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Technical Camera T/S Workflow
- Thread starter etrump
- Start date
Guy Mancuso
Administrator, Instructor
Ed general rule of thumb close focus point say 20 ft and far focus point of 90 ft look at focusing to 60 with 1 degree of forward tilt. About 2/3rds out . Been playing with this on my 60mm this seems to work pretty good. I need to get out more with this and test more. One other trick is watch your focus mask increase in pattern as you tilt. Get it up to a high setting like 70mm focus at say 60 ft and tilt and watch the pattern grow closer. Certainly worth playing around like this to see what effect you get at each degree mark. I am actually thinking of converting my 90mm to TS when I get some money. I think it's around 1200 dollars to convert but I really love it on my 60 so far plus nice Cambo advantage is you can swing at the same time. Been playing with that also. Arca , Alpa just eat my dust. Lol
I just had to get my dig in since I keep forgetting the myths around here on our inferior Cambo. Oh wait did i just say that mister neutral. Okay relax I'm just freaking teasing. I'm sitting in hospital waiting for a test to be finished on my wife. Just year end stuff here.
I just had to get my dig in since I keep forgetting the myths around here on our inferior Cambo. Oh wait did i just say that mister neutral. Okay relax I'm just freaking teasing. I'm sitting in hospital waiting for a test to be finished on my wife. Just year end stuff here.
Jack's general rule of thumb for landscape or any image where infinity is part of the desired focus plane AND your camera is at about eye level:
With the camera zeroed, focus 1/3 from your near focus point to your far focus point then add 1º forward tilt for every 30mm to 35mm of focal length. Note that if your camera position is lower to the ground, you will need MORE forward tilt; and if your far subject is closer than infinity, you will need MORE forward tilt.
Obviously this only gets you close, but often it's very close; regardless you should use live view or shoot and review to confirm you nailed the correct desired subject focus zone. After the above, all that's usually required is a slight tweak on the focus ring to place the zone precisely where you want it.
When using combined tilt and swing movements, focus becomes an iterative process, and here live-view or a perfectly calibrated ground-glass previewing system is desirable.
With the camera zeroed, focus 1/3 from your near focus point to your far focus point then add 1º forward tilt for every 30mm to 35mm of focal length. Note that if your camera position is lower to the ground, you will need MORE forward tilt; and if your far subject is closer than infinity, you will need MORE forward tilt.
Obviously this only gets you close, but often it's very close; regardless you should use live view or shoot and review to confirm you nailed the correct desired subject focus zone. After the above, all that's usually required is a slight tweak on the focus ring to place the zone precisely where you want it.
When using combined tilt and swing movements, focus becomes an iterative process, and here live-view or a perfectly calibrated ground-glass previewing system is desirable.
GrahamWelland
Subscriber & Workshop Member
BTW, there's light at the end of the Alpa tunnel at least for wide angles with T/S although we've just got to wait it out, focus stack and listen to the Arca and Cambo folks in the meantime.
I've been shooting with the Alpa T/S adapter this week and I found the following article and corresponding tables useful. The tables pretty much match up to Jack's shortcut and you can calculate the actual amount if you really want 180/pi x arcsine(focal length/height in mm)
http://www.northlight-images.co.uk/article_pages/using_tilt.html
The main thing really is to get the approximate tilt and focus and your shooting height has an impact on that as a starting point. I would expect that with Guy and Jack shooting side by side with the same lens that each would need different amounts of tilt, albeit only fractionally, due to their different camera heights (unless Guy is on a box or Jack is crouching over).
I'm still struggling with the live view though - I get sensor blow out even in early morning shots when I try to adjust for shadow foreground -> brighter horizon. I still have to rely on the shot/review focus mask cycle.
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Guy Mancuso
Administrator, Instructor
**** it's a difference of almost a whole foot and I keep shrinking. LOL
Bryan Stephens
Workshop Member
Sounds like Jack and I have a similar problem.
[email protected]
Member
Hi, the best rule for tilt I found in the following article, the charts at the end I always carry with me.
Best regards
Wolfgang
http://www.davidsummerhayes.com/Focusing the tilt-shift lens.pdf
Best regards
Wolfgang
http://www.davidsummerhayes.com/Focusing the tilt-shift lens.pdf
MGrayson
Subscriber and Workshop Member
The correct formula, ArcSin( f / d ), is fortunately very very close to simply ( f / d ) as long as you're not doing macro. The problem is one of units, as the ratio ( f / d ) is in radians. (Note that radians, being the ratio of two lengths, are actually dimensionless units!) To translate into degrees, which is what most cameras are marked in, multiply by 180 / Pi, or about 57.3 ... actually, 60 is probably good enough, so taking the example of a 90mm (that's 0.09 meters) lens 1 meter off the ground, we get 60 * 0.09 / 1, or 5.4 degrees. The correct answer is 5.2 degrees.
Now we can see where Jack's rule comes from. For a 2 meter camera height, the formula gives a tilt of 57 * f / 2. For an extra degree of tilt, the focal length would have to increase by 2/57, or 0.0351 meters = 35.1mm. From this, we can conclude that Jack is tall.
