Focussing inconsistent

edmnottm

Hi,
I have the D3200 with a Tamron 18-270mm lens and have found that the pictures are inconsistent when refocussing. Some are sharp and some are not, even when using the same focus mode. I have tried each of the modes with the same outcome.
Any suggestions would be appreciated together with advice on how best to set up this camera with this lens.

ohyeahar

Are you shooting a moving subject? If so, then it’s expected for some shots to be out-of-focus.

If you’re shooting a static subject, is there enough light? Just as light is required for the actual exposure, light is also required for auto-focusing. Keep in mind that the 18-270mm is an f/3.5-6.3 lens. If you’re zoomed all the way in, then your maximum aperture is just f/6.3. Depending on how bright it is, the lens may not be letting in enough light for the AF to work efficiently (especially if you're indoors).

edmnottm

ohyeahar
Thank you for your reply. The pictures were taken in South Africa with good light.
I have noticed that when the bleep sounds indicating that the lens has focussed that there is a small movement of the lens straight afterwards. I don't know if this is normal and could cause the slight out of focus. I contacted Tamron about this issue 3 weeks ago but have not received a reply; support seems to be non-existent.
Any users of this lens have a similar problem?

ohyeahar

@edmnottm
That tiny movement you described sounds to me like it's just the optical image stabilization working. Tamron calls it VC for Vibration Compensation (Nikon calls it VR, Sigma calls it OS; same thing). So it's normal. To test it, try to turn VC off. That little hiccup you described should no longer happen.
Test your focus on a stationary object and shoot at a shutter speed that's fast enough to eliminate blur from camera shake. If your shots come out properly focused, then maybe the problem is not the AF but motion blur from slow shutter speed?

edmnottm

Thanks ohyeahar.
Did what you suggested, and no hiccup. When VC is on should I wait for the "hiccup" to finish before taking the picture?
As you may gather this is my first DSLR. I guess I am going to have to experiment to find out what focussing mode works best with which AF mode and which metering mode.
Do you know of any link which would give a beginner like me any advice?

ohyeahar

@edmnottm
That slight “hiccup” is normal. So if you’re shooting hand-held, it’s a good idea to keep the VC on. And yes, wait for it to finish before shooting, but it happens in a split-second so don’t even pay attention to it.

There are plenty of resources online to learn. Among others, I like reading from http://photographylife.com/

I also recommend the book “D3200: From Snapshots to Great Shots” by Rob Sylvan. I have the D5100 version of his book and it’s great. It’s like the manual on steroids. Lots of practical tips and real life examples and it's easy to understand.

Everybody sets up their camera differently according to their own preferences. Here’s how I set up my metering and AF modes for your reference. Try these settings as a starting point.

Metering: Keep it on Matrix by default. That works well most of the time. The only time it seems to struggle is when the subject contrasts greatly with the background (eg, someone on stage who is lit by a spotlight, or a bride in a white wedding dress, etc). In those occasions, switch to either of the other 2 metering modes.
Use center-weighted if the subject fills most of the frame and use spot if not. It’s important to note that center-weighted doesn’t care where you put the AF point. It just meters the center of the frame. Spot metering will meter around your AF point.

Autofocus Modes: I keep it on AF-A. I’ve never had a time where the camera chose the wrong mode for me yet.

AF Area Modes:
I use 3D-Tracking mode most of the time. If I’m shooting a stationary object, I can compose and then move the AF point to the subject just like in Single-Point mode.

Where 3D-Tracking excels is when you want to focus and then recompose before shooting. You can do this in Single-Point mode too, but by recomposing you actually move the plane of focus and you risk moving the subject out of that plane. With 3D-Tracking, as long as you recompose your subject onto any of the AF points, the camera will reacquire focus on that point.

The only other AF Area mode that I use is Dynamic-Area. Use this for moving subjects where you want to pan with the action. For example, a race car, a flock of flying birds, a running child, etc.

edmnottm

Hi all,
A further update on my problem. After getting a reply from Tamron I sent the lens back for testing. It was returned after only 2 days. They stated that they dismantled and replaced F. gear assy, maincircuit board assy, middle lens barrel assy, full clean, check and test.
At this time I would point out that I returned the lens complete with a circular polarising filter attached which I put on the day I bought it and sent an SD card with about 60 photos that I had taken with the lens.
I went out and took some pictures of the same scenes as I had previous to returning the lens. I was still unhappy that the results appeared no better.
I then decided to take the polarizing filter off, and lo and behold, the photos were much sharper and clearer. I can only assume that the filter cuts out that much light that the focussing system could not cope.
It could be something for owners of this lens to bear in mind.
Would be interesting to know if any other owners have attached the same filter and if they found a problem.
Has anybody any comments on the above scenario?

Haggis

Are you using AFC for focus? AFA can be an issue with Tamron, I had a 18-200mm Tamron, it appeared to work reasonably well on focus AFC. I changed to single point focus AFA and between 20mm and 35mm it wouldn't focus lock most of the time. After several attempts to work out why, I gave up and took it back to the shop. I then bought a Sigma 18-250mm which is excellent. Tamron have focusing issues, look on you tube.