does not need much light, but at the same time, one will lose colour and increase noise in the picture. It is an abbreviation, anyhow, and it stands for International Organization for Standardization.
JPEG - The arguably most common format for digital photographs. The abbreviation means Joint Photographic Experts Group.
NAS - Nikon Acquisition Syndrome. A state of mind where you cannot help but buy more and more Nikon gear.
NEF - Nikon Electronic image Format. Nikon's format for raw files.
NR - Noise Reduction.
OOC - Out Of Camera
OVF - Optical View Finder
PP - Post Processing. Any change to a photo after it has been imported to a computer.
PS - Adobe PhotoShop
P&S - Point and Shoot (compact camera). Not a DSLR
RAW - Not an abbreviation, even though it usually is written with upper case letters. It means raw data, as in unmodified data directly from the camera.
RGB - Red Green Blue. The most common colour space for digital images.
SLR - Single Lens Reflex. Originally used to differentiate from a twin-lens reflex cameras. Now used to differentiate high end cameras from Bridge and Compact cameras.
SWM - Silent Wave Motor. Nikon's name for an ultrasonic motor.
TIFF - Tagged Image File Format. The arguably most versatile non-compressed image format. (There are also compressed variants.)
TTL - Through The Lens.
USM - UnSharp Mask. A filter in Photoshop. Also UltraSonic Motor, Canon's name for an ultrasonic motor.
VR - Vibration Reduction in Nikon lenses.
WB - White Balance.
XMP - Extensible Metadata Platform.
ACR - Adobe Camera Raw.
ADC - Analogue to Digital Conversion.
ADL - Active D-Lighting.
AF - Auto Focus.
AF-S - Auto Focus lens with SWM.
AI - Automatic Indexing. Used to describe a lens technology from Nikon that was introduced in 1977.
CCD - Charge-Coupled Device - A type of camera light sensor. Not CMOS.
CMOS - Complementary metal–oxide–semiconductor. Not CCD.
CMYK - Cyan Magenta Yellow blacK. A colour space used mainly for printing.
CNX - Capture NX. Nikon's program to edit raw NEF files.
CR2 - Canon's current raw file format.
CRW - Canon's old raw file format.
DAM - Digital Asset Management. Storing, cataloguing and finding digital documents like digital images.
DNG - Digital NeGative. Adobe's attempt at a standardized raw file format.
DOF - Depth Of Field. A long or deep DOF means that objects both close to the camera and further away are sharp. A short DOF means that only objects at a particular distance are sharp, something that makes them stand out against the blurry background and foreground.
DPP - Digital Photo Professional. Canon's program to edit raw CR2 and CRW files.
DSLR - Digital SLR.
DX - Abbreviation for the digital format used by sensors in most Nikon SLR cameras and in DX lenses. Not FX.
DR - Dynamic Range.
ED - Extra-low Dispersion. Nikon's special glass to avoid chromatic aberration with tele lenses.
EV - Exposure Value.
EXIF - Exchangeable Image file Format.
fps - Frames per second. The number of images a camera can take per second.
f-stop - Predefined values for Focal number.
FX - Full size.
HDR - High Dynamic Range.
HSM - Hyper Sonic Motor. Sigma's name for an ultrasonic motor.
HUD - Head-Up Display.
IF - Internal Focusing.
IPTC - International Press Telecommunications Council.
IQ - Image Quality.
ISO - Hardly even an abbreviation but a setting to control how much light the camera will need to produce a picture that is not underexposed. High values mean that the camera does not need much light, but at the same time, one will lose colour and increase noise in the picture. It is an abbreviation, anyhow, and it stands for International Organization for Standardization.
JPEG - The arguably most common format for digital photographs. The abbreviation means Joint Photographic Experts Group.
NAS - Nikon Acquisition Syndrome. A state of mind where you cannot help but buy more and more Nikon gear.
NEF - Nikon Electronic image Format. Nikon's format for raw files.
NR - Noise Reduction.
OOC - Out Of Camera
OVF - Optical View Finder
PP - Post Processing. Any change to a photo after it has been imported to a computer.
PS - Adobe PhotoShop
P&S - Point and Shoot (compact camera). Not a DSLR
RAW - Not an abbreviation, even though it usually is written with upper case letters. It means raw data, as in unmodified data directly from the camera.
RGB - Red Green Blue. The most common colour space for digital images.
SLR - Single Lens Reflex. Originally used to differentiate from a twin-lens reflex cameras. Now used to differentiate high end cameras from Bridge and Compact cameras.
SWM - Silent Wave Motor. Nikon's name for an ultrasonic motor.
TIFF - Tagged Image File Format. The arguably most versatile non-compressed image format. (There are also compressed variants.)
TTL - Through The Lens.
USM - UnSharp Mask. A filter in Photoshop. Also UltraSonic Motor, Canon's name for an ultrasonic motor.
VR - Vibration Reduction in Nikon lenses.
WB - White Balance.
XMP - Extensible Metadata Platform.
Thursday, June 26, 2008
How many pixels do I need?
If you want to take normal holiday snaps and family photos, the number of pixels in a modern digital camera is irrelevant.
You can stop reading there, if you want to, but if you want more details, you can go on.
All modern digital cameras have more pixels than you will need. The lowest number of pixels of any camera in the 2008 catalogue of fnac is 6 million, and that is a DSLR. Among the compact cameras that fit in your pocket, you do not find anything below 7 million pixels. With 6 million pixels you can print on A4 size without much problem. You can stretch it to about A2 format (42 × 59.4 cm) with acceptable quality.
