Lenses for macro on Linhof Tecknikardan

[vizion]

David, please tell us about your experience.

Apart from well over 60 years of image making ranging from wet plate to advanced digital techniques & much experimentation {including cracking the problem of how to shoot hdr images which include moving subjects (for which I was honoured by the RPS)) probably not very much that would interest you. I am a project photographer dedicated to experimentation and pushing the boundaries.

But can you not answer a simple question without needing to hold an opinion about either the person who poses it or their rationale for asking it?

I was impressed by your having a TK, even more by your having made bracing that works. Having a big expensive digital Canon counts for something too.

Fine but all these considerations are not pertinent when you are answering a simple question. It seems you have cultured an inner reluctance to assume that others are not entitled to ask questions unless you feel able to approve both their methodology and logic. If they fail that test I wonder why you give the appearance of feeling entitled to denigrate their endeavours.

That you persist in asking what seem like beginners' questions is puzzling.

If you understood the socratic method it would not be. What I have learnt in photography is that there are many many people who think they know it all. The consequence is that if say why you are asking a question they try and impress you with all their theories (the good and the half-baked) rather than concentrate upon providing the information you ask for. The only way to get useful information is ask deceptively simple open questions and hope there are a few people out there who will answer them.

If you know as much as you want us to think, you have nothing to learn from anyone here.

I have no need for you to think anything about me - I am not really that egotistical - I just get on with my own thing and am either dissappointed or delighted with the outcome. That is all I need. I need to say I wonder if you have a need to project your own attitude onto others. All I want people to do is, if they are willing, to answer questions I put; do me the courtesy of trusting I am asking them for a good reason and will put the answers to good use.

Now, about your problem.

I didn't pose a problem I just put a question!

You harp on lenses.

I have not harped -I leave that to the angels<grinz> and hope to avoid perjorative expressions myself- I have simply submitted a simple open question aski8ng people to share their experience with different lenses for macro on 4x5. It is you that dwelling on the false assumption I must be asking the wrong question even though you have, on your own admission, no understanding of why I asked it!

If you knew which lenses would do the job you wouldn't have asked.

I can see where you are coming from - but my suggestion is that you lack imagination about the ability of others to formulate questions where appropriate responses may help them to identify tests where the results may have a potential to push the potentials of our medium.

You must not know.

This is where assuming too much leads you into error.

If you knew the relationship between focal length, magnification, and extension you wouldn't have asked the questions you did and you wouldn't be thinking of getting an extension tube for your TK. Again, you must not know or you must not be telling us enough.

You are frustrated because you cannot guess why I am asking the question. I have no obligation to tell you and the reason I am not telling you is y because you, and maybe others, will be unable to answer it without that knowledge influencing the responses.

You say its incorrect of me to conclude that you don't know enough about how to reach your goal of photographing bees and their parasites at fairly high magnification. You might well be right. Since you say you do, you are right. That doesn't help me understand why you persist in asking questions whose answers you already know.

You assume the subject of the photography is my goal. Whilst I can understand the mental jumps your conclusions are both incorrect and simplistic. In my defence I would mention my experience with research has inclined me to the view that open questions best reveal information which is subjective and lies beyond simple measurable outcomes.

Smug? Probably not.

It seems to me that way!

Stiff-necked, yes.

I felt arrogant might be more appropriate <chuckles>

Annoyed? Absolutely.

My reaction is you need to be annoyed a little more frequently if you are going to appreciate the innate humility which IMHO forms part of our mutual genetic heritage.

I would add:
Humour & gentleness - possibly but pretty well hidden!


Take care

David

[vizion]

David, I hope you are using a digital back because the amount of film you will use under these conditions before you obtain an aesthetically pleasing image where you have constant movement would, for me in any event, be monitarily wasteful.

Well I use the canon 5D as a quasi back with my own adapter that places its sensor on the same plane as the GG screen. Even better is my laptop monitoring system which not only shows the GG screen but also corrects the image for viewing. This works well but is still a bit too Heath Robinsonian at the moment.

