Can we talk F stops

[8ball]

Is there a rule of thumb or any guidelines as to f stop settings?

How do you determin which Fstop you should be using?
Is it all determind by how you feel it should be?
I know on portraits you want lower Fstops but what about other things?

Should I Just do it how I feel it should be and do a trial and error type thing?

I'm sure this post does not make sence because I think I just confused my self haha!

 

[mwcfarms]

Is there a rule of thumb or any guidelines as to f stop settings?

How do you determin which Fstop you should be using?
Is it all determind by how you feel it should be?
I know on portraits you want lower Fstops but what about other things?

Should I Just do it how I feel it should be and do a trial and error type thing?

I'm sure this post does not make sence because I think I just confused my self haha!

I think it depends, if you want a shallow depth of field you want a low fstop which isn't always recommended for portraits. Portraits should be clear from the tip of nose to behind the ear. So sometimes you have to increase it to achieve that. When you want the background blurred and a very narrow DoF you lower your Fstop Ie macro of flowers. This is what I have learned.

Larger depth of field you want a high f-stop ie landscapes and scenes where you want all the details.

 

[Big Mike]

Yes, the primary reason to choose your aperture/F-stop, is to control the DOF. If you want a shallower DOF, then use a larger aperture (lower F number) and if you want more DOF, then you use a smaller aperture (higher F number). It doesn't really have anything to do with portraits or what you're shooting, because you can shoot just about anything with either a shallow or deep DOF.

Aperture is also one of the three variables to exposure. So while you can choose your aperture based on the DOF you want, it may cause you to sacrifice on the other variables. For example, maybe you want a deep DOF, but with the lighting you have, you can't shoot with both a small aperture and a fast shutter speed...so you must choose. Or you could adjust the ISO and sacrifice image quality (add noise).

Also, lenses have different optical performance at different apertures. It's usually the worst at the minimum and maximum values. Most lenses are 'best' around F8. So if you can, you may want to choose an aperture that will give you optimum image quality.

 

[clanthar]

DOF decrease <--------------- -----------------> DOF increase

1.4 -- 2.0 -- 2.8 -- 4.0 -- 5.6 -- 8 -- 11 -- 16 -- 22 -- 32 -- 45

aberration limited <----- best quality --------> diffraction limited


NOTE: that DOF is a function of f/stop and magnification with magnification being the dominant factor. Magnification as a DOF control is complex and includes variation due to sensor size (smaller sensor = more DOF all else equal) and reproduction size and method.

For example little pocket cameras with sub-postage stamp sized sensors can't do limited DOF in a portrait because the magnification factor is too small. On the other hand they're great for landscapes with everything in focus.

Lenses exhibit variations in performance over their aperture range. It's a rare lens ($$$$) that won't show some sharpness and contrast loss shot wide open. At the smallest f/stops diffraction caused by the iris will again degrade the image quality. For most photographers the benefits obtained in DOF control from shooting at larger or smaller f/stops typically outweigh the performance losses.

Joe

 

[8ball]

Guys I thank you very much!

 

[sobolik]

Very simple you refer to a chart of facts: Online Depth of Field Calculator

OR

IF YOU ARE LIKE ME YOU STUDY THE CHART A GREAT DEAL AND THEN CHUCK IT. THEN YOU SIMPLY GO MAX OR MIN F STOP FOR MAX DEPTH OF FIELD OR MINIMUM DEPTH OF FIELD. THERE IS NO IN BETWEEN IN MY WORLD. (all caps are a clue which way you should go) For normal shooting I do use the middle F stops. But not when my main concern is DOF.

I don't worry about the idiosyncrasies in the middle. No one will notice. But they do notice the max and min effect oftentimes.

