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03-18-2014, 04:46 AM   #1
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Should I ask a partial refund for this Pentax-A 28/2?

I just recived this lens for very little money - with shipping 175 us$. When I bought it, there wasn't any informations about little "scratch" on the rear part of the lens (see the picture) which is there (I suppose) due to an impact; all there was was a sign "used" and words "obvious signs of use". Is this going to affect on the quality of image and do you think that I should complain and ask a partial refund? Or perhaps, I should be happy to have this this lens for this amount of money which, in reality, is more than two times expensive (around 400 us$)?

Thanks!

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Last edited by malenisjaj; 03-18-2014 at 04:47 AM. Reason: typos
03-18-2014, 05:00 AM   #2
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First of all, I believe the seller wasn't 100% honest with you for not mentioning about this scratch (or whatever that is). Even though, because the price was so low, you took the risk and the responsibility to check the item more thoroughly.

But the best thing you could do IMO, is to analyze the photos taken with this lens for any artifacts (which I believe won't be visible) and enjoy shooting
03-18-2014, 05:00 AM   #3
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QuoteOriginally posted by malenisjaj Quote
Is this going to affect on the quality of image
I would suggest the easiest way to find out is to shoot some blank, even surfaces in as high quality as possible, and do some pixel peeping with various settings of contrast, etc.
Then you should be able to say if it affects the image quality in any degree noticeable to you...
03-18-2014, 05:37 AM   #4
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I recently bought 2 ebay Tamron lenses. Each was $50-$65 with shipping. One was "excellent", really like-new with original box, caps, etc. I'm very pleased with it. The other was "excellent", but... not really. But the latter was "no return", and I did get some other pieces with it (hood, filter, caps), so I probably won't complain. But it's certainly not an "excellent" lens.

I'm gradually learning better what to ask before purchasing, and what to look for in ads, but I think it's important to keep the damage to amounts you're comfortable losing. For me that's about the amount I paid; maybe for you that's $175. I've bought 4 lenses from ebay now, plus one from the forum here, and overall I have just this one not-so-good lens, plus an excellent-but-mis-described 18-55 (it was v1 while the ad specifically said v2 - I think I got $10 of the $60-ish price refunded.) Otherwise all were as described.

You can test but I'm guessing that a rear element scratch could affect some images, although it may be difficult to produce an obvious failure (until you're not trying, of course.)

I try to look for "no scratches, dust, haze, fungus, minimal play/creep in focus/zoom", etc, and you'll find that in a lot of postings. In my not-so-good case I settled for "excellent" and that didn't work out so well. The glass is excellent (as in the photos in the ad) and the lens functions perfectly, but there's excessive barrel wobble. You settled for "obvious signs of wear", so I'd say you got what you agreed to buy.

If you're like me I think the lens will annoy you until you replace it with an unscratched version, so if I were you I'd move on. Or, maybe find a 28/2 with completely smashed front-end, and salvage the rear element from it. But that scratch will just annoy you until you fix or replace the lens.

03-18-2014, 05:49 AM   #5
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Well, I did some pixel peeping and I found a issue due to the scratch on the rear part.
I shot the blue sky and first picture is magnified 127% and the other 439%. Obviously, there is an "error".

Problem?
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03-18-2014, 05:52 AM   #6
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I fail to see the "error" in those pictures - maybe my eyes are going bad!?

The only "problem" I see in those pictures is the dust spec... the lens or sensor needs to be cleaned.
Unless what I think is a dust spec is a chip on the lens... !?

Generally, small, light scratches on the rear element doesn't affect the image. Chips however is a different story.

In the end though, if I would not be happy with my purchase, I would just return it and get my money back - put a little more money and get a better version of this lens.

Last edited by mrNewt; 03-18-2014 at 06:00 AM.
03-18-2014, 06:12 AM   #7
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This is wierd. I started the dust cleaning option and shot another picture of the blue sky and now, when I compare the old image with this new one, I can't find a problem. Perhaps it was dust?
03-18-2014, 06:15 AM   #8
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QuoteOriginally posted by malenisjaj Quote
This is wierd. I started the dust cleaning option and shot another picture of the blue sky and now, when I compare the old image with this new one, I can't find a problem. Perhaps it was dust?
Haha, I guess I'm not getting blind yet .

03-18-2014, 06:17 AM   #9
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QuoteOriginally posted by mrNewt Quote
Haha, I guess I'm not getting blind yet .
Well, new update. Another shoot and there it is again. I'm not normal anymore.

Update: Shot a few photos and on one picture that dark-blue dot (now, there are two!) is on the other part of the image. Not that far abut it seems, afterall, that I have problems with dust. Dust cleaning option started.
MrNewt, it seems your eyes are still in excellent condition.

Last edited by malenisjaj; 03-18-2014 at 06:28 AM. Reason: Update!
03-18-2014, 06:27 AM   #10
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QuoteOriginally posted by malenisjaj Quote
Well, new update. Another shoot and there it is again. I'm not normal anymore.
... maybe the dust spec moved back in place... maybe it just went out for a coffee!?

Do you have an actual ding chip on the rear element!? Or is just a slight scratch!?
Hard to tell from the picture.

Last edited by mrNewt; 03-18-2014 at 06:36 AM.
03-18-2014, 06:32 AM   #11
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Here is magnified part of the rear part of the lens. Also, there is an update to my previous post.
Btw, what's "ding"?
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03-18-2014, 06:35 AM - 1 Like   #12
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QuoteOriginally posted by malenisjaj Quote
Here is magnified part of the rear part of the lens. Also, there is an update to my previous post.
Btw, what's "ding"?
Oh man... I would not worry about that! It should not affect your image .
Enjoy the lens .

And well... by ding I meant to say a chip in the lens

Btw, that rear element is in need of some cleaning.
I see some smudges .
03-18-2014, 06:44 AM - 1 Like   #13
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I used to have a second hand FA*85/1.4 that had the same kind of blemish on its rear element. It never showed on any shot, nor did I notice irregular contrast or sharpness on any image. Similar to your case, the spot was situated sufficiently far off-center, which made it fall outside the optical path when the lens was stopped down (large enough DOF that it might be noticed), and on the contrary, when shooting wide open, DOF was too short and any spot on the rear element blurred too much to see any localized effect. There was no overall effect either, as the lens was sharp and contrasty.

Of course, at 85mm DOF is much shorter than at 28mm and as such perception may be different. Do try shooting a evenly textured subject framed to fill the image (preferably at close range at different apertures), to see whether sharpess or contrast falls off in the area of the blemish.

Wim

PS: I sold my FA*85/1.4, but not because of this blemish. The lens was too big for me and the 85mm focal length just didn't work for me on APS-C.

Last edited by Ishpuini; 03-18-2014 at 07:06 AM.
03-18-2014, 06:52 AM   #14
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Thank you folks!
03-18-2014, 07:48 AM   #15
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Yep, that looks like a "ding" and yes, it has the potential to effect image quality. That is the way things are when they are on the rear element. Will it be a problem? It may or may not. Its location may be in your favor when shooting APS-C. Any image problem may be outside the cropped frame. What would a problem look like? I would suspect a discontinuity in fine detail or (in bright light) a flare spot. BTW, there also appear to be a few shallow scratches in the rear coating.

Looking forward...if you keep the lens, you must realize that your resale value will likely be lower than what you paid. As such, I would suggest that some communication with the seller might be in order.


Steve
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