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Archive 2010 · Sigma's Sticky Zen And 500/7.2 APO Examples
  
 
Bifurcator
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p.1 #1 · Sigma's Sticky Zen And 500/7.2 APO Examples


I guess it's well known by most here that for quite a few years Sigma applied a finish to their lens bodies they called the "Zen" finish - a black rubbery powder-velvety low-gloss surfacing. I also guess most here know that after 5 to 10 years that finish melts or breaks down.

Here's a shot of a recent lens I got that had this problem.





I also have quite a few others like it although only 2 or 3 are as bad as this. Some of these lenses are worth quite a lot (if the surface isn't sticky) and with all mine the glass is pristine, clear, and scratch free. This makes it a terrible waste! I guess we all agree Sigma blundered big-time by using this material on otherwise such nice (high-end consumer grade) lenses. I have a number of questions and I'm hoping some here may know the answers.

  1. What is this finishing made out of?
  2. What causes this material to turn to gum like that?
  3. What can be done to prevent it from happening?
  4. What can be done to fix it once it has already happened?

Any information or comments are extremely welcome!

- Thanks!




Edited on Dec 28, 2010 at 09:04 PM · View previous versions



Dec 23, 2010 at 07:04 PM
davenfl
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p.1 #2 · Sigma's Sticky Zen And 500/7.2 APO Examples


Wow, that is an absolute shame. I hope you get some answers Bifurcator, I just happened to buy a 500mm at a yard sale some weeks ago and noticed it was downright tacky, nothing like your example but I fear it is going in that direction.

Dave



Dec 23, 2010 at 07:22 PM
Vertigo2020
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p.1 #3 · Sigma's Sticky Zen And 500/7.2 APO Examples


I was going to recommend some nitrile gloves to start, but after closer inspection I think they may be...ahhh...pointless...


Dec 23, 2010 at 07:25 PM
Bifurcator
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p.1 #4 · Sigma's Sticky Zen And 500/7.2 APO Examples


davenfl wrote:
Wow, that is an absolute shame. I hope you get some answers Bifurcator, I just happened to buy a 500mm at a yard sale some weeks ago and noticed it was downright tacky, nothing like your example but I fear it is going in that direction.

Dave



Yeah, the others I have (including another 500 APO) are just "tacky" - probably like yours. I'm hoping someone knows a way to solidify it before they get marred and more gummy. Sun makes them worse in the short term. >90% isopropanol will remove the finishing all together - but the lens markings and ID goes with it.




Dec 23, 2010 at 07:36 PM
dasrocket
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p.1 #5 · Sigma's Sticky Zen And 500/7.2 APO Examples


I had the 70-200, not with this finish but the typical textured sigma material: my experience was that the finish actually flaked off. What I did, was buy a can of Fixatif spray from a local art store, mask the front glass and mount, and spray in layers the remainder of the lens. The spray is non acidic, non corrosive (neutral), clear, UV resistant and thin enough not to interfere with the operation. I sprayed everything, including the grip, aperture window, mount. It worked for the remainder of the year and a bit I had the lens.
You may want to try a small part of the lens to se if it actuall stops the breakdown.

What you are showing, to me, looks like UV degredation; not sure if you can stop it, my suggestion here is for sealing it.



Dec 23, 2010 at 08:40 PM
---XR---
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p.1 #6 · Sigma's Sticky Zen And 500/7.2 APO Examples


is that 500mm f/7.2 any good? relative to price anyways..


Dec 23, 2010 at 09:01 PM
Lotusm50
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p.1 #7 · Sigma's Sticky Zen And 500/7.2 APO Examples


Have you asked Sigma? I know that seems obvious, but you can really tell what kind of company they are by their response to this problem. If you expect most people here to know about the problem, then I would suggest Sigma is aware of the problem, and they may have put something in place to address the problem when it arises. I can't hurt to call them. I would certainly see a Japanese company in Japan (where the consumer is God) being a lot more helpful than the same company's marketing division in another country like the US or UK.




