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Tamron AF 24-70mm f/3.3-5.6 Aspherical Review

September 3, 2018

This lens is a blast from the past.  The lens was introduced in 1991, and (if what I’ve read is correct) is the very first 24-70 zoom lens.  It was developed during ‘film’ days, so of course it’s full-frame. Back then, this zoom range was considered a bit odd, but it’s now probably the most common zoom range used by professional photographers.

 

Tamron made this lens for Nikon, Canon, and Minolta (remember those guys?). I’m just reviewing the Nikon mount, but the optics aren’t any different for the other mounts.  As the title suggests, it’s a variable-aperture zoom.

 

This lens has a funky very thick rubberized zoom and manual focus ring.  After having thought more about it, however, it’s a very sensible design idea.  Your gear WILL get knocked around, and having a thick rubber bumper around it might just save it someday.  The zoom ring is nearest the camera body; it’s very grip-able and plenty wide enough.

 

Not many lenses had an aspherical lens element when this lens came out, so Tamron marketers really played it up.  They needed aspherics to achieve the zoom range on the short end (28mm was the typical barrier at that time).  They succeeded in this goal; the lens works best at 24mm, as a matter of fact. 

 

What you won’t notice with this lens is any objectionable distortion.  It’s quite impressive for a lens this old to not see the typical heavy barrel distortion.

 

The lens extends maybe a half inch when you zoom it to 70mm, so it stays short.  Being a screw-drive lens, you can’t just alter focus by twisting the focus ring; you need to place the camera body into manual-focus mode first.

 

I discovered that it works well for infrared photography.  Most lenses leave a white hotspot in the middle of your IR pictures, but not this one.  Here’s a link to common lenses (all camera brands) that have been evaluated for their utility with infrared. Its IR capability is the reason that I keep this lens around.  I just wish the lens had a focus scale, since IR photography requires a focus shift.

 

The biggest complaints from users of this lens include noisy focus and poor contrast at some aperture/focal length combinations (mid-frame weakness).  The lens also has a rotating front element, which really annoys people that use polarizers.  My own biggest complaint might be the corner sharpness, having gotten used to the Nikkor 24-70 stellar performance. The bokeh isn’t the greatest, either.

 

I find it hard to get over how much smaller this lens is when compared to the Nikkor 24-70 f/2.8 E VR.  Not that I consider the Tammy to be competitive; the Nikkor smokes it in every way optically (except for infrared photography).  The Nikkor doesn’t smoke this lens in price, however; you can pick one up for dirt cheap on E-bay, but the same can’t be said for the Nikkor.  It’s only 9.7 ounces and 3 inches long, compared to 38.4 ounces and 6 inches long for the Nikkor!  I remember a long hike in the desert where I definitely would have swapped that Nikkor for this Tammy.

 

It has a filter thread of 62mm.  It comes with a ‘tiny’ bayonet-style lens hood that’s only about a half inch long; there’s really no reason to remove it unless you’re changing filters.

 

This lens is the old-style “screw drive” auto-focus, compared to the modern AF-S lenses with an internal silent-wave motor, so it won’t work on lesser Nikon camera models.  Speaking of focus, the Tammy focuses down to 15.7 inches, which is about the same as the 24-70 Nikkor.

 

I noticed while performing focus calibration testing on my D610 that the 24mm fine-tune value (10) was about 2 counts different from the 70mm fine-tune value (8).  Interestingly, I noted the same thing when I calibrated the Nikkor 24-70 lens. I wish all manufacturers used the Sigma USB dock technology to allow custom calibration at different focal lengths and focus distances.  I heard as of this writing that Tamron, in fact, does provide a USB “TAP-in Console” for their newest lenses for calibration similar to Sigma!

 

Resolution Tests

 

As the following measurements will show, this lens struggles in mid-frame at all focal lengths.  If you’re willing to stop down to f/8, you can get good results from 24mm through 50mm and generally even better at f/11.  At 70mm, you need to stop down to about f/11 for good resolution across the frame.

Don’t shoot with this lens wide open. Period. You have been warned.  You can get by at f/4 from 24mm through about 28mm, but lens performance is vastly improved by f/5.6.  The sweet spot is generally f/8.0, which should surprise nobody.

This lens is much better at short focal lengths, particularly at 24mm.  The EXIF data identifies 24mm as 25mm.  At any focal length, the meridional-direction resolution is pretty bad.  The substantial difference between meridional and sagittal directions spells significant astigmatism.

I used the Nikon D610 FX for testing.

 

 

24-70 Tammy on Nikon D610. Funky rubberized zoom & focus rings.

 

 

This is why you were warned to never shoot this lens wide open.

 

 

 

Terrible corners and pretty heavy vignetting wide open 24mm

 

 

 

Better, but not good at 24mm f/4.0

 

 

Pretty useful at f/5.6

 

 

Much better at f/8.  Note characteristic weak mid-frame performance

 

 

Corners are pretty good now, but the meridional remains weak

 

 

Pretty sad meridional performance leads to substantial astigmatism

 

 

Strong performance at 24mm, f/11 in sagittal direction

 

 

Diffraction setting in by f/16.  It’s much worse at f/22

 

 

38mm f/8 Not as good as 24mm.  Pronounced mid-frame weakness.

 

 

48mm f/8 Better than 38mm, but 24mm is still better

 

 

Up through about 50mm, the lens makes a good showing of itself by f/8.  When zooming out to 70mm, the lens performance gets weaker.  Let’s look at the whole f-stop range (except f/22) at 70mm next.

 

 

70mm wide open at f/5.6 is downright embarrassing

 

 

 

 

70mm f/8 still isn’t acceptable

 

 

70mm f/11 Center is fine, but nowhere else

 

 

70mm f/16 sagittal is fine, but meridional edges aren’t acceptable

 

 

Samples

 

850nm Infrared, 24mm at f/8. Works great for this.

 

 

Color comparison shot, 24mm f/11. Full frame edges are soft.

 

 

 

Close focus 70mm f/5.6 Note bokeh of highlights is poor.

 

Summary

 

Truth be told, modern 24-70mm lenses annihilate this Tammy, particularly in the corners, but that doesn’t mean you can’t take good pictures with it.  The bokeh isn’t very good, if that’s important to you.  It’s very small and light, which I love.

 

I find this lens most useful to me when I shoot infrared on full-frame.  IR is inherently slightly soft anyway, so the lens resolution isn’t much of an issue.

 

You can pick this lens up for less than the sales tax on the other modern lenses of this focal range.

 

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