When the film is in place I monitor the subject with a videocam connected to the laptop and operate the shutter remotely.

You also have to calibrate manual flashes, both primary and slave, on subject and background, so that your exposures are on. If you have a predetermined pattern of movement across the film plane, which would seem unlikely, or a series of infrared trip lights your success rate will increase; nonetheless, you will have to keep exacting records of aperture/shutter speed and distances/position/angles of flashes to the subject to perfect final images. ....A clear issue for you is keeping track of the exposure and flash distance calculations, angles etc for each sheet. With roll film this is less of a problem since you have an uninterrupted series.

Well I pre-number my sheets when I load them using a cutter which puts a binary number onto each sheet using a series of nicks on the leading edge of the film. The same number is printed in large letters (a)on a label stuck to the cut film holder and (b) on my record sheets. (When hooked up to the laptop the notes go straight into the database.)

And of course it takes time to have the film processed and returned and then you have to evaluate it vis-a-vis your records (I'm assuming you are shooting color).

I have just built a new studio in my backgarden which has a new darkroom attached. I am lucky enough to have my own Colenta system which automatically processes 20 5x4 sheets at a time. So the processing problem is no problem!

I do not envy you taking on this project but I respect your desire to experiment.

Thanks I appreciate your support

BTW, as with Dan, I have the Nikkor 50mm F2.8 micro and can attest to it's value reversed for > 1/1 magnification. But I have not employed it for greater than say 3/1, so Dan's suggestion to calculate your magnification is critical as that will determine which lens is right for you. You should however consider the Olympus 38mm lens as I believe it pushes up to 20/1. OLYMPUS has several now discontinued macro series that are touted very well with excellent color characteristics. Nikon, Zeiss, and Leitz all produced lenses for this purpose as well. They all must be used within 2 stops from wide open aperture to obtain maximum sharpness. Finding one of these specialized lenses may be the biggest challenge. Others have suggested reversing an enlarging lens for jewelry and this may be another avenue for you to consider.

Helpful comments - incidentally have you noticed any differences in these lenses regarding what I call DOF distortion?

Good luck and keep us informed of your progress.

Thanks

David

[Bob Salomon]

"DOF distortion"

What is this?

[vizion]

"DOF distortion"

What is this?

The best way I can explain my tentative grasp of what I believe to be an actual phenomena is as follows:

It is the term I give to any percieved differential in apparent size of the closest and furthest parts of an image that lie within the depth of field of a lens that cannot be accounted for just by the difference in the angle of view.

I am quite curious about why some lenses of the same focal length, focused at the same distance with the same aperture appear to markedly differ in this respect. I cannot be certain whether differences in apparent size are just due to local adaption within the viewer's visual cortex and/or physical characteristics of individual lenses.

i.e is it all in the mind and the way it interprets an image or is it something which can be physically controlled either by lens design and/or other optical adjustments.
David

[Dan Fromm]

Which lenses show the effect and at what magnifications?

I ask for two reasons. It would be helpful to try to reproduce the effect. And at magnifications above 1:1 depth of field is very thin, so I have to wonder what can vary across it.

[Bob Salomon]

You seem to be describing foreshortening and that is focal length dependant. Perhaps what is causing this to your eye is that the marked focal length on any lens is only the nominal focal length. If you have 3 identical lenses from the same manufacturer with successive serial numbers no two will be exactly the same focal length. But the minute differences in focal length would not result in any difference as you see it. But the difference in focal length from two different manufacturers of the same focal length lens may account for it.

But even more likely would be the comparison between a true macro lens and another non macro lens.

What type of lenses were you using to experience the problem you refered to?

[aduncanson]

Fascinating. In the realm of 10X magnifications where propose to work, the depth of field (by the conventional CoC = Negative Diagonal/1800 criteria) is on the order of 0.11mm. (Makes wonder just how "exactly" you can lure or manipulate your live subjects to the desired focus point.) Even at the small working distance provided by a 50mm lens, your subject distance is something like 500 times the depth of field. In that respect it would be like making a portrait from 80 feet. I would not expect the one or two percent or so variation in focal length/working distance from one lens design to another to make a perceivable difference in perspective over that slim a depth of field.

