After only four years on the market, the “old” Tamron 15-30 f/2.8 VC got replaced with the G2 version last autumn (2018). Not that the old version was performing badly by any means, but think about it, the legendary Nikkor 14-24 f/2.8 was released back in 2007 and there are still no rumors about a replacement or upgrade, but I guess Tamron was eager to get the full set of Holy Trinity of f/2.8 zooms out in “G2” style.
Anyway, at first look, the new 15-30 f/2.8 VC G2 lens looks like the same lens in new wrapping, as it has the same number of lens elements and groups. But it is clear that Tamron has done something more to this lens than just a new casing. The sharpness has improved, the vignetting is less, the Vibration Control has improved and the build quality is on the same high level as the other f/2.8 G2 lenses. And last but not least, it is compatible with the Tap In Console with the benefits that comes with it, like firmware update, focus limitation possibilities, VC behavior and focus fine tune at multiple points. Now, firmware update via the Tap In Console may not be a selling point for the Nikon F-mount, as I’ve hardly seen any update for the F-mount, but for the Canon EF and EF-S mount on the other hand, I’ve seen multiple firmware updates for the Tamron lenses. Why they need more updates for the Canon-mount than Nikon-mount to ensure compatibility when new cameras are being released, I don’t know.
This is not meant to be a review of the lens in a traditional way, the intention is purely to see how the autofocus behaves. To help me determine the accuracy of the autofocus, I use a computer program called Focal from Reikan Technology. This program, among other features, takes a series of photos at different autofocus fine tune settings to determine at which setting the sharpness of the lens is at its best. Before the fine tune in camera and later multiple fine tune points in the lens, the optimum should be closest possible to zero at all apertures and focal length combinations. Obviously, this is extremely difficult, especially with a wide angle zoom lens.
Before continuing, it could be an idea to read some of the following articles as get a better understanding of autofocus in general and Reikan Focal.
Tamron SP 70-200mm f/2.8 Di VC USD G2, calibrating with the Tap-In Console
Tamron SP 24-70 f/2.8 VC USD G2, calibrating the lens with Tap-In Console
Tamron Tap-In Console, my experience
Why and how you should use AF fine tune in your Nikon DSLR
When I started to examine the focus of the lens, I used the new beta of Focal (2.9.5) and only after some time I realized that I couldn’t alter the aperture, as I couldn’t find the Preference settings, so I could only continue with max/largest aperture at all focal lengths. Being lazy I was thinking, this would be easy and fast, but then I realized that this wouldn’t be much useful or interesting if I don’t do the whole set of apertures as I’ve done earlier. So, I was thinking to publish with testing only at f/2.8 and redo the whole thing later, but then I was fooling around with the program and clicked on the “About” button just for fun and surprise, there was the “Preference settings” hiding. Hallo Reikan Technology? Why are you hiding one of the most important features of the program behind the “About” button? In the Preference you may alter many ways the program behaves, accuracy in the test procedure, what it should check before and under the procedure, jpeg or RAW, defocus away from or towards the camera, ISO, aperture, color temperature, exposure compensation and a lot more. I would say that this is so important that it should be among the tabs on top of the main window, not hiding it under “About”! I wasted a couple of days testing because of this. In the last final version, 2.6, the “Preference” settings have its own separate button on the main window where it belongs. When it was gone, I was thinking it’s not there yet because it’s a beta…. Update: the new final version has a “Settings” button on the main screen and from there you may find the “Preferences”. Good enough, thank you Reikan!
Enough of the ranting and over to the serious stuff.
So, at 28 cm we see that at f/2.8 the lens backfocus quite a bit at all focal lengths. This changes rapidly to frontfocus at f/4 and increases at f/5.6, and stays more or less the same at f/8. When seeing the whole result, the behavior is somewhat predictable, but the jump from pretty high numbers in plus at f/2.8 and rapidly into relatively high numbers in minus already at f/4 and more at f/5.6, makes it close to hopeless to calibrate at this focus distance.
At 43 cm we can see more similarities than differences to the results at 28 cm, it starts in medium plus and goes directly into minus at f/4. The upside is that it doesn’t go so far into the minus as at 28 cm, still though, big differences between f/2.8 and f/5.6.
Finally at infinity things starts to calm down a bit and most runs ends up on the plus side of zero. I would like that as it doesn’t go far over to the minus side, the results could have been more balanced, mean more equal on both sides of zero.
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.
Tamron Tap-In Console and Utility.
Tamron SP 15-30 f/2.8 Di VC USD G2.
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.
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 will most likely do it 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, and that is also why the Tap-In utility is shown empty.
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