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12-31-2010, 03:32 PM - 1 Like   #1
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645D lens test results

I finally found time to do a little lens testing today. I used targets on a studio wall, and a carefully measured and aligned setup. All tests at 50x magnification (subject:sensor). Mainly looking for camera alignment problems and lemon lenses. I tested the new 55/2.8, FA 75/2.8, FA 120/4macro, FA 45-85 and 80-160 zooms. There's good news and there's bad news:

SMC Pentax-FA645 Macro 120mm f4---

GOOD news: Consistent with what others have reported, this is a really sharp lens. Good at f5.6. Really good at f8 or f11, OK at f16, downhill from there. f22 is soft. f32 is mushy. (All of these lenses are mushy at minimum aperture and soft one up from there.) No problems I could see with this individual lens.

SMC Pentax-FA645 75mm f2.8---

GOOD news: Another good sample, it looks like. The center is sharpest at f5.6-8, the corners are sharpest at f8-11. Second sharpest lens in the bunch.

SMC Pentax-D FA645 55mm f2.8---

GOOD news: Tack sharp in the center, at f5.6 or f8.

BAD news: As Lloyd Chambers has reported, really soft in the corners. Worst of all the lenses I tested in that regard. I'm thinking about sending it back.

SMC Pentax-FA645 45-85mm f4.5---

GOOD news: At 55mm, this lens gets sharp really quickly, by f5.6. That's where the center of the new 55mm f2.8 gets sharp, too, except that the zoom gets sharp all over. At longer settings it needs f8. I haven't tested 45mm yet. Most of the time, sharpness is close to what I'm seeing from the 75 f2.8. Looks promising, EXCEPT...

BAD news: at the longer end of the zoom range (75-85mm) the right sides of my test images are noticeably softer than the left sides. Looks like this particular lens is flawed somewhere. Not sure what to do about that yet.

SMC Pentax-FA645 80-160mm f4.5---

GOOD news: Another eBay find, this one just arrived yesterday. Very close in terms of sharpness and optimal apertures to the 45-85, also same layout, feel, filter size... would be a nicely matched pair if the 45-85 wasn't cockeyed. Fortunately, I don't see any asymmetries with this lens.

Overall---

GOOD news: I see no signs of any camera alignment problems. And what limited focussing I did (AF center spot on a centered target) seemed to be accurate in all tests.

I'm really happy with the 120mm, the 75mm, and the 80-160. I think the 45-85 is a good lens in general, but mine has a problem that needs attention--a disappointment. The 55mm? I hate to say it but it's starting to look like Pentax screwed up on these, either with a design problem or with a serious manufacturing issue.


Tim Wilson
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12-31-2010, 03:54 PM   #2
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Great info Tim, thanks for the update. Anecdotally, I've been quite happy with the results of my FA 45-85mm, FA 80-160mm and FA 300mm. I will get around to some more formalized tests at some point, but so far haven't wanted to spoil the fun of just shooting with them and getting to know the feel of the system.

Hopefully you can get your 45-85 sorted; aside from that one issue with it you seem to have the classic FA glass in good shape. I want to build out my FA set a bit more but in the short term will try my eye at manual focus with A versions of the 75mm, 120mm, and also a 67 105mm.

As I mentioned in another thread, I returned my FA 55mm. I just don't know if that lens is going to come through for my kind of subject material in landscapes and architecture...
12-31-2010, 04:03 PM   #3
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Tim,
Just what we need in this forum, some good testing of fa lenses, I have a used 45mm fa on the way and a manual 120mm on the way also.
Plus a new 200mm fa and a used 75mm fa. I am happy to hear that the 75mm fa performed well.
I hope other 645d owners post there comments also.
As diglloyd says about the 645d, great camera but lens selection is critical.
Should have my 645d on monday.
I purchases mine from ace photo
Steven
12-31-2010, 05:07 PM   #4
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Wow, Tim, it must be you then who barely edged out me for the 80-160mm FA on eBay? Really sorry to drove the price up (with these $.33 ending maximums)!

Thank you so much for your posting the results. Helps everyone in the Forum.

Happy New Year!!!


Last edited by leping; 12-31-2010 at 05:13 PM.
12-31-2010, 06:38 PM   #5
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Thanks for your testing. No 645D in the coming year for me. I do have some lenses at home, FA75mm, FA80-160, FA45. For the future.
01-01-2011, 12:27 AM   #6
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The past couple of days, I've had a chance to test on the 645D the following FA lenses: 120/4, 150/2.8, 200/4, 300/5.6 and A-600/5.6. I have yet to test the FA-35 and 75.

All lenses were spot-on with AF, as was the 600 with AF-confirmation (visually, it was not difficult to focus). All of the lenses were sharp wide open, but improved closing down 1 stop. I had no issues with variation in side to side sharpness; at least, after stopping down 1 stop.

The 600/5.6 was much better at f8 with improved contrast. It seems to have a tendency to flare a bit at f5.6 and have lower overall contrast.

I particularly like the 300/5.6 for traveling as it is 1/2 the weight of the f4 version. While f5.6 was sharp, f8 seemed optimum with greater contrast.

In terms of sharpness at f5.6, the 120 and 200 seemed best, closely followed by the 150 and then the 300.

Overall, I am very, very pleased with the Pentax 645D system.

