Questions about Macro with non-macro lens

[StoneNYC]

To expand a little on the point made by mdarnton and maris rusis, for all film-to-subject distances except 4f + i, where f is the lens' length and i is the lens' internodal distance, there are two magnifications (1:n and n:1) at which the subject will be in focus. In normal photography this doesn't matter -- with a distant subject this isn't a problem -- but in close-up work it can be a killer. This is why focusing by changing extension with the film-to-subject distance fixed is so problematic close-up.

When the film-to-subject distance is 4f + i the magnification is 1:1. At all other magnifications the film-to-subject distance is greater than 4f + 1. Set up the camera and subject so that the film-to-subject distance is less than 4f + i and getting the subject in focus by changing extension with the film-to-subject distance fixed will be impossible.

This is why most photographers who work at near distances set up the camera-lens assembly to give the desired magnification and then move it or the subject to position the plane of best focus as desired.

Thanks everyone for the input.

Bob, I wasn't trying for 2:1, just trying for a little more than 1:1 which is all I have for extension (325ish)

And Dan, I had wondered why when I was shooting macro with my RZ67 and extension tubes, why I discovered at one point that there were two distances that were in focus and was very confused but was shooting a model and didn't have time to think about it or investigate it at the time and it slipped my mind until just now.

I still don't at all understand the math part, I'll have to look at what you said again in the morning with a clear head, or ask my dad to help explain it.

But you are suggesting doing math ahead of time, and setting the camera that way prior to shooting, that would be difficult with how I work, not just because I can't do the math, but that when shooting fast with a model, I don't have the time to pre-set-up. I know that sounds backward but macro is always the last thing I do as it's the most ... Intimate... So I prefer to wait till they are comfortable before doing that work.

If it's a still life macro I could certainly do that though.

Thanks to everyone else who mentioned back focus, I feel foolish not understanding that at first, I couldn't figure out how using front over back would make a difference till it was mentioned about the subject distance changing on the lens side... DUH! I feel foolish not thinking along those lines.

I will also try back focus next time, especially if I can't figure out the math bit.

[tgtaylor]

As you may have already noticed, every lens has a minimum focus distance: the closest the front of the lens can get to a subject and still focus it. Sometimes that distance is noted in the manufacturers lens data and sometimes it is not. Once that distance is determined, I would place the subject at that distance from the lens and apply the formula noted above for the required magnification. Having your camera/tripod mounted on a dolly and moving it forward or backward instead of relocating the subject facilitates focusing. I have used this dolly with a Toyo 810G and series 5 Gitzo tripod: http://www.bhphotovideo.com/c/produc...ly_with_3.html

Thomas

[StoneNYC]

As you may have already noticed, every lens has a minimum focus distance: the closest the front of the lens can get to a subject and still focus it. Sometimes that distance is noted in the manufacturers lens data and sometimes it is not. Once that distance is determined, I would place the subject at that distance from the lens and apply the formula noted above for the required magnification. Having your camera/tripod mounted on a dolly and moving it forward or backward instead of relocating the subject facilitates focusing. I have used this dolly with a Toyo 810G and series 5 Gitzo tripod: http://www.bhphotovideo.com/c/produc...ly_with_3.html

Thomas

Thanks.

[Tin Can]

Thanks for the handy and simple Toyo macro formula.

Nice!

http://www.toyoview.com/Products/Acc...s/45AIIac.html See the formula at the bottom of the page.

Thomas

[pasiasty]

As you may have already noticed, every lens has a minimum focus distance: the closest the front of the lens can get to a subject and still focus it.

That's true for medium and small format lenses, where the barrel determines maximum extension, but even there you can overcome this limit with tubes or bellows. In case of large format a lens there is recommended magnification ratio range, for which the lens is optimised - but this does not prevent you using for sub-optimal magnification; you only have to accept some quality (mostly sharpness) deterioration and to have enough bellows extension.

