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Author Topic: How much movement? Is there any way to calculate?  (Read 2818 times)

henrikfoto

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How much movement? Is there any way to calculate?
« on: March 08, 2011, 03:30:48 pm »

I am teaching myself how to use view-cameras and wonder how much I can move without compremising on the image-quality?

I use a back with 39x50 mm sensor on a P3. The lensea are 100mm Sinaron digital hr and Sinaron 180mm hr.
The image-circle of these lensea are 70 and 80 mm.

I wonder if there is any way to calculate how much I can move before the image-quality is affected?

I mostly do tilting and sideways twisting. How much is it normal to tilt the front at maximum?
« Last Edit: March 08, 2011, 03:51:22 pm by henrikfoto »
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Doug Peterson

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Re: How much movement? Is there any way to calculate?
« Reply #1 on: March 08, 2011, 04:14:00 pm »

When we sell a view or tech camera we offer our clients a visual guide with the image circles of their lenses and the size of their sensor.

If your dealer doesn't do this sort of thing you can make it yourself in Photoshop or with construction paper an a drafting compass. It's simple geometry - circle with Xmm of diameter and a rectangle te dimensions of your sensor and I'd MUCH rather SEE the image circle vs sensor size then have a number of mm.

ChristopherBarrett

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Re: How much movement? Is there any way to calculate?
« Reply #2 on: March 08, 2011, 04:14:08 pm »

With the huge variation in the pixel pitch of sensors and resolution of lenses combined with the variations due to given apertures and focal lengths... refraction from movements, etc.  There's no way to forecast degradation without real world test.

I almost never tilt or swing.  With a P65+ I try not to shift my 35 mm or 45 mm more than 7-10 mm.  Lenses longer than that offer more movement than my Rm3d is capable of... view cameras are a whole other story.

Shoot, zoom in check it out, repeat.
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ChristopherBarrett

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Re: How much movement? Is there any way to calculate?
« Reply #3 on: March 08, 2011, 04:16:53 pm »

Beware of going by image circles.... though.  Most images will lose sharpness due to diffraction before the composition actually reaches the edge of the image circle.... much more so with wides than long lenses.
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henrikfoto

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Re: How much movement? Is there any way to calculate?
« Reply #4 on: March 08, 2011, 05:09:47 pm »

With the huge variation in the pixel pitch of sensors and resolution of lenses combined with the variations due to given apertures and focal lengths... refraction from movements, etc.  There's no way to forecast degradation without real world test.

I almost never tilt or swing.  With a P65+ I try not to shift my 35 mm or 45 mm more than 7-10 mm.  Lenses longer than that offer more movement than my Rm3d is capable of... view cameras are a whole other story.

Shoot, zoom in check it out, repeat.

So is it correct to say that you have more movements the more open the apperture is?
Will the degradation of the photo show more in the corners?

If you shoot tabletop of smaller objects would more distance with a longer lens give more freedom of movements?
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henrikfoto

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Re: How much movement? Is there any way to calculate?
« Reply #5 on: March 08, 2011, 05:26:32 pm »

Sorry I explain this bad.
I am doing tabletop shots with objects about 10x15 cm.

I mean I am turning the front to the right or left and also tilting the front to lay down the focus plane.

What would be the correct lens for this work? The 180 mm?

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Kumar

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Re: How much movement? Is there any way to calculate?
« Reply #6 on: March 08, 2011, 07:51:24 pm »

"Photo Know-How" a Sinar book by Koch & Marchesi and "Using the View Camera" are excellent references. The Sinar book is naturally geared towards Sinar, but the principles remain the same. The exercises are very good at demonstrating the practice behind the theory.

Kumar
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ErikKaffehr

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Re: How much movement? Is there any way to calculate?
« Reply #7 on: March 09, 2011, 12:11:44 am »

Hi,

My answers below. What I say is based on knowledge of optics and not experience with LF photography, but it may still help...

So is it correct to say that you have more movements the more open the apperture is?
No, that's wrong. But it may depend on lens, a lot.

Will the degradation of the photo show more in the corners?
Essentially all lenses are weaker in the corners than near the centrum. Stopping down is limited by diffraction. Diffraction is probably little affected by movements.

If you shoot tabletop of smaller objects would more distance with a longer lens give more freedom of movements?
Hi, that depends, a longer lens gives less keystoning effects and image circle is possibly (probably) larger. Visual effect of movement may be less.
« Last Edit: March 09, 2011, 12:13:59 am by ErikKaffehr »
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Erik Kaffehr
 

henrikfoto

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Re: How much movement? Is there any way to calculate?
« Reply #8 on: March 09, 2011, 01:52:33 am »

Thanks to everybody!
I understand this is more complex than I thought. I need to do some reading!

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IanB

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Re: How much movement? Is there any way to calculate?
« Reply #9 on: March 09, 2011, 05:30:30 am »

Remember you also have to compensate for light fall-off within the camera for close-up work. At reproduction ratio of 1:1 you need 2 full stops.

If you want to read up, Stroebel is the bible - contains all the formulae if you really do want to calculate!
http://www.amazon.com/View-Camera-Technique-Leslie-Stroebel/dp/0240803450
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wollom

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Re: How much movement? Is there any way to calculate?
« Reply #10 on: March 12, 2011, 09:04:58 am »

The advice to shoot and check is most suitable.
There are ways to calculate limits of tilt and shift, but given that even 'simple' information like image circle is lens, aperture, subject distance, and repro-scale dependent; and that tilt and shift each affect the projected image circle independently; recording the calculations is beyond even a 2D spreadsheet.
Your eyes are the best measuring tool.

Wollom
« Last Edit: March 12, 2011, 09:15:05 am by wollom »
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