Saturday, May 12, 2012

Nikon D800 - Hints and some kind of Review

This spring Nikon launched a ridiculously performant camera, the D800. According to one test with certain variables, it is the best camera in the world. However, that is of course completely irrelevant if one does not care about those particular variables. There is a good description of the camera at DPReview. This blogpost will just take up some personal notes around the camera.

The D800 by default takes photos in FX format with 36 M pixels. If one wants to take a photo for a blog or some social site, one can get away with a photo that has about 500 times fewer pixels. That means that one easily may discard 99% of the D800's pixels. However, you will store them on your memory card and your harddisk, which quickly fill up. So if one only takes pictures for blogs and social sites, the D800 is more of an inconvenience than the best camera there in the world.

One of several ways to save disk space is to shoot in DX mode. A D800 photo in DX mode is usually less than half the size of an FX photo. One can assign for example the Fn or Preview Button to quickly switch between FX and DX mode (options f4 or f5 in the camera menu). One can then use FX to get a wider angle of view, to get more detail and a more narrow depth of field, and DX to save space and speed up the number of frames per second (fps).

When one shoots DX, there is a thin black line in the viewfinder to show the image area that will be ignored on the photo. To see this even better, one can set the camera menu a5 "AF point illumination" to "Off". For some reason, this greys out the area that is removed in DX mode. Don't ask me why that menu item changes the image area display, but it does.

One of the really nifty things with the D800 is Easy ISO to change ISO directly with the command dial without having to press the ISO button. This is activated in the camera menu d7.

The d7 option does not allow you to switch between manual and automatic ISO, but one easy way to do so is to hold down the ISO button and spin the front command dial.

One of the more peculiar features is the camera option f9 - Aperture Setting. Some older lenses, like on the picture below, have a physical aperture ring to change aperture. Modern cameras usually ignore that ring and require that it be locked. If one really likes using the physical aperture ring, one can use f9 and choose "Aperture ring" instead of "Sub-command dial", and it will work exactly like it did when granddad was young. I see no benefit with this except that it is fun.


Another nice feature is the Virtual Horizon, an indication in the viewfinder if the camera is aligned perfectly horizontally. Activation can for example be assigned to the Fn or Preview Button (options f4 or f5 in the camera menu). In Live View, Virtual Horizon is activated by repeatedly pressing the Info button.

Not all of the features mentioned above are unique to the D800, but they were things that came as nice surprises to me when I started using the camera.

Monday, April 30, 2012

FX - DX - CX - Why does the sensor size matter?


There is one not so obvious difference between Nikon cameras, and that is the sensor size. The sensor is the part of the camera that senses incoming light. Some high end cameras have big sensors and low end cameras tend to have small sensors.

There are three main sizes with Nikon cameras with exchangeable lense: FX, DX and CX. The big FX sensors are used in cameras like D3, D4, D700, D800. DX is used in cameras like D3200, D5100, D90, D300. The smallest CX sensors are used in J1 and V1 cameras.

A Nikon lens made for a big sensor works with any smaller Nikon sensor. This means that any Nikon lens fits a CX camera - in theory. (You need an FT-1 adaptor, and autofocus may not work and there may be some other limitations.) A DX camera can take both FX and DX lenses. An FX camera only works well with FX lenses.

The focal length of a lens does not change with the camera. This means that magnification, zoom and angle of view are the same for all lenses with the same focal length on that camera. If you take a 200mm CX lens and a 200mm DX lens and a 200mm FX lens and put them on the same CX camera one after the other, the magnification is identical for all of them.

However, the same 50mm lens magnifies more on a small sensor than on a big one. In the picture below there are three shots of the same object with the same lens and focal length, but three different cameras. 


The FX camera (a D800) covers the widest angle. The DX camera (a D5100) covers a smaller area. It has been given a green cast to make it stand out from the two other photos. The CX camera (a J1) covers just a small fraction of the FX area. (The photos have been resized to overlap, so the density of the pixels does not correspond to the size of each photo.)

If I had wanted to cover the same angle of view with each photo, I would have had to choose different focal lengths. If the FX camera uses 200mm, the DX camera would need to be 133mm and the CX camera 74mm to give the same angle of view (or zoom factor or magnification). A table with conversions of some common values can be found here.

