Scheimpflug and another question

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Re: Scheimpflug and another question

Post by Charles Twist » Fri Aug 26, 2011 2:35 pm Etc/GMT-1+01:00

@Tim: needless to say, the bride was late. :wink:
@Valerio & Dave: The wedge of focus is exactly that - a wedge. So, it's narrower near the camera than in the distance (as per my Rolls shot). Therefore you have to be very selective when choosing what you will focus at close range. In close-up mode, you really don't get much choice at all actually. The other thing with close-ups (and I include the sewing machine example) is that your diffraction limit kicks in a lot sooner. At f/45, you'll get quite a bit of fuzz. I would guess that in your example, the lens will be at its most resolving around f/11, maybe even a little wider. I don't see how you could have the whole machine in sharp focus. So I would choose to have the needle sharp, as well as the paintwork above it and the wheels at the right (you can't resolve more than three points which aren't part of the same plane). You'll need some back-tilt and some swing, but overall, you won't need buckets of movement (5-10 degrees?). Get that tack sharp, then close the aperture. That way, you bring the eye in to the elements that matter (to me) and soften the context which is secondary. That's what I mean about the movements driving the narrative.
HTH. Regards,
Charles

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Re: Scheimpflug and another question

Post by Charles Twist » Fri Aug 26, 2011 3:56 pm Etc/GMT-1+01:00


[JARRING CHORD]

Image
Good god! It's Joanna with facial hair!

:lol:
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Re: Scheimpflug and another question

Post by Joanna Carter » Fri Aug 26, 2011 8:34 pm Etc/GMT-1+01:00

Charles Twist wrote:Good god! It's Joanna with facial hair!

:lol:
Charles
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Re: Scheimpflug and another question

Post by Charles Twist » Fri Aug 26, 2011 9:01 pm Etc/GMT-1+01:00

Gadzooks! was it the flying helmet that gave me away?
No: your name is in red and apparently you're a moderator (not sure which church though). 8)
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Re: Scheimpflug and another question

Post by Valerio Trigari » Fri Aug 26, 2011 10:06 pm Etc/GMT-1+01:00

Charles Twist wrote:@Tim: needless to say, the bride was late. :wink:
@Valerio & Dave: The wedge of focus is exactly that - a wedge. So, it's narrower near the camera than in the distance (as per my Rolls shot). Therefore you have to be very selective when choosing what you will focus at close range. In close-up mode, you really don't get much choice at all actually. The other thing with close-ups (and I include the sewing machine example) is that your diffraction limit kicks in a lot sooner. At f/45, you'll get quite a bit of fuzz. I would guess that in your example, the lens will be at its most resolving around f/11, maybe even a little wider. I don't see how you could have the whole machine in sharp focus. So I would choose to have the needle sharp, as well as the paintwork above it and the wheels at the right (you can't resolve more than three points which aren't part of the same plane). You'll need some back-tilt and some swing, but overall, you won't need buckets of movement (5-10 degrees?). Get that tack sharp, then close the aperture. That way, you bring the eye in to the elements that matter (to me) and soften the context which is secondary. That's what I mean about the movements driving the narrative.
HTH. Regards,
Charles
As I said, I understand the Scheimpflug principle very well from a physical point of view, the difficult bit is putting it into practice and get the effect I want. Regarding my lens, it has the highest resolving power between f/16 and f/22, but I was trying to see what would have happened at f/45. With the sawing machine I was trying to get everything on focus, as a technical exercise, rather than obtaining a certain artistic effect. I certainly agree that needle should be the sharpest part of the machine though.
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Re: Scheimpflug and another question

Post by timparkin » Sat Sep 03, 2011 8:21 pm Etc/GMT-1+01:00

Hi folks

Regarding tilt, scheimplug and merklinger all add up to one simple rule. Draw a line through your film place, a line through your lens plane and your focus will go through this also. This makes it straightforward to put the right amount of tilt on without even looking at the ground glass.

1) Work out where you want your plane of focus
2) Draw an imaginary line through this plane until it meets the film plane (i.e. usually a vertical line)
3) angle your front standard until it points at where these two lines meet.
4) Rack your focus until a point on your chosen focal plane becomes sharp.

You can also use this to sanity check your focus

If you want to see how all these work (and more importantly, how depth of field works) have a play with my tilt simulator

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

Tim

p.s. Joanna's micro tilt is probably giving good results because having no tilt at all still gives the most depth of field. The more tilt you put on, the smaller your depth of field so it's a good idea to always use as little tilt as possible.

p.p.s. If Joanna's micro tilt actually worked, wouldn't camera manufacturers just set up the sensor with a tiny amount of tilt? Not wanting to get into that argument too much - but I will anyway :-) the figures in Merklinger represent mathematics near infinities and hence strange things happen. Try extrapolating the figures you have for small angles down to the point where the angle is zero and you'll see "theoretically" infinite depth of fields with zero tilt..
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Re: Scheimpflug and another question

Post by dennis » Sun Sep 04, 2011 10:31 am Etc/GMT-1+01:00

Surely the essence of a LF camera is that it is possible to see on the screen what you are getting. The camera movements are arranged to achieve that, so it doesn't really matter how you start out, it is how you end up? Dennis.

