[Timd]

The best is to use the 18-135 to determine the focal length of the lens that you can compose the shot, then get the appropriate prime. Being a faster aperture will enable better isolation from the background. However, the 18-135 is very quick to focus. Perhaps the hunting is due to the focus selection. Perhaps limiting to centre focus only will be better. Remember shooting at a faster aperture isolates the background by reducing the dof. It also makes focusing more difficult as the focal plane becomes less.

[ScooterMaxi Jim]

For most shooters these days, no one lens is going to give you the best portrait results in all situations. Longer lenses tend to do better for formal portraiture, and some faster short-range zooms are good for environmental portraits. Typically, long range zooms - beyond 3 to 1 range - do not provide enough speed or optical quality, and macros universally are designed for a very different purpose. Most 50mm lenses were designed for maximum sharpness and contrast as full frame lenses, but their overall bokeh often is a bit harsh.

It might be helpful to explore flickr portfolios from the lenses you're considering. Rather than looking for absolute sharpness, consider tonality and bokeh (quality of out-of-focus blur), as these are essential for quality portrait work.

Among the more-economical manual focus solutions known for good portraiture are the old Pentax A-35-105 f/3.5 (especially good in the middle to long end), and the Samyang/Rokinon 85mm f/1.4. Manual focus lenses are great for taking portraits because they are quiet, and you are more assured of nailing the focus point exactly where you want it (typically the eye closest to the lens).

[jaikumarr18]

Checked on few online stores regarding the lens availability and they all were recommending Sigma 35mm F1.4 DG HSM which costs around AU$899. I thought Pentax *DA 55 f1.4 was better than Sigma. Anyways, am not too sure if Sigma is worth for that cost.

[ScooterMaxi Jim]

Checked on few online stores regarding the lens availability and they all were recommending Sigma 35mm F1.4 DG HSM which costs around AU$899. I thought Pentax *DA 55 f1.4 was better than Sigma. Anyways, am not too sure if Sigma is worth for that cost.

These are very different lenses, so it is difficult to comment. Not sure that many people would recommend the Sigma as a "portrait" lens, but its reputation and ratings as a fast normal lens is very good. It might not quite match the color saturation or warmth we come to expect from the Pentax lenses. The DA 55 is one of those rare lenses under 60mm that really is designed for portraiture. Very few people rate it anything less than excellent. It can be a challenge to focus properly in AF on some cameras. But, again, most professionals using this lens (or any other lens for that matter), are going to be shooting most of their portraits in manual focus for a number of reasons.

[RGlasel]

You need auto focus for party shots, when you have to move around, and you can't pose people. If you can pose your subject, you can use manual focus. With a 50mm lens, you need a distance of 10 feet to get a full length shot. Get the DA 35 for the shots where you need auto focus and have limited space, and get an A 50 /1.7 for posed portraits. The f1.7 A 50's were a kit lens for lots of the Program film cameras and are readily available in the used market for a price that will leave enough in your budget for the DA 35 as normhead said. Or use the 18-135 when you have enough ambient light to get the AF right and you don't need or want a shallow depth of field. For me, that lens is the closest thing to instant focus there is, as long as you don't need to use the AF assist light. And don't delay, because the longer you overthink this, the lower your confidence in your final decision.

[6BQ5]

I don't shoot a lot of portraits but when I do I find myself either with my FA 50mm f/1.7 or I'm zooming to somewhere between 50mm and 70mm on my DA 18-135mm. Both lenses can render excellent images if used correctly but the FA 50mm definitely has a slight edge when it comes to sharpness. Still, I would say that you should put sharpness aside and look at the shoot environment. If you are in a dynamic, fast pace environment then the 18-135 won't hurt you as much as you may think. Take the shot. Better than missing it because you couldn't walk up fast enough to get the shot. If your situation is more controlled and sedentary then by all means switch to a prime (in my case, the 50mm).

