Do you need Macro if you already have a 85mm?

[osquar]

Hi,

Minolta 100mm Macro and Tamron 90mm Marco are often labelled as "poor man" portrait lens in regard to 85mm f1.4 lens of Minolta or Carl Zeiss. I wonder if you already have a 85mm, do you still need Marco lens? Is the 85mm able to give me a sharp image for close distance object? Adding an extension tube to bring you closer to the object shouldn't decrease image quality, right?

[Dr. Harout]

I don't think so. A macro lens remains a true macro lens. And there is no substitute for it. In itself even the lens design differs AFAIK.
Personally I wouldn't trade my Sony 50/2.8 Macro for an 85/1.4 definitely, except of course if they'll offer a brand new Zeiss 85mm, which I will sell and buy 3 superb lenses including the 50/2.8

[Cogito]

Hi,

Minolta 100mm Macro and Tamron 90mm Marco are often labelled as "poor man" portrait lens in regard to 85mm f1.4 lens of Minolta or Carl Zeiss. I wonder if you already have a 85mm, do you still need Marco lens? Is the 85mm able to give me a sharp image for close distance object? Adding an extension tube to bring you closer to the object shouldn't decrease image quality, right?

Macro lenses are are different kettle of fish altogether. They are capable of taking excellent portraits but their design means they have a very limited depth of field. Additionally they - the 2 you refer to - provide 1:1 magnification which the 85mm lens MAY manage with extension tubes. Those extension tubes should not diminish the IQ but will certainly require you to provide more light - i.e. wider aperture, slower shutter, higher ISO for the same shot as without any tubes....

[osquar]

Thanks Dr. Harout & Cogito,

I'm keeping the Macro lens on my wish list. Haven't decided which one yet but it would be in the range of 90mm or 100mm. If sigma 150mm Macro is available in A-mount, that would definately be on top of my wish list. Minolta 200mm Macro is too expensive and hard to find (too heavy as well).


Dr. Harout,
I see that you own a 50mm Marco. Do you use it much for portrait? Normally the 90mm & 100mm Macro are more common for that.

[Dr. Harout]

The Sony 50/2.8 Macro serves me mainly in my practice (skin diseases), but sometimes I do use it for portraiture. Take a look at this http://harmar.photoblogs.am/index.php?showimage=2437
Will be flattered to read your comments and critiques.
You may look on other photos with the 50/2.8
As for the Sigma, I posted a thread on this site commenting on their lens construction. Be careful with Sigma if you decide to get one. Personally, Sigma doesn't exist for me anymore.
Happy shooting

[01af]

"osquar" wrote:
> I wonder if you already have a 85 mm, do you
> still need a macro lens?

Depends on your needs, intents, and purposes. For perfect and comfortable macro shooting---yes, you'll need a macro lens. While you can enable regular (i. e. non-macro) lenses to do close-up photography using special accessories like close-up lenses, extension tubes, bellows, and reverse rings, those solutions usually are inferior to a dedicated macro lens with regards to usability, image quality, or both.


"osquar" further wrote:
> Adding an extension tube to bring you closer to
> the object shouldn't decrease image quality, right?

Wrong. It will bring you closer indeed but also will decrease image quality. The loss will be minor with a short tube but will increase significantly with longer tubes. Generally, in the moderate close-up range (at magnifications of 1:10 to 1:3), short and medium non-macro lenses will yield better results with close-up lenses than with extension tubes. However the 85 mm 1.4 lenses use 72 mm filters---and close-up lenses of this size are rare and expensive.


"Cogito" wrote:
> Macro lenses [...] are capable of taking excellent
> portraits but their design means they have a very
> limited depth of field.

Not true. All things equal (image format, focal length, aperture, and focus distance), macro lenses have exactly the same depth-of-field as non-macro lenses. Depth-of-field does not depend on lens design. Umm ... or actually, it does---but that will become evident only at very large magnifications way beyond 1:1. And it does not depend on macro vs. non-macro but on the exit-to-entry-pupil ratio.

-- Olaf

[Cogito]

"osquar" wrote:
"Cogito" wrote:
> Macro lenses [...] are capable of taking excellent
> portraits but their design means they have a very
> limited depth of field.
Not true. All things equal (image format, focal length, aperture, and focus distance), macro lenses have exactly the same depth-of-field as non-macro lenses.
-- Olaf

Not quite, but you are correct. Perhaps I should have added "at 1:1 and close focusing"

[osquar]

The Sony 50/2.8 Macro serves me mainly in my practice (skin diseases), but sometimes I do use it for portraiture. Take a look at this http://harmar.photoblogs.am/index.php?showimage=2437
Will be flattered to read your comments and critiques.

