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06-03-2018, 10:27 PM   #1
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Grand Lens Test 6: The 45-85 FA Zoom

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In short, this lens is simply stunning at f/8. My first project with this lens was a group photo at a motorhome rally. I knew this lens was sharp because I've owned it for 15 years--it's the lens I bought with my 645NII kit to use for weddings. The group photo included about 60 people standing in front of a row of classic GMC motorhomes, and the image was sharp enough to resolve the small print on in the nametags they were wearing. The 12x16" print I made for the host of the event is tack sharp, even when viewed through a loupe. I'm picky--this one is sharp, when it's stopped down.

I looked at three different focal lengths, because the lens has a reputation for not being quite as good at the long end. I'll just show the center crops at each focal length, wide open and at f/8. For the wide end, I showed a couple of corner shots, too.

45mm

Here's the full image at 45mm:


And the 1:1 center crop, at f/4.5:


This is sharp enough, but it does improve at f/8 (essentially, I can't tell much difference between f/5.6 and f/16, except in depth of field):


Here's the upper corner at 1:1 and f/8:


Nope, no chromatic aberration. DXO Photolab has this lens in its database, but there's no lateral color at f/8 even without those corrections. Also, the leaves that are sharp are at the focus plane, near enough, so there's not much field curvature.

Here's the lower corner, which is about half the distance to the focal plane:


Depth of field is decent at f/8 and 45mm. Remember, these are 1:1 crops--parts of images that would be 7 feet wide at the 100 pixels/inch of most monitors.

65mm

Full image at f/8:


1:1 center crop at f/4.5:


Okay, this needs a smaller aperture.

1:1 center crop at f/8:


At 65mm, it's still getting sharper at f/8, but by then it's as sharp as you could want.

85mm

Full image at f/8:


This lens really is soft at wide apertures and 85mm, so let's look at three apertures and watch it sharpen up by f/8:

1:1 Center crop at f/4.5:


1:1 center crop at f/5.6:


1:1 center crop at f/8:


As with 65mm, it takes until f/8 to get all the way sharp, and that's the only weakness at the long end that I can see. Wide open, it's actually sort-of dreamy, with a soft-focus effect and very smooth bokeh. This would be a good portrait lens at the 85 end, though to be honest I've never used it at wider apertures. It has a similar effect to the 165/2.8 Pentax 67 lens.

Just for grins, here's a reminder of the 55/2.8 at 2.8:


So, when people say a zoom is as sharp as a prime, well, no. But it can be as sharp as a prime when used with care.

Rick "Stop. It. Down." Denney


Last edited by rdenney; 06-30-2018 at 12:13 AM.
06-04-2018, 06:17 AM   #2
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Great test once again. Very helpful to have these in the database, so thanks for that. Yesterday I was shooting with the 45 while I'm up here in Canada, alongside the 55. Both well stopped down. It'll be interesting to see the differences---I may have shot one or 2 subjects with both. Tripodded, 2 sec delay. If I have something useful I'll eventually post it.

I got rid of my 45 previously, since I had the 45-85. But recently I found a NIB one (out of Canada, again....) that had been old stock at a Vancouver shop that got bought out by an Ontario one. So, I re-bought---it was a ridiculously low price, and it does indeed look new. It's a handy FL on the Z, and yesterday it came in very handy. For some dumb reason I didn't bring my 45-85! Knucklehead----I drove. Could have brought anything I wanted....
06-04-2018, 06:34 AM   #3
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At some point, I want to try the P67 45mm lens on the 645z. I adore that lens on the 67, and I wonder if it’s better lens than the 645 45, which I don’t own.

But the zoom is my standard walk-around lens, rather like the 24-105L on my Canon 5D, so it would be unusual to me without it.

Rick “who just made a print from a 67 negative made with the 45, which just reinforced the love affair with that optic” Denney
06-04-2018, 10:45 AM   #4
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QuoteOriginally posted by rdenney Quote
At some point, I want to try the P67 45mm lens on the 645z. I adore that lens on the 67, and I wonder if it’s better lens than the 645 45, which I don’t own.

But the zoom is my standard walk-around lens, rather like the 24-105L on my Canon 5D, so it would be unusual to me without it.

Rick “who just made a print from a 67 negative made with the 45, which just reinforced the love affair with that optic” Denney
The 645 45 is a much maligned lens....but mostly that's from wide-open comparisons to the 45-85, which is an unusually good zoom lens, as you know, and to the 55. But I started looking again at what had been said about it, and it seems that the way I would use it, always stopped down, then it could be fine. We'll see how my new project turns out from the preliminary shoot. It's dainty, so that is nice.

I wish Pentax would give it a little love: spruce it up, maybe work on/adjust the design, coatings, WR. Very handy lens FL wise.

Tex "Wide open? I don't need no stinkin' wide-open!" Andrews

06-04-2018, 12:45 PM   #5
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QuoteOriginally posted by rdenney Quote
At some point, I want to try the P67 45mm lens on the 645z. I adore that lens on the 67, and I wonder if it’s better lens than the 645 45, which I don’t own.
I use a P67 45mm on my Zoerk Pro Shift adapter and it works really well. It's nice to go wider than Mamiya's excellent 50mm shift lens. The Mamiya is more 'elegant' and is smoother to operate.


By the way, I e-mailed Zoerk the other day and they have a Mamiya 50mm shift lens that's been adapted to the Pentax mount for €980. If you send them your own lens they charge €580 for the modification (plus €120 for Customs charges if you're sending them the lens from outside the EU). All prices are without tax and shipping.

Just passing that on as I used to have one but stupidly sold it. Now that I have a Z I wish I still had it!
06-05-2018, 11:27 AM   #6
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The cross sections on the P67 55-100 and the 45-85 are nearly identical. The 55-100 is proven and it sounds like the 45-85 does well also. The 55-100 has performed so well that I sold my 75 f/4.5 and 105 as a result.
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