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02-09-2013, 04:21 PM   #1
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Advice on SMC M Lens

I've been asking questions and getting a lot of good advice in my short time here, I look forward to the day that I can contribute some back. But, here I go again, looking for some experience and expertise. I have a new K-5 ii inbound from Adorama, I expect to have it in hand in about a week. I've been shooting film on a Canon SLR that was my dad's.

I've located a local copy of a M 100 Macro, which I would really like to own for my K-5. It comes from a credible local source who I have no reason not to trust, but I don't know quite what I'm doing either. Looking through the lens, the outer perimeter is slightly cloudy/hazy. Maybe the outer 1% if that. It's not visible without really close examination through the lens at a light source and the other ~99+ is crystal clear, not even dust that I can see. Owner/seller suggests that it is separation, says it's common and doesn't feel it's a problem. I took a few pictures with it on their ist, but couldn't tell much from looking on that LCD screen. I'll of course check with my new camera when I get it and I think I have them holding it for me for about a week. The lens feels/looks/performs great otherwise and is more than fairly priced based on the review forum here, our closed sales forum and ebay listings.

Does this sounds like harmless separation to those of you who know or should I be worried? If it's the former, is it likely to get worse or is it common to stop at the edges? I have a K 55 f/1.8 that doesn't have this at all. Nor do my Canon film era SLR lenses, and they are dusty/speckly looking in a way that this Pentax lens is not. As a side note, I never noticed it until I started handling these old Pentax primes, but my Canon lenses from the same general era feel like a wooden rollercoaster that hasn't been properly maintained. Aperture rings are all hinky and jerky and whatnot. Very happy to be coming over over Pentax.

Would really love to own this lens, but would take advice against very seriously from this forum if offered.


Last edited by troika; 02-09-2013 at 04:45 PM.
02-09-2013, 04:52 PM   #2
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If it is haze and covers a very small percentage of the lens, then I wouldn't worry about it, especially if you're getting it for a good price. I don't think it will be an issue at all unless you shoot into a strong light source (doubtful since it's a macro lens).
02-09-2013, 05:09 PM   #3
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Shooting on APS-C, you're only using the center 66% of the glass. Shouldn't be an issue, to be perfectly honest.

Sounds like either separation, or like there's something degrading in there.

Last edited by Eulogy; 02-09-2013 at 05:16 PM.
02-09-2013, 05:30 PM   #4
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Oh...those are two answers that make me very happy. I said I would take advice to walk away on this one, but I was really hoping to get affirmation.

Didn't think about the crop sensor issue. If I'm only using the middle 66% of the lens, no way is this in the way. It's just the absolute edge, uniformly all the way around.

By the way, following this logic, if this is 1:2 ratio macro, will it be effectively a 1:1.4 ratio macro on the K-5 sensor?

02-09-2013, 06:05 PM   #5
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QuoteOriginally posted by troika Quote
By the way, following this logic, if this is 1:2 ratio macro, will it be effectively a 1:1.4 ratio macro on the K-5 sensor?
No, macro ratio is independent of sensor size. If the object you're shooting is 10mm long, at 1:2 it will be 5mm on the sensor, whether you are shooting with a "full frame" sensor, APS-C, or anything else. Of course that also means that you appear to get greater magnification with the smaller sensor, insofar as you view the image at the same size, whether it was shot on APS-C or "full frame".
02-09-2013, 06:59 PM   #6
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Ah yes, magnification doesn't change, only crop factor. Right, I learned that lesson before, but didn't think to apply it here. Thanks for the reminder.
02-09-2013, 09:53 PM   #7
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I have three lenses with separation between elements. I think only one has gotten worse over a few years. It's hard to see anything wrong with the images from any of these, but without a second copy and testing, I can't say there's no effect on quality.