Advantages with large sensor cameras:
  • Less noise, better dynamic range and colour depth. This is basically because the sensor has a bigger area to gather information from. However, note that a new camera with the latest technology and a small sensor can perform better than an old camera with a big sensor in these respects.
  • Wider angle of view. To get the same angle as a 14mm lens on an FX camera, you would need a 9mm lens on a DX camera.
  • Narrow Depth of Field and more appealing bokeh. This is actually a tricky one. If you look at the three superimposed photos above, you will notice that they have more or less the same amount of bokeh on the background. That is because they were taken with the same focal length and the same aperture. In this case the bokeh is identical, but the image area is different. It is only when you try to cover the same image area with different sensors that the difference in depth of field is apparent. The FX camera has a focal length 200mm. To cover the same area, the DX needs 133mm. With a smaller focal length, the same aperture value (e.g. f/1.4) actually corresponds to a smaller physical aperture hole measured in millimeters. A smaller aperture hole means a sharper picture overall. Therefore, to get the same depth of field at a smaller focal length, the aperture hole needs to get bigger. If an FX camera has focal length 200mm with aperture f/1.4 with a target at five meter, a DX camera will need to be set to 133mm to get the same angle of view. To get the same depth of field, the aperture may need to be set to something as large as f/1.0. As hardly any Nikon lens has an aperture f/1.0, the same depth of field is impossible on the DX camera. Ergo, FX has a narrower depth of field.
Advantages with smaller sensors:
  • Smaller, lighter and cheaper lenses possible.
  • Smaller camera. (This is not always the case, but an FX sensor will not fit into a really small camera.)
  • Cheaper than big sensor cameras.
  • Wider choice of lenses.
  • Less vignetting in some cases. (If you use an FX lens that has visible vignetting on an FX camera, the DX sensor will cut that part out.)
  • Bigger magnification. (To get the same zoom as a 200mm lens on a DX camera, you need a 300mm lens on an FX camera.)

Sunday, March 11, 2012

Ignoring Users at DPReview

At the excellent site dpreview there are discussion forums with some very knowledgeable people who can help you with hints to get better photos and advice when it comes to cameras, lenses, tripods and so on.

However, not everyone at the forums is knowledgeable. Just like many other mildly moderated internet forums, it has its share of space wasters. The remedy at DPReview is the wonderful Ignore User button. If you click on that one for a user, all his/her entries will be collapsed to just a title. In addition, threads that are started by ignored users are greyed out and shown at the bottom of the forum overview.

The tricky thing is how to choose which users you should ignore. It depends entirely on what kind of posts you want to read, of course, but if you want some inspiration, these are some of the rules I apply to determine whom to ignore:

  • People who ask for rumours, like "how many pixels do you think cameras will have next year?"
  • People who give overly definite answers: "You will never need more than 10 megabytes." "That camera (lens, printer, computer, motorcycle...) is simply useless."
  • People who think everyone else is just like them: "Carrying 15kg of camera gear wherever you go may seem heavy to start with, but you'll soon get used to it."
  • People who use swearwords. (I do not mind swearwords actually. It just seems to be a very strong correlation between people who swear in writing and people who are space wasters.)
  • People who use the expressions like "lol" or "awesome". (Same thing as swearwords. The words should be allowed, but a lot of the people who use them in writing are space wasters.)
  • People who claim to already know the strong and weak points of new cameras before the camera is actually released.
  • People who start off-topic threads. "I hate the parking facilities at Best Buy. Don't you?"
  • People who try to start brand wars. "I heard that Nikon has much better zoom lenses than Canon. Why do you think that is?"
  • People who are wrong. "Increase the shutter speed to get brighter pictures."
There are some things that do not trigger my Ignore User button - perhaps surprisingly.
  • Beginners asking for trivial advice. Most questions, no matter how trivial, can generate some interesting answer from people who know the subject well.
  • People who write lengthy essays as answers. A good answer is usually just a few lines, but sometimes a writer with a lot of experience has a lot of interesting things to say.
  • People who claim film is and always will be superior to digital. I do not think film is inherently superior to digital, but the arguments for film are often varied and interesting, and they may make you think about how you take digital photos.
  • People who feed the trolls. If one person trolls with some idiotic opinion, and another person insists on trying to rebut the idiotic opinion, it may seem logical to ignore both writers to avoid long uninteresting threads. Indeed, I often ignore both of them, but it is not automatic. Both writers have to show individually that they are time wasters before I ignore them. Sometimes a very sensible writer falls into the trap of feeding the troll, and it would be a pity to lose his input in other areas.
The last rule I apply is not to follow any rule blindly. Every now and then, I read what ignored users write to see if it has some value. In most cases it does not, but there are exceptions, and then I usually gnore (un-ignore) the writer.

