Potential dead horse: how bad is FF's deep DoF disadvantage?

Started 9 months ago | Discussions thread
Great Bustard
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On "exaggeration"
In reply to Ontario Gone, 9 months ago

Ontario Gone wrote:

sportyaccordy wrote:

Ontario Gone wrote:

I think i speak for many when i say, F1.X on MFT/apsc gives me as thin of DOF as i will ever want, to go thinner just because a camera offers it is a waste of money.

The whole "razor thin DoF" thing is a bit of an exaggeration. For wide angle photography, even getting down to 1.4-1.8 gives you a couple of feet to play with at relatively close distances. There are various forms of general photography that do just fine w/a few feet of DoF.

Actually it's not exaggerated.

It's actually a lack of understanding of how things work. Both wider apertures and tighter framing serve to reduce DOF. The fact of the matter is that *all* systems project the same total amount of light on the sensor for the same DOF and shutter speed.

So, the "razor thin DOF" thing is a *choice* to use a wider aperture in lower light to get less noise at the expense of a more shallow DOF.

This shot was obviously taken when she was asleep, and the DOF was just wide enough @F1.7 to get all her eyelashes in focus, which is what i wanted. If i were to give up two stops of DOF and shoot at just under F1 (or go FF @F1.7), this wouldn't have been easy, and stopping down would only lose SS, which i didn't want. Add to that if she was awake and moving around, or if i were standing up without a way to brace myself, this would have been a nightmare.

Sure FF can stop down aperture two stops and just use ISO 2 stops higher for the same IQ numbers, but that's the point. If i don't want DOF thinner than this, why pay more, carry more, and get less reach? The shots where DOF isn't an issue are also the shots where SS is not an issue, like landscapes. I don't shoot in any situations where i would need an extra two stops of ISO more than those two stops of DOF. For something like smart phones, sure, there is plenty of room to shrink the DOF. For MFT/apsc, there are lenses available that make moving to FF a moot point.

The only argument that holds traction in favor of FF is the base ISO argument (for landscapes ect), but my GX7 has more than exceptable noise performance at ISO 125 so there is no appeal for FF. Again 1/2" sensor at base ISO may be lacking, but anything MFT/apsc size is nice.

For the record the above shot was actually F1.7, 1/320 SS, ISO 125, used flash. I did however take several others before this one without flash using silent mode so as not to wake her while i chimp composition. This was the last shot, taken with bounce flash, but it still illustrates the DOF issues.

They aren't "DOF issues", they are choices you make as you balance DOF, motion blur, and noise. Note that I choose to stop down to f/2.8 to get a deeper DOF at the expense of more noise here:

Canon 6D + 50 / 1.2L @ f/2.8, 1/60, ISO 2500

Whereas I shot the following scene wide open:

Canon 5D + 50 / 1.2L @ f / 1.2, 1/50, ISO 1600

Despite it being a tightly framed shot.  Would it have looked better at f/2.8 ISO 6400?  Dunno.  Maybe I should have tried for f/2.8 1/13 ISO 1600 and risked motion blur and/or camera shake?

In any case, what I'm saying is the DOF / sharpness, motion blur / camera shake, and noise all go hand in hand.  Since the same total amount of light falls on the sensor for a given DOF and shutter speed for all systems, then anyone complaining of "razor thin DOF" has simply traded deeper DOF for a faster shutter speed and/or less noise.

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