How to deal with the central bright spot

Chris.R wrote in post #18238609
If you read widely, you'll find it definitely is not "always", and for varying very good reasons. The reasons depending on the context.

You haven't commented on the inconsistencies I pointed to in your previous answer, we so we don't know whether you mean, eg 1:2.5, = 0.4x, = "40% of life size" to be what you declared as "macro" or not.
I think you meant that it would not be, since you defined 1x (=1:1) to 1:10 (=10x) as macro.
Therefore several excellent "Macro Lenses"(as listed) by your definition are not capable of macro photography, so presumably aren't macro lenses at all.

(I see the invention of a new term "macrophoto lens" - nobody uses that to my knowledge. Canon use Macro Photo (note , as two words not one) for one of their current lenses. It makes no sense to corrupt one manufacturer's Trade Name for one of their lenses and apply it as a generality.)

I could fill the screen with a picture of the blunt end of a pencil, but you could't tell me whether it were a "macro" photograph taken with a "macro lens" or not. Even if you did have the definitions straight!

It's well within the range of a modern very ordinary camera (without cropping) or very ordinary microscope.
I'd be quite happy to call it a macro photograph - it's a photograph of a small thing.

This leads me to urge anyone to stop making authoritative-sounding assertions, expecially when they contain glaring inconsistencies which remain uncorrected.

Some conventions which applied in 35mm days don't apply any more, and are grossly misleading. Sites like this one have a responsibility to deepen understanding, and NOT support dogged adherence to accustomed misconceptions using in some cases, specious arguments and feeble distraction.

There is no inconsistencies to discuss. That is why I used that notation method 1X is 1:1, 10x is 10:1. Linear magnification is always object to sensor because that is what relates to light loss or DOF.

Macrophoto lenses are often designed back to front, the MP-E 65mm probably is.

Oh gawd, another internet 'war'! Relax, guys.

1:1 = 1X = 'life size'
When you shoot a 10mm long object at 1:1 it is ALWAYS going to measure 10mm on the focal plane, regardless of the sensor size around the 10mm subject.

"Macro" is a somewhat loosely defined term, especially as used by lens manufacturers...where 'close focusing' is often more appropriate than 'macro' designation of the lens. But generally when 1:2 is achieved by a lens it gets the 'macro' designation pn the market, even when for purists the term macro as meaning 1:1 or larger (e.g. 5:1). More importantly a macro lens has corrections for abberations that arise when the lens is focused at very close distances, while a close focus lens may not attempt that.

Anything looser of a definition simply illustrates how common usage may in fact may NOT be factual, but misuse of terms which have had tighter definitions than 'everyday speak'...like 'bokeh' is misused and defended with 'language changes'!

I agree, mostly . The poor OP wasn't even using a macro lens! "Macro" is "loose" as you say - I've taken it here https://photography-on-the.net …/showthread.php​?t=1474040

'Macro' is defined by the scale of the object Originally the term 'photo-macrograph' was proposed by W. H. Walmsley in 1899 for close-up images with about 1-5 diameters magnification, to distinguish from true photo-micrographs which he stated were about 5-10X and higher.

https://archive.org …kngoog#page/n11​2/mode/2up

Olympus has long had one of the dominant positions in both macro photography and photomicrograpy, along with Nikon. In 1985 Olympus published The OM System Lens Handbook, and they stated,

"Between a range of some 1/5 of life size, through those magnifications where the life size of the image on the film is the same as that of the actual subject in real life, and on the still larger images (up to some 16 times life size) is the magnic territory we refer to as the world of macrophotography."

...so you see the original definition of 'macro' is even modified by one of the giants in macrophotographic systems.

From Basic Photographic Materials and Processes, 1990 by four faculty of Rochester Institute of Technology,

"Macro lense are small-format camera lenses especially designed to be used at small object distances. The important optical characteristic of macro lenses is the excellent image definition they produce under these conditions compared with normal-type lenses."

...and they don't even relate the magnification factors, but the characteristic that Image Distance is smaller than the Object Distance.

This article in 2011 states a point I made about the loose quantification of 'macro' scale, and also echoes what the RIT faculty stated about very short object distances:

https://www.dpreview.c​om …derstanding-magnification

"A more specific definition of a macro lens, then, is one whose minimal focus distance is short enough to allow photography of a focused subject in 1:1 magnification.