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Re: Scheimpflug and another question

Post by timparkin » Sun Sep 04, 2011 10:39 am Etc/GMT-1+01:00

dennis wrote:Surely the essence of a LF camera is that it is possible to see on the screen what you are getting. The camera movements are arranged to achieve that, so it doesn't really matter how you start out, it is how you end up? Dennis.
The same could be said for driving but most people benefit from a lesson or two.. :-)
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Re: Scheimpflug and another question

Post by banana_legs » Sun Sep 04, 2011 10:47 am Etc/GMT-1+01:00

Charles,

A fantastic image of the Rolls. Out of interest, why did you choose to have the car wing mirror also in focus? I assume that the prime drive for the image was to throw the main part of the windscreen out of focus so that the flying lady stood out against a nice background; my instinct would have been to swing the back in the other direction so that the wing mirror out-of-shot was on the plane of focus, leaving just the Rolls sign and flying lady in focus in the captured part of the picture, however leaving much of the remaining picture out of focus.

Best regards,

Evan
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Re: Scheimpflug and another question

Post by Valerio Trigari » Sun Sep 04, 2011 1:06 pm Etc/GMT-1+01:00

Hi Tim,

thanks for your suggestions and for the link to your web app, it's really cool. :-)

Val
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Re: Scheimpflug and another question

Post by Charles Twist » Tue Sep 13, 2011 8:34 am Etc/GMT-1+01:00

Evan wrote:why did you choose to have the car wing mirror also in focus?
Well the mirror was clearly a part of the composition. Once I had decided to include it, I worked to make it sharp in order to provide a strong point in the distance. Gives the picture depth. I knew the wind-screen had to be soft to bring the Lady out and I figured that some sharpness in the background would replicate how the human eye works. What I failed to understand until I saw the print, is that the mirror provides context. I should have had it a little softer than it is, so that it's clear what it is, provides depth but is also definitely second fiddle. Oh well, live and learn.
Regards,
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Re: Scheimpflug and another question

Post by Bill Backhouse » Tue Sep 13, 2011 12:56 pm Etc/GMT-1+01:00

Great little simulator Tim, that has killed an hour this morning and given me a better understanding of how little tilt I need for landscapey stuff.

What situations would require you to tilt the lens back/up for achieve a large focal area in shot. My Graflex only allows you to tilt up/back which seems a bit counter intuitive to what I think I need to get my plane of focus along the ground for a landscape shot. I could spin the standard round to only allow tilting forward/down, but I'm wondering what photographic options I will lose by doing so?

thanks

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Re: Scheimpflug and another question

Post by Joanna Carter » Tue Sep 13, 2011 3:45 pm Etc/GMT-1+01:00

Bill Backhouse wrote:What situations would require you to tilt the lens back/up for achieve a large focal area in shot. My Graflex only allows you to tilt up/back which seems a bit counter intuitive to what I think I need to get my plane of focus along the ground for a landscape shot
Take a look at this shot:

Image

I wanted to get everything in focus, including the manhole cover in the foreground. The plane of sharp focus passes through the guttering on the second house down and then goes on to the lamppost at the bottom of the steps.

Setting up the shot took me over two hours but realising that back tilt was the answer would have taken an hour and a half off of that :oops: 8) :?
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Re: Scheimpflug and another question

Post by Valerio Trigari » Tue Sep 13, 2011 9:30 pm Etc/GMT-1+01:00

Joanna Carter wrote:[...] The plane of sharp focus passes through the guttering on the second house down and then goes on to the lamppost at the bottom of the steps.

Setting up the shot took me over two hours but realising that back tilt was the answer would have taken an hour and a half off of that :oops: 8) :?
Thanks Joanna! That made a lightbulb light in my head and I think I understood a few mistakes I did. :D
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Re: Scheimpflug and another question

Post by timparkin » Tue Sep 13, 2011 10:15 pm Etc/GMT-1+01:00

Bill Backhouse wrote:Great little simulator Tim, that has killed an hour this morning and given me a better understanding of how little tilt I need for landscapey stuff.
Glad to waste your time ;-)

Bill Backhouse wrote:What situations would require you to tilt the lens back/up for achieve a large focal area in shot. My Graflex only allows you to tilt up/back which seems a bit counter intuitive to what I think I need to get my plane of focus along the ground for a landscape shot. I could spin the standard round to only allow tilting forward/down, but I'm wondering what photographic options I will lose by doing so?
Can you explain what you mean by 'back/up' -- maybe in terms of which side of which standard comes towards or moves away from you. E.g. normal rear tilt for near far is rear tilt, top of rear standard moves towards you.
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