With 12 million pixels, like the D300, one has enough to easily print out a high quality picture the size of an A4. Stretching it and accepting lower detail, one can get a decent print out the size of an A1 (59.4 × 84.1 cm). One can, of course, ask oneself how many A1-size pictures one will ever print out, and where one would put them.
Usually one says that high quality print is 300 dpi (dots per inch). To see how big a picture you can print with a certain image size, just divide the dimensions by 300. (And then multiply by 2.54 to get it in centimetres.)
As a comparison, and A4 printed at 300 dpi contains 8,739,900 pixel, and a North American Letter size photo contains 8,415,000 pixel.
And what if you you do not want to print your pictures? If you just want to show them on computer screens?
Let's say you buy Apple's biggest Cinema Display that is 30 inches. To fill out every pixel of that screen you need no more than 4 million pixels - that is less than the worst digital camera you can buy today.
What is much more important than the number of pixels is the quality of the camera, the lens, the autofocus, the sensor and all that. If you compare the specifications of a DSLR with a digital compact camera, it is very possible that the compact camera has better specifications. However, when it comes to clarity and picture quality, the DSLR is almost always far superior.
A higher number of pixels may even make the picture worse. Let's say, that 6 million pixel sensors fit on a certain space in your camera. If you buy another camera the same space for sensors, but the number of sensors is 12 million, clearly each sensor is smaller in the 12 million pixel camera. Unfortunately a smaller sensor is also more sensitive to electric noise in the camera, so they are slightly more likely to register wrong values. This is especially visible with low light conditions and high ISO values. The result is noise, lighter dots, on the image. All cameras show noise under some conditions, but high pixel cameras have more noise than low pixel cameras.
Is there then no reason for a multitude of pixels? Oh, yes there is.
One is obviously if one really does want to print large highly detailed photos.
Another is if one crops a lot. In some conditions, like if one takes pictures of flying birds or fast cars, it may be difficult to target the camera right at the subject. One solution may be to use less zoom, take a picture of a larger area, and then crop it afterwards. If one does not have enough pixels to start with, this may turn out quite difficult.
There is just one main device one should avoid when taking holiday pictures, and that is the camera in a mobile phone. Currently none of them has any acceptable quality. It is very convenient to have a camera in one's phone. One always carries it around anyhow. However, in most cases the pictures that come out of it are not pictures one will be happy to look at in the future.
You can stop reading there, if you want to, but if you want more details, you can go on.
All modern digital cameras have more pixels than you will need. The lowest number of pixels of any camera in the 2008 catalogue of fnac is 6 million, and that is a DSLR. Among the compact cameras that fit in your pocket, you do not find anything below 7 million pixels. With 6 million pixels you can print on A4 size without much problem. You can stretch it to about A2 format (42 × 59.4 cm) with acceptable quality.
With 12 million pixels, like the D300, one has enough to easily print out a high quality picture the size of an A4. Stretching it and accepting lower detail, one can get a decent print out the size of an A1 (59.4 × 84.1 cm). One can, of course, ask oneself how many A1-size pictures one will ever print out, and where one would put them.
Usually one says that high quality print is 300 dpi (dots per inch). To see how big a picture you can print with a certain image size, just divide the dimensions by 300. (And then multiply by 2.54 to get it in centimetres.)
(Width of image file in pixels) / 300 * 2.54 = (Width of high quality print out)
As a comparison, and A4 printed at 300 dpi contains 8,739,900 pixel, and a North American Letter size photo contains 8,415,000 pixel.
And what if you you do not want to print your pictures? If you just want to show them on computer screens?
Let's say you buy Apple's biggest Cinema Display that is 30 inches. To fill out every pixel of that screen you need no more than 4 million pixels - that is less than the worst digital camera you can buy today.
What is much more important than the number of pixels is the quality of the camera, the lens, the autofocus, the sensor and all that. If you compare the specifications of a DSLR with a digital compact camera, it is very possible that the compact camera has better specifications. However, when it comes to clarity and picture quality, the DSLR is almost always far superior.
A higher number of pixels may even make the picture worse. Let's say, that 6 million pixel sensors fit on a certain space in your camera. If you buy another camera the same space for sensors, but the number of sensors is 12 million, clearly each sensor is smaller in the 12 million pixel camera. Unfortunately a smaller sensor is also more sensitive to electric noise in the camera, so they are slightly more likely to register wrong values. This is especially visible with low light conditions and high ISO values. The result is noise, lighter dots, on the image. All cameras show noise under some conditions, but high pixel cameras have more noise than low pixel cameras.
Is there then no reason for a multitude of pixels? Oh, yes there is.
One is obviously if one really does want to print large highly detailed photos.
Another is if one crops a lot. In some conditions, like if one takes pictures of flying birds or fast cars, it may be difficult to target the camera right at the subject. One solution may be to use less zoom, take a picture of a larger area, and then crop it afterwards. If one does not have enough pixels to start with, this may turn out quite difficult.
There is just one main device one should avoid when taking holiday pictures, and that is the camera in a mobile phone. Currently none of them has any acceptable quality. It is very convenient to have a camera in one's phone. One always carries it around anyhow. However, in most cases the pictures that come out of it are not pictures one will be happy to look at in the future.
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