[rick_reddy]

I am wondering if autofocus lenses for my 645N are suitable for the Pentax 645D, or if I should expect problems (CRA/image quality). I know they will mount, but how do they perform?

Several lenses have been put back into production, like the FA 45-85mm f/4.5 and the FA 80-160 f/4.5. Are the new lenses optically/mechanically different, or are the differences cosmetic? (There is certainly a big price difference) I realize the image sensor on the 645D is sub 645 and crops, I am curious to know if the 645D is really compatible with older lenses, or if using them is problematic.

[bsamcash]

As a prospective 645 owner, I too would like to know this.

[Jonathan Mac]

The digital 645s are both compatible with older A and FA series lenses in exactly the same way as A and FA K-mount lenses are compatible with DSLRs. They use screw-drive rather than the newer in-lens motors and they were designed and tested for use on film in an age where characteristics other than just sharpness were more highly valued. In short, they will work perfectly, but they may not produce the image quality of lenses designed for use on the digital bodies.

My three A series 645 lenses are fabulous, at least on my original 645 from the eighties

[Adam]

I am wondering if autofocus lenses for my 645N are suitable for the Pentax 645D, or if I should expect problems (CRA/image quality). I know they will mount, but how do they perform?

Several lenses have been put back into production, like the FA 45-85mm f/4.5 and the FA 80-160 f/4.5. Are the new lenses optically/mechanically different, or are the differences cosmetic? (There is certainly a big price difference) I realize the image sensor on the 645D is sub 645 and crops, I am curious to know if the 645D is really compatible with older lenses, or if using them is problematic.

A lot of the older lenses are great- but the new ones that Pentax has released in recent years are just superb and not to be overlooked IMO.

Adam
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[bull drinkwater]

I have nothing but older lenses about 10 of them. I have been getting great results with my 645d. i'm good with what I've got for my lifetime.

[gha128]

My thoughts: Guy Aubertin Photography | Review of the Pentax 645z from a landscape photographer - Guy Aubertin Photography

[Kolor-Pikker]

From the little I've been using the 120mm and 150mm lenses on my 645Z, it seems that they perform fairly well, but near wide-open they are close in performance to the 55mm SDM, which is a newer lens. It would leave me to believe a wide being sharper than a tele and macro means that the latter are under strain to resolve 51MP, at least at f/4, but stopped down to f/8 or lower they are all fairly good. On a 40MP sensor I reckon you should see less artifacts, but the Z aches for top lenses.

[Kolor-Pikker]

From the little I've been using the 120mm and 150mm lenses on my 645Z, it seems that they perform fairly well, but near wide-open they are close in performance to the 55mm SDM, which is a newer lens. It would leave me to believe a wide being sharper than a tele and macro means that the latter are under strain to resolve 51MP, at least at f/4, but stopped down to f/8 or lower they are all fairly good. On a 40MP sensor I reckon you should see less artifacts, but the Z aches for top lenses.

(sorry for double post)

Ok, so I did the dreaded thing and shot my lenses against a test chart in 1-stop aperture steps, I won't post the images, but here are my findings:

FA 150mm f/2.8 IF
f/2.8 -> f/4 Not much difference, a bit sharper
f/4 -> f/5.6 Massive difference, almost like a different lens
f/5.6 -> f/8 Sharpens up by almost as much as much as going f/4 -> f/5.6, crazy sharp and likely fully resolves sensor
f/8 -> f/11 No difference
f/11 -> f/16 No difference

Notes: Jump in sharpness is quite abrupt, especially in the corners.

FA 120mm f/4 Macro
f/4 -> f/5.6 Slight improvement
f/5.6 -> f/8 Slight improvement
f/8 -> f/11 Slight improvement
f/11 -> f/16 No difference

Notes: Surprisingly less sharp than the 150mm by a not-insignificant amount, and more CA.

D-FA 55mm f/2.8 SDM
f/2.8 -> f/4 Slight but notable improvement, corners so-so
f/4 -> f/5.6 Good improvement but corners still so-so
f/5.6 -> f/8 Good improvement but corners still so-so
f/8 -> f/11 Corners clean up a bit, probably won’t get better than this
f/11 -> f/16 no difference

notes: clearly some field-curvature is going on, since I couldn’t get the corners perfectly sharp on the chart; it has more CA than 120mm or 150mm as well.

Consensus:
Per-aperture value, the 55mm and 150mm lenses feature similar performance, with the 150mm being superior in terms of corners and CA control, and the 55mm arguably having more center sharpness at least until f/5.6.

The FA 120mm f/4 Macro is strangely a dog, it is noticeably less sharp than either of the other two lenses at equal aperture, the 150mm is as sharp at f/4 as the macro is at f/5.6, although the macro has better corners slightly.

I may end up not keeping the 120mm, but only until I get the 90... who knows when the macro capability might come in handy?

[Ryan Tischer]

The FA 120mm f/4 Macro is strangely a dog, it is noticeably less sharp than either of the other two lenses at equal aperture

You must have a bad copy because my 120mm is my sharpest lens. Others have commented that it's one of the sharpest macro lenses ever made.

[itshimitis]

Now there's the thing I hate about digital. Charts, graphs and obsessions with sharpness at 100%. (not having a pop at you, kolor-pikker). I don't go to the National Gallery and look at Turner paintings at brushstroke level so we smell the paint. Why do we need to look at pixel level? A good photograph isn't a good photograph because it is sharp. Henri Cartier-Bresson, "Behind the Gare Saint-Lazare," from 1932 has a feature that makes the shot something far from ordinary that isn't sharp. I went to an exhibition of photos by a famous Leica shooter Thomas Hoepker, and I had a chat with him. He also was disappointed in the modern obsession with sharpness. If you look at some shots by great photographers closely, you end up with a shot that might not be perfectly sharp. In focus, but not totally sharp. I'd rather have a shot that is slightly soft that has atmosphere than a perfectly sharp shot that speaks to no one.

