June, 2009

Workshops — No Comments
17
Jun 09

A pro photographer’s walk through the zoo (II)

Ups, just noted I still owe you the continuation of my report on the nature photography workshop with Konrad Wothe I took in April. Read the first part here.

So, after the first against the sun shots we arrived at Tiger’s headquarter, and it quickly turned out to be very difficult to say the least to get Tiger cooperating and be a willing model, and control the lighting with the sun coming in from the side already quite strongly. From the session with the tigers, there was not a single photo that did not contain either an unsightly fence not successfully blurred into the background, some other parts of the enclosure, or simply completely unmanageable contrast range. I spare you the results.

We started looking for alternatives to make some interesting photos.

[svgallery name="Hellabrunn2"]

Now, we found one cute little guy in his tree, and then it was when I came to dread the new camera…

Problem was, he was quite high up in that tree fork, maybe 4 meters, and the distance to the tree from the closest point where you can put your camera without actually entering the enclosure was also certainly 6 meters from the tree’s trunk. Taking my Pythagoras this would put me at a distance of about 7 meters from him to cross with my flash, because without any flash he was by far too dark. The image below was taken at camera automatic “neutral” position: No exposure correction, no flash exposure correction (using my SB800 flash, not the tiny internal one). So I started out at the neutral setting with ISO 400, camera on my monopod, aperture of 5.6 (wide open with my Sigma 100-300 f/4 with 1.4x TC) resulting in an exposure time of 1/500s. Image comes out ok, but I thought I could do better…

cute-guy

My goal was to emphasize the animal in the picture, and if at all possible get rid of the obnoxious bright sky background and try to turn it back to blue, because this is what my eyes told me it was. Below the series of pictures I took, with the following exposure changes:

  1. Test shot with exposure compensation dialed down -1 EV, no flash. The sky is more blue, and the animal is dark. Nice sun-lit fur. Data: f/5.6, 1/1000s, ISO 400. Now I just needed to flash that bear!
  2. Add flash, with flash exposure even dialed up to +1 EV. Data: f/5.6, ISO 400, 1/1250s. Doesn’t really pop – flash blinking, doesn’t have the reach! Ouch.
  3. Ergh. More flash reach? Well, I’m beyond the flash sync speed of 1/250s of the D300, so the flash is indicating with it’s FP marker it is operating in high speed sync mode. This is bad, because it reduces flash output, e.g. the guide number for max flash goes down from 112 to 28 at ISO 400.
    Solution: Get the exposure time down below the natural sync speed. Only idea: Close the aperture down to f/9, resulting in 1/500s. That was not enough! Resulting image: Not much difference, as the closed down aperture eats away the increased flash output! I would have needed to close the aperture down to f/14 to get 1/250s!
  4. Next idea – damn, he moves, looks up, catchlight in the eyes! frantic shooting – to increase the ISO to 800, to allow for the more sensitive sensor to pick up the flash light. Result: f/5.6, 1/2500s. Back into FP mode, and the result is not better at all…
  5. He is yawning! Don’t worry about flash output, keep taking pictures! He might decide to do a loooong nap soon!
  6. Next try: Lower ISO to 100 and close the aperture to get to the real flash sync speed of 1/250. Result: Bear is sleeping by now, but the camera reads at f/6.3 and 1/250s. And I actually like the result (but not the pose)!

[svgallery name="Hellabrunn3"]

Lesson learned: Better know you math before you do flash shooting. In FP mode, the SB 800 will no longer help you compute the flash reach, you need to go back to the old guide number formular:

distance in meters = guide number depending on ISO : aperture

So if I calculate this for the 6 pictures above, and find out the maximum flash reach at the settings I made (all with the zoom reflector of the SB 800 at it’s full position of 105mm):

  1. No flash
  2. Using the guide number of 40 at ISO 400 as the SB 800 manual indicates, I would have had a flash reach of 40 : 5.6 = 7 meters. Barely enough, and I was on 1/1250 and not on 1/300. The SB 800 manual does not state the effect of higher shutter speeds than 1/300s, it is assumed it gets even less…
  3. 14 meters on full flash output, so closing down the aperture had it’s effect. But with high speed sync I was down to 4.5 meters, not near enough. This was the wrong direction, because I did still required the FP mode at 1/500s.
  4. 20 meters on full flash output, guide number goes up to 56 for high speed sync – giving me theoretically 10 meters reach at 1/300s. Could be good enough? The picture doesn’t look like it, the dark shadows do not show any fill flash.
  5. :-)
  6. No high speed sync, so I get the full guide number of 56 for ISO 100 giving me 8,9 meters reach at f/6.3. Now I got the bear!

My old and loved D70 in contrast to the D300 I used got a fully electronic shutter – it was capable to sync to flash speeds of up to 1/2000s (I tried!) without the need for FP mode and the resulting loss of power. So with the D70, I would easily have had 20 meters and more flash reach with my first pictures, and neither missed the yawn nor had to start calculating guide numbers at all!