Saturday, February 4, 2012

Searching EXIF data with Mac OS X Spotlight

Using Mac OS X Spotlight, you can quickly search for certain camera metadata. A simple search would be "D300" (without quotation marks) entered in the field you get when you click on the magnifying glass in the upper right corner of your screen. That returns all images, both NEF and JPEG, that were taken with a Nikon D300 camera. By default you also get all other files that contain D300, like PDF files, word documents and old mails where you discussed the camera with friends. To limit the search to just images, go to "Show all in Finder". That will open a window with the title "Searching this Mac". Here you can click on a plus ⊕ symbol to get more search criteria. Click on it and select "Kind" as "Image", and you will only get image files.


If you instead of selecting Kind, select "Other", you get a vast number of search criteria to choose from, like ISO or EXIF version.

To really see all the criteria you can search from, you can use a Terminal window.
  1. Open the Terminal from Applications > Utilities > Terminal.
  2. Type "mdls " without quotation marks, but with the space after the last "s".
  3. Go to the Finder and drag an image file onto the Terminal window. It should now contain text that looks something like "$ mdls /Users/myhome/Desktop/mypic.jpg"
  4. Type "| less" after the file name and hit Enter.
What you now get is a list of searchable fields for the image, and their values:

kMDItemAcquisitionMake         = "NIKON CORPORATION"
kMDItemAcquisitionModel        = "NIKON D300"
kMDItemAlternateNames          = (
    "mypic.jpg"
)
kMDItemBitsPerSample           = 32
kMDItemColorSpace              = "RGB"
kMDItemExposureTimeSeconds     = 0.004
...

To move down to see more options, hit the Space Bar.
To move back up, type "B".
To leave the list, type "Q".

Now we can go back to Spotlight to use this information for an actual search.
  1. Click on plus ⊕ again, and select "Other".
  2. Select "Raw Query".
  3. In the search field, type a field name from the Terminal and some appropriate value, like "kMDItemExposureTimeSeconds < 0.003"
This will display all photos with a kMDItemExposureTimeSeconds (shutter speed) that is faster than 0.003 seconds.


If you know you want to repeat the same query over and over, you can hit the "Save" button, and you will get a virtual folder for quick access, whenever you need it.

Everything that is written here actually applies to all kinds of files, not only images, but as this is a photo blog, all the examples come from the wonderful world of images.

Searching in Adobe Bridge

If you want to find all photos you ever took with, say ISO 200, you can easily do that in Adobe Bridge. You just select Edit > Find, select "ISO" as search criteria and "200" as value.

It is slightly more tricky if you want to search for all files with a particular shutter speed or aperture, as these fields do not appear as search criteria. What you can do is to search for Exposure, which is a field that contains both those values. E.g.: "1/30 s at f/2.8". This means that you have to enter the values as free form text.
Some fields, like ISO and Focal length, are numeric, so you can search for all photos where the Focal length is greater than 50mm. However, the Exposure field is a text field, so it is very difficult to collect all files with shutterspeed greater than 1/200.

Friday, November 18, 2011

Conversion of Zoom Rates for FX, DX and CX sensors

Nikon has three sizes of sensors for their current models of cameras with exchangeable lenses. The same lens gives different angles of view depending on which sensor it operates on. If you, for example, like using a 50mm prime lens on your D700 camera (FX sensor) and you want to use a lens with a similar width on your D5100 camera (DX sensor), you should get a 35mm lens. (You should actually get a 33mm lens, but that does not exist, and 35mm should be close enough.) More about that here.

The table below gives some common focal lengths in mm and their equivalent with other sensors.

Sensor type: FX DX CX
Crop factor: 1 1.5 2.7

28 19 10

50 33 19

70 47 26

200 133 74

270 180 100

300 200 111


Some cameras with FX sensors are: D700, D800, D3, D4,

Some cameras with DX sensors are: D300, D7000, D5100, D3200, D40, D50, D60, D70, D80, D90

Some cameras with CX sensors are J1, V1.

Nikon J1 - Why I Love this Hateable Camera

Very recently, I defied my waning bank account and once common sense, and bought a Nikon J1 camera with two lenses: the 10mm prime and the 10-100mm zoom.

The camera has one big advantage with the 10mm pancake lens: it is small. It is so small that it fits in a trouser pocket. Almost. I cannot actually walk or sit down with the camera in the pocket, but I can push it in, and with some effort I can usually pull it out. The fact that the camera is only almost small enough, is one of the frustrating things with the camera. Realistically, I need to carry it in its strap or in a jacket pocket.

