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02-23-2010, 08:29 PM   #1
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Price to have Pentax check a lens? (FA* 24mm)

Hey guys, I recently bought an FA* 24mm lens used on eBay. Great condition, no scratches etc, but I usually like to have any lens that I purchase checked out and adjusted so I know that I get the best out of it. Usually I go to Eric (pentaxrepairs) for those needs, but usually it's with older glass.

I was just curious who here has sent a somewhat more recent (FA series) lens in to a pentax repair facility to have CLAd. If so, how much did it cost to have the lens CLAd, and did they actually do any good? Just want to make sure everything is seated/aligned properly so I don't get any unnecessary decentering/CA, particularly at the wider apertures.

Any thoughts or info about this would be helpful.

Thanks!

02-24-2010, 10:19 AM   #2
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Hi, Jim.

Why would you want to have the lens checked in the first place?
Did you see any problem from the pictures you're getting out with the lens?
Most lenses already went through a QC in the production line. Unless you/the previous owner dropped / modified the lens in a way, I don't think you need to have it checked.
I think it's just a waste of money.

I suggest try it first and see if you can see a problem with it.
I have the FA*24/2 also. It's a very good lens. Very high contrast and fast AF.
It's hard to miss focus with a wide angle lens like this and if it does need adjustment and you have a K20D, you still can adjust the focus manually without having to go to repair center.

My thought is, if I can't see a problem right now with my lens, would I be able to tell the difference after it gets repaired? Most of the time I won't.
You'll be better off to use the money to buy a more useful photography accessory, for ex: reflector, lens pen, good neck strap, etc.
02-24-2010, 10:27 AM   #3
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I can understand sending it in if you can see a problem, but if it aint broke don't fix it!
02-24-2010, 01:21 PM   #4
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Well, there are certainly no major issues with the lens. However, there is more CA wide open and at f/2.8 than I expected. I know the lens is not necessarily supposed to be spectacular wide open, but I'd rather know that it's OK rather than wonder if I could be getting more out of it. I have used a wide variety of lenses, and it just doesn't seem quite right. Of course, I have never had another copy of the lens, so it is difficult to judge. Later on (tonight, maybe) I can post an example of what I am talking about.

After I do that, someone else who also has a copy of the lens can comment (or share a similar picture). I try not to be a pixel-peeper, but I want to get the most out of my photos, and a smudgy look from CAs are not cool.

More to come later. Thanks!

02-24-2010, 01:34 PM   #5
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I also have one.

Please post some samples
02-24-2010, 07:13 PM   #6
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Ok,

Here is a good example of the CAs at wider apertures that I am talking about.

All of these shots were on a tripod, shot with mirror lock up using a remote. Focusing distance was about 1m. The subject was a K-7 box.

Shots were manually focused using live view (I did a few to get the best possible results...there is no focus error here). The box was at a slight angle (to help see any possible focus errors), I focused on the SilkyPix icon.

These are all 100% crops from a K-7, CENTER crops. Notice the downward ghosting of the brighter areas into the dark area at F2 and F2.8? These are not corner crops. If this was happening in the corners I would care much less. But I did not expect this in the center. It is weird to me because it is not uniform in the center, so it makes me wonder if something is misaligned a bit.

Apertures are F2, F2.8, and F4.

Thoughts?





02-25-2010, 07:01 PM   #7
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Ok, here are a few more examples. This time, I will compare it against a 28mm lens, the SMC Pentax-A 28mm F2. Sort of similar, also a wide aperture wide angle lens. So I would expect similar performance (well actually I expect better performance out of the newer, more expensive FA*). I adjusted distance to the target to acheive the same magnification for each focal length. Tripod, remote M.L.U. etc manual focus to acheive best results.

Here is the test scene:



100% Crops. A28 first, FA*24 second.

F2



F2.8



F4




The performance of the 28mm is sort of what I expect. A little bit soft/CA wide open, but still quite useable. F2.8 and on sharp as a tack with barely any optical aberrations.

But the FA*24mm seems to disappoint. It is not sharp, not high contrast. Even at F4 there is still CA. What do you guys think? I think I might send it in to Pentax repair to see what they have to say. I don't really need it anytime soon, so it would be ok to be without it for a few weeks.
02-26-2010, 10:17 AM   #8
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Something doesn't look right, especially if you manual focused (you said you did!)

My FA*24 is more like the A28 result; at F2 black is more like dark gray (vs purple), but there's no blur.

You might have a misaligned lens; try the same thing outside at a distant subject.