Thanks Dr. Harout, The images are great!

Now, I have to re-evaluate my wish list again. At first, for 50mm range, I hesitated between 50mm Macro and Lensbaby. I have heard that for Macro you normally focus manually anyway, so my plan was to go for Lensbaby.

Well I have to be prepared for varaible changes.

[osquar]

Depends on your needs, intents, and purposes. For perfect and comfortable macro shooting---yes, you'll need a macro lens. While you can enable regular (i. e. non-macro) lenses to do close-up photography using special accessories like close-up lenses, extension tubes, bellows, and reverse rings, those solutions usually are inferior to a dedicated macro lens with regards to usability, image quality, or both.


"osquar" further wrote:
> Adding an extension tube to bring you closer to
> the object shouldn't decrease image quality, right?

Wrong. It will bring you closer indeed but also will decrease image quality. The loss will be minor with a short tube but will increase significantly with longer tubes. Generally, in the moderate close-up range (at magnifications of 1:10 to 1:3), short and medium non-macro lenses will yield better results with close-up lenses than with extension tubes. However the 85 mm 1.4 lenses use 72 mm filters---and close-up lenses of this size are rare and expensive.


-- Olaf

Thank you very much for your input Olaf. I have a following question. I just checked the spec. of 85mm and it says the ratio for this lens is 1:7.87 (0.13x). Is there a way to calculate on how much extension tube I need or/and close-up lenses does it take to reach 1:1?

Thank you in advance.

[01af]

"osquar" wrote:
> I just checked the spec. of 85 mm and it says the ratio for this lens is 1:7.87 (0.13x).
> Is there a way to calculate on how much extension tube I need or/and close-up lenses
> does it take to reach 1:1?

Yes, sure. You'll need 85 mm of extension tube length (i. e. same as focal length) to reach a magnification of 1:1 (1×) with the lens set to infinity. With the lens set to its own minimum focusing distance, you'll get away with a little less extension length. How much less exactly depends on the lens' focal length, the minimum focusing distance, and (!) the lens design. So without precise knowledge of the focusing mechanism's design you cannot calculate the minimum required extension length precisely but we can estimate it: with the 85 mm lens set to its own minimum focusing distance, you'll need approximately 74 mm of additional extension length to reach 1:1.

A typical set of 3rd-party-made extension tubes (e. g. from Kenko, Soligor, or Vivitar) has three tubes of different lengths which add up to 60 - 65 mm of total extension length. With the 85 mm lens on such a set of tubes you'll get a maximum magnification of approx. 1:1.15 (0.87×). However, as I said previously, the image quality will be acceptable (not excellent) at the frame's center and drop significantly towards the frame's edges. So depending on your subjects and expectations, image quality may be just good enough (if stopped down to f/8 - f/16) but will definitely be inferior to a real macro lens.

To reach 1:1 (1×) with close-up lenses on the 85 mm lens, you'd need a strength of +11 dpt. I am not aware of any lens or filter manufacturer who offers close-up lenses of this strength and 72 mm size. Maybe your local optometrist can custom-make one for you. However, again image quality will be poor. It'll be slightly better when the close-up lens is achromatic (i. e. double-element). With weaker achromatic close-up lenses of +1 dpt to +4 dpt (and no extension tubes), image quality will be very good but max. magnification will be 0.21× - 0.47× only. In this range, close-up lenses on a non-macro master lens are fine. For larger magnifications, a macro lens is recommended.

You can also combine a weaker close-up lens and a shorter extension tube. The formula to calculate the magnification m reached with a close-up lens of strength s (in diopters) plus an extension tube of length e (in millimeters) on a lens of focal length f (in millimeters) which is set to infinity is here:

Code: Select all

m  =  ((f + e) * ((1000 / f) + s) / 1000) - 1

To estimate the magnification with the lens set to its own minimum focusing distance, simply add the lens' own maximum magnification (i. e. 0.13 in your case) to m. That won't be perfectly accurate but close enough. But again: image quality will drop significantly when going to magnifications beyond 0.3× - 0.4× this way.

-- Olaf

[osquar]

Hi Olaf,

Thank you very much for your information. I set up the model according to your formula in excel and I made simulation with all the lenses I have and the lenses on my wish list. The more I simulate, the more I understand how special Macro lenses are and why they are so expensive.

As a novis I have always looked at focal length and f-stops when considering a new lens. Lately, after seeing images of STF lens I discovered the beauty of bokeh. Now I have another factor to consider.

I think I will invest in extension tube & close-up lens first to use with my current equipment and see if Macro is something for me. If it's I will sure buy a true macro lens in the future.

Once again, thank you all you guys. You have been very helpful.