Ah, sentimental thoughts – my D70′s shutter (the additional mechanic one, not the electronic shutter) had died after about 60000 actuations. I couldn’t make me spend the money to repair that 4.5 year old digital camera but rather decided to go straight to a new D300, a step I did not regret, until maybe that day in Hellabrunn :-)

More tk…

Workflow — No Comments
3
Jun 09

Geotagging III – how to associate names to the places you have been to

As promised, here is the continuation of the series on my geotagging workflow!

Now, after steps one and two, I had my photos on disk with the GPS latitude and longitude position (and altitude) embedded within the JPG files. Specialized applications like GeoSetter would allow to open a Google Maps window at the location where the photo was taken, or offer export capabilities into Google Earth to place the photos onto the virtual globe.

But, my image archive is organized using keywords, and I usually manually tag images (add keywords) with the names of the places I have been. For instance, with a single click I can extract all images I have made in the Berchtesgaden alps area from my archive. I certainly wouldn’t want to fly around on Google Earth and virtually travel to Berchtesgaden in order to find them – so what good do those latitude / longitude coordinates do?

So, for example, I’d like the computer to automatically tag and file the following image of one of my absolute favorite places in Italy with the keywords: Italy, Tuscany, Castelnuovo dell’Abbate, Sant’Antimo.

antimo

As often today, out there the web already has the solution: Services like GeoNames, which usually are for finding the geo coordinates for a street address (something every car navigation system excels at), also offer a service which technically is called a reverse lookup: You would use this service if you know the geo coordinates of a place, but want to know the name of it. Or even the street address. And this is exactly what the photographer needs, right?

If you visit their website at GeoNames.org, you will not find the reverse lookup easily (because this is not the use case they have built their web site for). But if you technically savvy reader browse to the Download / Webservice page, you will find the documentation for the reverse geocoding services. Now, for example, we could ask the friendly site for the name of a location I had on one of my images, namely 43,049N and 11,489E. This would be coded into an URL, and you can click on this to see the answer of geonames.org: http://ws.geonames.org/findNearbyPlaceName?lat=43.049&lng=11.489

Now, don’t get scared. What you are looking at is the computerized reply of geonames.org telling you that this is a place in Italy with the name of Montalcino, home of the wonderful Rossos and Brunello red wines (Ups, it forgot to mention that! But it would, fasten your seatbelts, if we had asked the right question). But web services are really for computers to talk to each other, and not us to try to do this for the 897 photos I brought from Tuscany.

The good news is: This is how it works, and Friedemann Schmidt, the author of the GeoSetter software, has already built this function into GeoSetter!

Here is how I got the names of the places as keywords into my photos’ metadata using GeoSetter:

  1. I opened the folder with the photos from step 2, and GeoSetter displayed for those that had successfully received geo-coordinates the latitude longitude pair in the thumbnails’ subtitle.
  2. So, bold as I was, I again selected all photos using CTRL-A and then called the Images… Edit Data… menu item (or pressed CTRL-E ).
  3. In the dialog box that popped up, GeoSetter effectively allowed to change all data points of the images. In the Location tab, it has a Get from Web and a Get All From Web button. The latter is only enabled when more than one photo is selected. Here is a screenshot of a successful run of Get From Web for a single photo:
  4. So I pressed Get All From Web… and the magic started.
  5. Theoretically, I would have been done here and could just press CTRL-S again to save the data GeoSetter added to the images. There were two complications, though:
    • GeoSetter lost connection to the GeoNames webservice once in a while, making the processing of such a large batch of photos a bit of a stretch. This problem can be mitigated by increasing the WebServices timeout in the File… Settings… menu item’s dialog window in the Internet tab, entry box labeled Timeout for Web Services. I increased that number to 50, which fixed the problem for me.
    • For some places, obviously GeoNames did not answer with a unique place name, but with multiple possibilities. Seems logical, as I could have been right between two cities, so how should it know? The one problem was that GeoSetter did offer the option to say Select for All, but this led to all images being assigned the one selection I had made. So if it is unsure whether an image should be attributed to Montalcino, I had to confirm it image by image, because if I pressed the Select for all button, it would take that answer also for the images where it was unsure if they were in Siena… This leads to quite some clicking when doing many images at once.
  6. Now, press CTRL-S to save your work, and exit GeoSetter.

BTW, the save operation of GeoSetter does keep your original JPG file in case it screws up. It is a good idea to try out these more bleeding edge workflows only on copies of your images, not your originals! I always photograph raws, and run the geocoding on the JPGs I am creating for the image archive, so I still have the raw file in case the JPG breaks.

Done. After that, I did import the images as usual into my Photoshop Elements 5 image archive, and the tricks and hoops to jump through for that to work smoothly shall be part of another story to be told another day – maybe your favorite image archive works just as we all would envision it to work.