[infra4801]

I will insist what everyone else said: a 30mm is NOT a good portrait lens. It's great for many other things, but NOT for portraits.
At least get a 50mm. If you are on a budget, don't get the 55mm 1.4 SDM. Get the FA 50mm 1.4. Now, if you are lucky to find one, get the FA 50mm 1.7. It's dead sharp from 1.7. That is, if you are lucky to find one used. Now, any 85mm 1.4 are magic. The Sigma 85mm 1.4 is huge and expensive, but I hear nothing but wonders about it. And of course, the ultimate miracle worker, the FA 77mm 1.8.
But, like I said, for portraits, DO NOT get anything wider than 50mm. The 30mm is NOT a portrait lens. Look it up. Now, ideally, you could get a 50-135mm 2.8, also excellent.

These are with my FA 50mm 1.4.

[K McCall]

So just to play devil's advocate here, all of these were taken with the 31/1.8 (I know not a lens you're considering, but fairly close to 35mm):










And this one was at 35mm with the DA 35 Macro:

[stevebrot]

So just to play devil's advocate here, all of these were taken with the 31/1.8 (I know not a lens you're considering, but fairly close to 35mm):










And this one was at 35mm with the DA 35 Macro:

Keitha...Thanks for weighing in here with some superb examples.

It is not well understood that perspective is based on camera position relative to the subject and that there is nothing magic about the 70-85mm range of the traditional portrait lens. The only thing special is that focal length allows for a good working distance with 35mm film and also allows for a fast maximum aperture with reasonable bulk/weight. 50mm lenses for the same format were also acceptable and a lot of good work was done from the working distances available using those lenses.

Your 31mm and 35mm shots illustrate the point well. They could just as easily have been taken using a 46mm or 52mm lens on 35mm film and would have provided an identical perspective and composition. In my opinion, you can go as short as 28mm and still provide a pleasing portrait perspective on APS-C.

That being said, I am not convinced that the OP is really looking for a lens for portraiture at all. It sounds like the requirements are for a lens that will:

• Auto-focus quickly with little hesitation in low light
• Allow for selective focus (narrow DOF) for subject isolation
• Be usable in potentially cramped indoor locations

In other words, a party lens to allow for "capture and run" work on the fly. Many of the screw-drive Pentax lenses in the 28mm to 35mm range, f/2.8 and wider will work quite nicely for this.

The possible exception is the low light AF performance. The AF systems of all but one Pentax camera model will hunt in low light without a focus assist lamp regardless of lens maximum aperture. The explanation is complex, but the AF system on most cameras "waste" the wider aperture (generally wider than f/5.6). One of the big features of the K-3 is that it is able to use f/2.8 with three of its center sensor(s) for better performance with faster lenses. This is a characteristic that it shares with other premium cameras. The K-30 lacks this capability.

The result is that the 18-135 (one of Pentax's faster focusing lenses) is probably quicker in most conditions than many of the options suggested on this thread, but no better in dim light with the K-30. The weak link is the camera, not the lens.


Steve

[jaikumarr18]

Keitha...Thanks for weighing in here with some superb examples.

It is not well understood that perspective is based on camera position relative to the subject and that there is nothing magic about the 70-85mm range of the traditional portrait lens. The only thing special is that focal length allows for a good working distance with 35mm film and also allows for a fast maximum aperture with reasonable bulk/weight. 50mm lenses for the same format were also acceptable and a lot of good work was done from the working distances available using those lenses.

Your 31mm and 35mm shots illustrate the point well. They could just as easily have been taken using a 46mm or 52mm lens on 35mm film and would have provided an identical perspective and composition. In my opinion, you can go as short as 28mm and still provide a pleasing portrait perspective on APS-C.

That being said, I am not convinced that the OP is really looking for a lens for portraiture at all. It sounds like the requirements are for a lens that will:

• Auto-focus quickly with little hesitation in low light
• Allow for selective focus (narrow DOF) for subject isolation
• Be usable in potentially cramped indoor locations

In other words, a party lens to allow for "capture and run" work on the fly. Many of the screw-drive Pentax lenses in the 28mm to 35mm range, f/2.8 and wider will work quite nicely for this.