Dec 24, 2010 at 12:06 AM
Bifurcator
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p.1 #8 · Sigma's Sticky Zen And 500/7.2 APO Examples


Awesome guys! Thanks for the info and suggestions! I'm going to try both! I haven't tried either as of this writing. I'll try and remember to post back and let you know the outcomes.

---XR---,
Mmmm, yeah I think it is, yes. They go for about $275 to $350 used on e-pay with some e-pay "stores" trying to sell them for about $100 to $150 more than that. They really are APO... I can't get any CA out of them no matter what. They're sharp but maybe not as sharp as the $7K+ Nikkor ED's and Canon L's . A lot of the differences may be just the faster aperture (and maybe corners which I can't see on my M4/3 body) though. I guess you could tell the difference between the $7k Nikon 500/4 ED and this lens both at f/11 if you looked at the 100% images for a few moments? Scaled to web-size, mmmm, no, they're too close I think - almost any scaling at all past 90% will level the comparisons. But that's with both at around f/11. This lens only opens up to 7.2 and I think either the L or the ED will look better there... not to mention at the f/4 that both of the others open up to. I guess at 7.2 this Sigma lacks some contrast that the others have. But not too bad really.

Of course I'm only guessing at the quality of the ED and the L based on my experiences with shorter focal length EDs and older L glass. I'm assuming the Canon EF 500mm f/4 L is in a similar lead/league with the Canon FD 300 f/4 L over others and that the Nikon AF-S 500mm F/4 G IF-ED is alike to the league and lead that the Nikkor AIS 300mm F4.5 ED-IF is in. (two lenses I actually have. )

I'me probably just confusing you if you aren't familiar with those lenses tho. What I'm trying to say is that it's impressive but not stunning. It's certainly no loser. Well, except for the "Zen" finishing!

I think if you're looking for a very good and inexpensive 500mm with AF for around $300 this is probably the best you're going to get. I think it's better than reflex (mirror) lenses and better than any 500mm zoom you're likely to find for under $600. Ummm... Others here will know more, I'm kinda new (again) to anything over 300mm and only know the mainstream items that are in abundance on the auction sites.

Hmm, now I'm not even sure if that was useful. Oh well.

I'll post some sample shots with in a day or two...


Edited on Dec 25, 2010 at 02:22 PM · View previous versions



Dec 25, 2010 at 02:18 PM
Lasse Eriksson
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p.1 #9 · Sigma's Sticky Zen And 500/7.2 APO Examples


Wow that is bad


Dec 25, 2010 at 02:22 PM
Bifurcator
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p.1 #10 · Sigma's Sticky Zen And 500/7.2 APO Examples


Yeah... and the lenses are so clean and perfect too... such a shame!




Dec 25, 2010 at 02:26 PM
 

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Bifurcator
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p.1 #11 · Sigma's Sticky Zen And 500/7.2 APO Examples


Bifurcator wrote:
I'll post some sample shots with in a day or two...



I've slept in for the last day or two but here it is doing the moon - 100%

--- EDIT - Wrong Images - Sorry!
--- EDIT - Wrong Images - Sorry!
--- EDIT - Wrong Images - Sorry!


I'll post a few more when my schedule rotates back around.

Oh, and here's folder of the Sigma MF 400/5.6 (army green body) for a look-see - to get a feel for (older) long sigma primes: http://tesselator.gpmod.com/Images/_Image_By_Lens/Sigma_400_f5.6/ . There's 5 images with a really lousy ∅72mm close-up filter attached and two recent images of it in daylight shooting a birdy.






Edited on Dec 27, 2010 at 09:54 PM · View previous versions



Dec 27, 2010 at 02:48 PM
---XR---
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p.1 #12 · Sigma's Sticky Zen And 500/7.2 APO Examples


Bifurcator wrote:
Awesome guys! Thanks for the info and suggestions! I'm going to try both! I haven't tried either as of this writing. I'll try and remember to post back and let you know the outcomes.

