Thanks!
Someday I'll make a more polished write-up and put it on my web site.

Bill

Visit me, info and galleries at: Nikon Photos and Information

Please allow me to offer congratualtions and thanks for this incredibly useful chart. If you do not mind, I may use it as a basis for some calculations for my just-acquired 24-120 ED VR Nikkor.

Looking forward to your write-up!

Cheers,
Charles

First, I use my 12-24DX and D70 at 12mm and the offset is 100mm.

The triangles are simple to construct.
Assuming you are using the viewfinder gridlines, the 1/4 and 3/4 lines are 12mm apart horizontally on a DX sensor; so this is the base of the isosceles triangle.
The focal length, for example 18mm is the height of the triangle.
The only important thing is the proportion, so for example we can multiple by 10; and make a triangle that has a 120mm base and is 180mm tall.

Multiplying by 10 or 15 is a good idea.
You may have to tape together a couple pieces of paper for longer focal lengths.

Remember, it is very important to do this at infinity or whatever focus point you will be using.

Bill

Visit me, info and galleries at: Nikon Photos and Information

You also mentioned Field Of View (FOV) in your post.
When you constuct the traingles as instructed FOV "takes care of itself" because the focal length is the height of the triangle.

BTW, I seen no reason to measure the FOV of a lens unless you intend to focus at other than infinity.
In fact it's folly to measure at a short distance and apply that FOV for images taken at infinity.

Bill

Visit me, info and galleries at: Nikon Photos and Information

Chris B1

Your thinking on the problem is very sensible and has set me thinking...especially the part about tropical beaches, because I have just scheduled my annual trip to the Dutc Antilles for September and want to simply work and not think so much about the setup.

That said, rather than trying to solve this theoretically, I think it may actually be quicker to solve experimentally and then backfit the data. Something like three shot stitched showing a measured scale. Sounds like an early Sunday AM trip to the mall, where there is a virtual grid of lines in the parking may be in order!

Hyperfocus is often the difference between good and great, assuming that all other factors are relatively equal. A properly focused pano can certainly rival the best large-format shots, that much is certain.

Good shots to all, and cheers,

--Charles

I suggest using my technique at infinity and at a hyperfocal setting and seeing for yourself how the entrance pupil is affected.
With sophiticated lens designs it's not obvious what the result will be.

Bill

Visit me, info and galleries at: Nikon Photos and Information

Also note that focusing many of today's complexly designed optics will actually alter the focal length slightly. This will compromise the accuracy of any FL-based system. It should also be noted that the actual focal length and the "advertised", or marked, focal length can differ by as much as 10%, assuming the lens manufacturer is sticking to the old JCII standards, or more (if they are not). Each manufactured sample will be slightly different and the design target can be 5-10% from the marked FL.

FL-based alignment systems are only modestly accurate though probably good enough for landscape work where nothing is closer to the camera than about 50-100x the focal length.

-----
dwig
nikonian in paradise (KW, FL)
Current: CP8400, CP950
Retired: F, ELw
Usedto's: F, F2, F3, Nikkormat FTn, 20 f/3.5, 35 f/1.4, 45GN, 55 f/3.5 Micro, 105 f/4 Micro, 300 f/4.5, 180w f/5.6 for 4x5
-----

Chris B1

More pleasure is to let you know Bill, that this post of yours is the runner up in the Tip of the Month Contest.

The problem I have now is the need to buy a nodal plate. Oh well!

Have a great time
JRP (At the north-eastern Mexican desert) Gallery, Brief Love Story, The Team
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Here is a revised diagram.

Bill

Visit me, info and galleries at: Nikon Photos and Information

Have a great time
JRP (At the north-eastern Mexican desert) Gallery, Brief Love Story, The Team
You value our community? Upgrade your membership.
Silver is 7 cents per day, you get benefits and can take pride in helping to support this your community.