Please explain macro lenses too me !


justa

Link Posted 01/10/2010 - 09:18
Hi all

I would like to invest in a macro lens - i understand that they are for taking close up images and I have used macro before on my bridge camera.

However, what i don't understand is the different focal lengths - why would you go for a 100mm over a 50mm etc

What is the most versatile macro lens ??

hope thats clear !!

thanks

davex

Link Posted 01/10/2010 - 09:22
the longer the fl the further you can be away from your subject and still get 1:1 images. Also because you are further away you are not casting a shadow on the subject, and it`s easier to use flash. As for the most versatile I will leave that to others more worthy than I.

Davex.
K5 + 8mm-500mm zooms and primes
Please feel free to play with any images I post.
My flickr: link

davex

Link Posted 01/10/2010 - 09:32
You may find this useful.

Davex.
K5 + 8mm-500mm zooms and primes
Please feel free to play with any images I post.
My flickr: link

Helpful

prsjnb

Link Posted 01/10/2010 - 10:40
Hi Justin,

There are two factors you need to consider: magnification ratio and working distance.

A 'true' macro lens is one capable of capturing the subject on sensor or film at 1:1, that is to say 'life size', or greater. Some 50mm macro lenses capture at 1:2 (half-life size)unless coupled with an extension tube of 25mm, which may be a 'matched accessory' produced by the lens manufacturer.

The other consideration is working distance. 50mm macro lenses have a short working distance which is ideal for still life work and plants and flowers in the wild. It is not a good choice, however, if your main interests include photographing insects and other forms of wildlife that are easily 'spooked'.

100mm macro lenses are of intermediate working distance and are well-suited to those whose interests encompass still life and wildlife. For this reason, they are the most widely available. Not all lenses in this range have a focal length of exactly 100mm, the range extending from 90mm (Tamron) to 105mm (Sigma).

150mm macro lenses and above (200mm is the longest I am aware of)have a long working distance and are considered ideal for those whose main interests include insects and small animals.

Any macro lens from a reputable manufacturer will have been designed to give its best performance at or around its minimum focus distance, but, in most cases, produce sharp images with good definition and contrast throughout the range. They also tend to work well at their minimum aperture (typically between F2.8 and F4), allowing for the creative use of depth of field when photographing larger subjects. For this reason, many photographers also use their macro lens for portrait work.

From the above, you will appreciate that it is best to have thought carefully about your specific needs before making any purchase. If you are just starting out and not yet sure in which direction your interest in macro photography will develop, it would make sense, IMHO, to go for a 1:1 lens of intermediate working distance (90 - 100mm). Weight, handling and weather resistance are also important considerations, especially if you envisage most of your work being 'in the field'.

Macro lenses in current production to fit Pentax DSLRs are available from Pentax, Sigma and Tamron, all of which come highly recommended I have owned lenses from Tamron and Sigma and been delighted with the quality and IQ of both). The range is a little wider if you are considering a second-user lens (Tokina,Vivitar, Cosina and Panagor,among others). A good place to start narrowing down your choice would be the review section on the 'other place' link.

Focus is critical in macro photography, as is DOF link and AF is not always the best choice. AE, whilst helpful, is not always essential, especially when using flash, as for a given magnification, and hence working distance, the user quickly learns which aperture to set and to recognise when exposure compensation may be necessary. For these reasons, I suggest that you do not dismiss the idea of purchasing a second-user manual lens 'out of hand', as the quality of the optics and bokeh of some of these older lenses is quite remarkable if they have been well cared for.

Finally, there are many other ways of achieving magnifications of 1:2 - 1:1 or greater that do not require the initial expense of a true macro lens (extension tubes, reversing rings and Raynox DCR Macro converters are all used with considerable success by many users on this forum: just check out the gallery).

I hope the above proves helpful and does not leave you feeling even more confused.

