Helicoids vs Extension Tubes vs Bellows for Close-ups and Macros

[Andrea B.]

The topic of this thread is helicoids, extension tubes and bellows.

 

In the future if anyone wants to switch topics, I would kindly ask you to start a new thread.

[colinbm]

If the notion that the EL-Nikkor 63 is good for UV has been debunked, then I must now debunk the debunking. Which returns us to this: The EL-Nikkor 63 is OK for generic UV photography. Really it is. Used on a typical broadband converted camera with a Baader-U, this lens will give you a *good enough* UV shot.

 

It is overly obsessive, imho, to worry about the differences between an EL-Nikkor which can transmit from 325nm versus one which cuts in at 350nm unless you are doing some kind of specialized research and have filters and UV illumination and a sensor to support sub-350nm. Of course, I'm not going to deny anyone their fun factor who wants to try shooting below 350nm. Tried it myself a couple of times. "-)

 

But it is *very* misleading to call a 350nm lens "inferior" to a 325nm lens. Seriously, 25nm somehow makes a difference ? Especially when a lens like the UV-Nikkor can reach 200nm ??

 

"Processing", by which I guess is meant "editing", is irrelevant to to this discussion.

 

"helicoids, extension tubes and bellows"

OH I don't see any of these mentioned anywhere, here ?

I did see a lot of ###nm, so I asked about ###nm, Huh ? Was that bad ??

Col

[Andrea B.]

No, Col, you didn't do anything bad. "-)

 

The first 7 posts were about helicoids, ext tubes, bellows and closeups. After that things veered off into UV lenses. A lot of good info gets buried in forums because of 180° topic switches like that.

 

Sometimes I break off the topic switch posts into their own thread. Which was how this thread itself came into being. So we have now 180-ed the first 180. But don't seem to be back where we started. Hmm......

[rfcurry]

Okay, back to helicoids. I have a helicoid which has its own tripod mount and additional extensions. Supporting the helicoid/extensions on the tripod has proven to work better for me than supporting the camera on the tripod. YMMV

Add a solid two-axis rail to the above, for fine tuning, and life is good.

 

Bellows, of which I have a few, tend to eat up too much space between camera and lens. I don't use them, but keep them as "pretties".

 

Actually, I don't use any lenses these days that are without internal helicoids.

[igoriginal]

If the notion that the EL-Nikkor 63 is good for UV has been debunked, then I must now debunk the debunking. Which returns us to this: The EL-Nikkor 63 is OK for generic UV photography. Really it is. Used on a typical broadband converted camera with a Baader-U, this lens will give you a *good enough* UV shot.

 

Perhaps I wasn't clear enough in my initial post, concerning what I was trying to explain, and for that I apologize. This is why, I had already elaborated to Bjørn that my argument was really hinging on relative comparison (price, versus return). And given that the 63mm El Nikkor was artificially (and quite ridiculously) bumped up to prices that could no longer be justified (compared to its UV performance), this was what I was really trying to infer. Considering that the remaining El Nikkor line remained reasonably priced.

 

(See the remaining conversation between myself and Bjørn).

 

Secondly, yes, I feel that I was well within my point ... to "debunk" the ridiculously-hyped 63. This is because the hype in question involves the fact that it had been going around many seller's circles / advertising (in recent years) that it was "the best UV performer of the entire El Nikkor line", and this is simply false advertising at this point in time (whether deliberate or unknowingly), now that spectral testing has shown otherwise. Regardless of what else is said, I am calling it for what it is. Just expressing my right to voice my opinion, of course.

 

It is overly obsessive, imho, to worry about the differences between an EL-Nikkor which can transmit from 325nm versus one which cuts in at 350nm unless you are doing some kind of specialized research and have filters and UV illumination and a sensor to support sub-350nm.

 

Not really obsessive at all, considering that exposure time can be dramatically different between the El Nikkor 80 and the other El Nikkors. And that can impact the ability to obtain usable photos, especially in outdoor conditions where longer than necessary exposure times can make it that much more difficult to get a sharp shot without a brief puff of wind (or a random insect landing on the flower) messing up the entire exposure at any given moment.

 

We have to remember that "transmission curves" are more than just depth (bandwidth), but also about height (photonic intensity per unit of time, within any given wavelength).

