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01-11-2015, 07:40 PM   #1
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Pentax-F* 300 4.5 lens fungus...worth the price or headache?

I'm looking for feedback and support regarding a lens that I just purchased. The other day I pulled the trigger on Pentax-F* 300 4.5 , taking a small risk knowing that there was a little fungus on the inside of the front element along the edge, so little impact on IQ. It was advertised as the rest of the lens being clean and came with a 14-day, no-hassle return policy, so I spent $500 on it, about half what the current going rate for this lens is with a body in excellent condition. I receive the lens and the body is in excellent condition, along with the exterior of the front element and the rear element. I take a look through the lens and appears crystal clear except for the fungus that was disclosed. Put a flashlight up to it and it was a whole different story. I could see a couple spots of fungus on one of the internal elements, and at least one element that had some faint, tiny things across the whole element, I would imagine is fungus as well, but not sure since it looks different than what's on the front element. So I take some test shots (see below), but not having another of the same lens to compare to I don't know how much the IQ is impacted by the fungus.

I have three options at this point. Return the lens as soon as possible, try to get a discount since it wasn't as advertised (and send it back if I don't get a discount), or keep it, try to kill the fungus to clean it the best I can (I figure I can easily access two of the internal elements as the lens disassembles easily by 3 screws under the focus ring cover but I wouldn't want to explore further than that).

Photo 1-2: Two separate internal elements
Photo 3: Inside of front element.
Photo 4-6: Test shot on tripod with on camera flash at F4.5, 5.6 and 8, respectively. (just worked with what I had at the moment and wanted to capture some vivid color and text to assess contrast/sharpness concerns). Note: The text on the yellow marker on right looks hazy, but it's actually how it looks on the marker, semi-transparent, in case it appears as though the contrast is bad, which is what I originally thought.

Photo 7-8: Couple more test shots at f4.5, 4.5 and 8.
Last photo, extremely close up macro shot of some element in the lens, I can't see any of that looking through the lens with or without the flashlight test. But it's a scary picture, so I figured I'd post it to get others input.

Bottom line, is this worth $500 (I can't afford a $1000 lens at this point) and/or how much should I ask it to be reduced to?

Without a fair comparison, I thought that the images lacked some contrast and sharpness at f4.5 and cleaned up at 5.6, and I think they look excellent at f8. With most lenses these findings would be okay, but everyone raves about the excellent IQ wide open with Pentax's 300mm prime lenses. Fungus issues aside I absolutely love everything else about this lens.

I'll give it a week before I decide what to do with this. I am looking forward to all your input and want to thank everyone in advance for their help with this.

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01-11-2015, 07:58 PM   #2
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I would say it well worths $500 you have spent. They do look like fungus and are cleanable. Just send the lens to Eric and I think he can get it done under $150, even under $100.
The last photo looks bad, but few used lens can pass that flashlight test. And they could be cleaned as well.
Congratulation on the great deal! Have it cleaned and enjoy the wonderful lens.
01-11-2015, 08:00 PM   #3
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If you can't afford a $1000 lens, can you afford one for half the price which is defective?
I would have a professional restorer look at it and give a quote before I made any further decision.
That may be difficult for you with only a couple of weeks before the return period expires.
I have never had any experience with fungus in a lens, but my experience with fungus in other places is it never goes away quietly!




Just saw grahame's post. He seems confident, and from what I have heard Eric is the man
01-11-2015, 08:10 PM   #4
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Fungus, not all granted, tends to etch the glass. The photos look good but fungus grows and it looks like you have two different strains running amok in that lens.

01-11-2015, 08:24 PM   #5
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It would be worth contacting a lens recoating firm to see if they can clean that lens up for you. The modern coatings are superior to what was available years ago. You may end up with a really nice and unique camera lens which would be worth more than a "standard" one.


Just a thought.