I look forward to welcoming you to the fascinating, and hugely addictive, world of macro photography, as I'm sure others on the forum do too

1:1 best wishes,

Jon
Last Edited by prsjnb on 01/10/2010 - 10:43

Helpful

justa

Link Posted 01/10/2010 - 12:48
wow thanks John - really appreciate the time and effort you have taken there !

kimisara

Link Posted 01/10/2010 - 15:04
me too....learn a lot from just reading 1 topic.

Hyram

Link Posted 01/10/2010 - 15:14
An excellent article from prsjnb.

My first macro lens was a Sigma 105.

I then bought a Pentax 35 macro for those occasions where I could not get far enough away from the subject matter using the 105.

This tends to occur when shooting indoors.
Hyram

Bodies: K20D (2), K10D, Super A, ME Super, Auto 110 SLR, X70, Optio P70
Pentax Glass: DA* 300, DA* 60-250, DA* 50-135, DA* 16-50, DA 70 Ltd, FA 31 Ltd, DA 35 Ltd, DA 18-55 (2), DA 12-24, DA 10-17, M 200, A 35-70, M 40, M 28, Converter-A 2X-S, 1.4X-S, AF 1.7, Pentax-110 50, Pentax-110 24
Other Glass: Sigma 105 macro, Sigma-A APO 75-300
Flash: Metz 58 AF-1 P, Pentax AF160FC ringflash, Pentax AF280T

Anvh

Link Posted 01/10/2010 - 17:40
Good post Jon.

Just wanted to add that Macro lenses compared to normal lenses offer a very flat field of focus, so the focus through it frame is the same. With many normal lenses you see that the focus bends slightly at the corners. This of hardly any concern with normal shooting but with macro you can very easily see the field of focus so it's important it's perfect.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

prsjnb

Link Posted 01/10/2010 - 22:18
Stefan wrote:

Quote:
Just wanted to add that Macro lenses compared to normal lenses offer a very flat field of focus, so the focus through it frame is the same. With many normal lenses you see that the focus bends slightly at the corners. This of hardly any concern with normal shooting but with macro you can very easily see the field of focus so it's important it's perfect.

You'd make a damn fine copy editor, Stefan

"Close but no cigar", as Mr T Dolby would say

Thanks for noticing the important omission

Best wishes,

Jon
Last Edited by prsjnb on 01/10/2010 - 22:18

Mannesty

Link Posted 02/10/2010 - 00:01
The longer macro lenses can be used for just about any macro subject, including flowers, documents, creepy bugs, crawly bugs, jittery bugs, and flying bugs.

The shorter a macro lens is, the closer you need to be to the subject so you can start ruling out flying bugs if the lens is much less than about 90mm.

For some potentially dangerous subjects like snakes, spiders etc. The further away you can be when you press the shutter button, the better.

I couldn't decide what I wanted when I was buying my first macro lens so I bought the middle-of-the-road in focal length terms, which was an SMCP-F 100mm 1:2.8 Macro lens.

Since then, I've sold the SMCP-F and replaced it with the FA version (stonking lens). The FA is now in new ownership since buying the SMCP D-FA 100mm. My favourite lens of all though is the Sigma EX DG 180mm 1:3.5 Macro, but it's heavy.

My advice is to start with a Tamron/Sigma/Pentax lens of 90mm - 105mm focal length, and start practicing. You'll need a decent light too, but that's another topic entirely.
Peter E Smith

My flickr Photostream

Daniel Bridge

Link Posted 03/10/2010 - 00:05
Another big thumbs up for Jon's explanation above.

Focal length also affects the field of view and perspective, in just the same way that it does at 'normal' distances. The first shot below was taken with a 24mm lens with an extension tube, and to further clarify the working distance comments above, the nearest toadstool was nearly touching the front element of the lens. Notice how there is obvious 'distance' to the background.

The second shot was with a 105mm, and everything looks more 'contained', as perspective has been compressed by the use of the telephoto lens.







Often it won't be noticeable, but sometimes the focal length you choose will have a big impact on the look of the background.

Dan
K-3, a macro lens and a DA*300mm...
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