 

Thus, my own tests in the field have only confirmed what Dr. Schmitt had found with his spectral results. That it took a significantly longer exposure (or compensated / ramped up ISO) to obtain comparable results. Sometimes, the differences were in 3 to 4 whole seconds longer with the El Nikkor 63, compared to the El Nikkor 80! (Although probably more like 1 to 2 seconds longer, in more common conditions.)

 

Further more, a significant focus shift can also be a pain, at times, and can also potentially mess up a photo opportunity (since added steps consume more time, and things can happen during that added time, especially outdoors).

 

If that doesn't matter, than why are lenses with little to no focus shift more desirable than those that do exhibit considerable focus shift? Let's not kid ourselves, here. A cow is a cow, and a horse is a horse. There's no skating around that.

 

Hence, I hardly call my points "insignificant." At least, in my own opinion, anyway.

[igoriginal]

But it is *very* misleading to call a 350nm lens "inferior" to a 325nm lens.

 

It's not misleading at all, because if the El Nikkor 80 (compared to the 63) has: 1. Deeper transmission curves. 2. Higher transmission throughput. 3. Little to no focus shift ...

 

... Then that does make the El Nikkor 63 more inferior to the 80. I am calling it for what it is: Inferior (relative to the 80). Especially so, since the El Nikkor 63 has been ridiculously price-gouged, while the El Nikkor 80 has remained reasonably priced.

 

Why should I pay $200 to $250 (average price ranges) for an El Nikkor 63, when an El Nikkor 80 costs about $50 to $80, AND has better transmission curves / transmission height / less focus shift?

 

"Obsessive?" Not at all. Quite logical. It is the other direction that is quite irrational and unfounded. The increased price hardly justifies the reduction on returns. Pointing out this discrepancy (and needless waste of money, on mere hype) is quite a sensible point, in my opinion. And it needed to be pointed out, so that others do not fall for the continued and disproportional hype awarded to the 63.

 

(Whether or not I am using the full potential of that extra transmission curve / transmission height of the El Nikkor 80 is not the point. The point is what I am paying for it. Otherwise, utilizing additional potential of a lens can change, over time, depending on one's tastes / needs / tech capabilities. But meanwhile, having those added capabilities is a fair argument, seeing that the overly price-gouged El Nikkor 63 is actually a step down, and not a step up, from the more fairly-priced El Nikkor 80.)

 

In fact, I see sellers on Ebay right now, trying to sell an El Nikkor 63 for $400, $600, and even $800! Seriously?! That is just plain ridiculous!

 

If I am obsessive over this craziness, then so be it. Ech.

[igoriginal]

Otherwise, I concur. We have gotten way off topic. Thus, no more about the lenses, here.

 

(However, I should point out that there is some initial relevance, to this split, because we were discussing how flat-field lenses ... especially enlargers ... can add some advantages to macro photography via bellows / tubes / helicoids. So, this is how we ended up here. :) )

 

Anyway, indeed, no point in discussing and debating UV transmission / focus shift / performance within a macro thread.

 

I guess in this coming weeks, I will try to compare some shots using enlargers on helicoids or a bellows, versus "regular" lenses (with no flat-field design), and hopefully post my results ... to examine if there is any noticeable change in the consistency of what is focused on throughout the entire frame (all other factors remaining equal, including using matched lenses of the same focal length, same macro extension / distance, and same aperture settings, for a fair comparison).

 

That way, I can also stay on topic.

 

Anyone who is very experienced in macro photography, I would appreciate some suggestions in how to carry out such a test, or if my premise is even worth the trouble.

 

(My impression would be to use a high-quality bellows mounted on a tripod, so that very careful and precise measurements can be achieved. I also have the idea of placing the subject of the photograph on a sturdy platform, as well. And also taking all photos on remote shutter. Maybe take comparison photos at various apertures, to see how the DOF changes in its distribution across the entire image frame?)

 

Thanks all!

[Andrea B.]

Agreed we should not pay ridiculous prices for lenses. Market values ebb and flow. Be patient and you can often find yesterday's over-priced darling at a more sensible price.

 

Some other points remain to be proved about such things as 63 vs 80 EL-Nikkors, etc. because measurements of one sample (or even a couple of samples) of a particular lens does not yet make a pattern. Sometimes one measurement is all we have - and we are thankful for having that - but we should not take one measurement as gospel truth given such things as experimental error, instrument calibration and sample variation. Bring me actual transmission measurements of several samples of a lens and then we will talk. Gotta keep some scientific perspective on this whole thing.

 

[Focus shift is moot with Live View.]

