How many extra f/stops with a 1.8 lens?

[OGDaniel]

Ok, so I have my Nikon D3000 and my kit lens, and I love it. I know my next step is getting new glass, and I think the next lens I'll be getting is the 35mm f/1.8. All my shots indoors generally come out too noisy because I have to keep bumping the ISO up to get a decent exposure.

The kit lens is f/3.5-5.6, and what I want to know is how many extra stops will I get with a 1.8 lens? And the same with a 2.8 lens?

Thanks in advance

 

[white]

It's about 2.75 extra stops with the 1.8. Or .75 extra with the 2.8

 

[Jcampbelll]

3 and 1/3 from 1.8 to 5.6

 

[reznap]

f/2.8 is two-thirds of a stop faster than f/3.5. f/1.8 is another one and one thirds stop more than f/2.8. So... f/1.8 is two stops faster than f/3.5.

 

[KmH]

f/1.8 x √2 (1 stop)= f/2.5

f/2.5 x √2 = f/3.5

So, I concur with Reznap, it is 2 stops more than f/3.5, and I also concur with Jcampbelll f/1.8 is 3.33 stops more than f/5.6.

The √2 = 1.4142135623 - for aperture just use 1.414 and round.

A stop of aperture is equal to the √2, because the aperture is an area, not a diameter. :thumbup:

The closer to midnight it gets, the more typos that need to get fixed before posting. Demon DOM B&B (Bénédictine and Brandy, 86 proof)!

 

[OGDaniel]

So with the f/1.8 lens that I'll be getting soon I could take my ISO down from 1600 to 400 at least with the lens being that much faster?

It's not like the noise looks like classic film grain or anything either, just irritating intrusive digital noise.

 

[table1349]

Full f stops = f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22

How to figure f stops = A Tedious Explanation of the f/stop

f stops in thirds = 1.0 1.1 1.2 1.4 1.6 1.8 2 2.2 2.5 2.8 3.2 3.5 4 4.5 5.0 5.6 6.3 7.1 8 9 10 11 13 14 16 18 20 22

 

[KmH]

So with the f/1.8 lens that I'll be getting soon I could take my ISO down from 1600 to 400 at least with the lens being that much faster?

It's not like the noise looks like classic film grain or anything either, just irritating intrusive digital noise.

Yes, but the lens doesn't perform at it's best when the aperture is used wide open. Few fast lenses do.

That's because a lens is not as thick at its edges as it is in the middle, and light from the edges focuses just enough away from where light from the middle part of the lens focuses that focus is soft overall.

The 50 mm f/1.8 is sharpest when it is stopped down a couple of stops.