Last edited by rlj; 01-02-2011 at 12:15 AM.
01-01-2011, 07:09 AM   #7
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Tim:

Thanks for the post; your findings parallel mine, although my copy of the 45-85 FA seems excellent at all focal lengths. Hitting focus with A lenses can be a challenge, but when it's on I'm seeing good results from the old 55, 150 and 200.

rlj:

I'm envious of your 600. I let one slip away this summer on ebay that went for about $1700.
01-01-2011, 07:13 AM   #8
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leping,

Umm... yeah, that was probably me. You may have noticed that I used the bidding technique known as "sniping": one bid only, the maximum you're willing to pay, placed at the very end of the auction. I recommend it to all eBay buyers. It has the effect of keeping prices down.


Tim Wilson
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01-01-2011, 08:12 AM   #9
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leping,

I looked again at the bidding history, and if you were the 633.33 bid, then it looks like you and I were the two snipers. You got your bid in even later than I did, but, alas, not higher. If it's any consolation, there are currently at least 3 more active listings for FA 80-160s.


Tim Wilson
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01-01-2011, 11:01 AM   #10
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Tim,

Yes I used the same technique. I am glad it is a good copy for you, and sorry again to have bumped price up!

Lloyd also just found asymmetry on his borrowed copy of the 45-85, the "skew problem", but the direction of the tiny amount of swing changed from 45mm to 85mm -- one is unsharp on the right but the other on the left!

I hope my Pentax 67 lens will do better at the edges and on the corners through an adapter. They performed wonderfully on a Canon 5DII body, as I posted a 100% image elsewhere. We all know how hard the other MF users, Joseph Holmes for one, have to also struggle with the Mamiya and Hasselblad lenses, finder, alignment, etc. in order to get everything sharp.

Joseph Holmes - News: Medium Format Methods for Sharpness

Happy New Year again with best wishes,

Leping
01-01-2011, 04:07 PM   #11
rlj
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Today, I tested on the 645D the following FA lenses: the 35-AL, 75 and 45-85. All lenses seemed equally sharp from edge to edge.

The 75 is excellent. A tad soft at f2.8 with a flared look, but sharpened nicely by f4. It was very, very nice at f5.6 with high contrast. So far all lenses look great at f5.6 (and f8 and f11; I cannot see much difference at f11, including diffraction, just greater DOF).

The 35 was interesting. It was my first 645 lens to measure that had the plane of focus off. It back-focused, requiring +6 to fix. But as I re-tested to trim in the focus adjust, and examined all the f-stops, I found something odd. The 35 still back-focused at f3.5-f4, despite having adjusted it for accurate AF at f5.6. (The AF was consistent from f5.6-f11). It would appear to be a shift in plane of focus with stopping down. The target was about 3 m away. Since I don't shoot wide angles open, it is not much of an issue for me, but thought i'd pass it along.

The 45-85 is nice. It did require +1 in focus adjust, but aside from that, it is very good. The only lens in the same range I have for comparison is the 75/2.8. At f5.6, the 75/2.8 is superior. So while the zoom is good, it is not as good as a prime, at least my copy. It also seemed to have a tendency to flare when used wide open (like the 600/5.6 did wide open). f5.6 is where I'll shoot it as the contrast is better.

Last edited by rlj; 01-01-2011 at 05:55 PM.
01-01-2011, 05:41 PM   #12
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One thing that's struck me in reading reviews of the new 55/2.8 AL, is that they sound just about like the reviews for the Pentax 55/1.4 DA* for the K-series APS bodies: center is very sharp but edges are soft.

I've not tried to track down the schematics for the two (AL is 9-7, the DA* is 9-8 groups), but maybe they share similar design goals. I can understand for the APS lens since it behaves like a portrait lens and one could argue the edges can go soft, but for a modest WA on 645, this would seems like an odd choice.

here is one detailed review of the DA*; kinda sounds like Lloyd's review:

[url=http://www.lenstip.com/163.4-Lens_review-Pentax_smc_DA*_55_mm_f_1.4_SDM_Image_resolution.html]Pentax smc DA* 55 mm f/1.4 SDM review - Image resolution - Lenstip.com[/url

I need to add, however, that somewhere I read that Lloyd and others had not found any Pentax ads using the new 55mm. This may be true outside of Japan, but not true in Japan. While in Japan a couple of months ago, I bought a copy (Japanese text only) of Pentax's "645D Official Book". It has numerous examples using the 55mm and all of them look outstanding.

Last edited by rlj; 01-01-2011 at 10:27 PM.
01-02-2011, 10:40 AM   #13
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Diglloyd just posted his results on the fa 45-85mm lens.
Interesting, some good news and some not as good.
Again, how important it is to get a good "copy" of the lens seems to be the key with all of theses lenses being tested.
I wonder if you sent in one of the "older" out of warranty lenses to Pentax if they could be adjusted.

Steven
01-02-2011, 01:23 PM   #14
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My 45-85mm requires a +5, at 85mm it requires a +7 but I went ahead and averaged it because +7 caused 45 to be off a bit so +5 seems to get all focal length close enough. With that said I really only plan to use this lens at f8-f16 so its really not that huge of a deal. Corner sharpness on mine seems to be fine.

In fact almost all of my lenses seem to need either a + or - depending on the lens. My 75mm is the worse, it required a -8 to nail focus properly.

The only lens that doesn't need the adjustment is my 120mm macro and thats great for me because I plan to use the 120 for most portraits and all my other lenses for landscape work...the 75mm is the exception. I may return my 75mm I just need to do some more testing with it.
01-02-2011, 03:53 PM   #15
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My 45-85mm with the asymmetry issue was purchased from Samys, but via eBay, and listed as "new in box". So the issue of what remedy to pursue is complicated. My thinking is that, being "new", it should be covered under Pentax USA warranty, so that's probably where I'll start.


Tim Wilson
Chicago
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