DOF... where's it going?!

[HoppyUK]

LOL at you guys, seriously This is an internet forum where anything more than a one line answer is a bonus. I'm not writing a thesis on the concept and application of DoF in today's multimedia. Some things are a given, or at least assumed to be, and the fundamentals of DoF calculation have been set in formulae for decades. It's true that they're not often spelled out, but as it happens, I have actually done that in this thread too (post #51). Then read all my posts, right from #22, and see who's making the mess here.

Del, maybe you need an eye test rather than a camera check. As I originally stated, the sharpest point in the OP image is most clearly visible around the guy's necklace and shirt collar, his sideburn and ear. That is about 80-100cm behind his eye, and a long way behind the guy on the left. It's seriously back-focused, as others have also stated. If you still think the eyes are on the sharpest plane of focus, then you have no need to worry about a little thing like DoF.

Edit: just to add to this, nothing is really as sharp as it should be because of the long 1/3sec exposure time. This has brought the ambient light level up high and allowed the significant and obvious movement blur to overlay and soften the sharp(er) flash image.

 

[Davince]

The next object behind the happy couple is too far away to be in focus

high ISO = high noise = lower resolution
you are not accurately focused on the eyes
you have a little movement blur

What you need is some off camera flash, triggered by a little on camera flash. The focus assist on the on camera flash will nail the focus. The off camera flash will both light the subject well, and get your apeture/shutterspeed/iso back to a more acceptable level

Off camera flash can be as simple as bouncing a single flashgun off the ceiling / wall

It's got an SB900 on the camera bounced off the ceiling / rear wall with a modified diffuser to give a bit of forward spill too, slightly underpowered in this shot unfortunately so the noise is a little worse than it could of been, looking on screen blown up I can't find anything more focused than the RHS blokes right eye (his right from his pov)

 

[Richard King]

It's got an SB900 on the camera bounced off the ceiling / rear wall with a modified diffuser to give a bit of forward spill too, slightly underpowered in this shot unfortunately so the noise is a little worse than it could of been, looking on screen blown up I can't find anything more focused than the RHS blokes right eye (his right from his pov)

You say : ISO 1250, 1/3rd sec, f/5.6

You say "It's got an SB900 on the camera bounced off the ceiling / rear wall with a modified diffuser to give a bit of forward spill too"

I say: You are trying to be too clever with the flash. just bounce it off a wall, and make sure the focus assist is on (and pointing at the subject) Additionally, (while you are figuring this out) to start with go auto (flash) everything (and set the camera to aperture prioitory, choosing about f8 Set the ISO to about 200

 

[Davince]

You say : ISO 1250, 1/3rd sec, f/5.6

You say "It's got an SB900 on the camera bounced off the ceiling / rear wall with a modified diffuser to give a bit of forward spill too"

I say: You are trying to be too clever with the flash. just bounce it off a wall, and make sure the focus assist is on (and pointing at the subject) Additionally, (while you are figuring this out) to start with go auto (flash) everything (and set the camera to aperture prioitory, choosing about f8 Set the ISO to about 200

LOL Flash is about the one thing I'm not worried about

Focus assist is on, it's pointing at the subject, the settings you have described in the venue I'm in will give a photograph looking like two people brightly lit in a cave, which would have the client looking at me asking 'why doesn't it look like any of the shots we chose you for, your slow shutter ones that we asked you to do'.

I do do some 'bright and clear' shots for them, not with anything like those settings as I still want a little ambient light involved. I do some even longer shutter ones too! The question posed isn't how to get a bright clear photo, it is (was) purely one of the DOF being nowhere near as expected and why, and it looks like an equipment fault, fortunately still under warranty!

 

[Richard King]

LOL Flash is about the one thing I'm not worried about

Focus assist is on, it's pointing at the subject, the settings you have described in the venue I'm in will give a photograph looking like two people brightly lit in a cave, which would have the client looking at me asking 'why doesn't it look like any of the shots we chose you for, your slow shutter ones that we asked you to do'.

I do do some 'bright and clear' shots for them, not with anything like those settings as I still want a little ambient light involved. I do some even longer shutter ones too! The question posed isn't how to get a bright clear photo, it is (was) purely one of the DOF being nowhere near as expected and why, and it looks like an equipment fault, fortunately still under warranty!

Get the shot sharp, clean and clear, work back form there

 

[Davince]

LOL at you guys, seriously This is an internet forum where anything more than a one line answer is a bonus.

Okay, no problem I've made it simpler for you, no thesis needed, we'll go for one word answers, I've even given both options, you don't even have to type them just delete what is in your opinion incorrect:

1:Is there any difference in DOF in these two images on your screen:

[/QUOTE]

YES / NO


2: Do you actually believe the ears in this image are more in focus than the eyes?

