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04-02-2012, 08:47 AM   #1
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New FA 31mm and 77mm - Update: second 31mm copy

FA31mm AIV version

- slight wobble to the hood (very minor)
- solid when shake lightly while holding the hood
- focus ring turns very smoothly
- wide open, it's not sharp as DA40, but by f2.2, FA31 is about the same as DA40 at 2.8; by f2.5 FA31 is very slightly sharper than DA40 @ f2.8
- stop to f2.8, FA31 is sharper than DA40 at f2.8
- need -2 on micro adjustment

FA77mm AIV version

- solid all around
- focus ring doesn't turn as easily/free as FA31 (feels like there is slightly more resistance)
- focusing speed is about 0.75-0.85sec from min to infinity - this feels quite a bit slower than either DA40 or FA31 (both are about the same in speed, DA40 slightly faster)
- stop to f2.0 FA77 is about the same as DA40 at f2.8
- need +1 on micro adjustment

reasonably decent copies? I am well within my return period.


Last edited by chesebert; 04-12-2012 at 09:05 PM.
04-02-2012, 08:50 AM   #2
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Re: FA77mm focus speed, I believe I've read from many people that the FA77 is a slow focuser.
04-02-2012, 10:40 AM   #3
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Hi,
My FA 31mm behaves the same except microadjastment value. It is AIV version purchased recently.
Concerning FA77mm you seem like describing my copy but it is MIJ version and it looks slightly sharper wide open than 31mm.
Focusing speed is faster with 31mm but I'm not sure about actual timings.
04-02-2012, 12:19 PM - 1 Like   #4
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It's difficult to determine w/o pics but my experience with multi copies of each lens, the FA31 should be sharper than the FA77 wide open from corner to corner. Due to the way the FA31 is constructed, this lens is more prone to optical misalignment which impacts the wide open performance significantly. The FA77 has good center sharpness but the corners struggle until f4. The perfect FA31 should have firm lens hoods but many of them wobble due to slightly imprecise inner barrel dimensions. This doesn't affect the integrity of the lens but has negative effect on optical alignment. Personally I would seek for an exchange until the one with firm lens hood. Turn the focus ring quickly and make sure there is no whining noise from the barrel (not the AF mechanism). As to the FA77, if the focus ring is smooth then there is nothing to worry.

04-02-2012, 01:18 PM   #5
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QuoteOriginally posted by wlachan Quote
Due to the way the FA31 is constructed, this lens is more prone to optical misalignment which impacts the wide open performance significantly. The FA77 has good center sharpness but the corners struggle until f4. The perfect FA31 should have firm lens hoods but many of them wobble due to slightly imprecise inner barrel dimensions. This doesn't affect the integrity of the lens but has negative effect on optical alignment.
Thank you for this honest assessment of the FA Limiteds.
This is the kind of information that is helpful for us when we make buying decisions,
but which is often regarded as heresy among Pentax enthusiasts.
04-02-2012, 07:02 PM   #6
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I don't think that you have anything to worry about. Just enjoy using these two outstanding lenses. Maybe someday, you will add the FA43 to replace the DA40. That's what many people do, after they get a taste of the FA Limiteds. This is not meant as a knock on the DA40, which is a very fine lens, but just a recognition of the fact that the FA Limiteds have a different rendering quality that many users find irresistible. I'm one of them.

Rob
04-02-2012, 07:47 PM   #7
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Original Poster
QuoteOriginally posted by wlachan Quote
It's difficult to determine w/o pics but my experience with multi copies of each lens, the FA31 should be sharper than the FA77 wide open from corner to corner. Due to the way the FA31 is constructed, this lens is more prone to optical misalignment which impacts the wide open performance significantly. The FA77 has good center sharpness but the corners struggle until f4. The perfect FA31 should have firm lens hoods but many of them wobble due to slightly imprecise inner barrel dimensions. This doesn't affect the integrity of the lens but has negative effect on optical alignment. Personally I would seek for an exchange until the one with firm lens hood. Turn the focus ring quickly and make sure there is no whining noise from the barrel (not the AF mechanism). As to the FA77, if the focus ring is smooth then there is nothing to worry.
This is helpful. I have been so far looking only at the center sharpness. I will take a few pattern shots between the two lens to see if FA31mm is sharper across the frame than FA77mm.
04-03-2012, 10:06 AM   #8
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Here are som test shots. As it turns out I entered an incorrect micro adjustment value (the DOF is razor thin at 1.8)

All pics are 100% crop. I tested the FA31, DA40 and FA77, and based on what I can see, FA77 is very sharp at 1.8, DA40 is sharp wide open at 2.8 and FA31 is ok at 1.8 and sharp by 2.2. I am still on the fence whether to ask for an exchange on the FA31, knowing FA31mm "should" be sharper than 77mm wide open, which is not the case based on my copies. If my copy of FA31 represents an "average" FA31mm, then I guess I am ok with that, as I hardly use f1.8 anyway.

