View Full Version : Need some help with these lenses

alex from holland

16-Sep-2011, 14:12

I recently acquired the following lenses for my large wet plate adventure,

Nikkor apo 480 mm 1:9 (beautfull lens, light and even fits in a large universal iris !)

rodenstock klimsch apo ronar s 800mm 1:9 (heaaaaavy)

although they are slow ( at least for wet plate) i want to try them outside for landscape. I treid to find some info about these lenses in the net, but so many answers...

what is the coverage of these lenses ????

Alex

Dan Fromm

16-Sep-2011, 15:07

According to Nikon, the 480/9 Apo-Nikkor covers 46º, probably at f/22.

Rodenstock claims 42º at f/32 for the 800/9 Apo-Ronar.

You'll find claims that these lenses cover enormous circles. This is true, but at 1:1, not at infinity. Many of the published circles are for 1:1.

alex from holland

16-Sep-2011, 23:22

Thanks !

But how about wide open ?

I think i will have to use them open as collodion is slow.

Alex

alex from holland

18-Sep-2011, 03:40

anyone ?

alex

Hermes07

18-Sep-2011, 04:42

Alex, they don't gain a huge amount coverage-wise by stopping down. Don't have either of those focal lengths so I can't give you an exact answer though. Don't imagine they get used much wide open at infinity so you won't get many replies.

What plate size are you aiming for?

alex from holland

18-Sep-2011, 05:35

Alex, they don't gain a huge amount coverage-wise by stopping down. Don't have either of those focal lengths so I can't give you an exact answer though. Don't imagine they get used much wide open at infinity so you won't get many replies.

What plate size are you aiming for?

My new camera is 20 x 20 "wet plate.

I love to uselenses wide open as i prefer to have shallow dof.

alex

IanMazursky

18-Sep-2011, 23:52

The 480 APO Nikkor covers my 12x20 Korona nicely with plenty of room for movements.

I haven’t tried it wide open but around F22/32 it covers with enough room for a good 2-4” of rise.

Dan Fromm

19-Sep-2011, 04:26

Alex, I gave you the angles covered. Do the arithmetic to convert to circles.

alex from holland

19-Sep-2011, 08:08

Dan,

this may sound stupid, but i don't have the knowledge to do so.

This is a new world for me......

Jim Graves

19-Sep-2011, 08:32

this may sound stupid, but i don't have the knowledge to do so.

This is a new world for me......

Not "stupid" at all ... I've been doing this for 5 years, have 20+ lenses and don't have a clue how to figure out image circle from the angle of coverage information ... and we're probably in the majority here.

Dan Fromm

19-Sep-2011, 08:32

Oh my. Every Netherlander I've ever met has tried to convince me that he/she/it was better educated than me, ignorant barbarian that I am. Oh my. What is the world coming to?

In Excel, circle covered's diameter = focal length*2*TAN(RADIANS(angle/2))

alex from holland

19-Sep-2011, 09:28

Not all Dutch people are the same....

thanks

alex

Miguel Coquis

19-Sep-2011, 13:09

an + 2 = an − qn + 2an + 1 = aun + bvn − qn + 2(aun + 1 + bvn + 1) = a(un − qn + 2un + 1) + b(vn − qn + 2vn + 1)1

2

3

4

(define eucl

(lambda (x u v x2 u2 v2)

(cond ((= x2 0) (list x u v))

(else eucl x2 u2 v2 (- x (* x2 (/ x x2))) (- u (* u2 (/ x x2))) (- v (* v2 (/ x x2)))))))

no ?

Jim Graves

19-Sep-2011, 19:57

circle covered's diameter = focal length*2*TAN(RADIANS(angle/2))

Dan ... I'm assuming that FL*2 is FL times 2 and not FL squared. And, what is TAN(RADIANS(angle/2)) ... is that simply half the angle of coverage converted to radians? Does "TAN" stand for tangent or something else? It's time I learned this stuff! Thanks

Dan Fromm

20-Sep-2011, 05:23

Jim, in Excel the ways to say "x squared" are x**2 and x^2. x*2 means x times 2.

TAN is an Excel function, TAN(x) returns the tangent of x.

We usually talk about angles using degrees. RADIANS is an Excel function that converts degrees to radians. It is used in the Excel formula I posted because TAN(x) expects that x will be in radians.

I gave the formula in Excel pseudo-code because many, clearly not all, of us have Excel or a compatible spreadsheet.

Jim Graves

20-Sep-2011, 07:30

circle covered's diameter = focal length*2*TAN(RADIANS(angle/2))

Okay ... Thanks!