---XR---,
Mmmm, yeah I think it is, yes. They go for about $275 to $350 used on e-pay with some e-pay "stores" trying to sell them for about $100 to $150 more than that. They really are APO... I can't get any CA out of them no matter what. They're sharp but maybe not as sharp as the $7K+ Nikkor ED's and Canon L's . A lot
...Show more

Thanks for the review, I've already have a number of the high aperture ($$$$$) lenses, but this lens intrigues me for it's size, looks very light, mabey nice for when i don't want to drag out something 10-13lbs.

saw these off google some great result by this guy-

http://www.birdforum.net/showthread.php?s=6dfd038c9799e656d1673e8f8f5f4a76&t=101197



Dec 27, 2010 at 03:21 PM
Bifurcator
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p.1 #13 · Sigma's Sticky Zen And 500/7.2 APO Examples


Whoops, I posted images of the Tele-Takumar 300/6.3 by mistake. Here's the Sigma 500/7.2 wide open:








And at 50% scale:







And here's the lens as there are like, 3 different versions of it - this one is slightly different from the melted version although this one is "tacky" as well.:












Mine is the Nikkon mount tho. This image is of the EF mount. Here's where the lens images came from and some user reviews of the lens: http://www.dyxum.com/reviews/lenses/Sigma-500-F7.2-APO_review228.html


And like I say I'll take it out in daylight and see how it does. Sorry for the confusion!




Dec 27, 2010 at 09:53 PM
Bifurcator
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p.1 #14 · Sigma's Sticky Zen And 500/7.2 APO Examples


Here it is from today in a more normal usage.

The first two show the difference between wide open and stopped down one click. (7.2 vrs 8.0) No processing!:





About 30 feet away








Here it is again but this time 7.2 vrs. 11. No processing!




About 50 feet away







Here's the difference between f/8 and f/11 Processed somewhat.




I can't really see any difference - even the blur looks about the same. (About 12 feet away)







Here's some images with my typical processing. I dunno what aperture. I think I shot the rest of the time at from 8.0 to one click past 11 whatever that is.


50% Crop - About 35 feet away.


60% Crop - About 65 ~ 75 feet away







And you can use these to compare the difference between this lens and the Canon FD 300mm F4.0 L (these are 70% crops tho instead of 90% ~ 100%)


70% Crop - About 50 feet away


70% Crop - About 35 ~ 40 feet away.

See this thread for the Canon 300/4L examples: http://www.fredmiranda.com/forum/topic/965188









Dec 28, 2010 at 08:57 PM
Navyblue
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p.1 #15 · Sigma's Sticky Zen And 500/7.2 APO Examples


Though I have some background in chemistry and polymer stuffs, I am no expert in this matter. Without having more facts here are my best guess:

# What is this finishing made out of?
My guess would be it contain some sort of polymer.

# What causes this material to turn to gum like that?
If it is what I imagined, over time some of the additives in the polymer (my guess would be plasticiser, something to make the polymer soft/flexible/grippy) leach out and concentrate on the surface, which then make the surface very soft and gooey and dissolve other stuffs along with it. Some cables casing do that.

# What can be done to prevent it from happening?
I don't know, but with my experience in cable, it tend to happen when it is old and wasn't used for a long time. Do you happen to have kept it for a while without using it? Although theoretically speaking keep using it won't stop it from happening.

# What can be done to fix it once it has already happened?
Again, if it is what I imagined, I don't think it can be fixed, or covered up. Instead I'd try to remove as much as the coating as possible. Solvents would work, however they are very very bad with lens coating and rubber and you have good chances of screwing up.



Dec 29, 2010 at 01:07 AM
Bifurcator
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p.1 #16 · Sigma's Sticky Zen And 500/7.2 APO Examples


Thanks Navy!

99% isopropanol removes it entirely for cleaning and maybe as an indication/confirmation to you of it's chemical structure.

