Tamron SP 35-80

[Rob Leslie]

Test shot with the Tamron SP 35-80.
Shot this evening around 8-00pm when having a walk about.
I think this lens performs at its best in low contrast dull lighting. In bright conditions it is susceptible to flare which can take the edge of its resolution and sharpness.
IMO a lens to judge others by. Marvellous for a Zoom

[Nesster]

A lovely lens, still my favorite mid zoom after 25 years...

I agree with you - in part - about the flare... though when I tested it vs a couple of others I didn't get the exposure the same, I found the Pentax 43 Limited held the contrast and detail much better than either zoom. But the Tamron I feel consistently beat the Pentax 16-45 in both... though the Pentax can appear contrastier as it seems to bunch light... um... macro contrast may be the term ... at the expense of micro contrast and resolution.

I really ought to test out your observation a bit more, controlling exposure more closely. In identical conditions, setting the camera to Av and the same aperture, I got 1/60 with the 43, 1/40 with the Tamron, and 1/50 with the 16-45! The Tamron is a bit over exposed looking, and the 16-45 actually looks a smidge darker than the 43.

Now, maybe the over exposure in bright daylight (though shooting into open shade) is caused by the Tamron's losing it in contrast.

[Rob Leslie]

[Attila]

I can confirm this is a beautiful lens I bought and kept two copies. Currently my youngest daughter abuse it with a Tamron SP 60-300mm.

[Nesster]

Now I'm getting eager to try out this flare theory, given this article:
http://www.luminous-landscape.com/columns/sm-03-01-12.shtml

Since I have both the 43 and the Tamron, I should be able to test out Mike Johnson's tests #2 and 3, as well as a general sunny day scenario. If theory holds, the Tamron should be much better where flare is minimal, but start to lose out in the flare conditions.

I should be able to do something this weekend

[Rob Leslie]

An excellent article Thanks for the link.
There does seem to be a few who don't understand flare.

[Nesster]

I've run into an interesting problem with the Pentax metering and exposure, trying to make this test. Seems the modern digital lenses have some chip or something, they invariably produce a darker image than older ones, including the SMC-A mf lenses.

So: first on a sunny morning I take a series of photos, at f/5.6 first with the Tamron then with the Pentax. Of course the Pentax come out darker as the camera gives a different exposure.

Plan B, mid day, I go out and do manual metering, the same setting. Should work, no? And it does, only again the Pentax gives a darker image than the Tamron.

Finally, I have to shoot a control: cloudy morning, manual exposure, and again the Pentax is darker. To the degree that the Tamron produces a larger jpeg - usually this means more resolution, in this case it's probably that the under exposure with the Pentax shadow detail is lost.

The bottom line: I'm not sure I've been able to generate a good test yet. I'll take some more looks at the photos to see if there's any worth posting.

[Rob Leslie]

[Nesster]

Yes I agree with what you say. This IS a consistent thing with the K100D, I've noted it before... I'd rather avoid the trouble and simply get the same treatment lens vs. lens.

Anyhow, here are a couple of test shots. The objective: determine if the 35-80 indeed loses contrast in bright light. One control: Pentax 43 Limited, reputed to have good resistance to this sort of glare, plus I use its lens shade (and non on the Tamron). So what we need to detect here is how much less contrast there is with the Tamron vs. the Pentax. The sun is to the side in both photos, which is a condition that SHOULD result in lowered contrast without a shade, or if the lens is prone to this sort of thing.

1) Morning, Av mode, same aperture set by camera, different shutter speeds computed by the body.

Tam


Pen


2) mid day, manual metering, kept same body-set aperture and speed

Tam


Pen


The histograms from these samples, Tamron first then the Pentax.




All are crops of the full photo, as the theory is that flare/glare will reduce the Tamron's contrast, and this should be seen in a subset of the whole frame. The captures were straight to JPEG, with all sliders set to 0, and no post processing apart from cropping the images.


OK, what do you all think?

[Nesster]

Here's the 'control' - manual exposure, same for both lenses, early morning, cloudy day.

[Rob Leslie]

Well to be honest I can see no flare on those. I thought the first Tam shot may be showing a little loss of contrast (Flare Haze) but I think it is just very slight over exposure.
How about that second test shot set. The Tamron seems to be showing more or at least equal detail to the Pentax lens.
That looks like an very interesting building?
Did you try to induce flare. usually you can see the blue cast come over it in the viewfinder?

[Nesster]

I wish I'd thought to bracket, but I'm not sure actually that would have made much difference: the Pentax shows a greater overall dynamic - there's more at the far right AND there's more to the far left. Unless I made some mistake with the histograms, this seems to indicate that flare haze is taking its toll on the Tamron.

If I'd given the Pentax less exposure, there wouldn't be as much high side spike, but the overall dark areas would be even darker. And more exposure on the Tamron would have made everything equally dark, the sky would have started to not be burnt out. I might conclude that at least in this sample, the Pentax lens overwhelms the K100D sensor, and the Tamron does not.

In general the Tamron seems to have less apparent contrast. But the detail is there, just with different light values.

I think the Pentax SMC-A 28/2.8 is similar to the Tamron, in that it doesn't have the (engineered?) dynamics overall. It does resove very well too, but people tend to like the more dramatic contrast.

When I've shot into the light, the modern Pentaxes tend to produce a small green ghost flare.