Calculating Bellows Extension from Magnification Factors? Anyone?

[Sparky]

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/WBM2/Library_files/TemplatesEd2.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....

 

[Sparky]

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.

 

[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.

 

[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/photography/enlargerlensespm.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...

 

[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.

 

[Sparky]

no. micro nikkors. Specifically the venerable 55/2.8 i was thinking. apparently it IS quite competitive with the luminars if you would just take a second and visit a few of the pages I posted you can see for yourself...

 

[Dan Fromm]

no. micro nikkors. Specifically the venerable 55/2.8 i was thinking. apparently it IS quite competitive with the luminars if you would just take a second and visit a few of the pages I posted you can see for yourself...

We're not as far apart as it seems. The 55/2.8 MicroNikkor reversed and shot at f/4 is indeed competitive with the 63/4.5 shot wide open, its best aperture. With the 40 and 25 Luminars at their recommended magnifications shot wide open, maybe, but at the cost of considerably more extension. Not competitive with the 16/2.5, which benefits from having a larger numerical aperture.

Note the qualifications. The 55 MicroNikkor's major advantage over shorter Luminars, if the extension can be obtained and managed, is somewhat greater working distance. Its major advantage over all of them is cost.

Um, er, ah, about tests that don't have features at a range of spacings, well, they're really acceptance tests. The lens can resolve the features in front of it or it can't, but the test tells nothing about whether it can separate more closely spaced features. Most of the tests I've seen on the 'net were done at arbitrarily selected magnifications, not stepping over a range of magnifications. Klaus Schmitt and I had a strong disagreement about this some years ago. He tested every lens he had by shooting a microchip at 10x. This is a fine test for deciding which lens to use at 10x for subjects with features spaced no closer than the chip's closest features but isn't very informative about which lens to use at other magnifications with subjects whose key features are more finely spaced. If you want to know what a macro lens will do, shoot the USAF 1951 on glass at a range of magnifications. This is what I did after I got organized and this is why I insist that most macro lenses are optimized for a range of magnifications and have an optimum aperture that sometimes varies with magnification. It all comes down to asking the right question in an appropriate way.

 

[Sparky]

well yes agreed and agreed I suppose. All other things being equal - which they seldom are (in my experience anyway).

Thinks like the perez-thalmann lens resolution tests drive me a little bit crazy. I think they are GROSSLY misleading (although the fact that the results are all OVER the place prove this to a degree) due to only using a single sample of EACH lens - and then again - each from an unknown origin - in the meantime lens cell spacers are lost, cells are put on the wrong shutters, the variation in manufacturing tolerances can be very significant, etc etc etc...

This is not a comment directly on your discussion of testing - so much as venting about 'limited sampling' - even doing EXTENSIVE tests but only with a single sample can be misleading. It violates the first principle of scientific testing - which is 'take many many samples!'

But then again - who has time?

 

[Sparky]

as for using the 55 micro 2.8 - the 600 to 800mm of extension required to get the 10x is FINE. It's not an IDEAL setup but I've gotten stunning results with a 180mm sironar at 1:1 with it. Just a Sinar P2 clamped to two rall clamps bolted to a masonry wall. Pretty solid especially since everything is being shot with strobe...

 

[Dan Fromm]

Sparky, when I was testing macro lenses I had the good luck to have access to the late Charlie Barringer's collection. So I tried multiple examples of some, not all, of them. They weren't all equally good. Surprising bad results generated a retest to check for operator error. Many are the ways to screw things up.

You're a little unjust to Kerry and Chris. They did a small pile of 90 Angulons, got interesting results. They're not all equally good and even late ones can be awful. Still and all, without resources one uses or tests what one has and hopes for the best.

With used lenses, condition is always a crapshoot.

When I was testing I was motivated by curiosity and by a goal, of shooting 2x3 macro with my 2x3 Graphics. So I really needed short lenses because of problems getting the extension. I eventually solved the extension problem by making a tandem Graphic -- two 2x3 Graphics front-to-back with a coupler between them. The longest focal length usable with it is around 480 mm. Anyway, when I decided which macro lenses to keep and got on with project they were for -- shoot fine details of small dead fish at home instead of trekking into the local natural history museum to use a Wild Photomakroscope -- I found that 5:1 was more than enough. Too soon old, too late smart. And I tried my 55 MicroNikkor only after I had 25, 45, and 63 Luminars and a 100/6.3 Neupolar. If I'd tried the MicroNikkor first I'd have seen it as good enough and would have stopped trying things out. As I said, too late smart.

I'm not surprised you shoot with flash. Motion is such a killer. Another reason I didn't want to use a Photomakroscope. The ones I've used have incident lighting and my subjects really needed transillumination. The one I used at USNM was on a slightly tilted bench. The subject had to be weighted down and even then some shots had motion blur. Flash, with GN calculations, is so much more effective.

