Re: time to stay with the brand: Pentax SLR Talk Forum: Digital Photography Review (2024)

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Paul_R_H wrote:

Hello James

I've been wondering this for a while, but if you don't mind I'll address the question to you as it seems to be something you're working on, whether for your own personal work or something demanded by clients…

What is the need for a 40MP photo focussed sharply on the veins of the eye?

It has struck me for a while that modern cameras are capable of showing such detail that it seems almost rude and intrusive to view them at 100%. If you met the actual model you'd have to come so close to them you'd almost be rubbing noses…

I realise wide-aperture lenses give a very nice look because the out of focus areas are _so_ out of focus. But should we worry about whether we're focussed on the eyelash or the veins?

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These days I can hardly bear to look at pixel level at the portraits in the DPR rest galleries, even the ones shot of professional models with good skin and lots of obscuring makeup. All you see is pores and imperfections, like the surface of the moon or dermatology images on wiki.

Best

Paul

Hi.

Part of the problem is that we (I) are making ourselves (myself) unhappy with corner cases and pixel peeping. I'm not sure that the answer is to hide details by pictures being out of focus to a degree (because some will be in focus and show blemishes, tiny hairs and so on)

I do quite a lot of shots like this

Which I've taken to calling "intimate". Herethe model is wearing almost no make up, has let her hair fall where it wants, her varnished nails and engagement out of focus in the foreground tell us a little about her.

It's really, really hard to get this "feel" with studio lights and lot of messing about with the camera, because a model tenses up and poses for the shot rather than relaxing into it.So I use natural light (1) and I don't want to be very painstaking about focus.

People can't keep perfectly still, so IBIS will let me handhold at a speed where subject movement is an issue. (2) This was with the DFA* 85 and I'm using 1/125th

I'm reluctant to use very high ISO. (3) But in fact for this I've used 3200.

1 + 2 + 3 rather than the desire for nicely blurred background push me to use wide apertures using 3200 I've got to f/4 - the out of focus hand is still recognisable. .

Some useful D.o.F numbers I keep in my head: for a A4/10x8" print viewed atarms length we don't notice a circle of confusion smaller than 0.03 mm on a 36x24 frame. This means to the nearest round numberthe hyperfocal distance for a standard 50mm lens at f/8 is 10M. 85*85 is ~3x 50*50 so H for 85 @ f/8 is 30M ; and at f/4 it's 60M, (at f/1.4m its a huge 170M.)
Secondly if you focus at H/n your d.o.f zone runs from H/(n+1) to H/(n-1)

With this kind of framing I'm less than 2M away from, probably 1.5m which is H/40 so my 'sharp enough' zone is 60/39 to 60/41 about 4CM and all's good.

Zoom in on the eye and the iris is a little of focus the lashes less so and the sharpest focus is the hair in front of the eye.

Now... a moment ago we were (I was) looking at the whole picture and things were fine: notice that hair that runs across her eye horizontally mid frame above?, you'd just about see that on an A2 size print if you looked closely and when I first started photography my lenses couldn't resolve detail that fine. But now we (I) can magnify enough to find very small faults.

The difference between full frame and 100% viewing is about 5x greater magnification, so we can see circle of confusion 5 times smaller, moving hyperfocal distance 5 times further awayso 1.5M is now h/200 and the sharp zone is h/201 to h/199 or about 7mm either side of perfect focus at f/4 and we can see things starting to go out of focus. At f/1.4 it's about 1.3mm.And the biggest problem with AF on something like the K1 is the focus point is probably on something more than 1.3 in front of the the Iris of the eye.

Where f/4 gave me enough margin for error, @ f/1.4 wouldn't have done. The proportion of shots that are acceptable at f/8 is pretty good, f/4 is ok. f/1.4 really isn't that good.

So the going though this set up. The questions will go something like this.

Q1 Have you got lots of light because you'll be OK if you have

No.

Q2. OK can you use a slow shutter speed

No. my subject will move before my hand is too unstable.

Q3. High ISO then?

No. Don't want to

Q4. Then avoid tight framing it makes small details bigger and reduces D.o.F

No I like tight framing.

Q5. OK, you'll just about get away with it if you don't pixel peep

Stop pixel peeping - preposterous!

Q6. Well you need to get a MILC then

But they all have horrible EVFs and I need to change lenses. And....