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03-27-2010, 10:57 AM   #1
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Macro lens question

Not sure whether this question really belongs here, but since I *am* a beginner, sort of (meaning I've not done much photography since my Canon F1 back in the early 70s!), I'll give it a try. I've decided to buy the K-x. My interests are in macro and portrait (plus candid group shots at parties), so I'm trying to figure out how to maximize dollars spent to utility. I've read that a 100mm macro lens can be used for both macro and portrait work; and the same is true for the 35mm version. I'm just not sure what the practical differences are...why would one opt for a longer focal-length macro lens over the shorter one? Which is the more versatile? Aren't both "1:1" lenses? does this mean the magnification is the same? It seems like the 100mm would magnify more. Anyway, you can tell what a beginner I am! Thanks for the help, though!
And one more related question: are their macro zoom lenses that are the same speed through all the focal lengths?

03-27-2010, 11:05 AM   #2
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QuoteOriginally posted by p-bags Quote
Not sure whether this question really belongs here, but since I *am* a beginner, sort of (meaning I've not done much photography since my Canon F1 back in the early 70s!), I'll give it a try. I've decided to buy the K-x. My interests are in macro and portrait (plus candid group shots at parties), so I'm trying to figure out how to maximize dollars spent to utility. I've read that a 100mm macro lens can be used for both macro and portrait work; and the same is true for the 35mm version. I'm just not sure what the practical differences are...why would one opt for a longer focal-length macro lens over the shorter one? Which is the more versatile? Aren't both "1:1" lenses? does this mean the magnification is the same? It seems like the 100mm would magnify more. Anyway, you can tell what a beginner I am! Thanks for the help, though!
And one more related question: are their macro zoom lenses that are the same speed through all the focal lengths?
The longer focal length puts you further away from the subject and makes it more convenient when artificial light is involved. If you're using off camera flash or lamps, and trying to photograph a penny, the camera/50 lens will have to be so close that it gets in the way of your lighting, or will cast shadows.

Not all macros are 1:1.

I don't think any zooms have the same speed throughout the range, but I could be wrong. But if they exist, mortal men like us can't afford them.
03-27-2010, 11:30 AM   #3
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No, lenses marketed as "macro zooms" don't go 1:1 unassisted, and if they did and had a consistent fast aperture, the NSA could afford them but you couldn't. (Hey, Ira!)

No, 35mm macros aren't good for portraits, unless you mean family portraits. Yes, 35mm and 50mm macros are good for studio work, where you get REAL CLOSE to eensy weensy subjects. And a Fast Fifty is good for portraits.

Yes, ~100mm macros are also good for portraits, and they put you at a workable distance from eensy weensy subjects in the field. No, they needn't be expensive autofocus babies; you'll want them fast for portraits, but for careful work you'll want manual focus. My old M42 Vivitar 90/2.8 macro is manual, goes 1:1, and cost US$3 on eBay. I use Catch-In-Focus for sharp shooting. It's good in the field, and for studio work with controlled lighting.

Other possibilities, depending on your budget, are to find a non-macro lens in the 85-105mm range, and use macro extension tubes for those eensy weensy subjects. But that can get clumsy. I also use M42 135mm lenses on slight extension for portraits, that slight extension being just a (safe) flanged adapter. Also 50mm, 55mm, and 58mm glass on that same flanged adapter. Whatever works.
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03-27-2010, 04:35 PM   #4
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Thanks, Ira. Much obliged. So it sounds like the 100mm-ish lens is better for my applications (and RioRico seems to agree, too). How does one know whether a particular non-Pentax branded lens will work with the K-x?

03-27-2010, 05:56 PM   #5
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If it says it's for Pentax, it works with the K-x. Needs an adapter is it's a very old screwmountlens, or a lens for a much larger film format than the typical 35mm film most SLR's use, but assuming it's your standard issue K-mount - the kind Pentax has used for the last 30-40 years - it fits and works with no adapter.
03-27-2010, 10:12 PM   #6
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I use to own a Sigma MF 50mm macro which was a great lens but it didn't give me enough distance for imaging one of my other hobbies.....coins.

Light is good when you need some distance, and this is magnified using a lens under artificial light indoors. I happened to come across a Vivitar Series I 105 and haven't looked back, the extra distance makes a big difference!



