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Tamron 18-270mm – a hero, but no VC…

After using Sigma’s 18-250mm optically stabilised zoom on Alpha bodies for a year and more, the first thing which strikes about the Tamron 18-270mm for Sony mount is the lack of the VC (Vibration Control) stabiliser found on the same lens made for Canon or Nikon.

Tamron’s lenses come without a case, but with a custom fit petal lens hood, front and rear caps. Design is clean with a Nikon-like sleeve grip and Canon-ish gold ring. The PiezoDrive focusing is similar to Nikon AF-S/Silent Wave or Canon USM, or Sony SSM, but not identical and on Sony models it can contrast-detect autofocus reliably. Sigma’s HSM hunts.

With Sigma facing patent claims by Nikon – that parts of their OS technology infringe on Nikon VR – Tamron VC is a mature system not so far challenged in the same way. It is also a very solid kind of stabilisation, free from swimming effects, and in this respect closely matches Sigma’s approach. Both are generally more comfortable than Canon’s IS which often seems to attach the image by a bungee cord to the viewfinder screen.

For video work, in-lens stabilisation is generally better than in-body as long as there is a good stable view which does not tend to float free when you pan slowly. For long lens work in general – over 200mm – in-lens stabilisation provides a view which is easier to aim and compose. We had already checked the lens out on Canon, with its smaller sensor area missing off the extreme corners (and therefore doing the lens favoured compared to other brands) but to compare with Sigma’s lens, needed to look at it in Sony mount.

The lack of VC in the Sony version of this lens is regrettable. There is no corresponding reduction in retail price.

Against this the Tamron has a longer zoom range, and it’s much smaller and lighter than the Sigma, taking regular 62mm filters not the unusual and large 72mm size. It also offers Piezo Drive focusing, which almost as quiet as SSM yet as fast as SAM. Small adjustments make a sort of faint clicking sound and focus travel is unusually fast, but a range of freehand refocusing tests using the Tamron showed that it is just as reliable in locking on to difficult targets as any other lens. Usually fast focusing means lots of overshooting or hunting, but not on the Alpha 580 used for this test.

Although the size and weight difference between this and the Sigma doesn’t look all that extreme when photographed in the studio, the heft in your hand (volume) is much less for the Tamron. It does not really seem any bigger than the Tamron/Sony 18-250mm design or the earlier 18-200mm.

The design of the lens follows these, with the LOCK switch for holding the lens at 18mm when walking round positioned for the right hand to operate, a long way from the AF/M switch (which should be used instead of the body switch for changing to manual focus).

This is a better design than the Sigma which clusters the AF/M, OS on/off and Lock controls together on the left hand side. Even after a year of use, both Shirley and I regularly turn the lens OS off, or turn AF off, instead of operating the Lock. All three controls move in the same way and are intended for the same fingers. Tamron’s location of Lock on the right hand side is ergonomically better.

However, both lenses fail to do the one simple thing which would improve such zooms – make the Lock control operate at ALL focal lengths not just 18mm. The Tamron is firm as we test it, so was the Sigma when new, but our Sigma can not now be used to pan with a plane or bird flying overhead unless one hand is used to keep the zoom from collapsing to 18mm immediately the lens is aimed upwards. To do the studio shot, the Sigma had to be taped to keep the zoom extended. Otherwise, it can’t even sit on a table set to 250mm.

You can’t see the sticky tape stopping the year-old Sigma zoom from deflating itself to 18mm every time when placed in the studio for this shot. The new Tamron is still young and firm. But we need locks which work at ALL settings.

It can not be difficult to devise a zoom lock which works at intermediate settings and it would transform the functionality of lenses like this.

Apart from ergonomics, there is no significant difference in build quality. Sigma feels more solid but heavier in action, Sigma’s exterior finish is difficult to clean and collects marks and dust easily. Tamron feels more plastic in build but has a high quality metal bayonet just like its rival.

Performance

Just studying the lens coatings shows why the Tamron can be more contrasty and less prone to flare in some light – especially if you fit a cheap filter to the Sigma and get contrast-eroding reflection for that front element.

The Tamron lens has visibly higher detail contrast than the Sigma, and in the centre of its field produces a very sharp image. The edge of the image lets it down, however, rather badly. The detail is soft at longer focal lengths unless stopped well down (ƒ/11 or so) and red-green chromatic fringes are serious enough to spoil JPEGs. They are not even very well corrected by using Adobe Lens Profile to process from raw (there is no Sony profile but Nikon, using similar sensors, can be selected).

This is a Sony Alpha 55 ISO 400shot, deliberately off centred in composition, with the Tamron set to f/9 (a good compromise between diffraction and stop-down sharpness) and 270mm.

The focus point is away from the centre of the image, and the lens displays good contrast and sharpness, but even here there is a slightly dirty look to the detail and chromatic fringes hit the white edge. This is NOT by the way anything to do with the Alpha 55 translucent mirror!

Here’s the edge of the shot at 270mm and f/9. I feel it would be almost unfair to Tamron to publish some of the worst results I got wide open. This is a defocused distance, of course, but this is also real-life imaging. This is why we did not switch from the bulky, heavy Sigma to the neater, lighter travel-friendly Tamron.

At full aperture and 270mm the performance is markedly inferior to the Sigma at 250mm wide open. The lens has better multicoating but poor field flatness, which creates the softening to the edges and corners.

The Tamron at 18mm has pretty strong barrel distortion which, when corrected using a lens profile in Adobe Camera Raw or Lightroom, lost some of the wide-angle coverage.

At wide to medium focal lengths, the difference is less marked and the Tamron is more equal the Sigma or other ‘best’ superzooms. But this is a lens bought for its extra reach at 270mm; given the performance, it’s not all that much use unless your subject is centred and surrounded by out of focus background.

