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05-06-2009, 05:55 PM   #1
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A fungus comparison

Just how critical is fungus, or dust particles for that matter, on a lens surface?

I just picked up a Vivitar 400/f 5.6 P/K (Komine) for under $50. It was accurately advertised with haze and fungus so no surprise there.

I took the time to shoot a few "before" pictures (for a change) before I opened the lens for inspection and cleaning but I didn't take the time to look at the images. These old, long teles are pretty simple so in less than an hour I was ready to shoot some "after" shots for comparison.

That lens has three large (70+ mm) front elements in three groups. The front lens had/has a light, bluish haze and as is typical, cleaning didn't do much to improve that. The back-side of the third element was evenly covered with lacey fungus to about 15-percent of the total surface. Not TOO ugly looking, but certainly the sort of thing that turns off buyers. That cleaned up nicely with just alcohol and lens fluid.

I'll let you decide for yourself just how critical fungus was, at least in this particular case, based on these images of a super sophisticated test target. In my experience, this is a typical outcome.

K100DS @ ISO 400, Best JPG from a steady rest at a distance of 210 feet. All pictures are at F11 since that's how I shot the best "before" image. Cropped, equalized exposure and added the same very small amount of sharpening after resizing. Focus point on shiny bar behind seat. In order of upload:

1. The "before" shot. Surprisingly, just not much degradation due to lens condition IMO.

2. The "after" shot. If I don't compare 'em side-by-side I loose track of which is which. Compared to the original JPG files, there is a very slight increase in contrast and apparent sharpness in the "after" shots.

3. While I was about it, I added two TC's to the mix. This is a Tamron 1.4 AF. Check the speedometer and strands in the rope.

4. This is with a Tokina EL 2x Auto TC.

I'll refine these later. Harsh lighting won't be quite so kind and CA and fringing are present at F8 and F5.6 but just barely noticeable in this light. Nowhere near as bad as the Tamron 70-300. Obviously, this isn't an FA- or DA* lens but for < $50 it demonstrates what some of us have known all along, ugly lenses ain't all THAT bad - and the girls really do get prettier at closing time, too!

Incidentally, as I just recently learned , there's two (if not three) major variations in the Vivitar 400mm lenses. The current PF Lens Review is incomplete. This is the dedicated P/K mount by Komine. I'll put up some direct comparisons with the Tokina TX-version later.

H2

It just occurred to me that I see more difference/improvement in the OOF background of the "after" image than in the in-focus areas after cleaning out the fungus.

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Last edited by pacerr; 05-06-2009 at 07:19 PM. Reason: Added thought
05-06-2009, 11:18 PM   #2
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I have 2 of these Vivitar 400mm lenses, probably the same 2 as you have (both 77mm filter). There are actually at least 4 early Vivitar 400mm 5.6 versions, along with some 6.3 version(s). One is pre-1970, a simple preset lens, I'm guessing 77mm filter but not sure. Then there are 2 made by Tokina in TX mount in the mid-70s, one has a 77mm filter size and the other a 72mm filter size. Then there's the dedicated mount 77mm Komine version, which is about 3" longer than my 77mm TX Tokina, but they weigh about the same. I plan on doing more tests with them when I get my DSLR, but both have done fine when I've tried them out.
05-07-2009, 06:46 AM   #3
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Ya ought'a push that info over to the Lens Review - useful stuff. H2
05-08-2009, 12:14 PM   #4
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pacerr,

I should have known someone here would buy that lens. It was mine and I am glad to hear you sucessfully exorcised it. Like I said in the offer, the pictures were not too bad with the fungus. Your after shots show improvement but not by leaps and bounds. While fungus and other defects in lenses will dramatically devalue them I do not believe that they degrade picture qualtiy at the same level.

Looking forward to more shots with it.

Bill

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