i need 4x5 depth of field quick pointer

[Frederick Avery]

ok so im going to shoot my first astia and pretty much first 4x5 shots on monday.

i only have a 180mm lense on a 4x5

im unfamiliar with relative depth of field with different apertures with this camera, and so lets say i am going to shoot between 1 and two metres away from the subject, closely framed portrait shots.

im not really interested in soft focussing around someone with just their eyes ion focus or anything like that at all, what im looking for is really detailed and totally in focus so i can see what this format can do.

if i were shooting a head and shoulers, at about 1 or two metres, on a 180mm lense, what is a safe bet for an aperture that will keep most of the subject in sharp focus?

i can play about but i want to make sure i have one or two shots that are tack sharp. my lense is a rodenstock 180mm 5.6 sironar n

thanks in advance

frederick

[gari]

Hi Frederick, you should be able to see the DOF on the screen, that's one of the benefits of shooting LF.
But just in case you need to read what your eyes are seeing, try this link.
http://www.dofmaster.com/dofjs.html

Cheers
Gari

[Frederick Avery]

ahhhhhhhhhhhh amazing!!!! i shall bookmark that:)

thats one of the best tools i have ever seen for photography on the net. so useful.

yeah i knew i would struggle looking ast depth of field on the ground glass as it needs to be wide open to view decently, and it needs to be stopped down to f/64 to get what i want.

thanks so much though, thats brilliant.

frederick

[Joanna Carter]

i knew i would struggle looking ast depth of field on the ground glass as it needs to be wide open to view decently, and it needs to be stopped down to f/64 to get what i want.

Don't forget, if you stop down to f/64, you will start to get diffraction, which could reduce the sharpness of the image. A rule of thumb is to shoot at 2 stops wider than the smallest stop on the lens. So, for a lens with a minimum of f/64, you should try to avoid smaller than f/32.

You also have the possibility of front or rear tilt, which can greatly improve on the range of distances you can get in focus.

[Frederick Avery]

cool got it:)

i never thought to use tilt for things like that, but in time i shall have a play about with it.

lots of little rules, i like that. i think understanding these things as a pallete of pointers makes it so much more interesting. i shall have to add these kinds of things into my videos:)

frederick

[Joanna Carter]

If I can just elucidate about the amount of tilt you might require.

I don't know how much you have yet gleaned about the "Scheimpflug Rule", but it might help if you looked at these pages by Harold Merklinger. They include several movie files, which demonstrate quite nicely how altering the bellows length or tilt affects the angle of the focal plane and depth of field.

Basically, after you have read those pages and watched the movies, you will also need to realise that the hinge point can be placed several metres below ground, thus giving you a "wedge" of acceptable focus that is considerably wider at the height of the lens than if you had placed the hinge point near ground level, which is a common mistake made by many LF "young" photographers.

You should also realise that the less the angle of tilt, the greater the available depth of field. There are some, possibly confusing, possibly helpful, tables in this article on the Merklinger site, which demonstrate this principle. There is a point where it is theoretically possible to apply a minute amount of tilt (much less that 1°) and get around an 80° angle of acceptable focus. I have proved this to be the case and use the technique to get shots like this :



… where the prow of the boat, the surface of the water and the distance are all in focus. The hinge point had to be somewhere at or below the water line, which was something like 5 metres below the level of the quay on which I was standing and the plane of focus needed to be placed at around 40° to the horizontal.

There is no easy way to describe how to get this to work, there are no measurable angles/rules/etc, you really need to get together with someone who knows what they are talking about and see how it all looks on the ground glass screen. The big clue, if you want to experiment by yourself, is that less is more

[Frederick Avery]

i get it:) i had seen a video at some point that mentioned it:)

i try to imagine the plane of focus as an infinitely lage sheet of paper, following the same plane as the front standard, and when the front standard is tilted, the plane follows the sheet of paper wherever it goes.
its the hairdresser in me, you have to imagine where imaginary lines lead to or converge etc.

im quite intrested in this as far as swing goes, for getting both eyes in fosuc when they are at an agnle to the camera.

i had never really thought about adjusting the plane of focus this way though, its really very interesting.

i feel a little bit like ive opened a book thinking it was a diary and it turns out to be a thriller with many twists and turns and concepts.

brilliant, thanks for the input:)

Frederick

[Marizu]

I often use front swing to get both eyes in focus. Joanna's micro tilt technique should work for front swing, too, although with the huge wedge of focus that it gives I doubt it matters whether you swing or tilt. I've never actually managed to pull it off on a portrait. Has anyone successfully used micro movements for a portrait?
Gari and Joanna are totally right in that you can see what you are getting in the ground glass which is the most important thing.