The price should be pretty low for this lens, because you will probably take a hit yourself if you had to sell it. A fair value might be 60-70% of the typical market price.
02-09-2013, 10:31 PM   #8
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Thanks. Based on one that was "bought now" on eBay this week, it'll cost me about 60%. Based on the last one I can find for sale in the marketplace here, it's about 50%. Based on the average price in the lens reviews here, it's maybe 80%, but individual people report having paid between $50 and $300, so it's quite a spread.

I can get this one for $100. I want to test it first, but I think I'd really like it if it checks out and I'm sure that I'd get all or most of that back if I had to sell it at some point.

Again, thanks to everyone for their advice. This is a very helpful community.

EDIT: Adorama has one for $200 right now.


Last edited by troika; 02-09-2013 at 11:48 PM.
02-10-2013, 12:31 AM   #9
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QuoteOriginally posted by troika Quote
I can get this one for $100.

Adorama has one for $200 right now.

KEH currently has one (K version) for $119.
It's "BGN," but that might just be because it's engraved.
02-10-2013, 01:54 AM   #10
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I have to point out that the size of the sensor won't have any bearing on whether or not you'll get image degradation when there is damage to the outer perimeter of the lens. If you think about it, light has to pass through the entire lens, regardless of where it lands on the sensor (assuming you're operating at maximum aperture). So an APS-C camera will suffer just as much as a FF camera. There will be some degradation, but this will be drastically reduced when you stop the lens down. In practice though, I suspect any degradation will be very small - even wide open.
02-10-2013, 11:50 AM   #11
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QuoteOriginally posted by Eulogy Quote
Shooting on APS-C, you're only using the center 66% of the glass...
I don't think it works quite like that.

My advice to the OP is to avoid a lens that has visible haze or fungus. Ditto for scratches to the internal elements or the face of the rear element. There are plenty of fish in the sea, so to speak, and a different macro lens might be your better alternative.

Haze can be caused by a number of factors that might include:
  • Botched cleaning attempt
  • Condensation of lubricant oils on internal glass surfaces
  • Damaged or degraded coatings
Choose your poison. None of the above will improve image quality.



Steve
02-10-2013, 12:10 PM   #12
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QuoteOriginally posted by stevebrot Quote
I don't think it works quite like that.
I'd always been told such, always suspected it was slightly more of the glass than 2/3, but I know you're not shooting straight through it all. (Or else my rikenon 50/1.7 wouldn't be sharp at all)

My suspicions have always been that you utilize 66% of the rear element, and an increasing amount towards the front element, eventually nearing 85-90%. Of course, I'm not a physics major, nor do I study light passing through objects.
02-10-2013, 04:53 PM   #13
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I'm certainly no expert, which is why I asked in the first place, but the photo-examples of fungus I've seen do not look like this. For one, it's a very uniform parameter, fungus being organic seems to spread without confined symmetry like that or so it seems to me.

I could see it being uniform separation at the edges and I could see it being some sort of cleaning residue or scratch from something, like a cloth or something that someone tried to screw in or wipe with or something. But, I really don't know and it certainly gives me some pause. Hearing that some of you are living happily with lenses with similar issues helps.

When my camera arrives, I'll take it and my laptop up there and shoot some pictures and look carefully at them on the LCD and in Lightroom. If I see anything, I'll not buy for sure. If I don't, well we'll see. It is otherwise a really nice lens and I've seen some great gallery photos from it here. I can't imagine buying any 30 year old lens on line and having confidence that there wouldn't something with it.

I appreciate all of the advice. Thanks for the encouragement and warnings. I'll take them all to heart.
02-23-2013, 07:15 PM   #14
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Update: I bought it today after taking a few dozen pictures with it using my camera and looking at this closely on my laptop. I can't see any issues and it's a nice lens addition for me. I'll use the macro and will enjoy it as a whatever lens as well. Got a small price concession on it and they're going to service it for me before I bring it home.
03-04-2013, 08:27 PM   #15
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Brought this lens home today and had just a bit of a beautiful day left, so I snapped a few photos with it. I tuned the exposure on the sunset photo just a bit PP, the rest are as they came out of the camera.
















Last edited by troika; 03-04-2013 at 08:35 PM.
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