YES / NO

 

[Davince]

Get the shot sharp, clean and clear, work back form there

As I say, got plenty of those, worked back and couldn't come up with any reasonable or logical explanation for the intermittent DOF drop off I've been having. What I SHOULD have done was used a different example image, as people have focused on things I am
a: fully aware of and
b: were intentional and I can produce or remove at will from my images.

my error to use this as an example and I'll hold my hands up to that, it just happened to be the first in the set that showed the issues. I wanted ghosting, I wanted high ambient, I moved the camera intentionally during a long exposure to enable blurring of a cluttered background, sacrificing blur on the edges of the portrait as a trade off of having a flat uninteresting image. I used the flash burst as I did to give the sharpness in the centre of the portraits. Movement captured in the image is input by me, intentionally, not by the subjects, because I know that the controlled flash won't reach the background. It's not to everyones tastes, it's not technically great even when done well (which this one clearly isn't!) but its something I'd done before, the client had seen and wanted me to produce for them.

 

[antihero]

In a minute I think my radio alarm is going off to the tune of "I Got You Babe"

 

[Pookeyhead]

Hell's teeth... this still going on? LOL

 

[Davince]

In a minute I think my radio alarm is going off to the tune of "I Got You Babe"

The Good news is, this time we don't have to wait for loves first kiss, just a simple yes no answer!

The bad news is, that's probably not going to be forthcoming lol

 

[Richard King]

I tell you what, do what I say, and then progressively up the ISO, lower the shutter speed etc.. Post them as a sequence of shots and we can all judge where the issue is..

Basically you cont have enough light, you have bummped the settings to compensate, and your are blaming your camera for it

 

[kendo1]

Okay, campers, rise and shine,
and don't forget your booties
because it's COOOLD out there...

 

[Davince]

I tell you what, do what I say, and then progressively up the ISO, lower the shutter speed etc.. Post them as a sequence of shots and we can all judge where the issue is..

Basically you cont have enough light, you have bummped the settings to compensate, and your are blaming your camera for it

It's marginally underexposed compared to how I wanted as I said, but I'm not sure what you mean, I've not bumped any settings in PP at all. When I import to LR it runs a standard import with the exception of upping vibrancy by +15 and contrast up 15 over standard, both just to give the images a bit more kick, that's it, occasionally straighten up but pretty much just export them straight back out again, no editing, no time for that.

As I say anyway, I'm not concerned about nor asking for help on the particular image at all it was just the first example that showed the fact that the DOF is not as expected, that's all. I'm not blaming the camera, at least I wasn't, I asked expecting to be missing vital knowledge, the result of a posters help, the local camera shop and talking to Nikon, is that there is a fault with the camera.

 

[abdoujaparov]

Some things are a given, or at least assumed to be

"If you are new to photography, or just have a question you think is basic, then fire away! Absolutely no question is too silly or basic for us in here."

Still, I did learn a couple of things. One, DoF is dependent on the size and distance of the image you're looking at. Two, cropping an image does *not* change the DoF unless you also move it closer to your eyes. Both things were very helpful, thanks.

 

[Myrdhinn]

My useless 2 cents: all camera bodies front/back focus lens to -/+ xxxx degrees which is why some lens are fine, others are not. That is why many new higher/high end cameras come with focus adjustment for lens in the camera. Looks like even Nikon sees it's back focusing which is why they want your camera and lens.

 

[Richard King]

It's marginally underexposed compared to how I wanted as I said, but I'm not sure what you mean, I've not bumped any settings in PP at all. When I import to LR it runs a standard import with the exception of upping vibrancy by +15 and contrast up 15 over standard, both just to give the images a bit more kick, that's it, occasionally straighten up but pretty much just export them straight back out again, no editing, no time for that.

As I say anyway, I'm not concerned about nor asking for help on the particular image at all it was just the first example that showed the fact that the DOF is not as expected, that's all. I'm not blaming the camera, at least I wasn't, I asked expecting to be missing vital knowledge, the result of a posters help, the local camera shop and talking to Nikon, is that there is a fault with the camera.

In the original image the DOF is what I would expect, The issue with it is that it is not quite properly focused, suffering from a little movement blur and lacking in overall resolution - which is what happens when you shoot hand held at the settings you shot at

Yes you may need to do a manual lens adjustment, but the issue is wider than that, the whole shot is suffering from the issues outlined above, none of it is particularly sharp

 

[Davince]

In the original image the DOF is what I would expect, The issue with it is that it is not quite properly focused, suffering from a little movement blur and lacking in overall resolution - which is what happens when you shoot hand held at the settings you shot at

Yes you may need to do a manual lens adjustment, but the issue is wider than that, the whole shot is suffering from the issues outlined above, none of it is particularly sharp

as I've said previously in the thread, I know this isn't a great example but there is absolutely no reason for those setting not to give as sharp and usable image as any other image ( when taken at that ISO)

I was going to write a load about it but as Phil showed me earlier, a picture is worth 1000 words so here: an image taken a few minutes after the original pic, taken about 10ft to the right of the original pic, taken with the same settings as the original pic.

Maybe my expectations are too low? their features look about as crisp and clear as they'll ever get at ISO 1250 to me, or should they be better even if I need to get ambient lighting in too? It's got an acceptable dof that extends from the very front of his jacket back to the rear of his ear. About what I'm used to in this scenario. About what i'd expect.