Workflow — No Comments
2
Jun 09

Geotagging II – Adding GPS location data to the photos

tuscany

Wow – May is over as is my vacation :-(

Tempus fugit.

But of course I used the vacation for quite some photography, and also continued my engagement with geotagging. On our one week trip to beautiful Tuscany I had made sure to carry my Garmin Venture HC with my nearly all the time, switched on and set to record my track.

Now I downloaded and cleaned up the track just as I outlined in my previous post on geotagging, and will explain how to get the GPS information into the EXIF data of the photos!

After some searching and trial of various software packages for this, most namely the freely available gpicsync and a trial version of the commercial RoboGeo, I have settled for the also freely available GeoSetter software.

When you start up GeoSetter, the default view shows you the image browser on the left hand side, and a map window on the right hand side. This is not the optimal setup for what we are trying to achieve, so I changed my view setup by turning off the Map (for now) using CTRL-M or the respective menu entry in the View… menu, and turn on the tracks window using CTRL-T or again the menu item for this.

Now you need to locate the two data items you want to merge: In my case, I did:

  1. Browse to the directory on my hard disk where all JPEG images from Tuscany reside using the Explorer-like address bar. If you do this correctly, the thumbnails of your to-be-geotagged photos will appear, and the preview window will show a bigger version of the first photo.
  2. Use the Tracks window to browse to and open the GPX file with the positional track information created in the previously outlined process. You can additionally use the little checkboxes in the tracks window to turn off older waypoints or anonymous track information that you do not want to be used for geotagging. In my case, there were older waypoints in the GPS device I had used to relocate my favorite restaurants from my prior visits to Tuscany :-)
    So here is a screenshot of GeoSetter after I opened the two data locations:

  3. Remember my comment on making sure to synchronize the clocks between the GPS and the camera? Finally, this time I had remembered to do this by taking a photo of my GPS device while it is showing a second-accurate current time. We’ll be using this photo shortly.
  4. Now I was ready to perform the real geotagging: Starting with one picture first for the cautious, or do a CTRL-A in the thumbnail view to select all photos, and press CTRL-G or call the respective menu item Images… Synchronize with GPS data file… to open up the synchronization dialog. This will take a while to show up if you do it like I did with 897 images in one run, but GeoSetter is showing a nice progress bar while it retrieves the EXIF information from all the selected images.
  5. Now, this dialog is quite a beast, but don’t worry, I’ll walk you through it. What I did:
    • Selected Synchronize with Visible Tracks as we had already located the positional data we will be using.
    • Let GeoSetter Interpolate Regarding Shoot Time With Last Or Next Position, as this can improve accuracy of Geo information when the track log was not that dense (contained many data points).
    • Allowed for a maximum time difference of, let’s say, 3600 seconds. If I stayed longer that that in one place, I might have left the GPS at home :-(
    • Used the Use Time Zone method, as I knew my camera’s time zone (no jetlag going from Germany to Italy – how convenient!), and this is the only method that will allow for the picture of the GPS device to be loaded
    • Disabled the Request Time Zone checkbox as I knew the time zone – I rather selected the correct one in the combo box available for this.
    • Checked the Add Time Zone over to Taken Date check box to have GeoSetter add the time zone information to the EXIF shooting data so the information is in there once and for all.
    • And used the Additional Time Adjustment Method as described in the following paragraph!
      So I clicked on the Adjust by Image Content… button and simply enter the time displayed on the GPS device in your photo of it into the edit fields – in my case, this led to a time correction of my camera’s time by -54 seconds. Not dramatic, but it helps to be precise once in a while.

      (Tip for this step: If you have selected the 897 images like I did and the photo of the GPS is neither the first nor the last image, better select only the image of the GPS device before pressing CTRL-G in step 4. This allows for doing this time calculation with the image, and later reuse the value found. GeoSetter makes it a bit hard to find the image of the GPS in the large image set selected).

  6. That’s it! Easy, wasn’t it? We’re ready to press Ok in the large dialog displayed. For verification, here is the dialog after I had it filled out:
  7. All images for which a corresponding data point in the track was found are now marked in red in the thumbnail view and a latitude / longitude position is displayed next to it. The red color by the way indicates unsaved changes, so after a verification that all is well we should save the result of our work (well ok, it was more the work of the software).
  8. For verification of an image’s position, use the map window (turn back on pressing CTRL-M) by selecting only the image you want to find on the map, and press CTRL-Z (or use the curious looking glass icon in the map view’s button row that shows only a single exclamation mark… I found using CTRL-Z works better for me):
  9. The final step – don’t forget to save the data! Just press CTRL-S!

By the way, for my 897 images I could automatically geo-locate only 782, and GeoSetter provided a nice warning about this. The setting of so many images at once took also a while on my old desktop machine, but if I don’t have to work myself, I’m fine with that.

But the advantages of really doing geotagging don’t stop with the display of the position where the photo was made on a map, so stay tuned…

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