[Lowell Goudge]

why not try you r50mmF1.4

it will allow you to do some different things with isolation of subject at F1.4-F2 that you can;t do with the 50-135

Also, moving outside and stepping back a little with something in the 100-135mm range can work.

I like using my old MF 105mm and 135mm lenses for outdoor portraits. they allow you to get out of the subjects fase a little

[Douglas_of_Sweden]

I have been doing some successful portraits with strobes, and would now like to try a natural light pic of a mother and baby. Trouble is the only lens that lets me stop down to 2.8 or 4.00 is my ancient prime lens, which means I will be just about sitting on their heads. I have tried using 5.6 @ 125 with my 70 to 300 lens but the moment I zoom in I lose the setting. I have tried with the shorter 70ml lens but again if I zoom in I lose the apertature. I tried (all this with toys at moment)using the available winddow light, then bringing in the soft box (umbrella) and putting a continuous light on the object and an ISO of 800 but that was still too dark. Sooo any idea on what lens I should be looking for, or should I invest in one of those continuous light setups?
My strobes are pretty ancient and only have high and low settings. I don't want to use them as strobes for this shot unless I really have to.
cheers Trish

The "fast" portrait lenses I use/have used:

DA 70ltd/2.4 - Not that fast, but sooo smal, and a great street-portrait lens.
DA*50-135/2.8 - Good choise for a portrait zoom. One of my first threads on this forum in 2008 was a shoot out between this zoom and four A and A* primes. Conclusion was that while not so good at 135 (and 50) mm, it approach a prime in quality in the middle.
A*85/1.4 - Great portrait lens, from f1.8 it is really good, but a bit soft at f1.4. For that reason you may as well buy the FA77ltd/1.8 which is the same optical solution, but Pentax desided to drop the f1.4 and get a more compact lens since the extra stop wasn't that usefull anyway.
"K" 105/2.8 - Like this a lot, much better than the 100/2.8, renders faces like the K85/1.8, but for a smaller cost.
A100/2.8 (same as M100/2.8 optically) - not as good as the 105mm, but good enough to be my only portrait lens in the 80's until I got my first 85mm.
Super-Takumar 100/2.8 (non SMC version) - like this a lot, behaves a bit like the K105, but not as sharp.
DFA100/2.8 macro - good for portraits as well as for macro, sharp as all macro's, but when it goes hunting it goes a long way because of its close focus capacity which can be annoying. (Almost) identical optics to the F/FA versions but lighter and smaller filter. The new WR version with its rounded apperture blades should be interresting for portraits, but I haven't had a chance to try one.
A*135/1.8 - Great lens, truly great. Sharp from 1.8. I know it is a bit long for portraits on APS-C, but on film it works.
The other Pentax K-mount 135mm's goes like K135/2.5, fine and sharp, M135/3.5 compact, sharp enough, smother skin, K135/3.5, not that good.
On APS-C I coun't also 50mm as portrait lenses.
A50/1.7 (same optically as the other 50/1.7 lenses from Pentax) - fine portrait lenses, sharp from f2, the M50/1.7 is probably the best ratio between quality and cost that you can get for a Pentax 50mm.
FA50/1.4 (same optically as A and F50/1.4) - fine portrait lens, a little bluish color rending, which is unusual for Pentax
"K"55/1.8 or f2 (same optics), also same as SMC Takumar 55/1.8 or 2 - I like these for portrait, a little less sharp than the f1.7 and f1.4 but that may work well for portaits and a bit warmer color
Super-Takumar 50/1.4 - nice lens that works for portraits, but I actually prefere the 55 or 105 takumars


Some 3rd party
Tamron adaptal 2 SP 90mm f2.5 macro - good portrait lens as well as macro, available for good prices, but if you wan't A connection remember to include a KA adaptal adapter in the cost, it goes for much more than the K adapter.
Mamiya 85/2.8 (m42) - rare and small, not that fast, but works nice on portraits...but you can't mount it on a K mount camera without some modification.
I have too many other 3rd party 50 and 135mm lenses to even start writing about, some good some bad, but most so cheap that they are worth trying, and all fast compared to todays consumer zooms.

As for Pentax portrait lenses I don't own/haven't used enough to have a really well founded opinion about. Other's on the forum know the m42 85mm's well, but from what I have seen I suspect that the 85/1.9 Super Tak is better than it's reputation. Same applies to the M85/2, which is also amazingly small.
FA*85/1.4 and DA*55/1.4 you need to ask someone else about.

Edit: most shots in my flickr are sorted in folders according to lens if you want examples.

[rparmar]

Wow, that's some list! Nice overview.

A*85/1.4 - Great portrait lens, from f1.8 it is really good, but a bit soft at f1.4. For that reason you may as well buy the FA77ltd/1.8 which is the same optical solution, but Pentax desided to drop the f1.4 and get a more compact lens since the extra stop wasn't that usefull anyway.

Just another illustration of how smart Pentax are. Every lens is a compromise and the FA Limiteds are the best possible compromises: compact, sharp, excellent rendering, great build but with some purple fringing and not ultimately fast. Since, as you say, nothing faster than f/2 is that useful anyway. (At 2m distance to subject you get less than 5cm DOF; with f/1.4 you get less than 3cm.)

[Douglas_of_Sweden]

Wow, that's some list! Nice overview.



Just another illustration of how smart Pentax are. Every lens is a compromise and the FA Limiteds are the best possible compromises: compact, sharp, excellent rendering, great build but with some purple fringing and not ultimately fast. Since, as you say, nothing faster than f/2 is that useful anyway. (At 2m distance to subject you get less than 5cm DOF; with f/1.4 you get less than 3cm.)

Well, some bragging rights follows with the f1.4, and the A*85/1.4 looks far more impressive than the FA77ltd...

[Ira]

Also, moving outside and stepping back a little with something in the 100-135mm range can work.

I like using my old MF 105mm and 135mm lenses for outdoor portraits. they allow you to get out of the subjects fase a little

Man, I couldn't agree with this more, although it's been so long since I've done portraits.

With camera on tripod and focused, and being way back, it not only makes your subject 1000% more comfortable, but you can fire off dozens of shots without looking in the viewfinder and your subject doesn't even realize it. You can capture some magic that way.

[Marc Sabatella]

On M whatever I set the fstop, as soon as I zoom in it changes. Ie. I set the ap at 1/100 and the f @f35 on 28mm. As soon as I zoom to 75-80mm the f changes to f5.6.

Oh, sure - you can't keep f/3.5 through the whole range - it's a variable max aperture zoom. But you should be able to keep f/5.6 through the whole range no problem.

I assume it is because I don't have enough light once the zoom is used.

No, it's because most consumer zooms only support larger apertures at smaller focal lengths. All the light in the world won't change that.

[rparmar]

Well, some bragging rights follows with the f1.4, and the A*85/1.4 looks far more impressive than the FA77ltd...

Actually I think the FA Limiteds look nicer than any other Pentax lenses. And for bragging rights I have not one, but two f/1.2 lenses.

Though I don't use them enough to justify keeping them.