 

[Sparky]

Well I don't mean to be unjust to either of those two gentlemen - Mr Thalmann had been very generous with his knowledge with me in the past. They're both standup gentlemen. And it's a hell of a service to the photographic community. An awesome thing to have access to those tests. But I'm just saying that it's a bit 'folly' to test only one sample of each product. I strongly suspect that you would see MORE variation between samples in a single line of lenses (purchased from the secondary or used market) than you would between brands in principle. I would have liked to have seen, say, five identical models tested against eachother as a control for the tests... if you see what I'm driving at. But you're saying maybe they did this already (with the 90mm angulons)? I will have to look at that - perhaps it was embedded in the test. Seems it would have been good to address that in a more prominent fashion. At any rate - specifics aside - you seem to see a lot of this kind of behavior on the 'net - people dismissing a product out of hand because they had one bad experience. A woman I know was bashing hasselblad planars for being unsharp - when in fact it turns out she had a badly seated focusing screen... again - yes operator error syndrome rearing it's ugly head...

I think a lot of people get very badly misled by advertising and consumer jargon - i.e. the urge to buy 'brand new' equipment etc. I've had mindblowingly good results with 60s lenses (as mentioned) - under controlled operating conditions, some of the older 'junk' can be at least as good as the new stuff... if not better in some cases.

About the strobe -Yes for sure. Well I thought it smarter maybe, to use strobe for such work. For that reason. There's also the spectre of film creep too. I am also located in california where there's frequent low level seismic vibration going on all the time (not to mention passing vehicles, etc)... so it just seemed like a better plan...

 

[Dan Fromm]

Well, there's the must have the newest most best syndrome. I haven't transcended it, but have learned that good enough to use means just that. Beyond good enouth its all fine points that I usually miss completely.

As for operator error, I've learned that when results aren't as desired the cause is almost always me. Almost, I have a Perkeo II with Color-Skopar that I've never ever got a sharp shot with. I have though, got some fine slightly soft shots that I thought good enough to keep on my desk at work.

 

[Roger Hesketh]

I am not generally one who likes to piss on other peoples bonfires so please bear that in mind when considering the next piece of proffered advice.

Sparky With regards to what you are proposing to do. Achieve a 10:1 magnification on the film by utilising long bellows extensions and specialist macro lenses. DONT DONT DONT.!!! If you try Their will be tears and their may even be a little blood .You will spend a disproportionate amount of money, time and trouble and the results, no matter how good a photographer you are, you will not wish to show to anyone. What you are trying to do is extremely difficult to do.

Firstly you will need to use a reasonably long lens in order to gain a good working distance from the subject.Long bellows extension needed. Main reason being you need to light the subject and you need space for those lights or strobes and you will need a lot of them because for 10 times magnification on the film utilising this technique you need 11 extra stops of light. Sounds easy doesn't it.Just wheel up some lights/strobes. It's not. Not for 11 stops! You will end up having to use flasks of water as condensors to project the light through whilst trying to avoid frying your subject .This is were the tears and blood come into it. Even if you are successful with all this the depth of field that you will have available to use will be only slightly more than the thickness of a hair on the proverbial gnats bollock. Alright a slight exaggeration on my part maybe but only a slight one. Anything which is even slightly out of the plane of focus, which will be razor thin will be out of focus. If you stop down even a little you will lose resolution due to diffraction. Also at 10 times magnification on the film all the lenses discussed even the specialist macro lenses are reaching the edges of their comfort zones.

Save your self from the humiliation of failure by not even trying. Settle for say 5 times magnification on the film as Dan has suggested which is by comparison a walk in the park. Consider using digital as has already been suggested. IMHO this is the only field of photographic endeavour were digital has the edge over film due to the potential to stack images and consider using a double optical system.

Good luck

Roger

 

[Dan Fromm]

Roger, I've shot at up to 30:1, albeit not with a long lens. Getting the illumination isn't much of a problem. Small flashes close to the subject will do the job perfectly well without frying anything. If you don't believe me, do the guide number arithmetic.

The real problems with high magnification photography are getting focus, maintaining focus, and stability. Getting focus is possible, maintaining focus and getting stability require a combination of brute force and subtlety. The first stand I built for photomacrography wasn't rigid enough, lost focus if I leaned on it while focusing and then let go.

If you don't have the two books I suggested earlier in this discussion, do yourself a favor and get them and read them. Or buy a copy of Brian Bracegirdle's Scientific Photomacrography, which is in one of the RMS' series.

You're absolutely right that the technique of shooting at high magnification is exacting.

That " even the specialist macro lenses are reaching the edges of their comfort zones" at 10x is simply wrong. It depends on the lens and the range of magnifications it is optimized for. I tried my little fixed aperture 25/2.8 Summar from 5:1 to 15:1; resolution increases with magification. Since the lens was made for a projection microscope, this makes sense. The 10/1.7 Mikrotar is best between 15:1 and 20:1, the 17/4 Tominon at 20:1

Cheers,

Dan

Oh, yes, you're absolutely right that the technique of shooting at high magnification is exacting.

 

[Sparky]

well I'm not too terribly concerned about these technical aspects. The bigger hill to climb, I think, is going to be tidying up my subjects and getting the backgrounds right etc etc.. maybe I'll post something one day if I get some good results soon... thanks for the input.