Fungus Removal Sigma 400mm APO Photo Gallery by Pete Ganzel at pbase.com

Fungus Removal Sigma 400mm APO

Fungus or hazing seems to be common on this lens between the 5th and 6th or 7th element groups of this lens.
Access to the 6th element group must be from the front as it is in one piece. The first retaining ring has no slots so a friction tool must be used.

Friction Tool 0256.jpg	Friction Tools 0258.jpg	Group 1 Retainer PICT0293.jpg	Group 1 Retainer on PICT0292.jpg	Group 1 Removed 290.jpg
Group 2 Spacer 0289.jpg	Group 2 spacer 287.jpg	Group 2 Removal Reinsertion 0286.jpg	Group 2 on Tool 0285.jpg	Group 3 4 Removal 0154.jpg
Group 3 4 Retainer Removal 0280.jpg	Group 3 4 Retaine r0277.jpg	Group 3 4 Spacer 0276.jpg	Reinsert Group 5 0151.jpg	Group 5 tooll 0270.jpg
Group 5 and Ring Tool 0274.jpg	Group 5 and Ring 0271.jpg	Group 6 on Tool 267.jpg	Group 6 Tool 0269.jpg	Group 6 Retainer 0147.jpg
Etched Coating 260.jpg	Lens Polish 0262.jpg	Lens Polished 263.jpg	Group 7 in Lens 0251.jpg

comment |

Andre		22-Aug-2016 23:13
Hello! I just found this great instructable. I would like to know witch elements are APO finishing and witch are similar to the non APO version of this lenses? Best wishes

Lucato		08-Aug-2015 13:45
By the way, please, check this thread to see the image about the "T" piece shape. At dpreview dot com / forums / thread / 3884991?page=1

Lucato		08-Aug-2015 09:58
Nice tutorial. Does anybody know any link for assembling from back or does anybody know any link to a catalogue parts for this lens, scheme for this lens or also a dissasemble from back article or video? I have disassembled mine, and a little metal piece jumped (like a "T" shape) and I have no idea where does it fit. :0) Any feedback I'll appreciate.

Aj		12-Oct-2013 00:27
Hello, I bought a sigma 50-500 Os version with dust in between the first and the second element from front. I managed to unscrew the ring that holds the first lens in place. But am unable to remove the lens. Can you advice how this can be done? Regards, Aj

Pete Ganzel		30-Nov-2012 01:55
Because of multiple requests, the outer diameters of the smaller friction tools are 32mm and 37mm. bear in mind also that clearance on the inside is important to protect the glass. Inner diameters are 30 and 35mm. The larger friction tool just needs to clear the filter ring.

Mimmo		28-Nov-2012 21:27
Hello, may you give me your tools outer diameter ? Many thanks Mimmo

Pal Bodis		12-Jan-2012 19:55
Sorry, I talk about the second lens (that was the thick one :)

Pal Bodis		12-Jan-2012 19:52
Thank you for this good description Peter! I repaired my sigma lens following your instructions. My lens is different type. (https://picasaweb.google.com/100005290627416826130/Sigma#5696831671955932834). It has only 3 lens in the front part (not 4 like yours) it was in terribly bad condition, aperture mechanism didn't work, The front end the rear man part was loose (ther are four bolts which connects the two main part.), so i had to replace them, but its only possible if i Deassemble the first part of the lens, this is the only way to access those little pins :). Thank you for your good tips, especially of the pipe coupler :). ((Warning: The third lens (like the fourth in this type) was very hard to reassemble becouse its very-very tight fit!) Best regards ! Paul (from Hungary)

Piotr		03-Aug-2011 21:45
Hi Pete, It's a fantastic guide. Thank you for that! One thing the could improve it a little would be more accurate dimensions of the friction tools. You've turned them from 1 inch and 2 inch pipes, but what is the diameter after turning (preferably in metric system ;-)). I have the same lens and the same problem and I'm going to repair it soon. Best regards, Piotr

Eric		04-Feb-2011 03:07
First off I want to thank you Pete for contributing this! It's very valuable Information that I have found no-place else on the web. But I have a question. Do you know the diameter of the small Friction tool you're using and are you using both ends for different size Retainers withing the lens? I myself have managed to remove the 1st Retainer using a 67mm UV filter ring attached to my Sigma 10-50 f/2.8 EX but I obviously Have not went any further.

Eric		03-Feb-2011 23:35
First off I want to thank you Pete for contributing this! It's very valuable Information that I have found no-place else on the web. But I have a question. Do you know the diameter of the small Friction tool you're using and are you using both ends for different size Retainers withing the lens? I myself have managed to remove the 1st Retainer using a 67mm UV filter ring attached to my Sigma 10-50 f/2.8 EX but I obviously Have not went any further.

SCSI		06-Feb-2010 13:17
Thx a lot :)

Pete Ganzel		03-Feb-2010 00:09
Household ammonia removes the organic portion of the fungi. The areas that are etched slightly can be repolished with Cerium Oxide paste. Pete

SCSI		02-Feb-2010 10:17
Hi, before all, let me tell you again a big thanks about this amazing section Peter! And about your generosity to sharing this... Question: which product you use for removing the fungus, especially if the coating is damaged?

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