"Let me take this opportunity to point out that many lens makers employ a very liberal use of the term, and happily write 'macro' on a variety of zoom and prime lenses that are not capable of 1:1 magnifications. This is a sales tactic, and you can easily find so-called macro lenses that can only produce 1:4 or 1:3 magnification ratios. One can, of course, produce great results with such lenses, and it is often possible to achieve higher magnifications on these lenses with the use of optional accessories. When shopping for a macro lens, however, you'll want to look carefully at the magnification specs; most 'true' macro lenses will actually have 'macro 1:1' prominently displayed on the barrel. That removes any ambiguity."

Back to OP, yes it was contended that the bright spot was with a macro lens, when it was merely a photo taken with a NORMAL LENS at very close focus (macro photo of sugar crystals using Canon FD S.C. 50mm f1.8 @50mm, with extension tube or bellows?)

It's often discussed in those terms, but the references (thanks!) you cite, none of which claims to be authoritative, differ considerably on the numbers. Modern usage of the term "macro", while seeming reasonable, has muddied the waters more. It's probably about time (partly due to tiny sensor usage) we stopped trying to make the term mean something definite. Some use different forms of words, too defining macro photographs to be large photographs, so we're on about photomacrography not macro photography.
I've been watching since getting an Olympus FTL, then an OM-1 body when that came out, and fudging a pre-war Leitz macro lens onto it. They and the other 15+ manufacturers of macro lenses I now have, use their own interpretations - or use different words. In this thread we've had contradictory and overlapping assertions.
Having been admonished for commenting on such things in this thread on "off-topic" grounds I'll stop that there.

The original OP's problem came about because he/she put a lens on reflective extensions. The term "macro lens" was waved around as though it were significant, which it wasn't. Broadly, Canon/Nikon et al's on-camera "macro" lenses work down (merely!) to about 1:1 on sensor and don't give the reflection problem. Until you put them on extensions, then you might get a problem. Whether it's a macro lens or not, makes no difference, but we had the interjection which started the mess, of unsatisfactory definitions and inventions about "macro" used with lenses and magnifications.

So the guy who initially coined the term, and the company which dominates (along with Nikon) macro equipment systems, and instructors at one of the top photography schools in the USA, are all not 'authoritative' ?

The three sources quoted all pre-existed digital photography and small sensors, and the confusion brought about by small crop sensors. Yet THEY did not agree. So we cannot solely blame the present misuse of the term.

The OP obviously made an obvious mistake in calling an FD mount 50mm f/1.8 lens a 'macro' lens, a term which even Canon never applied in their marketing claims.

Just walk away..... it's not worth the effort....

I would suggest leaving the thread alone at this time until be Benitoite has more to add or questions to ask.

Well I've certainly appreciated all of the responses and thanks all for taking a look at my question.

At this point all I have to add is that I studied modern ελληνικά. I assure you all the word 'macro' implies nothing except the sense of bigness.

The irony is that macrophotography is of small details, and when the word small gets thrown around, the term 'micro' is a better representation and 'macro' a misnomer. We should be saying macro for ultra wide angle, and micro for pictures of the universe of the small. Yet we've put macro /and/ micro on the spectrum of photography of the small.

Micro is the ultimate macro, and with micro you reach a point where it ceases to be photography at all, as we no longer need light to discern detail (scanning electron micrography).

Also in the first post I didn't intend to imply I was using a specialty macro lens, just trying to reflect some statements about the central bright spot problem I came across. My experiments with "normal" lenses will continue no matter how hard someone wants to push me into buying a specialty lens.

Peace.

Have you had a chance yet to use any of your newer lenses with tubes? Also, like what was mentioned, you should see if there is a way to flock the inside of the lens with a flat black material, there should be no shiny surface inside at least where light travels through to the sensor. Or try to get a set of Kenko tubes, somebody was selling a set for $50 on either POTN or FM.

Way to go - you don't need one, just some black material to make sure, to jump to Latin, that your "camera" really is "obscura". Good luck with that.

Can we all keep on topic, all this theoretical discussion is not relevant to the OPs enquiry, Chris has a new thread for this.

Chris has also suggested a reason for the bright spot issue, if we have any other suggests provide those here.