As I learned on a full manual camera I feel comfortable with the easy maths of full stops, how they correspond to shutter speed stops, and how much brighter or darker my exposure will be a stop over or under.
With digital I'm chimping far more. If my histogram has room for a fraction more brightness, i'll nudge the aperture wider ending up on a intermediate stop.
looks like the monkey will have to change his name..'trenchnoob or noobmonkey'
some lenses work well wide open 300 2.8 is a case in point and I think if could afford to buy one I would want to use it wide as often as possible
as for the op's question I think its just a habbit we get into as its far easier to think in full stops when thinking about F's & shutter speeds & iso's
It's easier to envision the relationship between shutter speed, aperture, ISO, etc. with full stops and convey it to exposure. For example, if you jump from one f-stop to the next full f-stop, you've halved the light coming in. Dealing with the f-stops in between requires a bit more mental juggling, unless you want to rely on the camera for automatic metering. Same with ISO settings - I prefer the full ISO increments (i.e. 200, 400, 800, 1600, etc.) rather than the in-between steps.
For me, it's an old habit carried over from film days.
Now, I see that you're looking for a complicated answer. In the era of digital, the aperture settings allow more precision so sometimes I will dial in a bit more or less depending on:
a. direction I'm facing (I'll add .5 for North, .3 for South, .8 for East and .9 for West)
b. if the groom is ugly...I'll go down 3 stops
c. if the bride is beautiful, I'll go up 4 stops
d. if it's high tide, I'll increase the shutter speed by 2 stops and keep aperture constant
e. if the day of the week ends in "y", I'll dial up the aperture by 1/3
f. if the day of the week does not end in "y", I'll dial down the aperture by 1/3
Complicated enough? I try to follow those rules, but if I'm taking pictures of my significant other....I'll just move it to Program mode...I can blame the camera when she tries to point out an unflattering picture I took of her. (That is the most important rule in photography)
bluetsunami wrote:
hahahhaha, shooting wide open means your a noob? Oh geez
I know, I was up all night and teetering on throwing the 200 f2/300 f2.8 in the ocean.
Fortunately, I'm landlocked. Careful, you'll be accused of being lame for using condescending terminology.
What I don't get is why do people skip certain f-stops like f/9 and f/10 straight to f/11 then again skip f/13 and f/14 straight to f/16 and so on.
I'm an old geezer who learned on mechanical cameras that had the aperture ring up front and fully observable all the time, so I have the full stops in my head. Most lenses did allow you to set half stops, so I have those memorized as well.
To prevent confusion, I set the custom settings of my camera to give me just full and half stop indications. Did the same on my hand-held meters.
Although my camera provides 1/3 steps for the controls, I don't see the fine controls all that necessary ( it's me again ). Can I see the DOF diff between the 1/3 f-stops ? Can I see the extra blur caused by 1/3 stop slower shutter speed ? Oh by the way don't use any ISO except 100-200-400-800. Unlike you expect, ISO 125 and 160 are nosier than 200, 320 is nosier than 400 etc ).
And for almost every image I keep, I end up fine-adjusting the EV with the RAW converter anyway. I just make sure that I have the reasonably OK histogram, especially the top end.
Pondria wrote:
Oh by the way don't use any ISO except 100-200-400-800. Unlike you expect, ISO 125 and 160 are nosier than 200, 320 is nosier than 400 etc ).
I trust you my friend , but how did you arrive at this conclusion?
If you read the optical specifications for lenses, you will find that most lenses perform best (in terms of resolution, and conrast) at f/8, regardless of focal length or manufacturer, and that they tend to drop off both above and below that point. Faster f/stops are most useful in situations where low light and the need to stop action are the paramount considerations.
jmcfadden wrote:
I trust you my friend , but how did you arrive at this conclusion?
J
Oh, I posted this before. My data is from 1Ds2 but 5D users also conformed the same behavior. Here is what we did. Put the lens cap on it. And take the shots @ 1/120, f/8 ( really doesn't matter as long as the shutter speed is not very long ). You will get basically blank photo. Read the standard deviation of the black frame with Photoshop Histogram Pannel. Do this at each ISO step. Below is the data. http://www.sesee.com/Photo/Exports/ISO.gif
First of all, the data support my claim that you gently challenged
Now, here is the theory part.
You see the 4 straight lines or groups, 50-160, 200-320, 400-640, 800-3200. My theory is that the ISO is implemented with the combination of the Analog gain and the Digital gain. I speculate that there are 4 analog hardware gains. And ISO 100, 200, 400, 800 seem to be the natural ISO's set by the analog gain control. Within a group, the "Derived" ISO's are simply the SW multiplication of the data. For instance, for ISO 50-160, every one is taken at ISO-100, but the SW multiplies 0.5, 1.0, 1.25, 1.6 to "simulate" the ISO 50, 125 and 160.
bluetsunami wrote:
hahahhaha, shooting wide open means your a noob? Oh geez
That's not what he said. He said that if you're running round shooting wide open when there's no need to then you're a noob (paraphrased).
He's right. When I got my first SLR and a 50mm 1.8 I shot everything at 1.8 amazing myself with the shallow DOF before slowly realising that 1/ I didn't need to and 2/ It works better if I don't.
"Most people buy a fast lens to have the aperture when they *need* it."
and I stand by that. I have not met any long term photographer who has told me, "I bought this X f1.2 lens 25 years ago and in all those years *only* shoot it wide open." I'm sure there have been one or two that have relied on this (often tacky) effect for what they think is a personal signature look (just like Holga photographers, T/S toy effect shooters etc.)...
I'm not saying that fast lenses aren't good, needed or that razor thin DOF is never used well...
If you are one of the people insulted by my comment... well, sorry.
bluetsunami wrote:
hahahhaha, shooting wide open means your a noob? Oh geez
oh... and I started studying art/photography in 1977 at the Detroit College of Art and Design (whatever they call it now, was CCS), then went to the School of the Art Institute, Chicago. Doesn't mean that I am a better photographer than anyone else, but it does mean that I am no noob.
Careful, you'll be accused of being lame for using condescending terminology. 