[vizion]

You seem to be describing foreshortening and that is focal length dependant.

I agree foreshortening is a contributing factor but my visual experience inclines me towards the notion there is more to it. Foreshortening should be explained by angle of view alone. That is what "should" be the case but I am uncertain whether what "should" be is solely what actually occurs. I cannot prove whether my perception is accurate or inaccurate but I aim to try to test it.

Perhaps what is causing this to your eye is that the marked focal length on any lens is only the nominal focal length. If you have 3 identical lenses from the same manufacturer with successive serial numbers no two will be exactly the same focal length.

I agree this is a factor but I would ask is there evidence which conclusively demonstrates it is the only factor?

But the minute differences in focal length would not result in any difference as you see it. But the difference in focal length from two different manufacturers of the same focal length lens may account for it.

If foreshortening alone was the cause then lenses from two different manufacturers of exactly the same focal lengths "should" demonstrate an identical degree of foreshortening.

But even more likely would be the comparison between a true macro lens and another non macro lens.

I agree lens type may be a factor which does tend to muddy the water somewhat and make it more difficult to determine what, if anything, is going on.

What type of lenses were you using to experience the problem you refered to?

What made me sit up a few years back was two "identical" lenses I had for my pentax 6x7 kit. Both same year of manufacture. Both used on the same occasion, shooting the same subject but on two "identical" bodies. I finished the roll of film on the first camera and switched the second camera onto the first cameras tripod and shot using identical settings. When I processed the film the subject (a damsel fly shot at an angle of approximately 15 degrees to the film plane) had a noticeably greater depth of field on one roll of film. At the time I just put it down to inconstent management on my part. However I took the precaution of having both lenses and cameras professionally overhauled and checked.

I followed this up with a check in the studio using a long wooden rod painted with white marks at fixed intervals. This showed similar result. I had other things to do and forgot about it but from then on tended to favour one of the lenses.

I never saw similar results on macro work using 35mm but did see some similar discrepancies on MF. Now I am turning my attention to macro on 5x4 and thought ah well while I am doing the project I am currently engaged upon I will satisfy my curiosity and get a bit scientific about it. So my original questions was a fishing expedition to see if anyone would comment in detail upon the differences they have found between lenses.

[vizion]

Fascinating. In the realm of 10X magnifications where propose to work, the depth of field (by the conventional CoC = Negative Diagonal/1800 criteria) is on the order of 0.11mm. (Makes wonder just how "exactly" you can lure or manipulate your live subjects to the desired focus point.)

That is why I chose my bees - you can (if you know how) repeatedly get a series of bees tongues to precisely the same spot time and time again.

Even at the small working distance provided by a 50mm lens, your subject distance is something like 500 times the depth of field. In that respect it would be like making a portrait from 80 feet. I would not expect the one or two percent or so variation in focal length/working distance from one lens design to another to make a perceivable difference in perspective over that slim a depth of field.

Such a difference - (if it does exist) is of an as yet to be measured differential but at these magnifications the benefit of any gain (or disadvantage of loss) may be crucial.

[Dan Fromm]

<snip>

I followed this up with a check in the studio using a long wooden rod painted with white marks at fixed intervals. This showed similar result. I had other things to do and forgot about it but from then on tended to favour one of the lenses.

<snip>

This is very surprising. Are you sure that both lenses gave the same magnification? And, if you shot the rod with negative film are you sure that negatives from the two lenses are equally dense?

I asked the second question because if the two lenses' focal lengths are close -- they should be -- then the one that gave less DoF may have a somewhat lazy stop-down mechanism. Not likely given you had them checked, but still the most likely cause. If you shot reversal film when testing with the rod then the effect of one of the lenses not stopping down to the aperture selected should have been visible.

Please tell us more about the similar discrepancies you saw with other MF lenses.

And do explain again what you mean by "DoF distortion." I ask because the behavior of the two P67 lenses you described doesn't seem to conform to the explanations you've given.