Why yes, I was a math professor.:ROTFL:
Matt
Now we can see where Jack's rule comes from. For a 2 meter camera height, the formula gives a tilt of 57 * f / 2. For an extra degree of tilt, the focal length would have to increase by 2/57, or 0.0351 meters = 35.1mm. From this, we can conclude that Jack is tall.
Why yes, I was a math professor.:ROTFL:
Matt
David Duffin
Member
Matt,
This formula should apply equally well to swing, no? If I were to take a shot with a 90mm lens and the normal lens axis more or less parallel to an infinitely long brick wall and was set up with the centre of the sensor 2m from the wall, and I swing the lens 5.2 degrees toward the wall, would this result in maximum effective DOF with the lens focused at infinity?
This formula should apply equally well to swing, no? If I were to take a shot with a 90mm lens and the normal lens axis more or less parallel to an infinitely long brick wall and was set up with the centre of the sensor 2m from the wall, and I swing the lens 5.2 degrees toward the wall, would this result in maximum effective DOF with the lens focused at infinity?
David Duffin
Member
Ahhh, of course, 1 m. Thanks.
wentbackward
Member
Ed, It takes a bit of practice, which you must go through to get a feel for what's going on, then you'll end up with some 'rules-of-thumb' of your own, but also be able to deal with particular situations - basically you'll know where to look when focusing.
There are two well used approaches. First is iterative (with a few variations on how to actually achieve this), second is by calculation, and yes some LF Photogs do go out with protractors and do this.
Iterative variations:
http://www.largeformatphotography.info/how-to-focus.html
Calculation:
Of course grab any text book on lens/camera geometry and blow your mind.
Better and more practical, Merklinger came up with a very innovative method http://www.trenholm.org/hmmerk/
Once you have Merklingers book then COMPLETELY CHEAT and grab the s/sheet from Alpa's website: http://www.alpa.ch/en/products/tools/alpa-tools/alpa-comparable-focal-length-calculator.html
- Paul
There are two well used approaches. First is iterative (with a few variations on how to actually achieve this), second is by calculation, and yes some LF Photogs do go out with protractors and do this.
Iterative variations:
http://www.largeformatphotography.info/how-to-focus.html
Calculation:
Of course grab any text book on lens/camera geometry and blow your mind.
Better and more practical, Merklinger came up with a very innovative method http://www.trenholm.org/hmmerk/
Once you have Merklingers book then COMPLETELY CHEAT and grab the s/sheet from Alpa's website: http://www.alpa.ch/en/products/tools/alpa-tools/alpa-comparable-focal-length-calculator.html
- Paul
Shashin
Well-known member
With tilts, I eyeball it. I make an imaginary line from the image plane to the ground and then I tilt the lens plane to intersect that. That is basically the Scheimflug (Sp?) rule--the image plane, lens plane, and object plane intersect at one line (or point, if you it makes it easier). The object plane can also be the best plane that interests object space.
I confirm my tilt by shooting wide open to see how the DoF intersects the scene. I then stop down to get what I need in focus.
I confirm my tilt by shooting wide open to see how the DoF intersects the scene. I then stop down to get what I need in focus.
GrahamWelland
Subscriber & Workshop Member
Harold Merklinger's treatise on focus, tilt & DoF in general are all excellent. Download his articles & ebooks and send him a PayPal as he has always been a great contributor to the photographic community. :thumbs:
etrump
Well-known member
Since my height is about half way between Guy and Jack, I guess I'll just average their advice... LOL!
Thanks for the great information, I'll have plenty of ideas to test out before heading to Hawaii next month. It's amazing how my inspiration adapts to the weather, Hawaii and India in January, Tuscany in the spring, Alaska in June. Life is good.
Merry Christmas to all!
Thanks for the great information, I'll have plenty of ideas to test out before heading to Hawaii next month.
It's amazing how my inspiration adapts to the weather, Hawaii and India in January, Tuscany in the spring, Alaska in June. Life is good.Merry Christmas to all!
Shashin
Well-known member
Whatsa matta, can't expose correctly for snow?Since my height is about half way between Guy and Jack, I guess I'll just average their advice... LOL!
Thanks for the great information, I'll have plenty of ideas to test out before heading to Hawaii next month.
Merry Christmas to all!
Have a great trip. Really looking forward to seeing some work. India seems like a new type of adventure for you.
Merry Christmas.
198.9 cm to be precise
The reality is it is extremely difficult to hit a partial degree of tilt accurately to begin with. Moreover, in actual use at typical apertures like f8, 11 or 16, the difference of 1/2 degree plus or minus tilt will be of little net consequence to the final image focus "wedge," unless you are shooting a very short lens like a 23/24 or focussed at very close distances, like under 20x focal length...
Don Libby
Well-known member
Really? Here I thought you were taller. Heck, I'm only 205.7 cm......198.9 cm to be precise
It is more about Maths than Myths, but I thought it was ArcSin(f/j), and you calculate your tilt angle and set it before you start trying to focus... it is, of course, different if you are using a Sinar or a CAPcam... if you really want to know read Merklinger's "Focusing the view camera"... and this is independent of photographer's height - J could be 20 feet - or meters.
From memory I think I worked out an approximation: divide the focal length (in mm) by 20 and then divide the answer by J in meters, so for a 80mm lens and J=2m you get 2 degrees. (2.29 if you use a calculator and trig). It is very approximate, but useful if you do not have a scientific calculator on your phone.
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