Archive for February 2013
A new version of the digiKam Recipes ebook is available for download. The following material has been added since version 3.9.39:
- Create a Bleach Bypass Effect
- Export Photos via DLNA
- Process Film Negatives
- Calibrate and Profile Monitor for Use with digiKam
- Use Photoshop Curve Presets with digiKam
- Import Photos from a Remote Server into digiKam
As usual, the new release features minor fixes and improvements. Readers who already purchased the book will receive the new version free of charge. If you haven’t received your copy, please send your order confirmation as proof of purchase to firstname.lastname@example.org, and I’ll email you the latest version of the book.
I spent the best part of a day trying to create a lens profile for my trusty Canon PowerShot S90. In theory, it should be a rather straightforward thing to do. The Creating lens distortion models with Hugin’s lens calibrator article provides easy-to-follow instructions on how to create a lens distortion model.
I used a single RAW file to generate a simple model (see the screenshot above). I then added the following lens profile to the /usr/share/lensfun/compact-canon.xml file:
<model>Canon PowerShot S90</model>
<distortion model="ptlens" focal="6" a="0.01463" b="-0.07992" c="0.00461" />
So far, so good. digiKam seems to pick the added lens profile, but the Auto-Correction tool (Enhance → Lens → Auto-correction) produces a rather strange result:
I can’t figure out what I’m doing wrong, so if you have a suggestion, feel free to chime in.
Install the DSLR Dashboard app on your Android device, and you can use it to control a Nikon DSLR camera via a USB connection. But in certain situations, tethering the Android device to a camera using a cable is not ideal. This is where DSLR Dashboard’s wireless functionality can come in rather handy. Using this feature, you can link up two Android devices running the app via a Wi-Fi connection. In this case, the device connected to the camera acts as a wireless bridge (or client in DSLR Dashboard’s terminology) between the camera and the master (or server) Android device. And the latter is used to control the DSLR camera remotely. Here is a diagram that illustrates this setup:
- Nikon DSLR camera
- Android device running DSLR Dashboard that acts as a client
- Wi-Fi access point (AP)
- Android device running DSLR Dashboard that acts as a server
As shown on the diagram, both devices must be connected to the same AP. Instead of using a regular wireless router, you can opt for a mobile router like TP-LINK TL-MR3020 to make the entire setup portable. The clever part is that many mobile routers can be powered via a generic power adapter which can be bought cheaply on eBay. This allows you to create a wireless network whenever and wherever you need it and use it to link Android devices running DSLR Dashboard.
To set up this portable wireless remote control solution, you need the following items:
- Two Android devices running Android 2.3 or later
- A USB OTG cable (can be bought cheaply on eBay)
- A USB cable supplied with your DSLR camera
- A mobile wireless router like TP-LINK TL-MR3020
- A battery power adapter
Power up the mobile wireless router and configure it as an AP (consult your router’s documentation on how to do this). Connect the Android device that will act as a server (i.e., the device for controlling the DSLR camera) to the wireless network created by AP. Tap the Menu button and choose the Start Network Server command. Connect the other Android device to the DSLR Camera using the USB OTG and the USB cables. Enable Wi-Fi on the device and connect it to the wireless network created by AP. Turn the DSLR camera on and launch the DSLR Dashboard app. Once the app has detected the camera, tap Menu and choose the Start Network Client command. This should automatically hand over control to the server device which you can then use to operate the DSLR camera in the usual manner.
A wireless shutter trigger for a DSLR camera can come in handy in many situations. And if you already own an Android device, you don’t have to splurge on a dedicated remote trigger. To turn an Android device into a flexible tool for triggering the shutter wirelessly you need three things:
- The DSLR Remote app installed on your Android device
- TriggerTrap dongle and cable combination for your specific DSLR model
- Generic Bluetooth A2DP receiver (can be purchased on eBay)
Start with installing the DSLR Remote Control app on your Android device. Connect then the Bluetooth receiver to the DSLR camera using the TriggerTrap cable as shown below.
Enable Bluetooth on the Android device, and turn the Bluetooth receiver on. On the Android device, switch to Settings → Bluetooth and pair the device with the receiver.
Next, configure the DSLR Remote app. The exact configuration profile depends on the particular receiver. In most cases, you only need to specify the appropriate cable type in the app’s Settings section. To do this, launch the DSLR Remote app, switch to the Settings section, and set the Remote Type option to Cable S. Close the settings screen, switch to the Remote section and press the S button. This should trigger the camera’s shutter. If this doesn’t work, then try enabling the Bluetooth option, or set the Remote Type option to Cable A.