Lens mm differences

[bernard_wiessner1]

Does anyone know what the ground level difference in linear feet

would be between a 105mm lens and a 135mm lens?

 

Thanks to all.

[oceanphysics]

I'd say almost six linear feet above ground level when the camera it's attached to is up to my eye, or four linear feet above ground level when it's hanging around my neck on a strap.

 

What in the world are you asking?

[frank_skomial]

Not being able to answer this quastion kind of upsets me...

 

Perhaps the difference between 135 - 105 mm is 30 mm, or 3 cm.

 

If you want this in feet, then if 1 foot at ground level has about 30 cm, so the answer could be 1/10 of foot. Then again.. this could be true but only at the ground level, otherwise it can be totally wrong.

[frank uhlig]

Well, 135mm minus 105mm is 30 mm difference, or (an inch is about 25mm) 1 1/4 inches, or 1/10 of a linear foot (12 inches to a foot).

 

If that is what you were wondering. But that makes as little sense as your question does to me. Whose ground level, what has that to do with anything ... ? photographic?

 

Good luck sorting this one out, Bernard!

[SCL]

Bernard - would you care to explain your question...as it stands it makes no sense whatsoever.

[bernard_frank]

I think what Bernard means is how many feet would you have to walk towards your subject

to get the same crop with the 135 as with the 105.

 

Am I right, Bernard?

 

Now, I'm sorry but I don't have the answer :)

[david_h._hartman]

Maybe what he is interested in is image or lens magnification? If not I don't have a clue what he's on about.

[NetR]

>I think what Bernard means is how many feet would you have to walk towards your subject to get the same crop with the 135 as with the 105.

 

That's what I think Bernard means too. The geometry is linear, so you would need to be 105/135 as far away to get the same image size with a 135mm lens as you would with a 105mm lens = 78% as far, so you move in 22% closer. How far that is depends on how far away the subject is. For a subject at infinity, 22% of infinity is still a long walk ;-) For many optical purposes infinity is about 10m, so around 8m would be equivalent, but it depends very much on your subject and desired depth of field.

 

Regards, Ross

[b2 -]

If BF is right (and I think he is), you need to keep in mind that the difference will change as your initial distance from the subject changes. I think it's a percentage of the distance perhaps.

 

Just for example (these are NOT the right numbers)!

 

Lets say that at 10 feet with a 135, you need to go to 11 feet with a 105. But at 20 feet it might be 22, and at 5, it might be 5 1/2. Just guesses.

 

Perhaps someone out there with a 80-200 sitting around and a few seconds (and a tape measure) could find out for us.

 

Come on, some one has to have that grand old KING of the zooms (I made the mistake of selling the one I had back to my brother-inlaw with the F3 a few years back, UGH!).

 

B2 (;->

[anupam]

The galleries have a photo of the week. The forums should have a riddle of the week.

[rob_murray]

It might be easier to buy a zoom lens instead.. or walk a couple steps

closer using the 105 lens or use the 135 lens and take a couple steps back...my head hurts now....

[david_h._hartman]

If one is shooting portraits, one typical use of these lenses,

you shoot from about 2 meters and the perspective is the same as

your point of view or subject to lens is the same. The difference

is you get a head and shoulders portrait with the 105mm lens and

a tight head shot with the 135mm.<br>

<br>

My preference on film is the 105/2.5 AIS but I own a 135/2.8 AIS

also. They are sufficiently different for my purposes.<br>

<br>

The 135/2.8 AIS makes a great medium telephoto on the DX formats.

With the D2H its about like a 210mm lens on film, about

like a 205mm on the D2X.<br>

<br>

Regards,<br>

<br>

Dave Hartman.

[briany]

It really is a stunning question.. "whatchu talkin bout, Willis?" <br> <a href="http://home.aut.ac.nz/staff/rvink/nikon.html"> http://home.aut.ac.nz/staff/rvink/nikon.html</a><br>

If you're talking about the AF DC versions and lay them on their side, the 105 is 111mm, and the 135 is 120mm, so the difference in linear feet would be 9/25.4/12 = .0295 linear feet. Linear feet, mind you.. if you want board feet, it's a whole 'nother story....

[david_h._hartman]

<em>It might be easier to buy a zoom lens instead.. or

walk a couple steps closer using the 105 lens or use the 135 lens

and take a couple steps back...my head hurts now.... --Rob

Murray<br>

</em><br>

This depends on what you want. If the perspective is important or

the relationship and size of background objects zooming and

walking are different. When you zoom in the perspective says the

same as the angle of view gets tighter. You take in less of the

background. When you walk and the focal length is constant the

point of view changes and so does the perspective.<br>

<br>

If you move back and use a longer focal length you take in less

background. A slight change in position, left or right, may allow

considerable selection of background properties with telephotos.

For example you might avoid a confusing background or select a

dark or light background for contrast with your subject.<br>

<br>

The bokeh (excuse me ;-) of the 105/2.5 AIS and 135/2.8 AIS is

quite similar wide open but the size of the blobs will be larger

with the 135/2.8. I dont know where it is now but I did an

experiment with a nasty little point light source background hot

spot. The lenses were focused at 2m while the light, a bare AAA

Mini-Mag flashlight (as a candle) was at 5m. There are comparison

photos lost in the archives. <br>

<br>

There are different esthetic possibilities available with just a

change form 105mm to 135mm. I prefer manual focus primes if I

will be shooting a number of shots at one distance with one focal

length. To me they just handle better. I also love my AF zooms

where things are more random. The primes are great for high flare

situations. My 80~200/2.8D ED AF Zoom-Nikkor isnt nearly as

graceful when turned towards the sun as my 105/2.5 AIS.<br>

<br>

Its often been said that you can learn more about

perspective with prime lenses. I disagree, I think one can learn

equally well with either primes or zooms provided that they know

that its the point of view, not the focal length that make

the difference.<br>

<br>

Regards,<br>

<br>

Dave Hartman.

[b2 -]

..... The bokeh (excuse me ;-) ....

 

God Bless You

 

B2 (;->

[ilkka]

Lot of good answers to a question nobody understands.

[gaius1]

Download <a href="http://tangentsoft.net/fcalc/win32.html">f/Calc</a>.

[csuzor]

That is great little program Guy, thanks. Along with the online DOF plotter, both are indispensible.

[bernard_frank]

I love this forum!

 

BTW, where has Bernard Wiessner gone?

[Ed_Ingold]

This undecipherable question had the same effect as a bad packet on the internet - blue screen - dump everything you know.

[alex_lofquist]

D=cosh height(ft) x FL/DOF x T (in degrees kelvin) x coeff of linear expansion for each mile above the center of the earth. This applies strictly for only land forms. If the photographer uses the left eye the correction is small but noticeable. Variation in latitude affect the corliolis force and require an additional correction. A GPS is advised here!