[Ryan Tischer]

Now there's the thing I hate about digital. Charts, graphs and obsessions with sharpness at 100%. (not having a pop at you, kolor-pikker). I don't go to the National Gallery and look at Turner paintings at brushstroke level so we smell the paint. Why do we need to look at pixel level? A good photograph isn't a good photograph because it is sharp. Henri Cartier-Bresson, "Behind the Gare Saint-Lazare," from 1932 has a feature that makes the shot something far from ordinary that isn't sharp. I went to an exhibition of photos by a famous Leica shooter Thomas Hoepker, and I had a chat with him. He also was disappointed in the modern obsession with sharpness. If you look at some shots by great photographers closely, you end up with a shot that might not be perfectly sharp. In focus, but not totally sharp. I'd rather have a shot that is slightly soft that has atmosphere than a perfectly sharp shot that speaks to no one.

Totally agree, but for me it also depends on what type of photography...traditional landscape photography needs to be sharp for me, but fine art, abstract, and portraits (though I think sharp eyes are usually important) not so much. It's the elements within the image, light, composition, etc. that make a great photograph not the sharpness alone.


That being said, as a landscape photographer I like my lenses SHARP!

[Kolor-Pikker]

Now there's the thing I hate about digital. Charts, graphs and obsessions with sharpness at 100%. (not having a pop at you, kolor-pikker). I don't go to the National Gallery and look at Turner paintings at brushstroke level so we smell the paint. Why do we need to look at pixel level? A good photograph isn't a good photograph because it is sharp. Henri Cartier-Bresson, "Behind the Gare Saint-Lazare," from 1932 has a feature that makes the shot something far from ordinary that isn't sharp. I went to an exhibition of photos by a famous Leica shooter Thomas Hoepker, and I had a chat with him. He also was disappointed in the modern obsession with sharpness. If you look at some shots by great photographers closely, you end up with a shot that might not be perfectly sharp. In focus, but not totally sharp. I'd rather have a shot that is slightly soft that has atmosphere than a perfectly sharp shot that speaks to no one.

That's why I opened the post with the word "dreaded" ;p
I might try the test again just to make sure I had focus nailed, but you are quite right, until I did this I never thought of the Macro as being anything close to soft, and I was probably splitting some rather fine hairs. When I say sharp and sharper I mean a crisp black line being ever so slightly more crisp.

Since one of my professional services is art reproduction, you could almost say that I shoot charts for a living, it likely concerns me more than most on here.

---------- Post added 12-13-14 at 10:32 PM ----------

You must have a bad copy because my 120mm is my sharpest lens. Others have commented that it's one of the sharpest macro lenses ever made.

I have heard this claim too, which is why I myself am surprised at the results... well, I'll investigate this tomorrow.

[Vaards]

You must have a bad copy because my 120mm is my sharpest lens. Others have commented that it's one of the sharpest macro lenses ever made.

I compared Pentax 645 A 120mm and Pentax 645 FA 120mm against Voigtlander 125mm APO Lanthar (best macro ever). My point was to sell Voigtlander. For comparison purposes I used K---> 645 adapter and Pentax K-30. My comparison made confidence for me (that I can sell Voigtlander!) and it convinced my customer, who saw that Voigtlander is sharper than Pentax 645 format macro lenses and slightly more contrasty. But that difference was really small.


Besides - FA 120mm was slightly sharper than A 120mm


So, I assume Kolor-Pikker has bad copy. Or made some mistake at focusing (trusting to AF, or green confirmation light, etc?)

[Kolor-Pikker]

So, I assume Kolor-Pikker has bad copy. Or made some mistake at focusing (trusting to AF, or green confirmation light, etc?)

Nope! Manual focus with 16x live view magnification, and I'm pretty sure it was spot-on, so I could go with the bad copy theory until I take another look at it.
I'm not particularly mad if it does turn out to be a dud, I got it for dimes from a friend who sold his 645D, but I was expecting better results even at f/4.

[Vaards]

Now there's the thing I hate about digital. Charts, graphs and obsessions with sharpness at 100%. (not having a pop at you, kolor-pikker). I don't go to the National Gallery and look at Turner paintings at brushstroke level so we smell the paint. Why do we need to look at pixel level? A good photograph isn't a good photograph because it is sharp. Henri Cartier-Bresson, "Behind the Gare Saint-Lazare," from 1932 has a feature that makes the shot something far from ordinary that isn't sharp. I went to an exhibition of photos by a famous Leica shooter Thomas Hoepker, and I had a chat with him. He also was disappointed in the modern obsession with sharpness. If you look at some shots by great photographers closely, you end up with a shot that might not be perfectly sharp. In focus, but not totally sharp. I'd rather have a shot that is slightly soft that has atmosphere than a perfectly sharp shot that speaks to no one.

Rest in peace, Henri!
You used lenses on those days what we can`t beat even today!

Or our dear friend and pixel peeper Ansel - he carried his 8x10 camera everywhere. Imagine those unmached megapixels...

really soon it might be important - to enjoy crisp and clear image: Why Megapixels and Pixel Peeping may soon be important ? Thomas Fitzgerald Photography Blog