[mlag]

It's a problem of definitions.


To get pleasing bokeh, you need a lens capable of delivering it, regardless of its maximum aperture. To get shallow DOF, you need a wide aperture and possibly a longer focal length.

Add background separation distance as part of the formula to get nice bokeh, not a lens feature but more situational... increased distance between subject and background is favourable...

[Wheatfield]

Add background separation distance as part of the formula to get nice bokeh, not a lens feature but more situational... increased distance between subject and background is favourable...

Absolutely, if this is possible. Most of the time it is, sometimes not so much. Sometimes we just get too much ugly within the depth of field. This is why it's nice to have the option of a faster lens over a slower one. Also, a lens like an 85/1.4 will be far better at f/4 than a 70-210 f/4 lens will be wide open, so the faster lens really wins in every situation if bokeh is being considered an important to the image.
Once can certainly get good bokeh with a slower lens if one is willing to work a bit to get there (and presuming the slower lens gives nice bokeh to begin with) the faster lens will make it far easier to acquire the appearance shallow depth of field since it is actually capable of giving it.

[GUB]

Absolutely, if this is possible. Most of the time it is, sometimes not so much. Sometimes we just get too much ugly within the depth of field. This is why it's nice to have the option of a faster lens over a slower one. Also, a lens like an 85/1.4 will be far better at f/4 than a 70-210 f/4 lens will be wide open, so the faster lens really wins in every situation if bokeh is being considered an important to the image.
Once can certainly get good bokeh with a slower lens if one is willing to work a bit to get there (and presuming the slower lens gives nice bokeh to begin with) the faster lens will make it far easier to acquire the appearance shallow depth of field since it is actually capable of giving it.

Sometimes the slower lens is beneficial if it is critical for you to stop down a little to get a little more dof.
The slower lens is still wide open with a circular iris while the slightly stopped down fast lens is a hexagon etc.
And depending on the nature of out of focus effect you are looking for the hexagon effect can greatly diminish the effect - much more so than the slight change of size of the bokeh balls of the open lenses.

[Wheatfield]

Sometimes the slower lens is beneficial if it is critical for you to stop down a little to get a little more dof.
The slower lens is still wide open with a circular iris while the slightly stopped down fast lens is a hexagon etc.
And depending on the nature of out of focus effect you are looking for the hexagon effect can greatly diminish the effect - much more so than the slight change of size of the bokeh balls of the open lenses.

This presumes the slower lenses other imaging qualities wide open are acceptable and if there is enough clean space from subject to background, and if there are sufficiently sized specular type highlights in the background to be visible as aperture shaped.
The latter would tell me, if so, that the photographer had chosen his background poorly, perhaps out of desperation to get the required subject separation, and it also presumes the faster lens only has a 5 blade aperture. My portrait lens of choice at the moment has 9 rounded blades and doesn't give the house in profile look to highlights.
The faster lens will always be easier to work with and will give the photographer more problem solving opportunities.

[GUB]

This presumes the slower lenses other imaging qualities wide open are acceptable

The lens I was thinking of was the A series 50mm 2.8 macro as in this image.
I feel that in this field (bokeh) people go on too much about what is good and what is bad bokeh.
It is more important to think about cause and effect of various things going on in the image with an eye to a end result you want.
And the size of the open iris is certainly one of those ( and that validates this thread.)
Probably in this order of importance:
Structure and colour of background
Camera to subject to background distances and relationships.
Degree of openness (size) of iris
Shape of iris
are the key components of getting what you want from your bokeh
Given that in reality the bokeh tends to be secondary in importance compared to the subject it is likely you have already made your choices of lens, image magnification and dof.
So often the most important thing you can do is manipulate your background by moving around a little.

[biz-engineer]

Absolutely 👌 This actually works pretty well for simple subjects in the center of the frame. Darktable has a module called "low pass" that let's you fine tune the blurring algorithm and it's parameters, and it can easily be combined with either drawn masks or luminance masks on LAB. Tweak and export the OOF background, export sharpened layer, and brush the subject on in Photoshop / GIMP.

Even better (I stumbled on it), you can create realistic three dimensional lens blur by taking two "all-in-focus" pictures from a slightly different position, import the pair of stereo images in Stereo Photo Maker software to generate a depth map, apply the depth map as a layer mask so that more or less blur is applied depending on distances.

[Wasp]

To answer the question - probably not, but a fast lens helps a lot.

Taken with an SMC Pentax 50mm f/1.2:



For the ultimate bokeh, you can beat old school and fast.

Taken with a Takumar 35mm f/2.3: