Which lense?


macrumors member
Original poster
Dec 25, 2006
Manchesterish, England
Hey all, just generally looking for a bit of advice, recently won a Samsung GX-10 (rebadged k10D) and got a bit of cash after selling my D40 so I'm after some new lenses.

Was originally going to get a Pentax 10-17mm fisheye for it but didn't fancy going £240+ for it on ebay :( . So I'm now torn between either a 'Sigma MACRO 50mm F2.8 EX DG' or a 'Tamron 70-300mm F/4-5.6 Di LD Macro 1:2' , I'm swaying towards the Tamron Macro at the mo because I really do like Macro pictures and would love to have a dabble in it with a decent lens instead of those cheap screw on macro adapters. But on the other hand I'd wouldn't mind having a something with some extra reach and the Sigma is quite a bit cheaper.

I mostly shoot sports and mountain biking in dimly lit forests so I'm thinking a prime lens wouldn't go a miss either but the only one I can realistically afford is the 'Pentax SMC 50mm f1.4' and I'm just wondering would the 1.4 stop be much faster than the 3.5 on the kit lens?

Thanks :):):):D:D:D


macrumors 6502a
Jan 19, 2004
Northeast, CT
The f1.4 would be a great thing to have. Much faster than the f3.5. Try shooting at 3.5 and then try at 7.1. This would in a way show you how much difference there would be between the 3.5 and 1.4. Think of f7.1 as the 3.5 and the setting of 3.5 as the 1.4. The 1.4 will let in 1 stop more light, and that helps especially if you are shooting in the woods.

If that difference wasn't that much, pro sports shooters would be shooting with a 70-300 4-5.6 instead of a 70-200 f2.8 or 300 f2.8. Well maybe not as the glass on the higher end lenses are better as well.


macrumors regular
Jan 11, 2006
Ontario, Canada
The difference in focal ranges here is quite large. The 70-300 would probably be more useful in terms of composition. Allowing you to vary it greatly without having to move around as much, but the 50's wider aperture is going to more useful in darker environments. Obviously, neither will give you the same look as the fisheye... Also, the wider the aperture the faster the lens will focus and that will be useful in fast moving sports and that's going to be important since the Pentax focussing mechanism is less than ideal for sports applications; not unusable, just not fast. I think I would go for the Tamron out of the two if I was in you situation.

I might also recommend a Pentax/Samsung-user forum, as they will know more about specific combos. I don't know if we're allowed to advertise other sites her so just give me a PM and I'll forward you a link