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Dan Fromm
12-31-2010, 02:50 PM
The relationship between NA and f/ number is NA = 1/(2f) where f is the f/ number. f/0.5 means NA =1, and so on.

NA is defined concisely here: http://micro.magnet.fsu.edu/primer/anatomy/numaperture.html

Diapositivo
01-01-2011, 02:33 PM
If the problem is depth of field, I suggest looking for a solution with movable planes, like a view camera, that allows you to use the Scheimpflug law.

Some bellows exist that allow you to turn - in the sole domain of macro photography - you camera in a "view" camera, with all movements. I think some of those, for 135 format, even have support for automatic diaphragm mechanism (diaphragm stays open for focusing and closes automatically when you take the picture).

Those bellows should exists both for 135 and 120 film cameras, but I suspect they are easier to find for 135.

I never used them so I am only giving a theoretical suggestion here.

Fabrizio

dynachrome
01-01-2011, 03:58 PM
If you do not have a sufficiently short lens on a view camera then you will need a huge amount of extension to get the magnification you are looking for. In any format not every lens is well corrected for macro work. With enough extension the desired magnification can be achieved but the image quailty may not be very good. In any macro situation you need to to align the film plane with the most important part of the subject to make the best use of the available depth of field. A typical 50-60mm macro lens for 35mm use will not be at its best at f/22. Some bellows usits for 35mm cameras have front standards with movements. These include the Nikon PB-4 and the Minolta Auto Bellows III. These movements can be used to fine tune depth of field. There was an interesting Spiratone bellows with interchangeable mounts which had movements.

In any situation where medium format or large format is being considered for use in preference to 35mm, you need to see whether the size of the subject on the negative/slide is larger than what you would get with 35mm. A subject which is 24X36mm in size and which is shot at 1:1 on 35mm film will give an image area of 24X36mm. If your medium format set-up gets you the same 1:1 magnification then the image area of the subject will be the same 24X36mm on film. In this example there was no benefit in using the larger format assuming that both cameras had the same film type in them. With the 6X9 format, for example, you would need 2:1 magnification to get the same subject to 48X72mm on film. How much image quality you would get because of less enlargement of the film would depend on how large you wanted to make the final print. For black & white work you have films like Imagelink HQ which can withstand great degrees of enlargement without showing grain. Color films like Ektar and Velvia 50 aren't nearly as good as Imakelink HQ when it comes to grain but are still very good. Once Kodak discontinued Kodachrome 25 it became necessary to go up in format for certain color work.

As a general proposition the smaller your subject the easier it is to handle with 35mm equipment. The 35mm equipment is more flexible and allows you to adapt many types of lenses, bellows, extension tubes etc. All of my medium format SLRs are Bronicas with electronically governed leaf shutter lenses. I could get a bellows for any of the three formats but a Mamiya 645 with a focal plane shutter would be more easily adapted for higher magnification close-up work.

BetterSense
01-01-2011, 04:39 PM
I ended up shooting with my 4x5 monorail and my Rodenstock 135mm enlarging lens, turned around backward, at f/32, 1:2 magnification onto film (f/90 effective). The contact prints look pretty nice so far but I haven't enlarged them yet. I don't have a fancy bellows setup for 35mm and I needed significant geometric distortion correction. My bellows is just barely enough, after I cut a custom lens board out of cardboard with 2 inches of down shift built in.

I still don't fully understand the fundamental differences between shooting to a smaller magnification on the negative and enlarging more, versus shooting to a larger magnification on the negative and enlarging less. Is it better to shoot 1:1 on 4x5 and enlarge to 8x10 or is it better to shoot 1:4 on 8x10? I'm still not sure.

Sirius Glass
01-01-2011, 04:45 PM
For a given image size, regardless of the format and focal length, there is a DOF for each f/stop.
Therefore:

A 1" image on in 35mm film will have the same depth of field for a 35mm, 50mm, 100mm lens. The perspective will be different.
A 1" image on in 4"x5" film will have the same depth of field for a 90mm, 150mm, 200mm lens. The perspective will be different.

You are photographing a sphere. Therefore shifts, tilts, ... will not change the DOF.

