Have I been using the F-stop wrong?

Zackphotography · Feb 13, 2015

I have been shooting a DX camera for quite a while. I was under the impression that F4 is a nice F-stop to get the subject in focus and the background blurry. In the studio I use F8 because the background isn't in focus and I want the best possible sharpness.

Now I switched to FX, but after looking up some videos the F-stop that corresponds with DX is F6 and F12 to get the same DOF!

Were the values always named for FX (so that I had to use 2.8 and 5.6 on DX)? Or are F6 and F12 the best options for FX?

confyushis · Feb 13, 2015

Zackphotography said:
Zackphotography wrote:

Were the values always named for FX (so that I had to use 2.8 and 5.6 on DX)? Or are F6 and F12 the best options for FX?

the values you're using are suggested guidelines probably for full-frame sensors like the fx format, but shouldn't be taken as concrete rules ...

f/4 is not the only aperture setting that will get an out of focus background and in-focus subject, people use f/1.4 - f/2.8 also depending on on the lens and camera body and subject/camera and subject/background distance ...

f/8 is not the only aperture setting that will get the best possible sharpness ... some lenses do better at f/11 and others at f/5.6 ... also for macro shooters, f/22 may not be sharp enough ...

really there's no one perfect portrait f/# and there's no perfect landscape f/# ... again it depends on a lot of factors like lens, sensor size, subject distance, background distance, etc ...

sorry to burst the bubble ...

TTMartin · Feb 13, 2015

Zackphotography said:
I have been shooting a DX camera for quite a while. I was under the impression that F4 is a nice F-stop to get the subject in focus and the background blurry. In the studio I use F8 because the background isn't in focus and I want the best possible sharpness.

Now I switched to FX, but after looking up some videos the F-stop that corresponds with DX is F6 and F12 to get the same DOF!

Were the values always named for FX (so that I had to use 2.8 and 5.6 on DX)?

No. Lenses are typically get sharper as you stopped down. Stop down too far and diffraction starts to impact sharpness.

For an DX camera diffraction typically starts to impact the image around f/11. Meaning on your DX camera f/8 did provide you with the most sharpness and an increased depth of field.

Zackphotography said:
Or are F6 and F12 the best options for FX?

For a FX camera diffraction doesn't start to impact image quality until around f/16. So yes you can use f/11 on your FX camera and not worry about diffraction.

As far as FX goes with wider apertures, you have more latitude. They still are just as sharp or sharper as your DX camera at f/4, but, will have a shallower depth of field. But, there is no reason you couldn't use f/5.6 if you wanted more depth of field.

--
All statements in my posts represent my interpretation of data, research opinion or viewpoints.
The opinions expressed are not representations of fact, and are subject to change without notice.
All images are used for educational purposes.

Teila Day · Feb 13, 2015

Zackphotography said:
I have been shooting a DX camera for quite a while. I was under the impression that F4 is a nice F-stop to get the subject in focus and the background blurry. In the studio I use F8 because the background isn't in focus and I want the best possible sharpness.

The background blur is more about focal length and how close you are to the subject over aperture in most situations, though having a wide aperture helps... and in some situations is the only way to smooth out a distracting background. With experience you'll figure out how to use all three (distance-to-subject, focal length and aperture) to your advantage.

Shot at f5.6 and 70mm as we wanted to rough the background up a bit. 24-70 f/2.8 lens if I recall.

http://teiladay.com/#/photography/family-individuals/IMG_0271

Shot at f7.1 and 300mm for a decent depth of field, but also a rather creamy background. This is one reason why I really fancy using longer focal lengths for portraiture, 300mm is a nice sweet spot that I think flatters faces better than shorter focal lengths much of the time. Depends on the face of course, etc...

http://teiladay.com/#/photography/family-individuals/IMG_0258a_web

Zackphotography said:
Now I switched to FX, but after looking up some videos the F-stop that corresponds with DX is F6 and F12 to get the same DOF!

Forget about what f-stop corresponds with what. You want to be able to anticipate on your own what settings, distance from the subject, and focal length to get the results that YOU want. I recommend getting away from charts, DxO info, and all that stuff that makes photography a mechanical endeavor as opposed to an artful experience. Shoot, shoot, and shoot till you drop and experiment! Use different focal lengths/lenses and find out their strengths and weaknesses.

Zackphotography said:
Were the values always named for FX (so that I had to use 2.8 and 5.6 on DX)? Or are F6 and F12 the best options for FX?

There is no such thing really as a "best" option. What you find great might not work for me and vice versa.

Best in photography to all of you!

--
Teila K. Day
http://teiladay.com

Neez · Feb 13, 2015

Sharpness depends on the lens. My canon 85mm 1.8 reaches near peak sharpness at F2.8, max sharpness is F4-F5.6. Stopping up any higher doesn't give me any more sharpness, but does widen the depth of field(less background blurr).

thebustos · Feb 13, 2015

When you focus you only achieve absolute sharpness at one distance. Everything in front of and behind of this distance is gradually becoming less sharp. The area in front of and behind the distance you've focused at which is still perceivable as being sharp is your depth of field.

Depth of field is dependent on your focal length, aperture, and the distance to your subject.

You can make your depth of field shallower by increasing focal length, increasing the size of your aperture, or decreasing your distance to subject.

You can make your depth of field larger by decreasing your focal length, decreasing the size of your aperture, or increasing your distance to subject.

You need to learn how to control your depth of field rather than sticking to the idea that there is a particular aperture you should use.

For a good visual explanation:

A Simple Guide to Depth of Field:

-
Good luck and happy shooting!

J A C S · Feb 13, 2015

Multiply the FL and the f-stop by 1.5 (Nikon) to get an equivalent shot with FF; like 24/4 vs. 36/6.

What is FX and DX? (yes, I know, but it is a Nikon thing).

TNSean · Feb 14, 2015

J A C S said:
Multiply the FL and the f-stop by 1.5 (Nikon) to get an equivalent shot with FF; like 24/4 vs. 36/6.

What is FX and DX? (yes, I know, but it is a Nikon thing).

--
Formerly known as Just Another Canon Shooter

FX full frame

DX crop sensor

J A C S · Feb 14, 2015

TNSean said:
J A C S said:

Multiply the FL and the f-stop by 1.5 (Nikon) to get an equivalent shot with FF; like 24/4 vs. 36/6.

What is FX and DX? (yes, I know, but it is a Nikon thing).

Click to expand...

Search

Have I been using the F-stop wrong?

Zackphotography

Member

confyushis

Senior Member

TTMartin

Veteran Member

Teila Day

Veteran Member

Neez

Leading Member

thebustos

Senior Member

J A C S

Forum Pro

TNSean

Member

J A C S

Forum Pro

Keyboard shortcuts