[StoneNYC]

That's true for medium and small format lenses, where the barrel determines maximum extension, but even there you can overcome this limit with tubes or bellows. In case of large format a lens there is recommended magnification ratio range, for which the lens is optimised - but this does not prevent you using for sub-optimal magnification; you only have to accept some quality (mostly sharpness) deterioration and to have enough bellows extension.

There's always a limit somewhere... I couldn't shoot Protozoa even with enough light and bellows lol

[Dan Fromm]

Stone, there are limits and there are limits. The practical limit for photomacrography (photography with a single stage of magnification) is no higher 50:1, with a short lens and a lot of extension. Beyond that a compound microscope is preferable. The theoretical limit is as big as you want. Think of van Leewenhoek's simple microscope.

About intimacy and all that. Keep your distance from the model. To be exact, the front of the lens can't be closer than f to the model. That's the theoretical limit. With your extension and focal length, the practical limit is around 2f.

[Drew Bedo]

[B]
Camera: Kodak 2D (8x10)
Lens: 90mm/f8 Nikkor
Film: Ektascan film (Ultrasound/Nuc-Med film) rated at 200
Lighting: Two Vivitar 283 strobes at under 12"

I set up the camera and cranked it out to the end of the standard rail, without the rear extension. Then clamped a picture frame in front and taped a piece of paper with a strong pattern to the rear of the frame. I got behind the camera and slid it forward and back on the tripod sliding block till it was in focus. OK, this part took a bit of time and involved fooling with both the camera tripod and the picture frame. When things were pretty close to being right, I put a smaller target in to find the fine focus and locate the center. Then set up the strobes and did some exposure testing with a flash meter.

When it looked like everything was right, I sat down behind the picture frame and removed the paper target. My forehead went up against the top of the picture frame and I reached out to trip the shutter with a short cable release.

Made several exposures of my left eye.. The image on the left looked the most dramatic and is usually the one I show. It is printed reversed because that is how I see myself in the mirror. The other one is how everyone else sees me.

The negative is 8x10 and the image is at least life-sized or 1:1. I didn't record the exact data on magnification, bellows extension or exposure correction etc. The film was developed in a automatic processor in the X-Ray darkroom at the clinic where I worked at the time.

With all that said: I am sure that this technique could be refined.

Any help? Let us know what you do and post a few images.

[tgtaylor]

Here’s an equation that was supplied by Nikon with the 610mm Apo-Nikkor lens:

A= (2+M+1/M)*f
A= overall working distance
M=reproduction ratio
f=focal length of the lens

The equation given for determining the bellows extension is the same given by Toyo in the post above.

Thus the overall working distance for a 150mm lens @ 1:1 is:
A= (2+1+1/1)*150 = 4*150=600mm. So the lens should be placed 300mm from the subject. Note: The above equation is approximate and will be exact only when using “the precise data on the inspection card included with the lens."

Thomas

[StoneNYC]

Stone, there are limits and there are limits. The practical limit for photomacrography (photography with a single stage of magnification) is no higher 50:1, with a short lens and a lot of extension. Beyond that a compound microscope is preferable. The theoretical limit is as big as you want. Think of van Leewenhoek's simple microscope.

About intimacy and all that. Keep your distance from the model. To be exact, the front of the lens can't be closer than f to the model. That's the theoretical limit. With your extension and focal length, the practical limit is around 2f.

Thanks that made sense to me thank goodness.

Thanks to the other two who posted some examples and some help just now, but it was less helpful and left me brain-hurt.

What I surmise is simply that I'm limited by my camera spelling, and that anything more than 1 to 1 isn't really going to happen unless I use a lens that is going to add some really bad distortion like a 90mm.

And for the subject matter at hand, which is normally not eyes, distortion would be a really bad thing.

There is a gentleman on here, who has a really nice toyo rail camera for like 200 bucks which I totally want to purchase, however he knows the subject matter that I'm shooting and feels that it's not something he wants his camera to be subjected to, which I thought was a really interesting turn of events however such is life and it's his choice because it's his camera