[Zerv]

I recently acquired an FA 43 and it has been great thus far, giving me very pleasant and pleasing results that I wasn't getting from my other lenses. However, after taking more and more pictures, I am starting to make some observations about the lens itself and in general.

I took some head and shoulder shots of couples at a bright outdoor event, sitting across the table, about 4-5 feet away at most. The background behind them is quite far, I'd say 300-400 feet. I'm shooting in Av and at f2.8, I took a picture of a couple sitting together, just slightly staggered in distance to me, one shoulder behind another. In other words, their faces were not in the same plane, about 6-7 inches apart. As more experienced shooters probably would have known, the results were the person's face in front who I focused on was sharp but the one slightly behind them was very out of focus.

I tried again, this time at f4. Better, and usable, but person behind was still softer than I would like. I didn't have the opportunity to try again.

Calculating after the fact, at f2.8 I had about 4.5 inches of DOF. At f4, about 6 inches. I probably should have gone with f8 to get both faces in focus.

What I get from this is that with the FA 43, if I am taking head and shoulder shots of couples in a natural setting (unposed and likely not perfectly in plane) at a distance of about 5 feet, I can't go too much larger than f8. Thinking further, it seems like only single person portraits and things I want in focus under 6 inches could use f4 and larger. Increasing distance would help but this isn't always possible. Plus, luckily the background was far away. If there were things or people not far behind them, going to f8 would have not created the separation I wanted.

My question is, does this somewhat render the wider end of this lens with a max of f1.9 impossible to use without backing off quite a bit unless I am shooting for very small in-focus areas? I feel like if I did, I would always be cropping after the fact and I like to compose as shot. If I switch to a longer focal length lens such as an FA 77, this only compounds the problem. If I went shorter such as with a DA 21, it seems like I'd have to get in really close to recreate the shot plus more DOF, less separation. Strictly going by the calculator, it seems my DA 35 from a specifications point of view would have been more appropriate.

In this case, was I just not using the FA 43 as intended? Wide open, I'm getting that you need to be about 9 feet from the subject to get about 1 foot of DOF. This is shedding a somewhat different light on this lens for me. Not good or bad necessarily. Just different than I what I thought this lens was going to be used for. If anything, it definitely gives me more to consider when it's on the camera. And more to consider when choosing my future lenses. This kind of changes what I think about maximum apertures and what I need vs what I want. It's nice to have a large max aperture at your disposal but if it's not used as often and very situational, perhaps the costs may need more consideration.

In saying all this, I think I'm coming to more of an understanding. Am I on the right path or am I thinking about this the wrong way? Any thoughts are appreciated. Thanks!

[GUB]

If I went shorter such as with a DA 21, it seems like I'd have to get in really close to recreate the shot plus more DOF, less separation. Strictly going by the calculator, it seems my DA 35 from a specifications point of view would have been more appropriate

Generally speaking the dof of all would be the same. For a given format for a given image magnification for a given aperture all lens will have the same dof.
The dof calculators apply a coc of .02 to the apsc format. I think in practise you need to halve that if you want to get the best out of your gear. The DoF charts are based on some pretty obselete standards. So at f4 you are playing with 3 - 4 inches. I think the path forward is thinking of the areas that have to be oof and work to get the right balance. Alternatively it is not a biggy to push out to f11 or even f16 but you are losing the gains you have from using a prime.

[mtux]

I guess to have both people's face in focus and large aperture, you need to workaround this issue by either trying an angle which their faces are more in one focus plane or by putting the focus somewhere between them. (which I don't think is easy in the field)
BTW at the end, in situations like this, I opt for a balanced approach between in focus and out of focus people/areas. Sometimes one person being slightly oof isn't much noticeable from a normal viewing angle. so f/4 and trying to put them in one focus plane and then choosing that the person behind could go slightly oof.

[max_pyne]

or with software available take a in focus of both an stack them together...

[mtux]

or with software available take a in focus of both an stack them together...

That's hardly possible for people!

[bobD]

That's hardly possible for people!

I'm interested as to why not...? What are the limitations for stacking in this situation...

[Fogel70]

I'm interested as to why not...? What are the limitations for stacking in this situation...

It's can be difficult to get living persons to be still long enough to be able to use stacking.

A tilt lens can be used for tilting focus plane, but unfortunately there are not that many available for K-mount.

[GUB]

I'm interested as to why not...? What are the limitations for stacking in this situation...

Wouldn't it be simpler to just clone one figure across.

[max_pyne]

i have don recently some group portraiture where i was able to use sticking and in one case stacking... ;-) takes some time but it worked out really well... (lens was not wide enough and i could not walk back....)
and i usually do that stacking stuff with my macro. had recently a case where to reptiles where looking at each other from one cactus to another and it worked out well where moving like crazy.

cloning works as well (used as well in the above mention group pic)... but you need to be careful with the borders from one side to the other

it would need maybe 2 pictures and than stacking works like a breeze

[Geoff-Melb]

I'd go with Gub the kiwi's first comment.
Think about what you like oof and set your aperture to get that, working down rather than up.
Personally, forget the post processing stuff and get it as near as right in the camera.

[alamo5000]

The lens is performing the way it and any other fast lens will. It's up to you as a photographer to learn by trial and error things like you learned. I would say you might not have gotten the exact shot you wanted but you came away with something more valuable. You learned something many people never pay attention to.

If you as a photographer just sat on your chair and didn't try to observe or create the shot that's a lesson learned. If you had moved 3 feet to your left or right your plane would have been totally different.

The fact that you discovered this and will now pay attention to it means to me that your lens is performing great and you as a photographer just made a leap that can result in much better shots in the future.

[Venom3300]

If you want a picture of multiple people in focus in low light, you need a flash. Not a fast lens.

[aleonx3]

Your experience with the 43mm lens is what I find that most of my friends who shoot Canon or Nikon will never learn. Because with a zoom lens people tend to get lazy and turn the zoom ring instead of observing and adjusting focal plane and zoom with the feet. I have far more pleasing shots than most of my friends.

[Lowell Goudge]

You have just discovered what is behind the great myth and arguments about fast lenses and full frame camera.

Ultra fast lenses have one principal use only, isolation of the subject dorm the background.

Fill frame proponents argue that they need full frame cameras to make use of the shallow depth of field, BUT, as the OP discovered, it is a very limited use and artistic approach, which can become repetitive and boring after a while.

You don't need full frame, as the OP has demonstrated to isolate one face only when shooting wide open to achieve the effect, and you don't need ultra fast glass. While both may yeild a more dramatic effect. They are not necessary

[mtux]

I'm interested as to why not...? What are the limitations for stacking in this situation...

As others mentioned, it's hard to shoot two photos (by changing the focus in the middle and people in the shot don't move at all! if you are a photoshop expert like max_pyne, then it might be easy for you.