Lytro Camera (First Generation) Review

This is a review of the Lytro's First Generation camera, the first consumer light field camera that became famous for changing the focus after having taken the shot.

Sony a6000 Autofocus Speed Test: Bounce House

I know the Sony a6000 autofocus is fast.  However, I didn't know exactly how fast it was.  I had already taken test shots of cars moving at up to 40 mph, which the Sony a6000 captured with ease.  But I wasn't sure if it was fast enough to capture fast-moving kids.  I got the chance to test the a6000's autofocus at a bounce house.

Back Button Focusing, What? Why? And How?

Excuse the quality of the picture, this is the best I could get out of my wife's P&S

So you've heard about BBF or Back Button Focusing and was wondering what BBF is. Maybe you also heard that once you get used to it you will never go back. In this post I will tell you what is BBF and why it is one of the best things that makes using a DSLR more practical and enjoyable.

Focusing Tip: Zoom In (Basic)

If you have a zoom lens and your camera is having difficulty focusing, try to zoom in to get a larger image, half-press the shutter to lock focus on your subject, then zoom out. Even though you zoom out, the focus will be maintained so long as the distance between the camera and the subject remains constant (this characteristic of modern lenses is called "confocality").  You can try this out to confirm :)

Tamron 17-50 VC first impressions

I received the Tamron 17-50 VC that I ordered from Amazon (it even arrived one day early).  Unfortunately the lens I got was not focusing properly -- specifically, it was backfocusing behind the target (i.e., further away from the camera).  For what it's worth these are my first impressions:

• Build quality seems pretty good, subjectively speaking.  Noticeably heavier than the 28-75.
• The field of view at 17mm (25.5mm equivalent) is impressive.  In this sample shot, I took the shot of our shower from the opposite corner of our bathroom, about 11 feet away.  The field of view was wide enough to capture the wall facing the shower.

Given the wide field of view of this lens, I'm pleased with having chosen this lens over the Tokina 12-24.  I think it will take a while before I feel the need for a "real" wide angle lens.

• Barrel distortion at 17mm is quite noticeable.  Note: barrel distortion (which results in straight lines becoming curved) is different from perspective distortion.  The barrel distortion was not so easy to eliminate in post processing.  Paintshop Photo Pro X3 has barrel distortion correction but I could not correct the barrel distortion completely without introducing pincushion distortion at the borders.

Uncorrected image:

Partially corrected image:

• Resolution: When I first took sample shots the lens, it looked shockingly soft (compared to my 28-75), even at high shutter speeds.  I have since found a photozone review of the Canon version of this lens, with amazing resolution (at least at the center).  This caused me to suspect that there was something wrong with the focusing.  I took dozens of test shots, comparing it with my 28-75, and confirmed beyond doubt that the 17-50 I received had a focus problem, which was not great, but at least kept my hopes up for this lens.  Hopefully the replacement will not have that issue. 
  Given the focus problem on my sample, I would caution potential buyers to make sure they buy from a seller with a warranty (Tamron will not honor its warranty on a gray market item).
  
• Image Stabilization ("vibration compensation (VC)"): This was my first lens with image stabilization.  I previously had a Pentax K100D that had built-in image stabilization, which I found quite effective.  Sample shot from K100D (handheld, 170mm (255mm equivalent), 1/30 sec., 1600 ISO, all ambient light):

In contrast, I wasn't very impressed with the image stabilization of this lens, although in retrospect I think the softness was due to the focus problem, not camera shake.
I also found the sound of the VC working somewhat strange -- it sounded kind of clunky, not a high-tech whirr or buzz that I was expecting.  It's not something that bothers me though.

I look forward to re-evaluating this lens when I get a replacement.

Update: I received a replacement for the 17-50 VC.  It focused identically with the first.  Meanwhile, I upgraded my D80 to a D300.  Strangely, with the D300, both samples of the 17-50 VC focused correctly on the D300 (without micro-adjustment).

2nd update: Here are some real world shots with the 17-50 VC.

3rd update: Here is my 3-month evaluation of this lens.

Swing into focus (Basic)

Getting sharply focused images is a challenge for toddler photos. I want to capture shots of our toddler in all his joy and it is at those times when his movements are least predictable.  I tried out a few techniques to help improve focus.

Method 1: focus priority + hold down the shutter
I normally use the focus and recompose technique (select the focus point closest to the point of interest, half-press the shutter to acquire focus, recompose, then press the shutter all the way).  The problem with the focus and recompose technique is that there is an interval between the acquisition of focus and the release of the shutter.  When our toddler moves, as he frequently does, the focus is lost. 

Steps:

1. Switch to AF-S / activate focus priority. Some cameras like the D200 have a setting called "focus priority" (don't release the shutter unless and until the image is in focus). My D80 doesn't have such a custom setting but behaves as if it's on focus priority when I switch to AF-S (autofocus single).

2. Intentionally focus somewhere else first.  It seems the D80 has a threshold of acceptable focus that is not high enough for me.  In other words, sometimes it will consider the image in focus when I don't consider the image to be sufficiently focused. To avoid getting a shot that's not sufficiently focused, I intentionally put the image out of focus first by focusing somewhere else.

3. Put the focus point on the target and hold down the shutter. With the focus point over the now-blurred target, I hold down the shutter.  The shutter doesn't release immediately because it's on focus priority. However, as soon as the image is in focus, the shutter releases.

Method 2: AF-ON
The logic for this one is similar to the previous method but somehow, it seems I get better results with this method. I first customize the AF-L/AE-L button to AF-ON.  This means that pressing the AF-L/AE-L button will acquire focus. Pressing the shutter half-way no longer causes the camera to focus.

Steps:

1. Switch to AF-S / activate focus priority.

2. Intentionally focus somewhere else first.

3. Put the focus point on the target and hold down the shutter.

4. While holding down the shutter, hold down the AF-L/AE-L button. As soon as the image is in focus, the shutter releases.

Method 3: trap focus (aka focus trap)
Our toddler was playing with a swing and I used trap focus (which I read about at other sites) with some success to get shots of him on the swing. This one also requires customizing the AF-L/AE-L button to AF-ON.

Steps:

1. Switch to AF-S / activate focus priority.

2. Put the subject at the target distance and focus. In my case, I grabbed the swing with my free hand, held it in the position I wanted for the shot, then focused using the AF-L/AF-E button.

3. Allow the subject to move.  The subject comes out of focus.

4. Keep aiming the focus point at the same target you chose in #2. In my case, the eyes.
5. Hold down the shutter.  The shutter doesn't release immediately because it's on focus priority.

6. Wait for the subject to come into focus.  As soon as the subject moves into the distance where it comes into focus, the shutter releases.