[Fenwoodian]

.
I'm seriously considering getting a Pentax 645D camera.

I only shoot fast lenses wide open.

I reviewed the 645 lens reviews here on the PF, and no single 645 lens stood out as having the best bokeh.

From your experience, if you could have only one bokeh lens for your Pentax 645 camera, which lens would it be?

Thanks,

[RICHARD L.]

FA 75 mm f/2.8 or FA 150 mm f/2.8, I'd say.

[SylvainB]

FA 75 mm f/2.8 or FA 150 mm f/2.8, I'd say.

I would second the recommendation on the 150 f/2.8 ; among all the lenses I have, the FA150 is the one I prefer for bokeh. The FA120 macro is less smooth, and the DFA90 macro is between (more pleasant than the 120, this is for sure).
The 28-45 is just OK (not stellar, but I didn't buy it for that), the DFA35 is nice, the DFA55 OK. The rest I don't have or haven't used enough to comment.
Don't forget the 67 105 f/2,4 which can be fun.

[Alex645]

.
From your experience, if you could have only one bokeh lens for your Pentax 645 camera, which lens would it be?

My vote goes to the 645 FA 75mm f/2.8. Of all my 645 lenses, wide open it's the "dreamiest" bokeh.

[Ed Hurst]

If you don't mind an adaptor and manual operation, I would definitely vote for the 6x7 105mm f2.4.
And the 150mm FA f2.8 is lovely - one of those lenses that provides good resolution without clinical, modern sharpness - just right for the sort of shot where bokeh tends to be spoken of :-)

[texandrews]

FA 75 mm f/2.8 or FA 150 mm f/2.8, I'd say.

Agreed. Best of the bunch for the 645 system.

[Jonathan Mac]

While my experience is limited to three lenses (55/2.8, 75/2.8 & 150/3.5) and film, I would say that the 55mm or 75mm are best. The 150mm provides shallower depth of field of course, but using the 55mm or 75mm wide open and fairly closely focused, you can tell that the focal length is lower and it gives more of that "MF look". People expect shallow DoF from telephoto lenses, less so from normal and wide-angle ones.

It's a shame there's no 75mm f/2 (or faster) lens for the 645 system, that would be a beautiful thing indeed.

For example, here are some of my favourites along those lines from the 75mm.


Edinburgh Jan 2013 400H 026a by Jonathan MacDonald, on Flickr


P645, 400H 017a by Jonathan MacDonald, on Flickr


Paris P645 400H 012a by Jonathan MacDonald, on Flickr

[blackcloudbrew]

Interesting thread. I have a number of these lenses, some of which I've added only recently and not enough time on them to speak intelligently about them, but really I haven't be concentrating on bokeh for my 645 and 6x7 lenses. Sounds like I may have to though.

In looking at the PF ratings for a lot of the modern 645 DFA and FA lenses, most have 9+ numbers for bokeh. A few have rounded blades, notably the DFA 55, DFA 90, DFA 25 (good luck finding one), and the DA 28-45. One would think that rounded blades should produce a more pleasing bokeh. That has been my experience in my 35mm lenses between the DFA 100, and the DFA 100 WR lenses, (not rounded, rounded). The user ratings on the 645 and 6x7 lenses don't really show that though, as the ratings are all very high and very close together for rounded blades or not rounded blades. The exception being the DFA 28-45, as also noted above by SylvianB and PF members rating it 1 full point below most of the other modern lenses. Curiously, the best bokeh lens rated by PF members is the A 75 LS lens at 10, while the FA 75, which I believe has the same optical formula, only gets a 9. However, that may be attributed to the small number of reviewers for the 75 LS lens versus the other 75's. The point being here that I'm not really sure that user ratings can be counted on to be as sensing a difference in ratings between say 9.5 or 9.6, I can't. Not going to criticize the PF member ratings, because I've tossed out my share of them and it's hard to be objective or even have the same value of a number between raters.

So, I'm interested in the comments above because the consensus is not what I would have expected, based on what I've said above. Seems like I need to start shooting a lot of flowers and really observe and judge the bokeh of the lenses I have for myself. Until then, I'm going to follow this discussion and absorb the wisdom of those who post here.

