[Anvh]

..Huh?

Probably has to do with the EV scale you see in the viewfinder/ top LCD, it's the same with all the camera's 1/3th simply takes 3 steps between each stop and 1/2th takes 2 steps so you need more room to show the 1/3th step.

[maxfield_photo]

I use half stops because most of my film lenses use half stops. It's much easier to remember the numbers because there are fewer, and they are easier to calculate. (i.e. 1/500th to 1/1000th is a whole stop, what's a half stop? Take half of 500, or 250, and add it to 500 to get 1/750th)

There is another reason I use half stops, my light meter reads in 1/10th stops. 5/10th of a stop is exactly one half, but 3/10th of a stop is not exactly one third. That's probably splitting hairs, but since exposure affects the saturation of colors, and since I work hard to maintain perfect color fidelity (at least prior to artistic effects), it matters to me.

[CMG]

I use half stops because most of my film lenses use half stops. It's much easier to remember the numbers because there are fewer, and they are easier to calculate. (i.e. 1/500th to 1/1000th is a whole stop, what's a half stop? Take half of 500, or 250, and add it to 500 to get 1/750th)

There is another reason I use half stops, my light meter reads in 1/10th stops. 5/10th of a stop is exactly one half, but 3/10th of a stop is not exactly one third. That's probably splitting hairs, but since exposure affects the saturation of colors, and since I work hard to maintain perfect color fidelity (at least prior to artistic effects), it matters to me.

So then 1/2 stops are 100% accurate but 1/3 stops are a bit of an approximation.....like 50% vs 33.33333%?

[Allison]

I use 1/3. I just like being able to fine tune a little more in-camera. When shooting over 1000 pics at a wedding, I want to minimize PP as much as possible.

[builttospill]

Can you explain a bit more for me how 1/2 gives you greater range? I see how it is faster because there are less steps to a full stop, but I'm not sure about the greater range part. Thanks!

There are a few explanations. With 1/3 steps there is a greater range of flexibility, there's a broader range of steps, a greater range of precision. With your camera set to 1/3 you can dial in ISO 160, a shutter speed of 1/160 and an aperture of f/6.3, for example. You can't do that with 1/2 steps, so there's a greater range of settings.

I shoot JPEG as well so I appreciate your perspective on this issue. I try to get my exposures correct and do minimal PP. I guess the related question is how much finer is the fine tuning when you go from 1/2 stops to 1/3 stops. Is it "real" or is it a "bell and whistle" feature to market the camera? Or was it developed really for use in auto-modes? I mean, as I understand it, in the old film days it was all 1/2 stops.

I also shoot jpg only. But the example given in my earlier post of the setting sun may relate more to my K10D than your K-5 due to it's ability to shoot at higher ISOs. A K10D's ISO 100 is pretty much unbeatable and I rarely shoot at other ISOs. However, when I need to I'd much rather shoot at ISO 125 or 160 than 200 on the K10D, or at 320 (1/3) as opposed to 400 (1/2). It does make a noticeable difference in this case.

[maxfield_photo]

So then 1/2 stops are 100% accurate but 1/3 stops are a bit of an approximation.....like 50% vs 33.33333%?

Well like I said, it's probably splitting hairs, but yes except it's 0.300 vs 0.333. When I'm shooting on location I have to decide how I want to round off f/8 & 3/10ths, and actually I'd have to do less truncating if I were to use thirds of a stop. But somewhere between f/8 and f/11 one tenth of a stop gets lost, and that bugs me.

In the studio, I don't round at all. My monolights are adjustable in tenths of a stop. Or if I'm using a pack & head system, I'll change the position of the light until I have straight-up-and-down f/8. No guesswork in post for me.

[edit: Because once you get into guessing in post production, you have to ask "Is my monitor calibrated? Has it warmed up for 30 minutes prior to editing? Is my colorimiter working? Is that late afternoon light coming through the window affecting my perception? Do I trust my subjective memory of the scene?" I prefer to never guess.]

[audiobomber]

1/2 stops, because that's how manual lenses work and because using 1/2 stops allows 1/180s shutter speed with flash. There's less clicking and I see no practical advantage to 1/3 stops.

[TomTextura]

This is an interesting point....can you explain a bit more? It's funny, but until I read your post, I had not realized the fact that in 1/3 steps you can't hit a 1/2 stop. I suppose, I'm wondering about the significance of that and how it impacts exposure vs 1/3 steps. I understand that a full stop is a full stop, it's a question of whether you get there in 2 steps or 3...but is there more to the story?

The only thing more to the story, in my case anyway, is that the math is much simpler. Other than what maxfield_photo has elaborated upon about the not entirely accurate 1/3 stops, I don't know of there being anything more to it. I actually hadn't thought about maxfield_photo's points before. I suspect there may be some tricks, calculation wise with the meter/exposure, that the camera applies to get it pretty darn accurate but I don't know. I'm not sure if my point about the aperture being difficult to accurately hit 1/4 stop, or 1/3 for that matter, is valid or not; I was just guessing that there could be a mechanical factor involved that would come in to play.

..Huh?

That's what I was wondering too until Anvh pointed out the following:

Probably has to do with the EV scale you see in the viewfinder/ top LCD, it's the same with all the camera's 1/3th simply takes 3 steps between each stop and 1/2th takes 2 steps so you need more room to show the 1/3th step.