The possible exception is the low light AF performance. The AF systems of all but one Pentax camera model will hunt in low light without a focus assist lamp regardless of lens maximum aperture. The explanation is complex, but the AF system on most cameras "waste" the wider aperture (generally wider than f/5.6). One of the big features of the K-3 is that it is able to use f/2.8 with three of its center sensor(s) for better performance with faster lenses. This is a characteristic that it shares with other premium cameras. The K-30 lacks this capability.

The result is that the 18-135 (one of Pentax's faster focusing lenses) is probably quicker in most conditions than many of the options suggested on this thread, but no better in dim light with the K-30. The weak link is the camera, not the lens.


Steve

@ Steve, that is exactly what I was looking for. The reason being, I struggled to take pictures during my friend's birthday party due to low light. The auto focus really gave me a hard time and manual focus with 18-135 mm lens requires some skills I believe. Hence I thought a prime lens with f1.4 will be the best option during those situations. But as per your comment, I believe it might not resolve my issue. Am not sure if external flash might be an answer to the issue since I dont want to change my camera at this point of time.

[clackers]

The reason being, I struggled to take pictures during my friend's birthday party due to low light. .

That's not a formal portrait situation, carefully composed with natural light, Jai.

Ad hoc shooting in dark interiors is what your flash does.

A gorgeous f1.2 lens with wafer thin DoF is unlikely to be what you're after.

[infra4801]

Ok, so in the end, you can shoot portraits with a 30mm. I guess I'm gonna have to try that.
And maybe your low light situation is just too low light. My FA 50mm 1.4 hunts just as much (or should I say, as little) as my tamron 17-50mm 2.8 in low light. It is a lot sharper, though. The Pentax focusing system does already a great job. Perhaps you should try changing the setting in your camera so it doesn't have to wait to lock focus to shoot, will just shoot whenever you fully press the button.
And yes, a flash gun will improve your low light shooting enormously. I bought the Metz 52 AF-1, and use it all the time indoors. A flash gun and the 18-135 you already have will be a pretty decent combination, and maybe just all you need. There is the learning curve, though. I still use my flash gun fully manual with the camera in fully manual as well. Can't get the camera to agree with me.

[K McCall]

The result is that the 18-135 (one of Pentax's faster focusing lenses) is probably quicker in most conditions than many of the options suggested on this thread, but no better in dim light with the K-30. The weak link is the camera, not the lens.


Steve

A most enlightening synopsis of the problem, Steve! To be fair, my party days are long behind me, and it's been a while since I've been in such low light that my K-30's AF can't lock (much more of my frustration comes from the interminable AF search of the D-FA 100mm macro in excellent light). I suppose it's become second nature to switch to manual when the camera and I are having a disagreement.

And @infra4801, a 30ish-mm lens might not be the best option on paper for portraits, but I've learned that sometimes it's the best option in a real-life setting. I now live in Texas and am surrounded by wide-open spaces, but I moved here from a shoebox in NYC, and having a wide prime was a godsend there. I'll concede the point that for more traditional portraits, I tend to reach for lenses longer than 50mm if at all possible.

[LeRolls]

I'm with dcbear on this one! The FA77 all the way if you can afford it! This lens makes me excited to take portraits it's really that good! It will make you K-30 sing!

[jaikumarr18]

Thanks LeRolls. Those are amazing pictures. But again, the reason am looking for a different lens is to improve AF during low light condition. As per the above discussions, I believe that is something to do with the camera itself and might not be with the lens. Even if I go with an external flash, still it has nothing to do with the AF. Canon got a different way though and it uses flash to identify and focus subjects unlike focus assist lamp in pentax. The only way to resolve my situation might be is to use manual focus and not rely on the autofocus. To be honest, there are too many lens options available and most of them looks good to me.