# Calculating Bellows Extension from Magnification Factors? Anyone?

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• 02-25-2013, 02:30 PM
Mainecoonmaniac
Ralph Lambrecht author of Way Beyond Monochrome has a generous heart and has posted a templates online. There's one for calculating bellows extension and magnification. It's highly accurate and It's simple. Just print out the template, place the square target on your subject and measure fstop compensation with a ruler on the ground glass. I'm not good at math, so I use the template.

http://www.waybeyondmonochrome.com/W...mplatesEd2.pdf

I also recommend buying the book. It's helped me out a bunch. Cheers!
• 02-25-2013, 02:42 PM
Sparky
Quote:

Originally Posted by cliveh
Why don't you just meter at the focal plane?

why? when i can easily calculate the exposure based on the bellows draw (i always do it that way) - new F.L. squared over nominal FL squared...
• 02-25-2013, 02:51 PM
cliveh
Quote:

Originally Posted by Sparky
why? when i can easily calculate the exposure based on the bellows draw (i always do it that way) - new F.L. squared over nominal FL squared...

But is it not more likely that you could make an error in your calculations as opposed to reading the luminance at the focal plane? Or even do this to check you are correct?
• 02-25-2013, 02:59 PM
Sparky
Quote:

Originally Posted by Dan Fromm

Thanks - if you're referring to polyglot's post - I didn't see what I was looking for there. If you're referring to your OWN post - it wasn't at all clear to me that you were understanding what I was looking for. But only after seeing PP's post on the subject with the formulae I recognize the fxM constant... so - well.. thanks

Quote:

Originally Posted by Dan Fromm
What format are you shooting? I ask because the MicroNikkors sold for 35 mm cameras don't cover 4x5 at magnifications much below 4:1.

4x5. Should cover it just fine. I see no problems here.

Quote:

Originally Posted by Dan Fromm
Oh, and by the way, if you're going to use a MicroNikkor at magnifications > 1:1, it should be reversed. My tests of my 55/2.8 MicroNikkor AIS found that it is best at f/4 above 1:1 and that image quality rapidly vanishes as it is stopped down farther.

yes of course. I may be an idiot but I'm no fool! :) I've written and taught LOTS on technical photography over the years...

Personally, and through the findings of others (web pages with experiments and the like) I'm not so sure the practice holds up to the theory. I would go to a Zeiss Luminar directly ordinarily but it looks like others have found the Micro Nikkor superior for this application. I've also had ASTOUNDING successes with my own 1960s 180mm Sironar at 1:1 and beyond (as mentioned - enough for 40x50 prints - I get asked frequently if I've shot on 8x10 film! so that's good right?)

Quote:

Originally Posted by Dan Fromm
You and most of the participants in this thread should read a book. Two books, in fact, and the last time I looked the usual places (abebooks.com, alibris.com, amazon.com, ...) showed copies of both at reasonable prices.

Lefkowitz, Lester. 1979. The Manual of Close-Up Photography. Amphoto. Garden City, NY. 272 pp. ISBN 0-8174-2456-3 (hardbound) and 0-8174-2130-0 (softbound).

A thorough discussion of getting the magnification, lighting, and exposure. Especially good on working above 1:1. Extensive bibliography.

Gibson, H. Lou. Close-Up Photography and Photomacrography. 1970. Publication N-16. Eastman Kodak Co. Rochester, NY. 98+95+6 pp. The two sections were published separately as Kodak Publications N-12A and N-12B respectively. Republished in 1977 with changes and without the 6 page analytic supplement, which was published separately as Kodak Publication N-15. 1977 edition is ISBN 0-87985-206-2.

Gibson is very strong on lighting, exposure, and on what can and cannot be accomplished. His books, although relatively weak on getting the magnification with lenses made for modern SLR cameras, provide a very useful foundation for thinking about working at magnifications above 1:10 and especially above 1:1. Extensive bibliography.

