Tamron SP 15-30mm f/2.8 VC, checking focus with Reikan Focal 2


I’ve been hesitating a little bit if I should even post this or not, as it doesn’t add much in its own, but should be seen together with the other Tamron lens posts I’ve made. To be clear, this Tamron 15-30 f/2.8 VC is not compatible with the Tamron Tap-In Console, so no values can be altered or entered into the lens! But this doesn’t mean I can’t see how the focus behaves at different apertures, focal lengths and focus distances.

This lens was released in 2015, slightly too early to be compatible with the Tap-In Console (released in 2016), but still it was the world first wide angle zoom lens to incorporate stabilization in form of Tamron’s VC, Vibration Control. The look of the lens falls a little in-between the old style with golden markings and the new somewhat futuristic “G2-style”, in fact the style of the lens is only shared with the 18-300 VC, 28-300 VC and the 16-300 VC, making it almost unfamiliar in the Tamron world. That said, the lens is superb and one of the best wide angle zooms available, competing with the legendary Nikkor 14-24 f/2.8. Independent tests show the Tamron to be more or less equal with the Nikkor, but can brag with VC, witch the Nikkor doesn’t have.

Tamron-15-30-0068

A couple of things I’ve noticed with the design of this Tamron lens, it’s the shape and position of the switches. With several Nikkor and Tamron lenses with switches on the barrel, I’ve been able to involuntarily flip the switches on most of them, especially carrying the lens and camera with a Black Rapid sliding strap, making the camera/lens rub against the hip/upper thigh. The way this lens is constructed, I think this would be close to impossible. Further I think the zoom ring is a bit on the firm side to be comfortable, but maybe it will loosen up with use? Should also add that the lens hood is not removable. All in all, this seems like a winner from Tamron.

So, let’s see how the focus behaves in comparison with the other f/2.8 siblings from Tamron.
See the 24-70 f/2.8 VC G2 HERE
See the 70-200 f/2.8 VC G2 HERE
You may notice that I’ve skipped the 18 and 24mm settings, as the lens can’t be calibrated and this was just to have general look at how the focus behaved, I skipped those to save some time.

As we can see from the closest focus distance, there is a massive swing from plus to far into the minus side at all focal lengths. This seems to stop at f/5.6-f/8, but I think it starts way too much into the plus side, especially at 30mm.

15-30 0.45 meter

At medium focus distance we see a more mixed result with the swing coming back at f/8 and f/11 at 15 and 20mm. What I like less is that it starts in minus at 15 and 20mm and quickly goes farther into minus, while it looks much better at 30mm.

15-30 0.28 meter

Infinity focus distance gives also a mixed result with similar massive swing from plus to minus, although it looks like it stops or even turns back at f/5.6-f/8.

15-30 infinity

A short explanation of the letters after the values. I’m using Reikan Focal software to help me determine the correct value, and Focal are using four words to tell how good or the quality of the final value is. The best is Excellent, then Good, then Acceptable, and finally Poor. If I get an Acceptable or Poor result, I normally do another run to confirm the first one, and sometimes even a couple of more runs if there is a big difference in the values and in the end calculate the average value.

NA* means the curve is so flat that there is a hit or miss where the final valid value ends up.
NA** means the value is way off the scale, the scale actually only reaches until 20, but I think the result is quite reliable until 30, so NA** means it’s more than 30 off.

So what have I learned from this? That is a very good question that have raised more questions than I’ve found answers on, that’s for sure. One thing is, will this spread of plus and minus values matter in the real life? Or maybe better, how much spread can be accepted at witch focal length, aperture and focus distance? I think this will have to rest until the evenings are getting darker and the time to study gets bigger. Maybe it will be a post about my findings in the beginning of next year?

Tamron-15-30-0067

Another thing is that the camera and lens manufacturers have seen the need to incorporate focus fine tune, I won’t be surprised if it matters more than we think, or does it?

Equipment in use for the calibration:
Reikan FoCal 2 calibration software on my PC.
Reikan focus chart printed in highest quality on 120g non-glossy paper for close and medium distance, printed in A2 size for infinity.
Nikon D750.
Tamron SP 15-30 f/2.8 Di VC USD.
Manfrotto 475B tripod.
Kirk BH-3 ball head.
2x Dynaphos soft-boxes with total about 450 watts of low energy lights for illumination of the focus chart indoors and daylight outdoors.

NB, the values mentioned throughout this post is only valid for my lenses together with my camera, do not expect they will fit your lens and camera, they might end up making your focus worse! So, do your own calibration and find your own values. I posted those values only to prove the point, not to give the final answer.

If you have some comments or questions, let me hear from you in the comments below!

Thanks for visiting!

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