From View to Print

Discussion forum for techniques and issues relating to the creation of panoramic and/or "mosaic" images

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thinkstopthink
Posts: 11
Joined: Mon Sep 24, 2012 4:11 pm

From View to Print

Post by thinkstopthink » Mon Sep 24, 2012 4:24 pm

Hi,

I apologize, this is going to be a long post. But I'm not making a connection in the math somewhere, and I'd like some help.

Short story:

These days, I only print panoramas in three formats. I'd like to figure the best way to convert from FOV to inch/cm to go from shooting to printing. Its got to be easy, I'm just drawing a blank. I got an A+ in calculus, so math isn't the problem, I'm just not seeing a step.

Long story:

I first started shooting panoramics in 1999 on film. Processing film, scanning film, and then starting all over if there was a mistake was a slow process. I had one of the early heads with detents. You picked your lens, set your detent number, and fired away. Shooting was easy. Then I moved to NYC and worked for a studio that did mostly VR photography--we had every pano head made, a $60,000 PanoScan camera, a ten foot diameter computer controlled shooting table for doing object rotations, etc. But I still used pano heads with detents for my work. That company went bankrupt and then I started freelancing shooting 360 degree panos for restaurant.com.

After that I focused more on shooting street photography with my Leica and still life with my Linhof 4x5" view camera. When I would carry around that huge camera and all the assorted gear in my backpack, it was very heavy. So I made a viewing mask. A simple piece of mat board with a 4x5 inch rectangle cut out of it. You could get that out and frame a scene without dragging out the 40lbs of gear to see if the view had potential.

I'm back shooting panos and now I have the same tools: I have three viewing masks for my favorite formats: 2:1, 2.4:1, 3:1. I carry them around and can get an idea first if it is worth setting up my pano gear. Maybe I should have taken up a job with lighter gear! :)

So, I've never used FOV in any type of calculations. I would just find a scene through a viewing mask, figure which lens I wanted to use, and line up things visually. This usually works fine, but I invariably shoot too many frames, and as I'm now trying HDR panos, I'd like to get the correct number each time so I'm not filling up my hard drives unnecessarily. I only want to crop minimally if necessary. This visual approach works, but while I can do this without understanding the calculations, I'm the type of person that likes to know the underlying concept and math.

However, all of the pano calculators online are done in FOV. I don't know what FOV I want; I know for a given scene I want a 3:1 pano. And, when I go into my print driver on my Canon 6300, there is no setting for HFOV x VFOV! Likewise if I go into a framing shop and ask them to cut me a matboard 110 degrees HFOV by 45 degrees VFOV, I would get a strange look… :)

Question (finally!): How to go from viewing a scene through a viewing mask and then calculate the number of frames and correct overlap to print a pano of that scene out in the field.

Gear I'm using: Really Right Stuff Pano Elements Package and PCL-1 Panning Clamp (no detents, 2.5° graduations). 24mm, 45mm, and 90mm Canon Tilt Shift lenses. 5D MkII. AutoPano Pro (posted this on Kolor's forum also).

Phew! I hope some of you knowledgable people have the endurance to read all of that… :)

Jon
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dsp
Posts: 586
Joined: Tue Feb 20, 2007 11:09 am
Location: Hoboken, NJ

Re: From View to Print

Post by dsp » Tue Sep 25, 2012 4:53 pm

Hi,
You have a 5dMII, so your camera is full frame, and your focal length multiplier is 1 (smaller than full frame sensors will have values > 1). For each of your lenses, with the possible exception of the 24mm, which is starting to get a little wide, you can calculate the FOV your camera will capture with very high accuracy. See http://en.wikipedia.org/wiki/Angle_of_view

Why people don't simply use frame sizes is that for scenes wider than some angle, the physical size (in "frame" units) can be very different than the number of frames taken once the panorama is stitched together, simply because you are mapping a curved space (the world) to a flat surface (the film). As a result, objects get distorted in scale, and this changes with the projection used to flatten the image. Thus the final size of your pano (in "frame" units) will change depending on the projection (http://en.wikipedia.org/wiki/Map_projection), while the FOVs are invariant.

hope this helps, Darcy

thinkstopthink
Posts: 11
Joined: Mon Sep 24, 2012 4:11 pm

Re: From View to Print

Post by thinkstopthink » Tue Sep 25, 2012 7:44 pm

Hi Darcy,

Thank you very much. That was the explanation I was after.

Jon

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http://www.jonwitsell.com

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