What I was hoping for from this thread was that there is something I don't know about ambient light (I've noticed in the last 24 hours with all the checking I've been doing, that any pictures taken during the orange phase of the ambient are more prone, coincidence?) , or hell even links to something showing that 1/2 - 1 stop under on the flash could mean dof was cut by 3/4

I don't think nor have I every suggested it is back focusing, as I assumed that just moved the dof backwards to be fore/aft of the new, incorrect focal point, is that not the case? Back focusing was raised by hoppy when he started claiming that the ear was more in focus than the eye, which is I'm sure you'll agree completely ludicrous. I don't think anything in it is particularly focused which in itself is odd, something somewhere should be, and the DOF around the closest bit to what could be called focused - the eye, appears to be the depth of a gnats c**k.

ETA... one thing I have just noticed uploading this pic.... Photobucket appears to muller the hell out of an image!!! Just changed the first of these two to Flickr and it's 100 times better. Another thing learnt lol.

 

[kendo1]

It also helps that the two faces are in the same plane this time

Maybe something you'll have to take into account when composing the next pics at the settings you're using.

It will do no harm to get your equipment checked, bit of an inconvenience, but it will help to nail down the problem.

 

[Davince]

It also helps that the two faces are in the same plane this time

Maybe something you'll have to take into account when composing the next pics at the settings you're using.

LOL at composing... getting them to stand and look roughly in the right direction without dribbling too much is considered a victory by 9pm!

You're right, it does help, I'm still fairly sure the full foot dof helps too though

 

[kendo1]

LOL at composing... getting them to stand and look roughly in the right direction without dribbling too much is considered a victory by 9pm!

You're right, it does help, I'm still fairly sure the full foot dof helps too though

You're playing with fire, Del...

 

[Phil V]

It also helps that the two faces are in the same plane this time

...

But they're not. The girl is sharper than the bloke.

 

[kendo1]

But they're not. The girl is sharper than the bloke.

Here we go again...

On a second look, you're correct actually

My point was that the two were closer to being in the same plane than the first example.
I should have been more exact in my statement obviously...

 

[Phil V]

But the point is that DoF is highly subjective and prone to variables. The plane of focus is razor thin. It's not some foot wide block. Everything in front of and behind the plane of focus is Out Of Focus. The important consideration is:
How much out of focus is acceptable?
Even with hyperfocal focussing - the key point is 'acceptable' you don't have 'in focus from 3 metres to infinity' you have 'acceptably sharp from 3 metres to infinity'

And acceptably sharp depends on the size of the image and the viewing distance.

 

[Davince]

But the point is that DoF is highly subjective and prone to variables. The plane of focus is razor thin. It's not some foot wide block. Everything in front of and behind the plane of focus is Out Of Focus. The important consideration is:
How much out of focus is acceptable?
Even with hyperfocal focussing - the key point is 'acceptable' you don't have 'in focus from 3 metres to infinity' you have 'acceptably sharp from 3 metres to infinity'

And acceptably sharp depends on the size of the image and the viewing distance.

Oh yes absolutely agree on that, the dof by calculations should however be roughly a foot block (simplifying I know, but for the sake of argument go with it...) Looking at it from my perspective Phil, if you had a situation where you shot 20 or 30 shots, in succession, all within 10 ft of each other, using exactly the same settings, would you not generally expect the dof or 'acceptable' level of focus to remain fairly constant across those images, given each being viewed at the same distance and size?

Then to add to that, if you suddenly went from consistently getting a 75%+ success rate and very rarely failing to hit the focus you wanted, down to a 20% success rate, would you not find that a tad odd?

 

[Phil V]

Oh yes absolutely agree on that, the dof by calculations should however be roughly a foot block (simplifying I know, but for the sake of argument go with it...) Looking at it from my perspective Phil, if you had a situation where you shot 20 or 30 shots, in succession, all within 10 ft of each other, using exactly the same settings, would you not generally expect the dof or 'acceptable' level of focus to remain fairly constant across those images, given each being viewed at the same distance and size?

Then to add to that, if you suddenly went from consistently getting a 75%+ success rate and very rarely failing to hit the focus you wanted, down to a 20% success rate, would you not find that a tad odd?

Yes I'd find it odd. And to diagnose the problem I'd use scientifically proven methods of testing the gear.

After testing the gear properly, I'd know what the problem was and what was required to fix it.

 

[Ivan S]

Can you get consistently sharp shots in good light? forget all that slow shutter and blurring you are going for with what you are shooting in the club , but actually go for sharp and properly exposed shots?

If you can, then I would say it's to do with what you are doing, seems you are just on the edge of what your equipment can do and sometimes it comes out inconsistent.

 

[Davince]

LOL there's my real problem, I'm lazy, wasn't sure how best to test so just hoped someone had come across the problem before

Oh well, going into the hands of Nikon in a couple of days, as the lens had to go back anyway, might as well get it all checked and serviced, looks like I'm out of work for the next few weeks! Now then... if the sun would just come out...

Ivan, since this problem reared up, I'd done very little other shooting as my other business was taking my time, I've done two shoots over the weekend, and no, consistency is not there at all.

 

[Ivan S]

Well, good luck getting it sorted Del, if Nikon can't sort it, no one can