Thanks for the suggestions - I've probably read far too many books on the subject as it is!! But I just don't have anything handy right now (they're all in storage) - Langford and LP Clerc are my go-to enclyclopaediae normally.
• 02-25-2013, 03:02 PM
Sparky
Quote:

Originally Posted by cliveh
But is it not more likely that you could make an error in your calculations as opposed to reading the luminance at the focal plane? Or even do this to check you are correct?

not really. that's why you do exposure tests. Shoot film and see where you're at. with such bellows extensions it's pretty easy to be close to dead on in my experience (you can be out by several mm and it really doesn't make a difference). I'm far more likely to have variations in strobe power or development etc than be off in my measuring...
• 02-25-2013, 03:03 PM
Sparky
Quote:

Originally Posted by Mainecoonmaniac
Ralph Lambrecht author of Way Beyond Monochrome has a generous heart and has posted a templates online. There's one for calculating bellows extension and magnification. It's highly accurate and It's simple. Just print out the template, place the square target on your subject and measure fstop compensation with a ruler on the ground glass. I'm not good at math, so I use the template.

http://www.waybeyondmonochrome.com/W...mplatesEd2.pdf

I also recommend buying the book. It's helped me out a bunch. Cheers!

Thanks - I probably have that book somewhere - sounds real familiar... though I might not have thought to consult it. I was just looking for a quick fix....
• 02-25-2013, 03:06 PM
Sparky
Quote:

Originally Posted by Dan Fromm
P_P, I won't accept responsibility for the OP's inability to read. I hope he/she/it gets the books, reads them, and learns to think for himself/herself/itself.

haha well I'm sorry if I offended you Dan. NOT my intention - as mentioned (just now) - your post seemed overly concerned with subject/film plane distances and it seemed as though you were on the wrong track. I didn't have the confidence enough in how you started out to be able to glean what I wanted from your post.
• 02-25-2013, 04:55 PM
Dan Fromm
Sparky, depending on the magnification you want to work at, you might be better off with a 40/4.5 Luminar or a 45/4.5 Mikrotar or even a 25/3.5 Luminar than with a 55/2.8 MicroNikkor. One guy on the French LF forum insists that a reversed 55/3.5 MicroNikkor shoots better above 1:1 than the f/2.8er. We have a late 3.5er in the house; to my everlasting shame, I've never tried it. If you ever look for a Mikrotar, be very cautious. I've met a couple that wouldn't focus; they were missing an element.

The shorter the lens, the less extension needed to get the magnification. Adapters for holding lenses in RMS thread in front of shutters (#0, #1) used to be fairly easy to find, but I haven't chased 'em for a while. I have mine ... Although my tubby little MicroNikkor edged out two 63/4.5 Luminars (mine and Charlie Barringer's), our 40s beat it at higher magnifications. Adapters to hold a reversed MicroNikkor in front of a shutter are much less expensive. And MicroNikkors are much less expensive than Luminars.

If you need a 25 and can find a clean 25/1.9 Cine Ektar II (clean makes a big difference and many are filthy inside) shot at f/2.8 beats the 25/3.5 Luminar (two examples) above 10:1.

Thinking of which, one thing that many people don't fully appreciate is that real macro lenses are usually optimized for a specific range of magnifications, sometimes fairly narrow, and perform poorly out of range. Systematic testing is the only way to find out for oneself.
• 02-25-2013, 08:27 PM
Sparky
Hi Dan - thanks for the input... it's simply that every single 'experiment' I've found comparing luminars to micro nikkors have found the micro nikkors comparable enough to be a wash for the purpose. Also- I really feel I should contest the comment about the official or 'scientific' point of view about the optimization of formulae. If that were IN FACT true - then we would see regular taking lenses and enlarger lenses (reversed of course) outperforming micro nikkors and the like. It's just not so apparently.

http://www.tonipuma.it/tecnica/63vs65/index.htm

http://savazzi.freehostia.com/photog...erlensespm.htm

there are a ton of other photomicrography pages on the subject... I've read many of them. I included the two above because they show sample images from each...
• 02-26-2013, 08:14 AM
Dan Fromm
Sparky, are you thinking of MICRONikkors, which are taking lenses for 35 mm still, intended for use up to 1:1 (exception, the 105/2.8 MicroNikkor AI/AIS, which goes to 0.88:1) or MACRONikkors, which are designed for photomacrography? I ask because the shortest MicroNikkor is the 55. MacroNikkors are competitive with Luminars, and the shorter Luminars are easier to use and better than a 55 MicroNikkor at high magnifications (> 10:1).

Optimization is one thing, lens quality is another. The photomacrographic lenses I tried out varied in best resolution (USAF 1951 on glass), most, not all, were best over a not too large range of magnifications. They're optimized.

Few enlarging lenses are used for photomacrography because few enlarging lenses are very good. I've found an exception, Wollensak's 101/5.6 Enlarging Pro Raptar, which is nearly as good from 1:4 to 4:1 as my 100/6.3 Neupolar and tied with a 100/6.3 Luminar. Against this result, Klaus Schmitt has one and doesn't regard it as anything special.
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