Custom Reflective Thin Film Optical Coatings - Gold, Silver,Aluminum


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01-11-2015, 08:36 PM   #6
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With that amount of fungus I would have it professionally cleaned. To do it yourself would require the right tools; spanner wrench and JIS screwdrivers. I did it with a $30 lens but would think twice about doing yours. The big question is has the glass been etched or the coatings damaged. This is a lens I covet, at the price you paid it would worth contacting Eric to see what he thinks.
01-11-2015, 09:03 PM   #7
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On the photo where you can see the fungus in the left hand corner, you can pretty much bet that at this point, the lens has been etched by the fungus. I would strongly recommend contacting the seller, advise him/her of the problem and do what you can to get a full refund. The seller may offer to pay half of the service work, but again I would go for the touchdown and not the field goal. Great photos. Also, the cleaning materials used to remove the fungus are: Arsenic and Hydrogen Peroxide. Harsh chemicals, but no guarantee the fungus will not return. Good luck. Please let us know the outcome. Thanks.

tt
01-11-2015, 09:05 PM   #8
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QuoteOriginally posted by grahame Quote
Just send the lens to Eric and I think he can get it done under $150, even under $100.
I checked with him before I purchased it (and thought it only had fungus on the front element) and it was about $200 to clean it but also that he might not be able to do it but took a chance with the lens anyways. If most of it can be cleaned for $200 or less, it would make me feel better about keeping it. I can focus on making sure the fungus is killed (if not already) and maintain an environment that inhibits its growth.

---------- Post added 01-11-15 at 11:17 PM ----------

QuoteOriginally posted by Tonytee Quote
I would strongly recommend contacting the seller, advise him/her of the problem and do what you can to get a full refund.
The seller has no problems with giving a refund. Looking into whether I should work with him to get a further discount and explore repair options or just send it back.

QuoteOriginally posted by Tonytee Quote
Also, the cleaning materials used to remove the fungus are: Arsenic and Hydrogen Peroxide.
Some of the online research I've done people claim to have success with sunlight exposure (though takes many days), UV light bulb or in a tanning bed for an hour. I've also read about using alcohol or cold crème (Pond's brand). Not being someone that wants to believe everything on the internet, has anyone here had success with these less harsh methods?

---------- Post added 01-11-15 at 11:22 PM ----------

QuoteOriginally posted by atcoombs Quote
To do it yourself would require the right tools; spanner wrench and JIS screwdrivers.
I have a spanner wrench to remove the front element and can easily separate the lens in the middle to get to two of the elements in the middle, but wouldn't feel comfortable dissecting the lens any further as I don't have the experience or tools. I was thinking if I could clean at least three of the elements it would be some improvement from how it is now even if I can't get to all of the elements.

01-11-2015, 09:41 PM   #9
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QuoteOriginally posted by transam879 Quote
Some of the online research I've done people claim to have success with sunlight exposure (though takes many days), UV light bulb or in a tanning bed for an hour. I've also read about using alcohol or cold crème (Pond's brand). Not being someone that wants to believe everything on the internet, has anyone here had success with these less harsh methods?

I had a problem with fungus appearing on some of my deep sky photos. The problem was some fungus on the objective lens. I successfully cleaned the fungus using a concoction made from 45% fiber optic cleaner (Isopropyl alcohol), 45% distilled water, 5% Dawn detergent, and 5% Windex. The lens soaked for a while and scrubbed it while completely submerged using cotton balls and cotton facial cleaning pads. I dried it off with unscented, plain cotton tissue and then used a hair dryer set on low to prevent streaks. It worked perfectly.