Now we have eliminated movements. The first question is what size image do you want on the film, and hence the amount of enlargement involved. This eliminates the question of grain as you specified in your first post.

The second question, given that either the 35mm or the 4"x5" cameras can be set up and focused on your subject, you can now take a longer exposure and increase the exposure time in a trade off for DOF. Therefore, which camera do you choose to use?
The smallest 35mm f/stop is typically f/16 with the best performance without diffraction is around f/8.
The smallest 4"x5" f/stop is typically f/32 with the best performance without diffraction is around f/22 or f/16.

In summary, for a given image size on film the focal length does not matter. DOF is a function of f/stop.
The object is a sphere and therefore movements will not help.
To increase DOF, lengthen the exposure.
So pick the camera which will work for you, given any diffraction issues that you have.

Steve

Dan Fromm
01-01-2011, 04:56 PM
Um, Steve, doesn't magnification matter too? Or are you talking about effective aperture?

Transparency, all that movements do is shift the plane of best focus around. This allows better use of the depth of field. At the magnifications and set apertures the original poster is using there is very little DoF. Movements won't create more.

Q.G.
01-01-2011, 06:17 PM
Um, Steve, doesn't magnification matter too?

That's covered in that "For a given image size".

Sirius Glass
01-01-2011, 06:21 PM
Thank you Q.G. for answering for me. I specifically said "For a given image size" for a reason that you are wise enough to understand why it was included. I hope that 2011 is a better year than 2010 for you!

For those that missed it. "For a given image size" takes out format questions.

Steve

Diapositivo
01-01-2011, 06:33 PM
Well, we don't know how small are the objects that the OP is going to photograph. I certainly agree that, if they all are spherical, there is no point in rotating the focus plane. One assumes a photographer does not only take pictures of exactly spherical objects, and if they are not all exactly spherical (watches, jewels, who knows) a rotation in focal plane might give a substantial help for the final image quality (let's say aligning the focus plane with the dial - thickness of the watch). But I never used a bellows with movements, althought I've read it helps, I would be glad to be able to give an answer validated by experience.

IIRC there was a Kenko bellows in the eighties (for 35mm) that had movements in both standards.

Fabrizio

Diapositivo
01-01-2011, 06:34 PM
Well, we don't know how small are the objects that the OP is going to photograph. I certainly agree that, if they all are spherical, there is no point in rotating the focus plane. One assumes a photographer does not only take pictures of exactly spherical objects, and if they are not all exactly spherical (watches, jewels, who knows) a rotation in focal plane might give a substantial help for the final image quality (let's say aligning the focus plane with the dial - thickness of the watch). I never used a bellows with movements though, althought I've read it helps, I would be glad to be able to give an answer validated by personal experience.

IIRC there was a Kenko bellows in the eighties (for 35mm) that had movements in both standards.

Fabrizio

Sirius Glass
01-01-2011, 06:40 PM
Well, we don't know how small are the objects that the OP is going to photograph. I certainly agree that, if they all are spherical, there is no point in rotating the focus plane. One assumes a photographer does not only take pictures of exactly spherical objects, and if they are not all exactly spherical (watches, jewels, who knows) a rotation in focal plane might give a substantial help for the final image quality (let's say aligning the focus plane with the dial - thickness of the watch). I never used a bellows with movements though, althought I've read it helps, I would be glad to be able to give an answer validated by personal experience.

IIRC there was a Kenko bellows in the eighties (for 35mm) that had movements in both standards.

Fabrizio

See post #3


Recently I have been trying to photograph a small round seed pod at about 1:1 with my Olympus OM1 and 50mm Macro with extension rings. I put the lens on f/22 which is probably an actual f/45 or so at 1:1. The 8x10 proofs I made aren't impressively sharp, and I think I have eliminated camera/subject motion as a cause.

The maximum size would be 1" or 24mm, Next question?

Steve

Q.G.
01-01-2011, 06:59 PM
The maximum size would be 1" or 24mm, Next question?

I would like to know what question this is supposed to be an answer to first.

ic-racer
01-01-2011, 07:34 PM
Smaller format always wins... unless you desire shallow depth of field.

Q.G.
01-01-2011, 07:45 PM
Smaller format always wins... unless you desire shallow depth of field.