I've sent in lenses for this kind of issue before but in general they've never improved so I basically have to get rid of it.

02-26-2010, 10:49 AM   #9
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Oooh, that's not good. I had a FA* 200mm f2.8 arrive this morning and if it put out pictures like that I would be sending it right back to the seller.
02-27-2010, 11:31 AM   #10
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Here is my FA*24/2 test to compare

Hi Jim,

Sorry for the late reply. I just got a chance to do a quick test this morning for you to compare.
Below are some shots taken with my K20D + FA*24/2 with available window light. It's kind of dark because it just rained outside. The setting is:
- On tripod w/ 2 sec MLU
- Av mode, ISO 100
- Center weighted metering
- All photos are straight from camera JPEG at full resolution. I just saved as a copy to Quality 8 (High) from Photoshop CS3 to reduce the file size. If you want the original file, I have both the JPEG & RAW. Just send me a pm with your email and I'll send it to you.

Full size:


100% cropped at f/2:


100% cropped at f/2.8:


100% cropped at f/4:


Hope this helps.
02-27-2010, 11:49 AM   #11
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That's quite a difference, certainly looks like a misalignment of some description. I had a lens go like that (I dropped it).
02-27-2010, 12:07 PM   #12
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QuoteOriginally posted by HermanLee Quote
Hi Jim,

Sorry for the late reply. I just got a chance to do a quick test this morning for you to compare.
Below are some shots taken with my K20D + FA*24/2 with available window light. It's kind of dark because it just rained outside. The setting is:
- On tripod w/ 2 sec MLU
- Av mode, ISO 100
- Center weighted metering
- All photos are straight from camera JPEG at full resolution. I just saved as a copy to Quality 8 (High) from Photoshop CS3 to reduce the file size. If you want the original file, I have both the JPEG & RAW. Just send me a pm with your email and I'll send it to you.

Hope this helps.

Thanks for sharing! That does help, clarifies my fear that there was something wrong with the lens. I don't really feel like creating a dispute with the seller, since he described it as it was and the price was pretty good. However, I did send him a message about the issue and asked if he would be honest about any issues that he knew of before selling.

Anyways, I will send it to Pentax repairs and see what they say. Hopefully they can do something, but :sigh: somehow I doubt it. I just want a good copy of the lens, it will be filling a nice spot in my AF prime lineup. I'll report back once I hear from Pentax repairs on the matter.
02-27-2010, 12:36 PM   #13
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Only Pentax Japan serviced FA* lenses. Despite all the hype around some FA* lenses, this 24 was average from the start. The Sigma 24/2.8 beats it optically. The Pentax is not sharp until f4, and I have owned 2 brand new copies and they were identical. Moreover, there is a resin AL lens inside which should not be cleaned or wiped at all (unless you use the now discontinued Opti-clean from UK). Besides, how can you be certain the focus was accurate (quite impossible with wide angles even with 2x viewfinder magnifier)? You samples don't surprise me. I would look hard for any sign of repair (screws usually). If there is none, I personally would strongly recommend against sending it in for service, unless it is physically broken. Good luck.
02-27-2010, 01:14 PM   #14
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Jim,

I did some tests. Wide open, against a black background at 100% there is some ghosting, but not as bad as what you show there. But, against a light background like herman lee's I didn't see any ghosting.

Here is a 100% crop of the same K-7 box at f2. Some ghosting but not as bad. Shot in RAW opened in LR, cropped and saved as JPEG. But, lighting etc. may make a difference as well.

FWIW, here is the 100% crop

02-27-2010, 01:26 PM   #15
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QuoteOriginally posted by pcarfan Quote
Jim,

I did some tests. Wide open, against a black background at 100% there is some ghosting, but not as bad as what you show there. But, against a light background like herman lee's I didn't see any ghosting.

Here is a 100% crop of the same K-7 box at f2. Some ghosting but not as bad. Shot in RAW opened in LR, cropped and saved as JPEG. But, lighting etc. may make a difference as well.

FWIW, here is the 100% crop

Thanks pcarfan! Pretty good reproduction of my setup. Yours looks more like what I would expect, some very slight aberrations that don't really detract from the image. I could definitely live with that. I'm still curious about what Pentax will say about it. Even if they can't (or refuse to attempt to) fix it, maybe they can at least confirm that something is wrong and give me some insight as to why.

I appreciate the help and examples.

PS our prime lens lineup has been pretty similar until lately...when you started selling a few.

F28, FA43, FA77, F135, F*300.
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