[rdenney]

I have recently acquired a 150/2.8, but haven't tested it seriously yet. So, I have not yet formed an opinion. The real test would be between the 150/2.8, the 67 165/2.8, and the Carl Zeiss Jena Sonnar 180/2.8. The Sonnar has the best faded-edge bokeh (as in quality of smoothness) of any lens I have ever owned or handled. But I am persuaded it attains this with just a touch of undercorrected spherical aberration. So, in the film era using my 645N and NII, it was my specialty portrait lens. I used the 200/4 on the 67, and it was okay but not in the same league as the Sonnar. The 645 FA 200/4 is quite competent for bokeh, and I have tested that one extensively enough to know. Here is one example:


Captain Dave, Alaska, 2018. 645z, FA 200/4 at 5.6, 1/320.

Again, not the wide, smooth brush that is the Sonnar, but not bad.

The problem is that these are rather long for the 33x44 sensor. The 105/2.4 is closer, so maybe I'll look at that one, too. (Yes, I do have it.)

The 75/2.8 LS lens that I own isn't terrible, either, but it's a little short.

The 120 Macro lens is a superb macro lens. 'Nuff said.

Rick "with more projects than ever during the quarantine" Denney

[texandrews]

Interesting thread. I have a number of these lenses, some of which I've added only recently and not enough time on them to speak intelligently about them, but really I haven't be concentrating on bokeh for my 645 and 6x7 lenses. Sounds like I may have to though.

In looking at the PF ratings for a lot of the modern 645 DFA and FA lenses, most have 9+ numbers for bokeh. A few have rounded blades, notably the DFA 55, DFA 90, DFA 25 (good luck finding one), and the DA 28-45. One would think that rounded blades should produce a more pleasing bokeh. That has been my experience in my 35mm lenses between the DFA 100, and the DFA 100 WR lenses, (not rounded, rounded). The user ratings on the 645 and 6x7 lenses don't really show that though, as the ratings are all very high and very close together for rounded blades or not rounded blades. The exception being the DFA 28-45, as also noted above by SylvianB and PF members rating it 1 full point below most of the other modern lenses. Curiously, the best bokeh lens rated by PF members is the A 75 LS lens at 10, while the FA 75, which I believe has the same optical formula, only gets a 9. However, that may be attributed to the small number of reviewers for the 75 LS lens versus the other 75's. The point being here that I'm not really sure that user ratings can be counted on to be as sensing a difference in ratings between say 9.5 or 9.6, I can't. Not going to criticize the PF member ratings, because I've tossed out my share of them and it's hard to be objective or even have the same value of a number between raters.

So, I'm interested in the comments above because the consensus is not what I would have expected, based on what I've said above. Seems like I need to start shooting a lot of flowers and really observe and judge the bokeh of the lenses I have for myself. Until then, I'm going to follow this discussion and absorb the wisdom of those who post here.

I have both the FA 75 and the 75LS, and don't see a difference in bokeh---but since I'm not a bokeh nut, maybe I should look closer. Maybe a wild card here is the 135LS, which I also have, but have only noticed its sharpness....

[blackcloudbrew]

I have both the FA 75 and the 75LS, and don't see a difference in bokeh---but since I'm not a bokeh nut, maybe I should look closer. Maybe a wild card here is the 135LS, which I also have, but have only noticed its sharpness....

I would make the same comment as you about the 2, 75's of which I have both as well. Owned the 135LS for a time but I have no memory of it now.

[rdenney]

Interesting thread. I have a number of these lenses, some of which I've added only recently and not enough time on them to speak intelligently about them, but really I haven't be concentrating on bokeh for my 645 and 6x7 lenses. Sounds like I may have to though.

