I bought the Tamron 70 – 300 mm Macro tele zoom a couple of weeks ago for use with my Pentax K200D, shown above. I bought it because I wanted to try my hand at close up photography and I found this lens in pentax mount on-line for £80 at Camera World in London. I had been considering a Sigma 105mm ‘proper’ 1:1 macro but the Tamron at £80 seemed a good introduction to close-up photography and I can almost certainly get my money back in part exchange if I decide to get a proper macro lens later.
The lens is about 100 mm long at it’s shortest, which is when it’s focused at infinity and set to 70mm focal length, and extends to about twice that length when set to 300mm and focused as close as it can.
The operation of the lens is controlled by an aperture ring, which is usually set to A for a camera which controls the aperture, a zoom ring, a focus ring for manual focus and a normal/macro switch to set the lens to close focus mode. I had read reports of the zoom and focus rings being stiff to operate, but I find in my example both to be quite easy and smooth to operate. The lens is supplied with a good front lens cap which you remove by pinching two parts of an inner circle in the lens cap design, and a bayonet cap which is initially fiddly to fit until you realize that it only fits in one place and discover that the cap is marked with a line which you line up with the red mounting spot.
On the Pentax K200D, which is quite a heavy camera, the lens balances quite nicely and feels solid. Being F4 at it’s brightest it not the fastest lens available, but in it’s class it’s OK. The maximum aperture drops to F5.6 at 300mm but again it seems to be fast enough and it’s possible to get quite good ‘bokeh’.
To set the lens to Macro mode, you set the zoom to between 180 & 300 and switch the Normal/Macro switch to macro mode. You can then focus to quite a close distance from the lens. This is not a true macro lens and doesn’t give a 1:1 image, but it will go to 1:2 which still gives some pretty good images. Also since the closest focusing is at 300mm focal length you can stand quite a distance from your subject, which for butterflies and bees etc is quite an advantage since you don’t frighten them away.
The lens does not have a focus motor (at least not in the pentax mount) so it is driven from the screw thread in the camera body which makes it quite slow and noisy to focus and it also has a tendency to hunt a bit, particularly in macro mode. I’ve found in macro mode that if I find it focusing the wrong way ie de-focussing, that if I release the shutter button and half-press it again it will quite often restart in the opposite direction. However, quite often I will manually focus in macro mode.
Another slightly annoying thing with focusing is that the lens can’t be tweaked in auto focus mode. With the pentax lenses I own you can auto focus and then move the focus ring on the camera to ‘fine tune’. The Tamron won’t do that – the focus ring is locked and you need to switch the camera into manual focus mode to fine tune the lens. That’s another reason I tend to manually focus in macro mode.
Other reviews I’ve seen report a bit of Chromatic Aberration when used in bright conditions. I haven’t found any problems with this so far, but that is something which can quite often be corrected with post production software.
I find the performance to be pretty good and for the money the lens cost me fantastic. I’ve taken some pretty good (for me) shots with it. Some examples are here