Tokina 11-16mm.....Sigma 10-20mm f/stop question.

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Blacktop

Senior Member
I'm about to pull the trigger on the 11-16 f/2.8. It was my favorite lens before I had to sell it a few months back.

I was just looking at the Sigma 10-20mm f/4-5.6 lens as well. I don't know if that extra 1mm on the wide side would make much of a difference. It would be nice to go to 20mm once in a while ,but when I had the 11-16 I don't remember wishing for it that much.
Having said all that , How many stops would I lose on the wide side going from f/2.8 to f/4? I know how to figure stops for ISO and shutter speed, but f/stops confuse the hell out of me.
 
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Moab Man

Senior Member
Since you're shooting DX I would tell you stick with the Tokina for the f/2.8 for the extra light. I can't speak to quality of the Sigma, but we both know the quality of the Tokina is outstanding.
 
hark

hark

Administrator
Staff member
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I haven't used either one, but I'd bet the Tokina is a better lens.

The Tokina has a constant aperture of f/2.8. That means you can use f/2.8 while the lens is set at 11mm, and you can use it at any point all the way up to 16mm.

The Sigma is a variable aperture lens. You will be able to use the f/4 at 10mm, but when you start to zoom out, the widest aperture number will change. At 20mm the widest you should be able to go will be f/5.6. You shouldn't be able to zoom out to 20mm and use f/4. That's what happens with variable aperture lenses, and it's one of the reasons why they tend to be less expensive than a constant aperture lens.

Will the extra 1mm make a big difference? I don't think it will impact the view too much. Will you miss the 20mm view? Perhaps a little. But it is a trade-off you need to consider before making your decision. If you go with the Tokina, you can always zoom with your feet...well, in most cases. ;)
 
hark

hark

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Oh...and the Tokina is one whole stop wider at the 11mm end and 2 whole stops wider at the 20mm end over the Sigma.
 
B

Blacktop

Senior Member
hark said:
I haven't used either one, but I'd bet the Tokina is a better lens.

The Tokina has a constant aperture of f/2.8. That means you can use f/2.8 while the lens is set at 11mm, and you can use it at any point all the way up to 16mm.

The Sigma is a variable aperture lens. You will be able to use the f/4 at 10mm, but when you start to zoom out, the widest aperture number will change. At 20mm the widest you should be able to go will be f/5.6. You shouldn't be able to zoom out to 20mm and use f/4. That's what happens with variable aperture lenses, and it's one of the reasons why they tend to be less expensive than a constant aperture lens.

Will the extra 1mm make a big difference? I don't think it will impact the view too much. Will you miss the 20mm view? Perhaps a little. But it is a trade-off you need to consider before making your decision. If you go with the Tokina, you can always zoom with your feet...well, in most cases. ;)
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Yes,yes yes. Thank you. Can you answer my original question please!
 
B

Blacktop

Senior Member
hark said:
Oh...and the Tokina is one whole stop wider at the 11mm end and 2 whole stops wider at the 20mm end over the Sigma.
Click to expand...

Thanks. I was going with the Tokina 99.9% anyway. I was also looking at the Sigma 8-16mm but that's way over my budget. I'm gonna order the the used from Adorama in E+ condition for 316.00. There is one in E condition for 299.00 but I feel better with the E+
 
D

Don Kuykendall_RIP

RIP :(
F-stops1.jpg
 
hark

hark

Administrator
Staff member
Super Mod
For the most part, you will find the whole f/stops are:

1.4
2
2.8
4
5.6
8
11
16
22
32

There might be a few lower and higher, but these are the ones you will regularly see. The other f/stop numbers are either 1/3 stop or 1/2 stops.
 
B

Blacktop

Senior Member
Crazy way of doing things. Why not just have F/1 F/2 F/3 and so on. Then if you need a half stop or a 1/3rd stop then just have f/1 f/1.5 and so on.
 
B

Blacktop

Senior Member
Blacktop said:
Thanks. I was going with the Tokina 99.9% anyway. I was also looking at the Sigma 8-16mm but that's way over my budget. I'm gonna order the the used from Adorama in E+ condition for 316.00. There is one in E condition for 299.00 but I feel better with the E+
Click to expand...

Oh Great!! They are both gone. The only one left is in D condition for 369.00 Gonna grab it while it's still there.
 
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RocketCowboy

Senior Member
hark said:
Oh...and the Tokina is one whole stop wider at the 11mm end and 2 whole stops wider at the 20mm end over the Sigma.
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That has probably been my problem with the 10-24mm. I can't zoom out to 10mm due to vingetting with the filter (CPL), so I usually stay at 12mm or greater. At that point, I suspect I can't get the widest aperture, and so I'm noticing the extra stop(s) difference.
 
hark

hark

Administrator
Staff member
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RocketCowboy said:
That has probably been my problem with the 10-24mm. I can't zoom out to 10mm due to vingetting with the filter (CPL), so I usually stay at 12mm or greater. At that point, I suspect I can't get the widest aperture, and so I'm noticing the extra stop(s) difference.
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Do you use a CLP that is designed for wide angle lenses? They tend to be thinner (not as tall) then post processing can help to correct any vignetting. Sometimes they are referred to as slim profile.
 
E

Eyelight

Senior Member
Blacktop said:
Crazy way of doing things. Why not just have F/1 F/2 F/3 and so on. Then if you need a half stop or a 1/3rd stop then just have f/1 f/1.5 and so on.
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Not sure you really wanted to know the answer, and I mainly typed this out to get in straight in my head. But then figured why not share.

It is because we are doubling or halving the light and the number really means something related to doubling and halving.

At f/2 the aperture diameter is 1/2 the focal length of the lens. At f/4 it is 1/4 the focal length. The aperture at f/2 is twice the diameter as at f/4.

BUT, the area of the aperture at f/2 is FOUR TIMES the area at f/4. Four times the area allows four times the light, making 2 stops between f/2 and f/4.

The full stop in between is f/2.8, because an aperture diameter of 1/2.8 the focal length creates half the area for light to pass as the aperture diameter of 1/2 the focal length and twice the area than that of 1/4 the focal length.

So, f/2.8 is short hand for: Aperture diameter that is 1/2.8 the focal length of the lens.
 
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RocketCowboy

Senior Member
hark said:
Do you use a CLP that is designed for wide angle lenses? They tend to be thinner (not as tall) then post processing can help to correct any vignetting. Sometimes they are referred to as slim profile.
Click to expand...

My problem comes from filter stacking. I should be removing the UV filter when adding the CPL, instead of stacking the two together.
 
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