Tamron at 270mm.

Sigma 250mm view – at near-infinity, the Tamron is longer the Sigma but not quite as much as 270mm would indicate.

Another issue is that of focal length, above and below examples. If the Sigma is a true 250mm (which it is not, all such zooms are shorter than their stated figures) then the Tamron is actually 265mm not 270mm at infinity.

This is unscientific, but the baby owl did not move and both lenses were placed in turn against the wire of its enclosure ensuring the same shooting distance to within a centimetre or so (with lens hoods removed). Tamron at 270mm.

By this distance, the Sigma at 250mm really is no different in focal length than the Tamron at 270mm, due to internal focusing differences. And it focuses closer than the Tamron for a larger maximum subject scale.

Although the close focus is good, at 49cm and 1:3.8 scale it’s not as good as the Sigma with 45cm and 1:3.4 scale – the true focal length at closer distances also seems to be shorter than the Sigma, though this is hard to evaluate.

As for bokeh, that’s not why you buy these lenses:

How many stumps? Wiry would be a fair bokeh description at medium apertures and longer focal lengths (270mm again, above, at f/9).

The Tamron PZD focus does work on the LA-EA1 Alpha adaptor for NEX; it’s not fast, but can lock autofocus perfectly even in difficult light. The Sigma can not do this at all and is not AF-compatible with the NEX adaptor. But… manually focused, the Sigma has OS. Vital!

Most telling is the weight difference when mounted on a light body like the A55. The Tamron is a far better match even if not as ‘good’ a lens – 970g for A55+Tamron, 1400g for A580+Sigma. Check prices, and work out your priorities.

– David & Shirley Kilpatrick


7 comments to Tamron 18-270mm – a hero, but no VC…

  • Photorer

    Ok – here’s a challenge:

    I have the
    - A100 with Tamron 18-200 (beats the 18-70 kit hands down!)
    - A700 with Tamron 18-250 (very happy with this combo – it WORKS!)

    Will be getting the A77 next week with the 16-50 f2.8 (looking forward to that lens!) and I want to have something as flexible as the above combinations for travel. All the other lenses in my stable have their purpose, but I do want one that I can put on the camera and leave there for a light holiday trip!

    Which of the following should I consider for the A77:
    1. Keep the Tamron 18-250 for the A77, and not use it for any video work (due to screw focus noise)
    2. Get a Tamron 18-270 Piezo drive for the A77 (quiet)
    3. Get a Sigma 18-250 OS HSM for the A77 (quiet)

    I do realise the superzoom is a compromise for IQ, and it will probably be more so on the A77, but the flexibility will mean that I can get the shot. If you were me, which would you go for?

  • We have had the Sony 18-250mm and while it’s a good lens, from around 200-250mm it runs out of full aperture sharpness especially at the edges, even on 12 megapixels. I think it will be stretched on 24, but this will apply to many teleophoto/superzoom lenses. In fact I’m hard pressed to think of any really portable lens extending to 250-300mm which is going to be fully usable on 24 megapixels at an aperture wider than f/8 – except, perhaps, the very large and expensive 70-400mm SSM G lens. We shall try to test this on the 24 megapixel sensor as soon as both are available together for test.

  • AllanMarcus

    Thanks for the great review. I have a Sony 18-250 and an A700. I will upgrade next year to an A65 or A77. Since you discussed the above two lenses for use with the 24mp new cameras, does the same advice hold true with the Sony?

  • bakubo

    Last fall I had the Sigma 18-250mm, Tamron 18-270mm non-PZD, and Canon 18-200mm at the same time and used them for a couple of weeks on my Canon 60D. My take on it was the Tamron and Canon had a bit better IQ than the Sigma, but I didn’t compare the Sigma to my Sony 18-250mm since it was on my A700 and I just wanted to decide which of the 3 lenses to keep and use with the 60D. Then this year I bought the Tamron 18-270mm PZD in Canon mount and compared it to my Tamron 18-270mm non-PZD. I liked the smaller size and weight, but I reluctantly returned it because the IQ was clearly not as good as the non-PZD version. :-( I was also surprised to not notice much difference in AF speed or AF noise with the PZD. I sure did like the size and weight though.

  • madaleno

    Hi,

    Thanks!
    I will consider your suggestions.
    I was looking at the Tamron 18-270, just to avoid having to switch lens all the time.
    But now I will consider buying just the A65 body and one of these lens you suggested.
    My first and only SLR was a Canon 50E and the last time I used it was 10 year ago! :) So I know nothing about this now.
    But I want to buy a camera that will last for some years and that gives pictures with really good quality. So the decision I make must be the right one or I better stay with my compact Lumix TZ7. :)

    Thanks a lot for you help!

  • madaleno

    I am considering buying the Sony A65 with the 18-55 kit lens.
    But I was also thinking in this Tamron lens to complement the kit.
    I am a beginner in DSLRs but image quality for me is my first priority.
    Would you advise this Tamron lens in my case?

    Thanks.

    • I have to say no. The A65 has a 24 megapixel sensor and this lens is already struggling with 16 megapixels. Even the Sigma, which is slightly better, is not very good. If lens quality is your first priority I suggest you get the Sony Carl Zeiss 16-80mm f/3.5-4.5 instead of the 18-55mm kit. Sony makes a very affordable and good 55-200mm SAM lens which is way ahead of the Tamron 18-270mm in quality of results across its range.

      With 24 megapixel cameras, it is no longer so important to have a very long lens. A 20% crop equals 16 megapixels and a 33% crop equal 12 megapixels. So, if you thought that a 300mm lens was essential on an Alpha 700, then a 200mm lens will do perfectly on the A65 for the same level of actual subject detail (like wildlife or sports).