Pentax Imaging 21620 70mm f/2.4 Limited

A lot of people have a tough time choosing between DA 70mm Limited and the FA 77mm Limited. Both lenses have their merits, but I ended up going with the DA 70mm for a few reasons...

DA 70mm pros:
+ Much faster autofocus.
+ Much less CA (chromatic aberrations) and purple fringing.
+ Much cheaper.
+ Still works on film bodies, but you need a body that supports aperture controls.
+ Eolake points out in the comments that the DA 70mm is much more compact than the FA 77mm.
+ Lijia Zhang points out in the comments that the DA 70mm also supports Quick-Shift focusing.

FA 77mm pros:
+ About 1 stop faster (f/1.8 vs f/2.4).
+ Has an aperture ring so it works on all Pentax 35mm film bodies as well as digital.
+ General consensus that the bokeh is better.
+ Slightly longer reach.

Both lenses are sharp and render images beautifully, so as you can see, it really depends on what you want from the lens.

Since I wanted this lens for candid portraits, I needed the much faster autofocus capabilities. I also figured that I wouldn't shoot at f/1.8 much anyways since I find it difficult to work with such a small depth of field when shooting portraits. While most people find the FA 77mm's bokeh to be better, the 70mm still produces very pleasing bokeh. It's just different.

All in all, the DA 70mm seemed like a much better deal to me and I don't regret buying it over the FA 77mm at all.

Now I have used many different camera systems and their respective lenses, I am now buying my second 70mm Da limited, the first being stolen. This is the first lens I used that really shows of the K20D's capabilities, even the old faithful 50mm does not render as well nor is as sharp over all ( edge to edge ). This lens is Very sharp wide open edge to edge right to F16, great contrast, I even compared it's sharpness to the Sigma 70mm macro and at normal distances it beats the macro for sharpness and contrast and has much better bokeh.

The lens is small and light and surprisingly feels great when mounted on camera, the quick shift focusing ring is something I wish the older Fa limited lenses had so you can manual focus at anytime.

Af speed is fast, this is the fastest Pentax lens I had used until the DA 40mm limited and now newer sdm/hsm lenses, yes it is a little noisy but not so bad, it focuses with zest and lets you know it. I did have to adjust the AF on the K20D to fix a bit of front focusing with this lens but I think they are all like that on the K20D, once adjusted it is very accurate from 2ft to infinity with very little hunting.

But the lens does have it's real faults, first the close focus I wish was better, not macro but say to 1ft min distance, it does also purple ca at big apertures, not alot but just enough that you can see it, still much better than the FA 77mm in that regard. It handles flare well but has some ghosting, again not so bad but it is there. The last wish was that this was an F2 or better but F2.4 is just enough to get those shallow dof blown away bokeh shots, just.

So it's not a perfect lens but for it's price its a real bargain for how it performs and how well made it is, if your a prime shooter and need a short tele I think this is your best bet, even over the FA 77mm ( unless you really need the shallower dof/ faster aperture or are using it manual focus only ). This is one of Pentax's real "L" glass beating lenses, I have Nikon D300 and canon 5D owners jaws drop at the sharpness and clarity ( micro contrast ) of this lens, Only the Canon 85mm and 135mm L ( the 100mm to but they stopped making that one ) lenses are as good IQ wise.

I'm extremely happy with this lens. The speed is decent enough at f2.4 and the autofocus works fast with the K100D. Apart from film size advantages, one of the reasons medium format is such a good portrait format has to do with the 'normal' lens being in the 70-85mm zone. You get just the right perspective and DOF.

This lens is good to use across the room, as you can concentrate on one or two people at a time. On digital the detail and color resolution is very natural, not over done as with some. The smooth transition to really good bokeh is another advantage.

Even though Pentax does not recommend the DA lenses for film bodies, I tried it out with good results on a ZX-10 camera. No vignetting and decent sharpness across the field. There is no aperture ring on the lens, so you'd need a body that works with that.

Overall I recommend this lens as an excellent optic, well made and compact.