I don't think so. And i don't think so.

Smaller formats push you towards a format driven approach much sooner, i.e force you - because of compositional reasons - to make do with less in-camera magnification.

And that same size image mentioned before also means same DoF, no matter what format.

Sirius Glass
01-01-2011, 08:09 PM
I would like to know what question this is supposed to be an answer to first.

The question I answered was based on 35mm film. The maximum image size of a complete sphere on 35mm film would be 24mm. Therefore a 1 inch image on film would be the maximum size image that could be recorded on 35mm film. If the OP, as stated, did not care about the film format, 1 inch or approximately 24mm would be the maximum image size on film that the OP would be considering. The rest follows the logic out lined by the Greek philosophers approximately 2,500 to 3,500 years ago. The rest is supplied by W. Smith's book on optics, which is considered at many universities as a starting place for studying optics.

Any more hairs to split??

Steve

Q.G.
01-01-2011, 08:37 PM
The question I answered was based on 35mm film. The maximum image size of a complete sphere on 35mm film would be 24mm. Therefore a 1 inch image on film would be the maximum size image that could be recorded on 35mm film. If the OP, as stated, did not care about the film format, 1 inch or approximately 24mm would be the maximum image size on film that the OP would be considering. The rest follows the logic out lined by the Greek philosophers approximately 2,500 to 3,500 years ago. The rest is supplied by W. Smith's book on optics, which is considered at many universities as a starting place for studying optics.

Any more hairs to split??

Steve

Apart from quite a few in this post, yes.
And you call them hairs... It's something thicker than a hair.

Better sense complained about the lack of image quality at f/45 (effectively), and your answer was: 1 inch or 24 mm.
Have you been emptying left over bottles from a new years eve party?

lxdude
01-01-2011, 09:24 PM
Any more hairs to split??

Steve

OO! I got one!
1 inch is actually 25.4 millimeters.

There.

hpulley
01-01-2011, 09:41 PM
I think the point, said several times already, has still been missed though. A 50mm macro lens at focusing distance for 1:1 renders a 24mm object as 24mm on film regardless of film size or format. It is 24mm on 135, 120, 4x5 or 8x10 film. The depth of field will be the same too if the aperture is the same as the focal length and subject distance will be the same. Diffraction effects will also be the same at the same aperture. Printing the image to the same scale for the object will yield the same results given equal lens performance.

Things will only change if you decide that rather than 1:1 macro (which is what the OP asked for) you want to fill the piece of film with the image of your object. Then you need 1:1 on 135, ~2:1 (approximately double lifesize) on 120, 4:1 on 4x5 or 8:1 on 8x10 which will require you to change the focal length or subject distance which will change the depth of field and may require different apertures, yielding different diffraction effects. Printing the object to the same object scale will yield different results.

For diffraction you need to see the smallest detail you need to capture. f/22 is surely too small. f/11 would be much better and f/8 might be better still but you may then have too narrow a depth of field for even a seed especially if you go beyond 1:1 which you may need to do for a small seed even on 35mm film.

Sirius Glass
01-01-2011, 10:23 PM
OO! I got one!
1 inch is actually 25.4 millimeters.

There.

I said that 24mm was approximately 1 inch. Actually 24mm would not let the edges of the sphere show. By making the approximation and then using that image size, I was eliminating the format size from the question.

'dude, you gotta start drinkin' later in the day. :laugh:

Steve

BetterSense
01-01-2011, 10:31 PM
Things will only change if you decide that rather than 1:1 macro (which is what the OP asked for) you want to fill the piece of film with the image of your object. Then you need 1:1 on 135, ~2:1 (approximately double lifesize) on 120, 4:1 on 4x5

Exactly. But, you will have to enlarge the 4x5 sheet 1/4 as much as the 35mm! So does it all cancel out? Does shooting at 4:1 then contact printing have any advantage over shooting at 1:1 and enlarging 4x?

People talk like shooting to smaller magnification and enlarging is better than shooting at larger magnification then enlarging less. At least that's the way it seems because they always advocate 35mm for macro applications and say leave the view camera at home. Landscape, it's exactly the opposite, both for supposed image quality reasons.