Sigma 10-20 - f/3.5 or f/4.0?

bike21

So I am likely about to pull the trigger on the Sigma 10-20mm lens (Nikon mount) but can't decided between the f/3.5 and f/4.0 version.

The f/3.5 is only one stop 'better' and who knows if I will utilize that difference often enough. My primary uses will be some real estate photography, creative use during weddings, and likely have a go at landscapes which likely negate the stop difference anyway.

Anyone shot one or even better both? The savings is pretty significant, nearly $200 which is the amount of my B&H gift card that is burning a hole in my pocket.

canonboy

bike21 wrote: »

So I am likely about to pull the trigger on the Sigma 10-20mm lens (Nikon mount) but can't decided between the f/3.5 and f/4.0 version.

The f/3.5 is only one stop 'better' and who knows if I will utilize that difference often enough.

...

I don't have any opinions on this lens, but I just wanted to make a quick clarification.

f/3.5 is actually NOT 1 stop better than f/4. It's actually only 0.4 stops better.

Remember that each full stop is: f/1.4 - f/2 - f/2.8 - f/4 - f/5.6 - etc. ( each stop is a multiple of √2 ) So f/3.5 actually falls in between f/2.8 and f/4. If you do the math, f/3.5 is 0.4 stops "better" than f/4, and thus is also 0.6 stops "worse" than f/2.8.

I'm not sure whether a 0.4-stop difference is worth the extra $200. There must be something else to the f/3.5 lens that makes it worth more.

Qarik

there is the sigma 10-20mm f/3.5 constant aperture and the older 4-5.6 variable aperture lens. It has one more blad in the aperture (possibel better bokeh), a couple more lens elements for aberation and fringing I think. It's modest a redesign.

To me the constant aperture is worth it. I am of the philosphy to alway get the best glass you can afford.

ziggy53

For most super-wide applications the variable aperture doesn't matter for my purposes because I generally use a small aperture. If you need the larger aperture, especially at the long end of the range, by all means go for the larger constant-aperture version.

Nice review here. Be sure to read the final verdict:

http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/467-sigma_1020_35_nikon

bike21

Thanks for the replies so far! And to canonboy for the clarification.

I guess I need to decide if the speed is worth the extra 200 bones or not. Hmmm....

dantambok

i dont think that extra .4 stops will make much of a difference.. If your wallet is tight.. i still suggest buying the cheaper one:D

canonboy

bike21 wrote: »

Thanks for the replies so far! And to canonboy for the clarification.

I guess I need to decide if the speed is worth the extra 200 bones or not. Hmmm....

What I didn't realize (and what Qarik mentioned earlier) was that the 2 Sigma lenses have radically different apertures. One lens is the 10-20mm f/3.5 lens, which is a *constant* maximum aperture of f/3.5 throughout the focal lengths (ie. the maximum aperture is f/3.5 whether you're at 10mm or 20mm or anywhere in between).

The other lens is the 10-20mm f/4-5.6 lens (you left out the 5.6 part), which is a *variable aperture* lens. This means that the maximum aperture at 10mm is f/4, and the maximum aperture at 20mm is f/5.6.

At 10mm, the difference between f/3.5 and f/4 is a mere 0.4 stops, which I mentioned earlier. However, at 20mm, the difference between f/3.5 and f/5.6 is 1.4 stops. The difference of 1.4 stops means that the f/3.5 lens can let in about 2.6x more light than the f/5.6 lens (here the math: 2^1.4 = 2.6).

Based on all this, the $200 price difference is justified because (1) it's a constant-aperture zoom lens, and (2) it has a larger aperture throughout the focal lengths of this lens.

time2smile

Just wanted to add F5.6 in a wedding hall or church, you will spend more on the extra speedlights you will need, go with the F3.5, or look at the F2.8 that are out there...

Sorry Ziggy, I read after I posted, I just picked up a Tokina 12-24 F4 non HSM, and love it. No disrespect to Art, but I don't know why anyone would buy either of these Sigma's.

bike21

Alrighty then, went for the constant f/3.5! Made a large order to B&H along with the Sigma 70-200 2.8

Time to book some more gigs to pay all these new toys off :ivar

Thanks again for the input, dgrin never lets down.