PENTAX-D FA Macro 100mm

Hi everyone,

For those who own the PENTAX-D FA Macro 100mm F2.8, I would like to ask a few questions

(i) Is there a switch where you can turn on or off to shoot macro? (The reason that I ask this is because I have not use a Macro lense before. And I assume there is a switch to toggle between the Macro mode and Tele mode)

(ii) How would it compare with FA50mm F1.4 in terms of AF speed? Does it hunt during focusing under low light? (Assume we are shooting in tele mode)

Thanks
Daniel

I don't own the lens but you'll find the answers in the following review:
http://www.photozone.de/8Reviews/lenses/pentax_100_28_dfa/index.htm

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http://www.homepages.ucl.ac.uk/~ucsacco/

I don't own the DFA 100mm, but I looked into it and compared it with the Sigma 105mm macro. The Pentax lens does NOT have a focus limiter, but it does have a "clamp" button which locks the focus at whatever you have it set at. The Sigma DOES have a limiter, which limits the focus between infinity and about 1:3, which works great for regular shooting. If you are shooting true macro (1:1 or really close), you'll probably want to use manual focus anyway.

So no, with the Pentax there is no switch to switch it into "macro mode"

As for regular shooting, I'm sure the Pentax would do fine, although you could argue that the Sigma (with the focus limiter) might do a bit better as it would never go to 1:1 and then have to turn all the way back.

Good luck!

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http://photos.evangordon.com

No switch to turn off the macro mode, as there isn’t a macro mode as such – the focus is range is continuous from infinity down to 1:1 (30cm?) there is a focus clamp switch which disables the AF on the body but you can still adjust the focus manually by rotating the focusing collar on the lens – the clamp doesn’t actually lock the focus if you see what I mean.

When focusing at ‘macro’ distances the AF can hunt for focus – going to infinity and then back down. What I find best when shooting macro images is to let the AF acquire the subject, flick the clamp and then manually adjust the focus on the desired part of the subject.

I have both the DFA100 and the FA50.

indyjonesjr said:

(i) Is there a switch where you can turn on or off to shoot macro?

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No, no separate macro mode. The lens just has an extremely short minimum focus distance. It also focuses to infinity and can be used as a normal 100mm lens.

indyjonesjr said:

(ii) How would it compare with FA50mm F1.4 in terms of AF speed?

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The DFA takes longer to focus. Both lenses change focus with the same speed and accuracy, but the distance between the focus ring at minimum focus and the focus ring at maximum focus is longer on the DFA 100 than on the FA50. The FA50 is usually very quick to focus, because the glass doesn't have that far to move. The DFA 100 takes longer, especially if it hunts (goes all the way to opposite focus and back again.)

indyjonesjr said:

Does it hunt during focusing under low light?

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All lenses on my K100D hunt during autofocus in low light. The DFA 100 is no better or no worse than most. In practice the hunting bothers me slightly more, because (1) with macro shots you often use a smaller aperture to be more depth of field, so you are shooting in low light more often, and (2) when the AF hunts, it takes seveal seconds for the lens to go all the way to opposite focus and return.

These points having been made, the DFA100 has some strengths too. It is the smallest of the major K-mount 100mm macro lens. Size is almost exactly the same as the DA50-200, and weight is only 100g more. The Tamron 90 and the Sigma 105 are both larger and heavier. I bought the Pentax mostly because it seemed easier to wiggle into unusual places for unique and different viewing angles, and I have found that to be true. The compact size of this lens is a major benefit.

It's also a very high resolution lens, probably the best one I own for sheer optical quality, except maybe the FA50. The detail it captures on a close range macro is amazing. Because the focus ring covers so much ground, it is very easy to make fine adjustments in manual focus. You can do this even if you use AF, because the lens has the Pentax "quick shift" system where you can adjust focus manually even in AF mode. The long-turning focus ring is a minor annoyance when the AF hunts, but a major advantage when focusing manually, because it allows very precise focus adjustment---which is often useful when shooting high magnification macros.

--Brett
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K100D, March 2007