Optics coverage on 7x17inch - my math is wrong

That _is_ a bit of weight, eh? Seems that it could probably anchor the
Queen Mary with ease, I'll bet.

Maybe a 210mm SS-XL would weigh a little less?

Bob G wrote:

You can save yourself a lot of grief and go with the Super-Anglon 210mm. 100
degrees. 500mm circle of coverage.



At six and a half pounds.

Bob G

My thanks to everyone for correcting my math and terminology.

- Chris

Bob G wrote:

1) 9.19inches opposite side (diagonal from center of the 7x17inch format
to the corner) divided by 5.9inches adjacent side (150mm lens length)
equals 1.55

2) Tangent 1.55 equals 50 degrees

3) 2 times 50 degrees to get the full angle equals 100 degrees

This means several super-wide angle lenses might cover and be useful on
7x17. These would include:

* Schneider 150mm Super Symmar XL

* Schneider 165mm Super Angulon

* Nikkor 150mm SW

* Rodenstock 155mm Grandagon

But somethings not right. Where did I goof?

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To just cover the 7x17 format you need a circle of diameter = sq root of (7
squared + 17 squared) inches = 18.4 inches or about 467mm.

The diameter of the circle of coverage of a lens is (simple trigonometry):

C = 2 F tan (angle of coverage / 2)

Given an angle of coverage of 100 degrees, you would need a focal length:

F = C / [ 2 tan ( angle/2) ]

The tangent of 50 degrees (100 / 2) is about 1.19, therefo

F = 467mm / (2 x 1.19) = about 196mm

That is, a lens with an angle of coverage of 100 degrees would need to be at
least 196mm in focal length to cover the 7x17 format.

That eliminates every single lens in your list.




Bob G

"Jos. Burke" wrote in message
...
Darn,
That 305 G Claron (CopaL #1 SHUTTER--IF SO EQUIPPED) sure is looking

Tooooo long, Joseph.

Say, when we we see the list of goodies you got?

"Jos. Burke" wrote in message
...
Darn,
That 305 G Claron (CopaL #1 SHUTTER--IF SO EQUIPPED) sure is looking

Tooooo long, Joseph.

Say, when we we see the list of goodies you got?

Darn,
That 305 G Claron (CopaL #1 SHUTTER--IF SO EQUIPPED) sure is looking
good.
J Burke
"Bob G" wrote in message
...
You can save yourself a lot of grief and go with the Super-Anglon 210mm.
100
degrees. 500mm circle of coverage.


At six and a half pounds.

Bob G

Darn,
That 305 G Claron (CopaL #1 SHUTTER--IF SO EQUIPPED) sure is looking
good.
J Burke
"Bob G" wrote in message
...
You can save yourself a lot of grief and go with the Super-Anglon 210mm.
100
degrees. 500mm circle of coverage.


At six and a half pounds.

Bob G

And I thought the 305 G Claron on my Korona 7x17 was pretty dang wide!!
When I sold it with the 305 G Claron the buyer contacted me later for
recommendations on a longer lens (the 305 was a little too wide for his
liking)and , of course, the next logical step for big coverage brought the
355 G Claron to mind!
Hmm--maybe thats I like my 210 Fuji as my widest 8x10 lens!! I guess I'm
just not as extreme as I would like to think!! Maybe I've tamed with age! I
know I've gotten slower--in direct regard to getting that big lens list and
images together. I'm a real dragass turtle these days but I'll get it done!!
J Burke
"jjs" wrote in message
...
"Jos. Burke" wrote in message
...
Darn,
That 305 G Claron (CopaL #1 SHUTTER--IF SO EQUIPPED) sure is looking

Tooooo long, Joseph.

Say, when we we see the list of goodies you got?