[thomps]

I am going to get rid of my Sigma 70-300mm and have been looking at the Tamron 28-300mm Di LD macro and the Da 55-300mm I am leaning more towards the Tamron for the wider range but would like the lens with the best quality. Thank very much for your time

[Art Vandelay II]

I see that Tamron max aperture is only f/6.3 on the 300mm end. That alone is enough of a reason for me to go with the Pentax if I were you. I have the 70-300mm Tamron and have been very pleased with it, especially considering I only paid $130 for it, but I really do want something faster at the long end, and it's f/5.6 at 300mm.

[SpecialK]

Can't speak for the Tamron, but the Pentax 55-300 is better than the Sigma 70-300 APO and Pentax 50-200 in IQ, though it doesn't focus as close.

[audiobomber]

I am going to get rid of my Sigma 70-300mm and have been looking at the Tamron 28-300mm Di LD macro and the Da 55-300mm I am leaning more towards the Tamron for the wider range but would like the lens with the best quality. Thank very much for your time

I can't speak for the 28-300mm, but the Pentax 55-300mm has significantly nicer IQ than the 70-300mm (bokeh, CA, sharpness, colour, contrast). I rather doubt that the 28-300 would keep up, especially at the long end.

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Last edited by audiobomber; 06-23-2008 at 09:09 PM.

[madbrain]

I am going to get rid of my Sigma 70-300mm and have been looking at the Tamron 28-300mm Di LD macro and the Da 55-300mm I am leaning more towards the Tamron for the wider range but would like the lens with the best quality. Thank very much for your time

I just got the Tamron 28-300 today. It's not the DI model. It's the previous generation (A06P). But it does autofocus. I haven't had time to play with it yet. I only paid $125 used. I will compare it to the DA 50-200 that I have.

[opiedog]

I can't speak for the 28-300mm, but the Pentax 55-300mm has significantly nicer IQ than the 70-300mm (bokeh, CA, sharpness, colour, contrast). I rather doubt that the 28-300 would keep up, especially at the long end.

i have the tamron 28-300 non-di version and the da 55-300.
no question the tamron is more versatile w/ the wide 28, but in terms of IQ,
no comparison. DA55-300 wins.

tamron 28-300
pros'
closer focus
wider at the short end
cons
not so sharp at 300

pentax 55-300
pros
much better IQ
sharp even wide open at 300
cons
doesn't focus as close
noisier focusing

[thomps]

Thanks all of you for all your good info, with IQ on the top of my list it looks like it will be the da 55-300

[Miserere]

I see that Tamron max aperture is only f/6.3 on the 300mm end. That alone is enough of a reason for me to go with the Pentax if I were you.

The difference is 1/3 of a stop, so it's a non issue. What you need to compare is the IQ and distortions of both these lenses wide open at the long end. And It's not a given that the lens with f/6.3 will have worse IQ, so you can't just go with that. You should also compare IQ at f/8-11, which are the apertures you'll probably be using if you want maximum IQ.