I tend to work the f-stop backwards. I think about the subject, wonder how long they can sit still for, how much movement I am prepared to accept in the photograph and how much shadow detail I require. From that I derive the f-stop.
As an example, an incident reading in my garden has just given me f16 at 1/15s (spot metering an actual subject would probably indicate less).
For a tight face crop on my 210mm, I'd probably lose around a stop of light due to bellows extension factor which takes me to f11 at 1/15s.
Due to the close crop, the effect of movement will be exaggerated so I'd want a faster shutter speed than 1/15s.
That would leave me with f8 at 1/30s or f5.6 at 1/60s.

I've never managed to get into the diffraction limited zone shooting a portrait. Even my 1kw Bowens will only give me f32 if it's close to the subject and I generally lose a stop due to bellows extension on the tight crops that I favour giving me a shooting aperture of f22.
Use a pile of readily available maths to work out bellows extension factor or download and print a quickdisk (http://www.salzgeber.at/disc/) and free your mind for the art of photography rather than the science.

[Charles Twist]

I don't remember the detail of Merklinger's analysis, but I was less than convinced behind the maths of micro-tilt. So: buyer beware. In fact, I agree with Marizu: it's the art that matters, even if the science offers interesting insights. I would go so far as to say that you want to use tilt and shift to choose what you will have out of focus. The rest is your subject (and what matters to it - I am a narrative driven photographer) and you as the artist get to choose it. I tend to avoid the all-in-focus look, even though the DoF drop-off is sometimes only visible on larger prints. And that's the other consideration here - circles of confusion and all that. In regard of diffraction, lenses tend to be at their sharpest around f/11-f/16 after which diffraction starts coming in. But the effect won't be very strong and the extra DoF will give the impression of greater sharpness.
Does that help?
Charles

[Charles Twist]

Hello Frederick,
In addition to the previous post, here's a quick scan to show the point (in fact several points). I hope it'll suit your politico-erotic agenda...
Regards,
Charles

[Frederick Avery]

perfectly:)

when i look at that im looking at it as if it were the face, with the eyes along the plane of the fence. its just what im looking to do:) thankyou, so thats achieved by swing right? and i hear you dont match the exact plane, but a lesser version of it, the angles etc.

[Marizu]

To get an idea of the basics, there is a video on youtube called:
Scheimpflug plane of focus
I found the Symmons book, Using the View Camera, and Ansel Adam's, The Camera, useful for understanding movements and particularly the difference between front and rear movements.

[timparkin]

http://static.timparkin.co.uk/static/focus/

The microtilt thing just does't work - it can't - there is no possible way that a microtilt can increase the depth of field dramatically only to suddenly snap back to planar focus as you hit zero degrees (sorry Joanna!)

One fundamental quality of a tilting focus system is that the depth of field along the axis of the front lens *does not change* with rear tilt and conforms to standard depth of field calculations.

This useful fact allows you to visualise the depth of field using 'standard' depth of field calculations.. Just work out the near and far focus points and the Merklinger hinge point and you have all the information you need...

Try the simulator and see what happens

Tim

p.s. my simulation starts to fail at large angles of tilt due to some optimisations in the maths

[Joanna Carter]

I'm sorry Tim but, if you throw away the "science" and learn how to use microtilt on the GG screen, in the field, you'll be amazed just how much you can get into focus

[timparkin]

I'm sorry Tim but, if you throw away the "science" and learn how to use microtilt on the GG screen, in the field, you'll be amazed just how much you can get into focus

I thought you discovered the microtilt from looking at Merklingers maths tables? Science?

Anyone can confirm this anyway - set up their camera with tilts zero'd and then just move between 0 degrees of tilt and 0.02 degrees of tilt (in actual fact just put a little bit of ressure on the camera should be enough to make it tilt a tiny amount). If you see a dramatic increase in depth of field, I'm completely in the wrong. If nothing really changes, welcome to 'science'

Tim