I got it from an auction so I dunno if it sat unused or if it was his favorite lens. The auction text was the obligatory "I dunno much about lenses, the optics seem fine, the coating it wet", all of which were very true.

It sounds to me like I need to remove it all and then re-stincel on the markings and insignias. I removed all of it from a one-touch Sigma zoom a few months ago. It's a PITA but quite doable. I still have ins at a screen and print shop so screen-printing is also doable. Kinda sounds fun - errr, maybe.

Thanks again man!



Dec 29, 2010 at 02:30 PM
Navyblue
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p.1 #17 · Sigma's Sticky Zen And 500/7.2 APO Examples


Yes, try to remove them completely if you can, those stuffs might be carcinogenic, wash your hands thoroughly with soap after contact, or better still, wear vinyl gloves. Try to not let the alcohol touch the rubber and the glass, wouldn't melt them right away but I'd rather be safe than sorry.

Good luck and have fun.



Dec 29, 2010 at 02:48 PM
Bifurcator
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p.1 #18 · Sigma's Sticky Zen And 500/7.2 APO Examples


Navyblue wrote:
Yes, try to remove them completely if you can, those stuffs might be carcinogenic,


Hey, don't say that out loud the US government will start putting it in our water supply.

wash your hands thoroughly with soap after contact, or better still, wear vinyl gloves. Try to not let the alcohol touch the rubber and the glass, wouldn't melt them right away but I'd rather be safe than sorry.

Good luck and have fun.


Thanks man! The isopropanol should be OK for lens glass tho. It's what I use to clean lenses with normally. Occasionally I use it in 99% solution but mostly it's just a tad less than 50% sol. to water. In 80% or higher solution is discolors almost all black plastics (that I've tried it on) tho. Turns it kinda powdery white in blotches if it sits on the surface of the plastic for longer than a minuter or so.




Dec 29, 2010 at 03:19 PM
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p.1 #19 · Sigma's Sticky Zen And 500/7.2 APO Examples


Bif: are you focusing anything manually? From memory I remember a Sigma 400/5.6 ED I once had focused past infinity and looked verrrry soft just a wee nudge past infinity going into a heavy blur at the mechanical stop.

Are you sure your moon shots are properly focused) It looks like you overshot the true infinity stop on the lens? Just asking.

Maybe you could wipe down the tacky gunk with isopropanol and when dried up you could coat the barrel, adding a layer to cap in the gunk. I don't know really, it all boils down to what material that gunk is. You should be okay coating it unless you use a coat that exacerbates the problem and accelerates the gunkification of said (sad) lens barrel.



Dec 29, 2010 at 05:23 PM
Bifurcator
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p.1 #20 · Sigma's Sticky Zen And 500/7.2 APO Examples


kosmoskatten wrote:
Bif: are you focusing anything manually? From memory I remember a Sigma 400/5.6 ED I once had focused past infinity and looked verrrry soft just a wee nudge past infinity going into a heavy blur at the mechanical stop.

Are you sure your moon shots are properly focused) It looks like you overshot the true infinity stop on the lens? Just asking.


No, not sure. And it /looks/ exactly like it's OOF too... I focused manually of course and /tried/ to just use visual confirmation. I may retry with this lens at a later date. Most of my sigmas focus past infinity but I'm never sure if that's the adapter or not... I suppose I could put it on one of my Nikon bodies to find out.

Maybe you could wipe down the tacky gunk with isopropanol and when dried up you could coat the barrel, adding a layer to cap in the gunk. I don't know really, it all boils down to what material that gunk is. You should be okay coating it unless you use a coat that exacerbates the problem and accelerates the gunkification of said (sad) lens barrel.

I was toying with the idea of sewing one of those camouflage cloth covers and just covering it with that - and then selling it like that too. I figure if I offer full disclosure about the complete condition it should be OK and might even increase the price. What do you think?




Jan 01, 2011 at 07:01 PM





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