 

[Josh66]

Very simple you refer to a chart of facts: Online Depth of Field Calculator

OR

IF YOU ARE LIKE ME YOU STUDY THE CHART A GREAT DEAL AND THEN CHUCK IT. THEN YOU SIMPLY GO MAX OR MIN F STOP FOR MAX DEPTH OF FIELD OR MINIMUM DEPTH OF FIELD. THERE IS NO IN BETWEEN IN MY WORLD. (all caps are a clue which way you should go) For normal shooting I do use the middle F stops. But not when my main concern is DOF.

I don't worry about the idiosyncrasies in the middle. No one will notice. But they do notice the max and min effect oftentimes.

Oh, I'm sure they do notice...

There's a reason the middle is where it is...


I think I would give up on photography if all I used was f/1.4 & f/32...
I like the middle, it's comfy...

BTW - do all caps mean big aperture, or big f/#?

 

[MohaimenK]

Also remember f stop will not give you the same result with different lenses. The closer you are to the subject, whether its by going up close on someone's face or by zooming in, the shallower DOF you will achieve with the larger aperture. This also depends on the background, how far it is from where your subject is.

So standing 20 ft away from your subject at 70mm your DOF at f 2.8 would be shallow where's with a 16-35 lens standing 20 ft away with f2.8 will not blur much. (20 ft is an example, not a rule of thumb)

 

[sobolik]

Very simple you refer to a chart of facts: Online Depth of Field Calculator

OR

IF YOU ARE LIKE ME YOU STUDY THE CHART A GREAT DEAL AND THEN CHUCK IT. THEN YOU SIMPLY GO MAX OR MIN F STOP FOR MAX DEPTH OF FIELD OR MINIMUM DEPTH OF FIELD. THERE IS NO IN BETWEEN IN MY WORLD. (all caps are a clue which way you should go) For normal shooting I do use the middle F stops. But not when my main concern is DOF.

I don't worry about the idiosyncrasies in the middle. No one will notice. But they do notice the max and min effect oftentimes.

Oh, I'm sure they do notice...

There's a reason the middle is where it is...


I think I would give up on photography if all I used was f/1.4 & f/32...
I like the middle, it's comfy...

BTW - do all caps mean big aperture, or big f/#?

Dude, yes, take up bowling or something. "I think I would give up on photography.."
I could take a shot with each F stop and mix them up in the pile. You would not be able to sort them correctly. Take up bowling. But then again it's a digital age and so can you take the same photos and then get back to us about the "they do notice" giggle you provided us.

 

[Bitter Jeweler]

Ah, more, "throw information away" cuz it doesn't matter.
How very helpful.

 

[memento]

sobolik, go max or min? i usually don't flat out say someone is wrong
(because i'm usually proven to be the one wrong) BUT you are wrong.

there are BIG differences between 1.4,2.8,4.0,8,13,20...
not only in DOF but also shutter speed.
i've noticed colors will change with apurature as well.
smaller f stops seem to give brighter colors.

 

[kundalini]

I don't worry about the idiosyncrasies in the middle. No one will notice. But they do notice the max and min effect oftentimes.

As the shooter, I will notice. That's what matters. I may not get the exposure I want at f/5.6, but f/7.1 is perfect for the image I'm taking.

 

[sobolik]

OK all you geniuses with time on your hands (I don't) Here is an assignment for you.

Go outside and take one photo per f stop of the same exact scene.

Randomly assign them an index number that only you know the code.

Remove all exif data via multiple save as and program processing etc. as needed

Post all the photos with the assignment to put them in F stop order per "your ability to tell the difference"

It will be interesting to see just how many are correctly ordered "by telling the difference" even so the casual viewer can't tell unless extreme.

 

[Vinny]

I see that clanthar gave a graphical image and according to those who know and those who test lenses f8 and f11 seem to be the best f stops for most (?) lenses.

 

[Josh66]

I see that clanthar gave a graphical image and according to those who know and those who test lenses f8 and f11 seem to be the best f stops for most (?) lenses.

Yes, usually.

But according to some people, you can't tell the difference between f/4 and f/32 anyway, so it doesn't matter what you use.