Basic interactions

In the previous tutorial, we learned about the user interface and how to configure the CameraPixels to your needs. In this tutorial, we are going to look at the basic interactions in CameraPixels, how to adjust focus and exposure points, how to manually adjust focus, white balance, and exposure.

Adjusting focus and exposure points

The viewfinder of CameraPixels supports four main gestures:

• Single-tap with one finger
• Single-tap with two fingers
• Double-tap with one finger
• Press-and-drag

Single tap with one finger gesture

To adjust both, focus and exposure points at the same time use a single tap with one finger gesture. If focus and exposure points are both adjustable, you’ll see a square reticle on the screen. If only exposure point is adjustable, for instance, this is the case for most front cameras on iOS devices, you’ll see a circle reticle on the screen.

Instead of tapping on the screen to change focus and exposure points you can also use press and drag gesture. Press on top of the focus/exposure reticle and then drag it to the point where you want to focus or measure the exposure.

Single tap with two fingers gesture

By default, focus and exposure points are merged, and tapping on the screen changes them both at the same time. CameraPixels also supports a separate adjustment of focus and exposure points. To separate focus and exposure points use a single tap with two fingers gesture. Please note, the focus and exposure points could be separated only if focus and exposure are in auto-mode and the camera and capture mode both support the corresponding adjustments. After the split, each point can be adjusted separately by press-and-drag gesture only. Tapping with one finger on the viewfinder while focus and exposure points are separated will merge them together again. If focus or exposure is in manual mode, the corresponding reticle is hidden and cannot be adjusted using the on-screen gestures.

Double tap with one finger gesture

To reset the focus and exposure modes to auto and place the focus and exposure points at the center of the viewfinder use the double-tap with one finger gesture. Resetting the exposure point also changes the metering mode from Spot (when exposure point was set with a tap or press-and-drag gestures) to Center-weighted (when the exposure point was reset by a double-tap gesture or when the viewfinder first starts).

Manual adjustments

CameraPixels was designed and optimized for mobile photography using manual settings. The manual settings toolbar is always visible on the screen and is constantly updated to inform the user about the camera’s current parameters like iso, shutter speed, white balance, and focus. The user can then make an informed decision to leave the setting in auto mode or switch it to the manual one. Most iOS devices support manual adjustments of iso, shutter speed, exposure bias offset, white balance, and focus. The aperture is fixed on all currently available iOS devices.

Manual white balance adjustments

Switching the white balance to manual mode is done by pressing the White Balance setting button. In auto mode, the white balance setting button has a label AWB (auto white balance), while in manual mode the label changes to WB. The color of the label also changes from light grey (auto mode) to red (manual mode).

To access a list of white balance presets and tint adjustment, long press on the White Balance setting button. If you have a calibration grey card, place it in the front of the camera such that at least 50% of the viewfinder is covered, and press the Grey card button in the white balance presets dialog.

To hide the white balance presets dialog choose one of the options or tap outside the dialog.

If you want to reset the white balance mode back to auto mode, double tap on the white balance setting button while it’s selected (there is a selection border around the label of the button).

Manual iso and shutter speed adjustments

Pressing the iso setting button will switch the exposure mode to manual and depending on your CameraPixels settings will select iso and possibly shutter speed settings.

By default, CameraPixels is configured to support semi-manual (priority) modes: iso- and shutter-priority. If you have not disabled the ISO/Shutter priority option in the global settings of CameraPixels, pressing the iso and shutter speed setting buttons will switch the app into iso- or shutter-priority mode correspondingly. In the priority mode, you can adjust the iso or shutter speed and exposure bias offset, while CameraPixels will calculate the other setting of the exposure for you automatically.

To change iso or shutter speed back to auto-mode, double-tap on the corresponding setting button while it’s selected.

You can also quickly switch to iso or shutter-priority mode by long-pressing the corresponding setting button: a long press on the iso button will activate iso-priority mode; a long press on the shutter speed button will activate shutter-priority mode.

If you don’t like the priority modes, you can disable the ISO/Shutter priority option in the global settings of CameraPixels. In that case, pressing iso or shutter speed setting buttons will select both, iso and shutter speed at the same time and disable adjustments of exposure bias setting. Also, resetting one of the settings will reset the exposure mode to auto mode.

Manual focus adjustments

To manually adjust the focus tap on the focus setting button. Its label will switch from AF (auto-focus) to MF (manual focus).

The focus is expressed in percents, from 0% to 100%. This is because the focus distance strongly depends on the camera used and any lenses attached to your iPhone. Expressing the focus distance in percents helps CameraPixels cover all possible cases, where 0% is the closest distance a given camera can focus on and 100% is the most distant focusable point. The closest focusing distance can be from a few millimeters (macro lens attached to the iPhone camera) to a few centimeters.

To reset focus back to auto mode double tap the focus setting button while it’s selected.

Exposure bias adjustments

Exposure bias offset probably the only setting that can be adjusted in every capture mode and for every camera available on iOS devices. The only time when exposure bias offset is not adjustable is when the exposure mode is in full manual mode (both, iso and shutter speed are selected).

The exposure bias can be adjusted with the 0.1 F-stop precision. Double tapping on the EV button will reset exposure bias to 0.0. The long press on the EV button will switch exposure mode to auto.

Conclusion

In this tutorial, we learned the basic interactions within CameraPixels. You should now know how to adjust focus and exposure points, switch exposure, focus, and white balance to manual and auto modes. We also mentioned a few shortcuts to quickly switch between exposure modes:

• long press on iso button switches CameraPixels to iso-priority mode
• long press on shutter speed button switches CameraPixels to shutter-priority mode
• long press on EV button switches CameraPixels to auto-exposure mode

To access the white balance presets and tint adjustments, long-press the white balance setting button. In the next tutorial, we’ll look at how to select different capture modes and adjust their parameters.