So for the 488mm lens with the 46 degree angle of coverage:

1) I opened Excel

2) Left clicked on the fx near the top of the spreadsheet

3) Selected the "Math & Trig" category

4) Scrolled down the list to "Radians" and left-clicked on it and then left-clicked on "OK"

5) Entered "23" in the box titled "Angle" that popped up [23 being 1/2 of the 46 degree angle of coverage of the lens in question]

6) Wrote down the resulting answer of 0.401425728 radians

7) Closed the box and deleted "=RADIANS(23)" from behind the fx symbol on the spreadsheet

8) Left clicked on the fx near the top of the spreadsheet

9) Delected the "Math & Trig" category

10) Scrolled down the list to "TAN" and left-clicked on it and then left-clicked on "OK"

11) Entered "0.401425728" in the box titled "Angle" that popped up [the radians I got in the previous calculation]

12) Wrote down the resulting answer of 0.424474816

13) Substituted the values of 488 (focal length) and 0.424474816 (TAN(RADIANS(angle/2) into your equation and got 488*2*0.424474816 = 414.287 mm for the diameter of the image circle

Did I get it right?

Dan Fromm

20-Sep-2011, 07:39

Okay ... Thanks!

So for the 488mm lens with the 46 degree angle of coverage:

1) I opened Excel

2) left clicked on the fx near the top of the spreadsheet

3)selected the "Math & Trig" category

4) scrolled down the list to "Radians" and left-clicked on it and then left-clicked on "OK"

5) entered "23" in the box titled "Angle" that popped up [23 being 1/2 of the 46 degree angle of coverage of the lens in question]

6) wrote down the resulting answer of 0.401425728 radians

7) closed the box and deleted "=RADIANS(23)" from behind the fx symbol on the spreadsheet

I do it the easy way.

put focal length in a1 In your example, 488 goes in a1

put angle, in degrees in b1 In your example 46 goes in b1

put =A1*2*TAN(RADIANS(B1/2)) in c1 In your example, 414.2874206 pops up in c1

save the spreadsheet, and whenever I want to try a different focal length put it in a1, whenever I want to try a different angle put it in b1

Jim Graves

20-Sep-2011, 08:15

Dan ... thanks ... that is what I will do ... WAY easier!.

On my previous entry, I inadvertently posted it before I finished my list ... I edited as quickly as I could to add the rest (including the answer I got) but you had already answered before I got it done ... hence the incomplete quote of my earlier post in your response.

Jim Galli

20-Sep-2011, 10:35

Take your $1 plastic protractor (http://www.google.com/products/catalog?hl=en&biw=1152&bih=735&q=plastic+protractor&gs_upl=1537l8304l0l11088l18l18l0l3l3l1l367l3714l1.3.6.5l15l0&um=1&ie=UTF-8&tbm=shop&cid=2653085675597616431&sa=X&ei=a854Tohi5J6xAvfjudAN&ved=0CGsQ8wIwAg) and from a point on graph paper draw a 21 degree angle. From the axis, now draw the other one below. That's 42 degrees. Now on your graph paper make each block equal 20 millimeters. Go out 800 and draw a line that intersects your 42 degree angles. Add up the blocks. Bingo, that's your circle. If a dolt like me can do it, anyone can.

Dan Fromm

20-Sep-2011, 11:19

Jimbo, analog vs. digital. Both work, but graph paper is awfully scarce in my house.

If your lazy you could just use this calculator (http://imaginatorium.org/stuff/angle.htm). Enter your focal length and your desired width and height of the format in mm. Hit calculate. If your Diagonal angle is less than the stated coverage of the lens your golden.

Jim Graves

20-Sep-2011, 12:03

Jimbo, analog vs. digital. Both work, but graph paper is awfully scarce in my house.

I have 3 different tablets of graph paper on my shelf ... which goes a long way towards explaining why I had so much trouble figuring out the computer version!

Jim Galli

20-Sep-2011, 12:05

I have 3 different tablets of graph paper on my shelf ... which goes a long way towards explaining why I had so much trouble figuring out the computer version!

Graph paper and slide rules put men on the moon :p

alex from holland

20-Sep-2011, 12:51

Take your $1 plastic protractor (http://www.google.com/products/catalog?hl=en&biw=1152&bih=735&q=plastic+protractor&gs_upl=1537l8304l0l11088l18l18l0l3l3l1l367l3714l1.3.6.5l15l0&um=1&ie=UTF-8&tbm=shop&cid=2653085675597616431&sa=X&ei=a854Tohi5J6xAvfjudAN&ved=0CGsQ8wIwAg) and from a point on graph paper draw a 21 degree angle. From the axis, now draw the other one below. That's 42 degrees. Now on your graph paper make each block equal 20 millimeters. Go out 800 and draw a line that intersects your 42 degree angles. Add up the blocks. Bingo, that's your circle. If a dolt like me can do it, anyone can.

it would be nice if someone would make a small movie of that and put it on youtube....

alex

Graph paper and slide rules put men on the moon :p

so some say.....;)

it would be nice if someone would make a small movie of that and put it on youtube....

alex

me me me ! iw ill do it. i love making movies of jim galli! so much fun.

bwah ha ha ha!

be by soon jim....beware!'

eddie

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