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01-11-2015, 09:50 PM   #10
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All the tiny spots in the second picture look scary. I would not take the risk.
01-12-2015, 01:53 AM   #11
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I have taken lenses apart to clean them to remove fungus, yes it does attack the coatings of the lens, I have never seen any signs of the glass being etched however. It must be remembered that fungus is in the air around us and just requires humid conditions to thrive.
A Pentax service engineer who as part of his job cleans lenses screens etc. informed me some years back that they use dilute ammonia to clean optics, it leaves no residue, most window cleaning solutions have some ammonia in it. So when I found some fungus on some of my old lenses I was able to successfully take apart the lenses and clean off the offending fungus restore the lenses to a good level of condition, yes a very small amount of coating had been attacked but there was no sign of any image deterioration.
There's a lot of "panic" about fungus, what you have here does not look too disturbing, however you have already payed good money for this lens and any additional spent is starting to look a little expensive for a manual lens.IMHO.
I have the FA*300 F4.5 AF lens for sale and it is in very good condition clean etc. and am asking not a lot more than you lens cost with your servicing bill, I'm not at all trying to sell you the lens but just to point out that in your shoes I would think about a return and then finding a better deal!
01-12-2015, 02:33 AM   #12
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QuoteOriginally posted by Dave's clichés Quote
you have already payed good money for this lens and any additional spent is starting to look a little expensive for a manual lens.IMHO.
Thanks for the information on the fungus. This is an auto-focus lens too and optically identical to the FA version. When shopping around, I was looking at both these lenses (F and FA) but liked the built in hood and tripod mount of the F over the detachable hood and no mount of the FA. I am hoping that the seller is willing to refund some of the purchase price to make the decision easier to keep it. Do you have your FA lens for sale posted, if so could you provide a link to it. I would definitely check it out. Thanks.
01-12-2015, 02:53 AM   #13
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Hi,
Ok the fact that it's an AF lens is better,
I can give you the link just so you can see my lens, however I live in France and as such it's not really a practical proposition!

Pentax FA*300mm F4.5 objectif Image & Son H

Basically it just states that the lens is good condition with no scratches or fungus on the glass and that the lens is perfectly centered with equal sharpness on left/right side, only some minor marks on the paint finish!
01-12-2015, 03:34 AM   #14
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ok, i have this lens and have disassembled it, i thought on ebay it goes around 500-600 for a good copy, thus 500 with fungus infested is a bad idea.
now whether to return or experiment, needless to say it is one of a grt 300 mm lens sharp starting @ 2.8.
the dissembly https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/262251-pent...sassembly.html this is what i done to my lens, it was a dead lens and at almost no cost so the liberty to experiment.
its an easy lens to open, if u dont get to the mechanics.
so now your problem presuming u want to experiment and clean after getting ur discount (without dicount return the lens)
follow the procedure and remove 1) the objective front part. clean the front part, ( as i understand a damaged front element does not matter) refering my pic 3 the golden washer at that part unscrew it clean as much there. - i have not removed the front first element so no comment yet, but if u do do let the world know.)
2) remove the lens mount (i presume u may have done this to some cheap lens), then just unscrew the last element part.

now the disinfecting part, fungus has to be cleaned- killed so that it does not infect other part of the gear -this i am clear about, how do i do, well fabric bleach is the beast till date has not affected any of my coating, (do not use toilet WC cleaner which has acid it will etch the glass), use nailpolish remover, then rinse it with contact lens cleaner (i use contact lens) then water, what i mean out hear is use ear bud use those solutions by lightly rubbing across, finally use eyeglass cleaning fabric to remove all liquid, (the lens elements diagram is on the lens take care that noliquid reaches compound part, that is it does not go in between then u will need to seperate to clean.
then u are as good as new.
alternate i love gifts i will be considerate and pay shipping

---------- Post added 01-12-2015 at 04:06 PM ----------

that gift part is applicable if you open the lens and then cannot reassemble it back

---------- Post added 01-12-2015 at 04:17 PM ----------

but u dont have to get into the mechanical part from what i see
01-12-2015, 04:45 AM   #15
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I would return it. The new DA 300mm F4 goes for $700 on ebay so just barely more than what you would pay for the lens+ fixing it. Not to mention that your time has to be worth something as well and that the lens witch etched coating will not be as good.

---------- Post added 01-12-15 at 05:46 AM ----------

example Pentax Da SMC AF 300mm 1 4 F4 Ed If SDM Telephoto Lens Digital EX | eBay
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