Then there are all the other limitations. Forget about zoom. Forget about flash - especially off camera flash. Forget about quick adjustments of ISO, aperture, shooting mode (PSAM) or auto-focus options. There is no nice grip, no swivel screen and the battery life time is not very good. If one wants any of that, one has to use another camera.

But if one wants to simply take a picture, it works fine. It is easy to take sharp pictures that are not too grainy. And there is one unexpected bonus: Nikon's ML-13 remote control happens to work. With a Gorillapod or a Manfrotto table tripod 709B attached, it is extremely easy to just put the camera on a table or floor and trigger a photo with the remote.

10mm is slightly too wide for my taste, but it works. One just has to take one step closer to the target. 10mm on a J1 is roughly equivalent to a 18mm lens with a DX sensor or 28mm with an FX sensor.

10-100mm lens. 31mm focal length. ISO 100, f/5.3, 1/1250s. There is no denying there is some potential for bokeh in this camera and lens. It is not much, but it is much more than none.

Then there is the 10-100mm lens. The range is almost the same as the DX 18-200mm lens or the FX 28-300mm. There is no way the camera will fit in any normal pockets with that lens on. In fact, with the 10-100mm lens, you can forget about the camera's size. The camera is just a little adornment at one end of the lens. The best way to hold the whole thing, is to put the lens in a comfortable position in your left hand, and then fumble around with your right hand, until you get to the little camera at the end, and press the trigger button.

This lens is sturdy. The zoom is electric, but very, very quiet. It is apparently built for movie recordings, so we still photographers pay a lot for features that do not matter that much. But just hearing the absence of sound when you zoom, or feel the weight in your hand is a pleasure. And I love lenses that have internal zoom, so they do not change size when you zoom in and out.

It would be silly to complain too much about the weight and size of the 10-100mm. It is much smaller than Nikon's 70-200mm for example. When it is switched off and retracted, it is shorter than 100mm. (There is a function to keep it expanded, even when it is switched off, to save battery.) However, considering the large diameter of the 10-100mm and the fact that there is no good grip on the J1 camera, it is not that convenient to carry it around in your hand, especially not if you have short fingers.

All in all, the J1 with the two lenses is acceptable for travel shooting, at least for destinations where you can come back later with a DSLR and take some serious photos.

10-100mm zoom lens, 58.2mm focal length, ISO 100, 1/320s, F5.6. Handheld. There was no problem at all to get this sharpness. I in fact got much more keepers with the J1 in this Marathon than I usually do with my D300 and a 70-200mm lens.
10mm prime lens. ISO 100, f/7.1, 2.5 seconds. Taken with an ML-13 remote and a Manfrotto 709B tripod.

Saturday, May 7, 2011

How to live with the ergonomy of a D5100 or other "low end" camera

One reason to buy a "high end" or "professional" camera like a Nikon D3S, D300S, D700 or even a D90 or D7000 is that it is easy to change common parameters. It is also easy to change some less common parameters. The chances are that if you want to change a particular setting, you can do it without going into the monitor menus.

But what if you bought a "low end" camera, like a Nikon D5100? How do you quickly change settings there? Well, funnily enough, the chances still are that you can do them without going into the menus. Arguably, the most common changes you will make are shutter speed and aperture, and you do that almost as easily on a D5100 as on a high end camera.

There is no denying that several settings are easier to reach on a high end camera. There may be some settings you have chosen to change all the time in your daily shooting that are cumbersome to change on the D5100. But if Nikon have done their user studies correctly, most people should be reasonably happy with the ergonomy of the D5100.

Let's have a look at the difference in buttons between the D5100 and a D7000 or a D90. The D7000 and D90 have dedicated buttons for the following functions, that are not by default easy to access on a D5100:
  1. ISO
  2. White Balance
  3. Release mode (one picture, many, etc.).
  4. Bracketing button.
  5. Quality button.
  6. Metering (spot, matrix, center weighted).
  7. Autofocus mode (single-servo, face priority, subject-tracking, etc.).
For the first five of these, the photographer can select one of them to be assigned to the fn button on a D5100, which makes it easier to access them. I change the ISO all the time, but rarely the other ones, so the choice is easy for me.

For the Metering and Autofocus, they can be changed directly on the Monitor without going into the menu system on the D5100. It is admittedly more cumbersome than on the D7000 or D90, but even on those ones, you often have to take the camera down from your eye to look at the top LCD screen to see which values you choose.

