Pentax 100mm Macro - can it lead a double life as low light telephoto?

[calsan]

My question is for owners of the 100mm Macro:

Is this lens also useful as a low-light short telephoto lens?  How does it's auto focus hold up in low light?
Thanks

Cal   

[spyglass]

Calsan that is a great question as it is always useful to consider a lens "in a different light" - excuse the pun.

 With a Maximum aperture of f2.8 it is fast enough / lets in a significant amount of light to be consider a candidate for low light level work. A DSLR will, with the exception of screw mount lenses and older stop down lenses that lack the mechanical coupling between the camera and lens, provide maximum aperture opening during viewing and focusing (the aperture stops down during exposure).

While I find the mechanical screw driven auto focus to be loud, and roll my eyes when it wants to exercise through it full focus range, it does seem to arrive at an acceptable focus conclusion the majority of the time. I believe this is because of it's reasonably wide f2.8 aperture opening during viewing and focusing. At f2.8 the lens would let in above average levels (not as good as an f1.2. f1.4, f1.7. f1.8, or f2....... but better than the f3.5, f4, f4.5 or f5.6  that we find on many lens). While it is nice to have a lens with a large aperture opening for exposure purposes, it is also an important factor for focusing and viewing your composition (you might shoot a evening time delay at f4...... but in order to focus & compose f2.8 makes it twice as easy as f4 (you double the amount of light as you go down in f stops and half as you go up in f stops).

I used my 100mm for portrait shots before acquiring my 77mm. Light levels were often fairly low. I do not remember having trouble focusing or viewing. I do have to admit that I tend to manually focus 90% for portrait shots. I would say when used with a tripod, or hand held and high ISO, it would be capable in the field.   


Spyglass

[blackcloudbrew]

In addition to macro work, I've used this lens in low light (during concerts), for portraits, and for landscapes with great success, I might add. It's very sharp it shows in the images. I would echo Spyglass's remarks although when I was shooting a concert in low light, I did it hand held just fine on my K20 with the ISO around 800-1600.

Honestly, when I've used it in other situations than macro, I've been pleased and have to remind myself of it's verstilitiy. YMMV
 

[Ron Kruger]

I use my DA 35 Limited more for macro and my DFA 100 more for 100. Beyond sharpness, I love the way this lens renders images, so I find ways to use it even when a different FL makes more sense. It is (surprisingly) a great protrait lens that renders flesh tones beautifuly, and even is great for scenic shots.
I use MF most of the time with all lenses, but I did find the 100's long throw and hunting in low light a little worse than most. Doesn't bother me at all. All my focus (pun intended) is on final results.

[blackcloudbrew]

Here is a landscape shot I like with the DAF100.


And a low light shot.


The I would also say that the long throw on the focus may annoy others. But I've never been particularly bothered by it. In real macro work I'm in MF anyway, and other times I'll just let it AF and override it when necessary. This happens with other lenses too (Tamron 70-200 for example).

[calsan]

Thanks for all the feedback on this lens - these are the type of shots and situations I was interested in.
I don't have a fast telephoto or a macro, so I was hoping to kill two birds with one stone.  On the other hand, I'm not big on hauling heavy equipment around and I know this lens is very small.

Ron
I was wondering why you use your 35mm more for macro - why is this?

[Ron Kruger]

I like the POV of the 35mm macro better, it seems a little sharper to me and because I shoot most macro at f-22 with fill-flash for maximum DOF. The 35 makes fill with f-22 possible because of the close working distance.
Google my name and click on any link to Photoshelter, then click on Tiny Wildflower Macros to see a lot of examples. Only those with what I call black bokeh were taken with my 100 mm (f-18-16. Because of the longer working distance, the fill light only reaches the subject, not beyond, so the background goes black. Neat effect, too, but most of the time I want to show as much as possible, so I get the lens almost against the subject and flood it with diffused flash.

[calsan]

Ron
That was a clear example and a really inspiring collection of photos.  We get fantastic wildflowers here in September, so I'll make getting a decent macro my goal before then....
Cal