Test 1:

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_18.jpg

FA31 @2.0
http://home.earthlink.net/~jmei/fa31_20.jpg

FA31 @2.8
http://home.earthlink.net/~jmei/fa31_28.jpg

Test 2:

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_18-1.jpg

FA31 @2.0
http://home.earthlink.net/~jmei/fa31_20-1.jpg

FA31 @ 2.2
http://home.earthlink.net/%7Ejmei/fa31_22-1.jpg

FA31 @2.5
http://home.earthlink.net/~jmei/fa31_25-1.jpg

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_28-1.jpg

Test 3 (DA 40 vs FA31 vs FA77)

DA40 @ 2.8
http://home.earthlink.net/~jmei/da40_28-3.jpg

FA31 @ 1.8
http://home.earthlink.net/~jmei/fa31_18-2jpg

FA31 @ 2.2
http://home.earthlink.net/~jmei/fa31_22-3.jpg

FA77 @ 1.8
http://home.earthlink.net/~jmei/fa77_18-1.jpg


Last edited by chesebert; 04-03-2012 at 10:19 AM.
04-03-2012, 10:45 AM   #9
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QuoteOriginally posted by robgo2 Quote
I don't think that you have anything to worry about. Just enjoy using these two outstanding lenses. Maybe someday, you will add the FA43 to replace the DA40. That's what many people do, after they get a taste of the FA Limiteds. This is not meant as a knock on the DA40, which is a very fine lens, but just a recognition of the fact that the FA Limiteds have a different rendering quality that many users find irresistible. I'm one of them.

Rob
Already got the FA43, with crazy price increase these days, I didn't want to take a chance and miss the discount.
04-04-2012, 09:26 PM   #10
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QuoteOriginally posted by chesebert Quote
Already got the FA43, with crazy price increase these days, I didn't want to take a chance and miss the discount.
It was not clear from your original post that you have the three amigos. I got the FA31 and FA77 several years ago when the prices were relatively low. I added the FA43 one year ago to complete the trio. My DA*16-50 has seen little use since then, although I do consider it to be a very good zoom lens. It will be interesting to see where the prices of these lenses settle out. Pentax are not so stupid as to price themselves out of the market--at least I don't think they are.

Rob
04-05-2012, 12:51 AM   #11
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QuoteOriginally posted by robgo2 Quote
It was not clear from your original post that you have the three amigos. I got the FA31 and FA77 several years ago when the prices were relatively low. I added the FA43 one year ago to complete the trio. My DA*16-50 has seen little use since then, although I do consider it to be a very good zoom lens. It will be interesting to see where the prices of these lenses settle out. Pentax are not so stupid as to price themselves out of the market--at least I don't think they are.

Rob
FA43 was acquired after my initial post.

Regarding the FA31, any thoughts on the sharpness at wide open? Accetpable copy? or am I suffering from buyer's remorse?
04-05-2012, 02:26 AM   #12
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What do you mean you hardly shoot at f1.8!!? Surely you use it if you have it? At least that's my opinion anyway...
04-05-2012, 02:43 PM   #13
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QuoteOriginally posted by chesebert Quote
FA43 was acquired after my initial post.

Regarding the FA31, any thoughts on the sharpness at wide open? Accetpable copy? or am I suffering from buyer's remorse?
Congratulations on the FA43, which is my personal favorite of the FA Limiteds.

The FA31 has good sharpness wide open and excellent sharpness by f2.8. Have you calibrated the lens properly on your camera? I find that miscalibration is a frequent cause of complaints about certain lenses being soft at maximum aperture. Remember, at f1.8, the DOF can be very thin, and even a minor calibration error will show up as softness. In my own experience, when I switched from a K10D (which does not permit user calibration) to a K-7 (which does), I found that all of my lenses became significantly sharper after putting them through the calibration process with LensAlign. This was a revelation to me. Lenses that I had previously considered good, suddenly became great.

Rob
04-05-2012, 03:34 PM   #14
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QuoteOriginally posted by chesebert Quote
Here are som test shots. As it turns out I entered an incorrect micro adjustment value (the DOF is razor thin at 1.8)

All pics are 100% crop. I tested the FA31, DA40 and FA77, and based on what I can see, FA77 is very sharp at 1.8, DA40 is sharp wide open at 2.8 and FA31 is ok at 1.8 and sharp by 2.2. I am still on the fence whether to ask for an exchange on the FA31, knowing FA31mm "should" be sharper than 77mm wide open, which is not the case based on my copies. If my copy of FA31 represents an "average" FA31mm, then I guess I am ok with that, as I hardly use f1.8 anyway.

Test 1:

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_18.jpg

FA31 @2.0
http://home.earthlink.net/~jmei/fa31_20.jpg

FA31 @2.8
http://home.earthlink.net/~jmei/fa31_28.jpg

Test 2:

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_18-1.jpg

FA31 @2.0
http://home.earthlink.net/~jmei/fa31_20-1.jpg

FA31 @ 2.2
http://home.earthlink.net/%7Ejmei/fa31_22-1.jpg

FA31 @2.5
http://home.earthlink.net/~jmei/fa31_25-1.jpg

FA31 @1.8
http://home.earthlink.net/~jmei/fa31_28-1.jpg

Test 3 (DA 40 vs FA31 vs FA77)

DA40 @ 2.8
http://home.earthlink.net/~jmei/da40_28-3.jpg

FA31 @ 1.8
http://home.earthlink.net/~jmei/fa31_18-2jpg

FA31 @ 2.2
http://home.earthlink.net/~jmei/fa31_22-3.jpg

FA77 @ 1.8
http://home.earthlink.net/~jmei/fa77_18-1.jpg

Your pictures just don't look right to me... it seems like everyone one of them is not correctly focused. I'm wondering if your camera needs an adjustment, as every image looks about the same to me.

This picture here was shot wide open at f/1.9 and even though it's not at a static object, it's pretty obvious that it's correctly focused and is sharp.
04-05-2012, 06:14 PM   #15
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Are you using these lenses on a camera phone? Those sample pics are strange.
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