F 2.8 VS F3.5

[Riod]

How much of a difference is ther in the "fastness of these two lens speeds?

How many "stops" are there between the two?

Thanks.

[defordphoto]

See http://photography-on-the.net/forum/showthread.php?t=20447

[CyberDyneSystems]

1/2 stop

[slin100]

The difference between F2.8 and F3.5 is closer to 2/3 stop.

[Jeppe]

Yepp... it's 2/3 of a full stop..

[EXA1a]

The f-number is defined as f=2^i/2. From the table below you see approx. 2/3 difference between f2.8 and f3.5.
Practically there is only a theoretical difference between 1/2 or 2/3 of an f-stop.

--Jens--

i f
0,00 1,00
0,33 1,12
0,67 1,26
1,00 1,41
1,33 1,59
1,67 1,78
2,00 2,00
2,33 2,24
2,67 2,52
3,00 2,83
3,33 3,17
3,67 3,56
4,00 4,00
4,33 4,49
4,67 5,04
5,00 5,66
5,33 6,35
5,67 7,13
6,00 8,00

i f
0,00 1,00
0,50 1,19
1,00 1,41
1,50 1,68
2,00 2,00
2,50 2,38
3,00 2,83
3,50 3,36
4,00 4,00
4,50 4,76
5,00 5,66
5,50 6,73
6,00 8,00

[Riod]

I am not quite sure that I understand the table you have presented.