03-28-2010, 08:43 AM   #7
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Wow! Beautiful. What would you say are equivalent lenses on the market today, i.e. to the Vivitar you use?
03-28-2010, 08:57 AM   #8
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The Sigma 105mm Pentax DFA100mm and Tamron 90mm are all excellent lenses. It would be hard to pick a winner between them and Pentax might have a slight edge with the SMC coatings that it offeres (better contrast and flare control). But a macro lens can have one issue when shooting portraits. I needs to have a limiter switch. The reason is that the lens could try to take a close focus shot and might take a long time to lock the correct focus. When you use these lenses, you'll notice the focus barrel turns much more than a modern auto focus lens and the lens extends to about double it's closed lenght. as a result they can be (not always) slower to focus.

But they still make a good portrait lens at a distance. The other thing is they are long on a Digital body. The effective focal length is 150mm on a DSLR. So your portraits are going to be tight head shots unless you are 20+ feet away.

The best all round (head and chest) focal range on a DSLR for portraits is about 40-50mm. For full body, 35mm is very good.

So that's why you hear various opinions betwen the 35mm, 50mm and 100mm lenghts. There's really no perfect solution to getting macro and portrait in one fixed length lens.

Many portrait photgraphers now will use a lens like 17-50mm or similar for that type of photography. Macro shooters will just choose the lens that is right for their needs.

03-28-2010, 09:23 AM   #9
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If you want a dedicated 100mm macro lens but don't wish to spend the money on the DFA or Sigma/Tamron equivalents, check the markpetplace forum here or Ebay for the various manual focus 100mm macro lenses (often just the same lens sold under different names) that might run only $100 or so. You don't generally use AF with macro photography anyhow.
03-28-2010, 10:13 AM   #10
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QuoteOriginally posted by Marc Sabatella Quote
If you want a dedicated 100mm macro lens but don't wish to spend the money on the DFA or Sigma/Tamron equivalents, check the markpetplace forum here or Ebay for the various manual focus 100mm macro lenses (often just the same lens sold under different names) that might run only $100 or so. You don't generally use AF with macro photography anyhow.
A bunch of manual lens users instructively (and eclectically) discuss what they use for shooting macro here: Manual Focus Lenses :: Your form of Macro
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03-28-2010, 05:09 PM   #11
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Thanks, Peter (& everyone else here). One related newbie question that just occurred to me, and perhaps it's addressed someplace here in another thread, but if one uses a Pentax FA lens (which I see on the Pentax website is "full frame") on a camera like the K-x, what is the effect? Why would one use an FA lens (or other full-frame lens) on an APS-C camera?
03-28-2010, 05:50 PM   #12
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QuoteOriginally posted by p-bags Quote
t if one uses a Pentax FA lens (which I see on the Pentax website is "full frame") on a camera like the K-x, what is the effect? Why would one use an FA lens (or other full-frame lens) on an APS-C camera?
Optically, using a FA75 (if it existed) would be exactly the same as using a DA75 (if it existed). The main difference is that DA lenses are designed to cast an image circle big enough for the half-frame APS-C sensor, not for the larger full-frame, so those lenses tend to be smaller and lighter than their FA counterparts. Thus, they might AF slightly faster.

Why use FA lenses? Because you get great optics for the price, you get AF, and if Pentax ever comes out with a full-frame dSLR, they'll be directly compatible. Why use older full-frame lenses? Because they're superb, and a real deal. All the great old Taks and SMCs we talk about here are full-frame, and they give stellar performance. Try some and see.

[/me fondles the M42 Vivitar 90/2.8 macro that cost US$3 on eBay. /me gloats.]
03-29-2010, 07:27 AM   #13
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OK, /me convinced! Thanks much! My new K-x should arrive within a few days.
03-29-2010, 09:07 PM   #14
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Sigma 70mm macro

What do folks think of the Sigma Macro 70mm f2.8 EX DG? Perhaps this would be a nice compromise? It comes in a Pentax version.
03-30-2010, 02:45 PM   #15
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If I wanted one lens to work for portrait and macro and was equally concerned about both, absolutely no doubt the Sigma 70 would be my choice - no contest, really, as there are not really any options I'd even be considering. The 90/100/105 macros would get consideration only if I was more concerned about macro than portrait, the DA70 or FA77 only if I were more concerned about portrait than macro.

But since you mention candids at parties, do realize *all* of these lenses are really too long for that. This is a job for the DA40or something similar.
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