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Macro question
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PostPosted: Sat Dec 31, 2011 9:28 am    Post subject: Macro question Reply with quote
Can someone explain to me the differences and (dis)advantages of using:

1 A macro lens (the ones i own don't go 1:1, so there's one disadvantage)
2 Extender tubes
3 A reversed (macro) lens

I am especially interested in the difference between #2 & 3.

Thanks.


PostPosted: Sat Dec 31, 2011 10:30 am    Post subject: Reply with quote
Extension tubes will usually let you get 1:1 reproduction with a lens of "normal" focal length. They are a bit less convenient than a proper macro lens.

Reversing a lens on the tubes should give you some improvement in image quality, but that depends on the lens you're using. Purpose designed macro lenses will show less improvement than others. And I think it may also give you an even larger image.

You will lose auto-diaphragm when you reverse the lens.

Hope that helps a bit !


PostPosted: Sat Dec 31, 2011 12:51 pm    Post subject: Reply with quote
More than you want to know maybe: CHEAP MACRO -- Buying or exploiting a lens for ultraclose work

Reversing a camera lens lets you work close and provides flatfield sharpness but doesn't gain magnification -- only extension or supplemental optics provide magnification. If a lens has a deep front inset, that functions as extension when the lens is reversed. But for magnification, add tubes or bellows.


PostPosted: Sat Dec 31, 2011 1:50 pm    Post subject: Reply with quote
A rule of thumb:
with more than 50mm using extension tubes or bellows is better
with less than 50mm using a reverse adapter (+tube/bellows if wanted) is better

For magnifacations higher than 1:1 reversed postion is better in most cases.
There a few exceptions, especially lenses which where made reproduction, macrophotography, enlargements an so on.

Last edited by ForenSeil on Sat Dec 31, 2011 2:00 pm; edited 1 time in total


PostPosted: Sat Dec 31, 2011 1:59 pm    Post subject: Re: Macro question Reply with quote
Willem wrote:
Can someone explain to me the differences and (dis)advantages of using:

1 A macro lens (the ones i own don't go 1:1, so there's one disadvantage)


The word "macro" is used very loosely. On the one hand, there are lenses designed to give good image quality at near distances. In the bad old days these were all fixed focal length, more recently some are better thought of as fixed focal length zooms, e.g., the 105/2.8 and 200/4 Micro Nikkors. I think Nikon was the first to take this approach, could very well be mistaken. On the other hand, there are lenses, mainly zooms, engraved "macro" that can focus close. The second type aren't designed to be very good closeup

Quote:
2 Extender tubes


A lens is focuses closer by moving it away from the film plane. Lenses with built-in focusing helicals can run out of focusing travel. An extension tube allows closer focusing at the cost of losing the ability to focus on distant subjects.

Quote:
3 A reversed (macro) lens


A symmetrical lens' performance isn't affected by which end faces the subject. Nearly all lenses for small formats and most for larger formats are asymmetrical. Nearly all of them -- high performance lenses designed for working about 1:1, primarily on larger formats, are an exception -- are designed to give best image quality with a large subject in front of the lens and a small image capture device (film, chip, doesn't matter what) behind the lens. Such lenses are best used reversed at magnifications > 1:1 (small in front, large behind) to take best advantage of their optimizations.

The rule of thumb "reverse the lens when working closeup" make no sense at all.

Buy and read two books: A. A. Blaker's Field Photography and Lester Lefkowitz' The Manual of Closeup Photography. Blaker is better for people who want to work at magnifications below 1:1 and who know only 35 mm (and digital) SLRs. Lefkowitz is better for people who know the basics and want to work above 1:1. Based on what you've posted, if I had to recommend only one book it would be Blaker.

That said, Blaker's formulas for exposure compensation given magnification assume pupillary magnification = 1. Lefkowitz' formulas take account of pupillary magnification so are more generally userful. Retrofocus lenses -- that 's most wide angle lenses for SLRs -- have pupillary magnifications far from 1.

Whatever you do, don't buy anything John Shaw wrote. He's a fine photographer but a lousy teacher. Heather Angel -- see her book The Book of Closeup Photography -- does the John Shaw thing much better than he ever has.

Last edited by danfromm on Sat Dec 31, 2011 2:04 pm; edited 1 time in total


PostPosted: Sat Dec 31, 2011 2:02 pm    Post subject: Reply with quote
ForenSeil wrote:
rule of thumb:
with more than 50mm use extension tubes
with less than 50mm use reverse adapter

Of course there are exceptions Smile


Dumb and dumber.

Whether adding extension or reversing the lens (and adding extension too) will give better results depends on the magnification, not on the lens' focal length.
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