This weekend I had the chance to try the Tamron 15-30mm, one of the best wide-angle lenses out right now. For the past 6 months I've wanted to test this lens against the legendary Nikon 14-24mm. Unfortunately there was a full moon this weekend, so I couldn't capture any Milky Way photos. Instead, I went back to Observatory Park to do another Star Trails photo. The last time I was there, I was testing the Rokinon 14mm vs the Nikon. You can view the comparison in this blog post.
UPDATE - July 21, 2017: I just tested the Nikon, Tamron, and Rokinon on a beautiful, dark night at Cherry Springs State Park. These tests provided some great examples for Milky Way photography. Click here to read an updated look at the Tamron vs the Nikon on a dark night.
The comparison below shows the unedited images from the Tamron and Nikon. Each photo was taken at f/2.8, ISO 200, and 15 seconds. Oddly enough, the EXIF data shows each was at 15mm, but there is clearly a big difference. I'm not sure if that's just a miscalculated focal length, or the difference in distortion. I'm assuming the Nikon was actually at 14mm.
Next, I wanted to see how well the Tamron fared with coma. I had heard it was on par with the Nikon. The comparison below seems to verify that claim. After looking at both images up close in Photoshop, the stars in the Tamron image are slightly more distorted and stretched.
Keep in mind, the Tamron does have Vibration Control. I accidentally had it turned on, which caused the whole image to become blurry after 15 seconds. It appears the VC in this lens can not detect when it's on a tripod. Be sure to turn it off! The comparison below was taken after I turned off VC.
The next comparison shows how well Adobe Camera RAW's lens correction profiles work. In both cases the minor chromatic aberration on the stars was removed, the distortion was fixed, and the vignette was heavily reduced. The Nikon is still a bit darker, despite the fact that both lenses had the exact same settings. I would argue that the Tamron profile correction goes a bit too far in removing the vignette. The upper corners look too bright. Good thing you can manually adjust the vignette correction.
Let's base the final result on a few categories: vignette, coma, color, and price.
Coma Both lenses have minimal coma. However, after inspecting both images, the Nikon has a minor advantage. The stars in the Tamron image are slightly more stretched and distorted.
Color The Tamron appears to have more saturated colors. I'm assuming this is because of the better vignette performance. More light is able to reach the sensor and therefore the colors are able to come through a bit better. Again, a minor difference. Both lenses have good color rendition. (In my Nikon vs Rokinon test, the Rokinon had considerably worse color performance.)
Price The Nikon is currently selling for $1,700, after a $200 instant savings. The Tamron is currently selling for $1,100, after a $100 rebate. Clearly the Tamron is the winner here, over $600 cheaper!
Based on these quick tests, it's clear the Tamron 15-30mm is a worthy replacement for the Nikon 14-24mm. If you are in the market for an astrophotography lens, the Tamron is a great option!
Don't forget the recently announced Sigma 14mm f/1.8, which may beat both the Tamron and Nikon. It's currently listed at $1,600. I'm still waiting for some definitive examples of coma, vignette, and distortion on the lens. If this lens can perform well wide open, it may be the new Milky Way king!
Finally, here's a Star Trails photo I captured with the Tamron 15-30mm. The full moon illuminated the landscape nicely!