Help with lens choice for extreme close up on 8X10

[DrTang]

No, Dan.




and moving the camera
But people don't do that in the real world.

if one is shooting 1:1 - I'm guessing they are going to be moving the camera

[Taija71A]

I knew that this was going to happen...

... I guess my question is pretty basic - at 1:1 will the 115mm lens offer more depth of field than the 150mm lens when both are stopped down to f/45?

At the same magnification and relative aperture and desired image quality (that's what the dread circle of confusion is about) all lenses give the same depth of field...

Since, the OP 'clearly' stated his Parameters to begin with (1:1 Magnification and f/45 Aperture)... Dan's answer was of course correct.

Yes, if you want 1:1 magnification you must move the camera when changing lenses. But why would you do that?
At 1:1 you get the same Dof with any lens, so why change lenses in the first place?

Why would you do that? Leigh, one very good reason for 'Changing' Lenses...
Was already stated by Bob in Post #4. Thank-you! -Tim.

"You can't teach an old dog new tricks."
~~ John Fitzherbert. ~~

[Dan Fromm]

Leigh, I don't understand why I wouldn't have to move the camera closer or farther away to achieve the desired magnification when changing lenses. How could we assume that just changing the lens will give me the desired magnification without some modification of the camera to subject distance?

Randy, I caught my train, went into town, ...

To answer your question, here's how I understand the relationship between focal length, magnification and film-to-subject distance:

First, the lens front node-to-subject distance is focal length * (magnification + 1)/magnification

Second, the lens rear node-to-subject distance is focal length * (magnification +1)

With LF lenses we usually treat the internodal distance as zero (0). For most of the lenses we use it is much smaller than focal length.

Substituting and ignoring internodal distance, film plane-to-subject distance is focal length *(magnification +1) * (1 + 1/magnification). If you want to be more precise than necessary, add internodal distance to the total.

Now do you see why changing focal length changes all the distances?

If you do a little fiddling, you'll see that when magnification = 1 film plane-to-subject distance is 4 focal lengths. Also that for every other film plane-to-subject distance there's a pair of magnifications that give the distance. For example 1:2 (magnification = 0.5) and 2:1 (magnification = 2) both give film plane-to-subject distance 4.5 focal lengths. This why standard practice to focus at near distances is to set the camera-lens distance to give the desired magnification and then focus by moving the camera/lens assembly as a unit. Focusing the usual way (by adjusting extension) risks finding focus at the wrong magnification.

If you're serious about learning closeup/macro photography, buy a copy of Lester Lefkowitz' book The Manual of Closeup Photography. Out of print, usually available used at reasonable prices from vendors on abebooks.com, alibris.com, amazon.com, ...

[John Kasaian]

I've had good luck at 1:1 with the 159mm Wollensak WA Yellow Dot.
Just throwin' it out there

[Leigh]

Second, the lens rear node-to-subject distance is focal length * (magnification +1)

i believe you meant the rear node-to-film distance.

- Leigh

[Dan Fromm]

i believe you meant the rear node-to-film distance.

- Leigh

Thanks for the correction.

[Jac@stafford.net]

I presume the OP is photographing a three-dimensional object.

Doesn't spherical aberration contribute to a sense of greater DOF?

[Dan Fromm]

I presume the OP is photographing a three-dimensional object.

Doesn't spherical aberration contribute to a sense of greater DOF?

Nice fantasy.

Its brother "curvature of field improves DoF when shooting 3D objects" is equally bad. Interesting idea, but finding a lens whose curvature of field gives a field that conforms to a specific 3D object isn't easy. Since the 3D objects we photograph aren't all alike, we'll need heaps of lenses ...

[Joshua Dunn]

Randy,

I know you are considering the 150mm Konica Hexanon GRII and the Calter II-N 115mm but have you considered shooting with a Nikkor AM ED 210mm? It is a macro lens and was designed to do exactly what you are trying to achieve, photograph at 1:1 on 8x10.

-Joshua

[Leigh]

have you considered shooting with a Nikkor AM ED 210mm?
It is a macro lens and was designed to do exactly what you are trying to achieve, photograph at 1:1 on 8x10.

That lens has a 400mm image circle at 1:1.

That's more than adequate for 8x10 (325mm diagonal) with significant movements.

- Leigh