 

And since we all seem to be defending our opinions, I will say again that my point was simply about a 25nm transmission difference. Period. Nothing there about focus shift or exposure time or whatever. Just that for generic UV photography 25nm does not a big deal make.

This kind of line by line debate wears me out a little.

[igoriginal]

Some other points remain to be proved about such things as 63 vs 80 EL-Nikkors, etc. because measurements of one sample (or even a couple of samples) of a particular lens does not yet make a pattern. Sometimes one measurement is all we have - and we are thankful for having that - but we should not take one measurement as gospel truth given such things as experimental error, instrument calibration and sample variation. Bring me actual transmission measurements of several samples of a lens and then we will talk. Gotta keep some scientific perspective on this whole thing.

 

Very true. Test results should never be claimed as "conclusive", because technology is constantly changing, and with those changes come added and improved measurement accuracy as well as the discovery of previously unknown variables through new testing methods that may have been impossible or inaccessible with former-generation testing methods.

 

And since we all seem to be defending our opinions, I will say again that my point was simply about a 25nm transmission difference. Period. Nothing there about focus shift or exposure time or whatever. Just that for generic UV photography 25nm does not a big deal make.

This kind of line by line debate wears me out a little.

 

You're very much correct. Especially so, if the only goal is to examine the presence (or lack) of UV patterns, which Col also very correctly pointed out. So, it all depends on what you really want to do, with what you have.

 

Sorry for "beating a dead horse." No more on this, since it is wayyyy off-topic, anyway. Agreed.

 

Now ... about testing for comparison shots between supposedly flat-field lenses, versus non flat-field lenses (and how that might effect imaging, especially in UV macro photography) ... is my assumption correct in considering that using a high-quality bellows, mounted on a tripod, is the better tool for such testing?

 

Another speculation I have, is if a flat-field lens will improve the patching together of multiple images, when doing "focus stacking" work via bellows? Perhaps a flat-field lens will reduce the amount of images required to yield a satisfactory result from focus stacking?

 

(My assumption is based on the fact that flat-field lenses remain consistently focused within the DOF that one is focused to, throughout the entire frame, with no DOF drop-off. And so, this may yield better "precision" when stacking multiple images, by feeding the focus-stacking software "slices" or "cross-sections" of all focus points, with no DOF deviation within any single image. Does my premise have any merit?)

[Johan]

Another speculation I have, is if a flat-field lens will improve the patching together of multiple images, when doing "focus stacking" work via bellows? Perhaps a flat-field lens will reduce the amount of images required to yield a satisfactory result from focus stacking?

 

(My assumption is based on the fact that flat-field lenses remain consistently focused within the DOF that one is focused to, throughout the entire frame, with no DOF drop-off. And so, this may yield better "precision" when stacking multiple images, by feeding the focus-stacking software "slices" or "cross-sections" of all focus points, with no DOF deviation within any single image. Does my premise have any merit?)

 

No. The step size (slice size, whatever you want to call it) for extreme macro stacking is a calculated value based on depth of field which is based on f/stop, mag & optic mm. For extreme macro we tend to use optics only at their sharpest value, stacking these rather than setting it at any particular desired f/stop - because we want to minimise diffraction softening above all else. For example a lens used at f/16 at 5:1 actually has effective f/64 which gives diff. softening. See examples here. A flat field lens gets you a nice sharp slice from edge to edge, but doesn't lead to less of these slices being neccessary. All covered in http://extreme-macro.co.uk in probably the most detailed overview you'll find anywhere online, rather than repeating that site here your best bet is to have a thorough browse there.

[Andrea B.]

Johan - do I have this correct? (Thank you.)

 

Physics tells us that narrower apertures cause more light wave bending, i.e., diffraction.

 

But magnification, per se, does not cause more such aperture diffraction.

Instead, magnification increases the size of the Airy disks produced by aperture diffraction.

And thus there is less resolution at a given aperture under this magnification

because the magnified Airy disk covers more sensor sensels than an unmagnified Airy disk.

 

*******

[Johan]

I wouldn't necessarily claim to have the deepest understanding of theoretical physics so maybe you know a thing or two beyond me here, but this is my understanding too - increasing magnification spreads the airy disk over more sensor pixels (itself a whole other subject). But it's quite a complex subject because there are even more variables like for example the wavelength of the light - with diffraction blur being worse for red. And this is where Fierce Bear's earlier comment comes into its own - more resolution because of shorter wavelength