And when it comes to ergonomy, a large number of buttons is not necessarily good, as the photographer will have to learn where they are, and s/he is likely to occasionally press the wrong one, as the choice is so big.

This does of course not mean that a D5100 is as good as a high end camera. It is not. It lacks plenty of functions, and one does not have to be that experienced a photographer to take advantage of the additional buttons of a higher end camera.

However, if weight or price or a swivel screen are important factors, one should not discard the D5100 for its bad ergonomy. It is not a perfect camera, but to most photographers in most situations, its limitations should be acceptable.

Sunday, August 22, 2010

Pronouncing "Bokeh"

Bokeh is a modern word to describe the background blur of a photo like in the photo below. The rusty iron is in focus but the sea behind is not.



A common question is which lenses have the "best" bokeh, but that does not interest me very much. It is like asking which colour is best, red or green? Or which is best, food or drink? Sometimes you need one and sometimes the other. Sometimes a lot of blur is needed. Sometimes it just looks artificial.

However, what I think is interesting is the pronunciation and origin of the word.

It is generally agreed that it comes from Japanese ボケ (boke), which is a technical photo term with the same meaning as in English. The Japanese word is an abbreviated form of the verb 暈ける (bokeru), which means "fade" or "appear blurry". It may be worth noting that Japanese classical art, like the 狩野派 (kanōha) or Kanō school, works a lot with detailed foregrounds and non-intrusive or even empty backgrounds. However, the expression ボケ is usually not used in this context, but only when it comes to photography.

The word has only been used since the late 1990s in English, so no widely accepted pronunciation has yet evolved.

If you want to use the Japanese pronunciation, it is /bɒkɛ/, with "bo" of "Bob" and "ke" in Kenneth. However, in English, it does not sound very natural to end a word with a short ɛ. Besides a vowel before a syllable starting with a single k in English is usually long, so the "bo" bit does not seem natural either. It therefore seems perfectly acceptable to pronounce it exactly like "bouquet" in English.

If someone laughs at your pronunciation, you can be confident that other people laugh at their pronunciation as well.

And now for a warning. If you think that you learnt a Japanese word today, you need to make sure the context is right, when you use it. Even though 暈ける (bokeru) means fade, the word 惚ける with exactly the same pronunciation means "to become senile". 呆け or 惚け, both pronounced /bɒkɛ/ mean senility. Another meaning of the same pronunciation is the plant 木瓜, Japanese Flowering Quince (Chaenomeles speciosa). In other words, when you use it, make sure the context shows which boke/bokeru you are talking about.

Deleting photos from your iPad

Deleting a large number of photos on your iPad may not be obvious. There are a few solutions.

Deleting Several Imported iPad Photos using a Mac

The most convenient way to delete a large number of photos is probably to use your Mac. (It is probably possible to use some similar method on the PC, but I do not know which application to use.)
  1. Connect your iPad.
  2. Open Preview on your Mac (Image Capture would also work with a slightly different scenario).
  3. Go to the menu item File > Import from (the name of your iPad)...
  4. Select the pictures you want to delete.
  5. Click on the red delete icon at the bottom of the screen.
To better select the photos you want to delete, you can use the two icons in the bottom left corner.

In the icon view you can get reasonably large previews of the photos.


In the list view, you can sort the images according to a large number of criteria. You can also move the columns around, so you see the information that interests you.


To select several pictures, you can use the standard multi-select shortcuts: Click and shift-click on another photo to select all photos in between. Command-click to toggle selection of an individual photo without affecting which other photos are selected. Command-A to select all photos on the iPad (in all folders!).

Deleting Several Imported iPad Photos on the iPad

You can also delete several photos at the same time on the iPad itself, but it is not that elegant. If you have a large number of photos in the same folder, it is not easy to select them all, and if you have photos in several folders, you often have to delete them folder by folder.
  1. Locate a view with the photos you want to delete.
  2. Click on the Export (!) icon with the arrow in a square in the upper right corner.
  3. Do not click on the tempting red Delete button, but click once on each of the pictures you want to delete. You can also drag with two (!) fingers over the photos you want to select. (In the first version of the Photo app, you used one photo, but Apple thought that was too easy.)
  4. Click on the Delete button.
Synched photos

Photos you have synched with iTunes, you can remove in iTunes, by simply not synching them any more. It seems impossible to delete them from the iPad itself in iOS3.
  1. Connect the iPad.
  2. In iTunes, click on the iPad icon.
  3. Click on the tab Photos.
  4. In Projects and Albums, unselect the folder you sync.