[oldman]

I am planning on buying a 70-300mm lens for use with my K100D Super body. I am looking at the following lens:
Pentax SMC DA 55-300mm F4-5.8 ED w/ AF - approx. $275
Sigma 70-300mm F4-5.6 DG Macro w/ AF - approx. $170
Tamron AF 70-300mm F4-5.6 Di LD Macro w/ AF - approx. $200
Which would anyone recommend and why.

[Marc Sabatella]

If you search for previous discussion of this topic - it comes up once a week - you,ll see he overwhelming preference for the Da55-300, with detailed reviews, sample images, etx.

[luftfluss]

I've owned 2 copies of the Tamron AF 70-300mm F4-5.6 Di LD Macro, the similar Quantaray model (which is made by Tamron but not Di) and the Pentax 55-300.

In short:

- The Pentax has better color, contrast and flare resistance, and of course goes wider.
- The Tamron and Pentax have about the same sharpness. I think any differences would simply be sample variation.
- The Tamron has pretty bad purple fringing in high contrast areas.
- For some reason, the Quantaray version, even though "older" and lacking the Di of it's Tamron brother, has less purple fringing. I paid under $70 for mine.
- I've found the 1:2 Macro of the Tamron & Quantaray to be extremely useful. You get nearly twice as much magnification in "Macro mode" on the Tamron compared with the Pentax.
- If the Pentax 55-300 you are looking at is the DA version, and not the DA L, you get Quickshift, which can be useful.

Sorry I don't have any info for you on the Sigma. If the version you are looking at is not the APO, I wouldn't get it. If it is APO, then maybe. It is reputedly softer @ 300mm than the Pentax & Tamron, but has the 1:2 Macro mode and doesn't have the purple fringing issue of the Tamron.

Hope these impressions prove at least slightly useful for you.

[Eulogy]

Silver FA 100-300 is quite nice. Seems to be almost as good as the 55-300 at 100% crop, and resists flaring well enough. Further focus throw as well, so nice to MF.(Though it's about 20% slower at AF)

Edit: Also, due to 1.5m Focusing distance of the 100-300, at 300mm, it's around 1:2.5 macro ratio.

[m42man]

I think consensus has it that the DA55-300 is very much the best of this bunch, but it's the most expensive. However, if you can get hold of the DAL version, you should find it a lot cheaper. You won't get the clip-on hood or quick-shift focus, and the lens mount will be plastic, but everything else is the same.

As with any lens nowadays, test your purchase out thoroughly as soon as you get it, and check for nasty decentring effects (i.e. loss of sharpness towards one or more edges of the frame).

[mbukal]

I used the Sigma APO 70-300mm F4-5, 6 DG Macro, it is faster than the Pentax DA55-300, but Pentax is sharper, especially above 200mm, Pentax has a better color, has a greater range in mm Pentax DA version of Quick-Shift the super-function (indispensable), Tamron AF 70-300mm F4-5.6 Di LD Macro I tried and it is sharper than the sigma but in everything else behind,
1.pentax DA 55-300
2.other pentax
3.sigma Apo 70-300
4.tamron 70-300

[Ahab]

Yes, the Pentax has an edge. The Tamron is next and really is not a bad choice. The purple fringing has been overstated and I have not heard anyone complain who has a recent model. I can cause a purple fringe with the Pentax under the right conditions.

[crewl1]

I compared the Tamron di version to the Pentax.

They are both sharp.

The Tamron suffers from purple fringe in high contrast so the Pentax wins on IQ.

I mainly use this range for outdoor sports and the Tamron has a shorter focus throw which let's it AF faster.

I have also found the macro mode of the Tamron useful on occasion.

I kept the Tamron as i felt it was the best value for me and the purple is an easy fix if it shows up. .

[pacerr]

My preference through experience is the DA 55-300, then the Tamron 75-300 over any of the 70-300's or the DA 50-200. The Promaster 70-300 is made by Tamron and duplicates the Tamron 70-300 Di results.

H2

[luftfluss]

Edit: Also, due to 1.5m Focusing distance of the 100-300, at 300mm, it's around 1:2.5 macro ratio.

Actually, the "macro" ratio is 1:3.9.

[Eulogy]

Actually, the "macro" ratio is 1:3.9.

Hrm...calculator I'd seen was reporting for 300mm at 1.5m, it'd output about 1:2.5.

[luftfluss]

Hrm...calculator I'd seen was reporting for 300mm at 1.5m, it'd output about 1:2.5.

I'm just going by what's listed in the lens database here.

Perhaps the minimum focus distance does not work at full telephoto.

[sterretje]

1:2.5 is probably meant to be .25x (which is indeed roughly 1:3.9)

[Eulogy]

I'm just going by what's listed in the lens database here.

Perhaps the minimum focus distance does not work at full telephoto.

Scratch that, just tested it. It's about 1:3.2-3.5.(Just barely outdoes my F 28-80, which is confirmed at around 1:4

Perhaps the calculator is flawed. Seemed to be accurate before though.

[sterretje]

Which calculator did you use?