In looking at the PF ratings for a lot of the modern 645 DFA and FA lenses, most have 9+ numbers for bokeh. A few have rounded blades, notably the DFA 55, DFA 90, DFA 25 (good luck finding one), and the DA 28-45. One would think that rounded blades should produce a more pleasing bokeh. That has been my experience in my 35mm lenses between the DFA 100, and the DFA 100 WR lenses, (not rounded, rounded). The user ratings on the 645 and 6x7 lenses don't really show that though, as the ratings are all very high and very close together for rounded blades or not rounded blades. The exception being the DFA 28-45, as also noted above by SylvianB and PF members rating it 1 full point below most of the other modern lenses. Curiously, the best bokeh lens rated by PF members is the A 75 LS lens at 10, while the FA 75, which I believe has the same optical formula, only gets a 9. However, that may be attributed to the small number of reviewers for the 75 LS lens versus the other 75's. The point being here that I'm not really sure that user ratings can be counted on to be as sensing a difference in ratings between say 9.5 or 9.6, I can't. Not going to criticize the PF member ratings, because I've tossed out my share of them and it's hard to be objective or even have the same value of a number between raters.

So, I'm interested in the comments above because the consensus is not what I would have expected, based on what I've said above. Seems like I need to start shooting a lot of flowers and really observe and judge the bokeh of the lenses I have for myself. Until then, I'm going to follow this discussion and absorb the wisdom of those who post here.

My experience is that ratings are not reliable here. One reason is that faster and longer lenses make more blur, and more blur is often confused with the quality of that blur. Another is that bokeh, while real, is subjective.

I have done some detailed bokeh comparisons of a range of non-Pentax lenses, looking for patterns related to lens design (finding not too much), and looking for better ways to describe it. I came up with three categories of bokeh:

1. Bright-edge bokeh, where out-of-focus point highlights present as a disk with a bright edge. From my perspective, this is the worst bokeh, resulting in false details and swirls, but some old lenses that produce are revered, so what do I know?

2. Neutral-edge bokeh, where out-of-focus point highlights present as a smooth disk with a sharp, but utterly un-emphasized edge.

3. Faded-edge bokeh, where out-of-focus point highlights present as a smooth blob with no distinct edge. The old Sonnar design fits in this category, and is the reason I describe it as a wide, smooth brush.

And then there are other artefacts, including double lines, where the edges of out-of-focus details sum up to create false edges that make the out-of-focus areas noisy and distracting. I've seen that effect quite a lot on lenses praised for bokeh just because they are fast. The 200/4 image I posted above reveals a touch of this problem, which is why my praise of its bokeh is muted.

And some lenses seem to make the out-of-focus details look bumpy or clumpy, instead of creamy and smooth.

One of the myths I debunked was that the number of aperture blades is the primary determinant of bokeh. This is just false--many use fast lenses wide open when they want the bokeh effect, and no matter how many blades are in the aperture, it's always round when wide open. Sometimes, bright-edge bokeh is particularly distracting when few blades made sharp points, but in that case it's the bright edge that is the problem, and the aperture just makes it worse. With true faded-edge bokeh, nobody notices the number of blades, or can even tell how many there are. The worst lens in my test has a dozen or more blades and makes a very round aperture at all settings.

Here's a link to the test I conducted: Kiev Cameras

If I tested lenses for the 645z in the 150-200 range, I'd do something similar to what I did before. And that was at least a dozen years ago, maybe more.

Candidate lenses:

645 FA 150/2.8
645 FA 200/4
67 165/2.8
CZJ Sonnar 180/2.8 (with P6-Pentax 645 adapter)
Maybe: 645 A 80-160, at 160.

And, for shorter lenses:

645 FA 45-85 at 85
67 105/2.4
645 A 120 Macro (don't own the DFA 90, unfortunately)
645 A 75LS
67--I have actually forgotten what lenses I own in the 75-90 range, but I have at least the 75-Shift and one other. I'll have to look.
Maybe: 645 A 80-160, perhaps at 100.

I don't think I still have that bottle of Lindeman's, but I do still have the kachina dolls.

Rick "but somewhat down the project list" Denney

[blackcloudbrew]

Thank you rdenney for a very informative post.

[SylvainB]

Rick, english is not my native language, so I probably would not have been able to express bokeh judgement as you did, but I actually think exactly like you on this matter !

[mikeSF]

I'll jump in. My experience has me favoring the FA150 2.8 and 67 105/2.5 for smooth bokeh.