Post Processed Test Shot
The same test shot, after a bit of post processing and cropping, microcontast adjustment, and color push.
Cleaned Yashica ML 28-85mm - Test Shot
After the teardown and cleaning. Test photo subject: 1946 Leica IIIc w/ 1932 Nickel 50mm Elmar f/3.5, and a Tewe Poly Focus 35-200mm Zoom Finder (RAW conversion only, no post processing)
Yashica ML 28-85mm, Cleaned and Ready
The freshly cleaned Yashica ML 28-85mm back on the NEX F3 to try a new post-cleaning test shot. Included is a screw-in metal hood (attached) that covers the shading duties for an APS-C sensor size, and a Mamiya M645 55-110mm hood that's size appropriate when using the lens on full frame bodies to avoid edge vignetting from the smaller hood.
Yashica ML 28-85mm Cleaned and Assembled
Cleaned lens after full reassembly with the face ring in place. No residue or hazing is visible. The outer front element gets the same cleaning routine as the inner elements did, with an added 99% alcohol pre-clean wipe down on the front element for grease ooze-out removal before 3 last passes with R.o.R. (or more, if needed).
Yashica ML 28-85mm Reassembly
Reverse the tear-down process, using a new/clean Pec-Pad to support the optical block as it's raised and inserted into the upside-down barrel, before flipping the lens over to an upright position. Using the spanner, tighten the block to be a snug fit, then clean the inner threads with 99% alcohol to clear grime and debris before replacing the face ring.
Yashica ML 28-85mm - Group 2 Clean
A front view of the cleaned 2nd optical block that is exposed after the 1st block's removal. This is the other element that develops a hazy coating related to 'pumping'. Exposed threading here is also cleaned of excess helical grease to minimize later contamination.
Yashica ML 28-85mm - Group 1 Cleaned
The cleaned lower lens of the optical block. There is still a minute amount of haze on another element in this group, but it isn't severe enough to warrant removal and cleaning. I always use at least 3 full rounds of R.o.R. solution in an apply/clean-off/buff routine to finish any haze removal, with a new swab on each pass.
Yashica ML 28-85mm Teardown and Clean
View of the optical block from the side. Note the long threaded section with excess 'gunk', the screw-on edge cap at the rear of the block to further dismantle the group, and powder free latex gloves worn for oil-free/smudge-free glass handling. I applied 99% alcohol for grease removal on the threads to knock down further contaminations.
Yashica ML 28-85mm Teardown
Place a Pec-Pad on the lens front and quickly invert it. The entire front optical block will drop into your hand. A view of the convex underside of the last lens in the block clearly shows the concentric rings of haze that have been deposited over time.
Yashica ML 28-85mm - Group 1 Removal
The spanner is opened to near it's maximum width, and the brad-point tip ends are placed into the 2 holes on the block. Counterclockwise turns of about 12 revolutions will release the block from the lens barrel threads. There are no rotational indexing issues at all on removal, with only 1 thread entry point on the inner barrel.
Yashica ML 28-85mm Teardown
Lens ring removal shows the 2 spanner holes in the threaded holder for the front element group's assembly block. No screw loosening or removals are necessary to gain access to any of the affected glass surfaces that need cleaning. This lens had no patches of lacquer or thread-locking compounds to deal with. Truly the easiest lens teardown I've ever had in getting to the internal elements on the front block!
Yashica ML 28-85mm Teardown Workspace
Repair workspace: Using a black 3mm Neoprene sheet for a non-bouncy work surface, Pec-Pads for glass handling, Feola watchmaker dust blower, lens spanner, dividers, locking forceps, 8 inch tweezers, natural bristle brush, laser pointer / flashlight, medicine cup (parts holder), hex screw bits and handle, and paper shafted swabs (off-camera) for cleaning.
Yashica ML 28-85mm
Another view angle before cleaning. Faint traces of the blue-ish haze rings are visible behind the front element block. The deposit is thick enough, and large enough, that it has a negative impact on image quality under any lighting condition.
Yashica ML 28-85mm - Cloudy Haze
The front ring is ready for removal. Notice the cloudy/milky haze in the front lens block. I prefer to clean optical glass with "Residual Oil Remover" (R.o.R.) as the final lens cleaner solution. 99% alcohol or other solutions are great starters, but don't always emulsify particles well enough for complete removal.
Front lens Ring removal
The filter size is 67mm. An inverted 58mm metal hood with 65mm lip diameter is placed on a scrap of 3mm neoprene for grip, and a folded Kim Wipe for scratch protection underneath it. Press down lightly and twist CCW.
Lens prior to cleaning
It's difficult to view the haze in photos due to the lens coating. Left: Front element before cleaning. Right: A yellow overlay illustrates the location and pattern of the large rings of haze. [ All repair shots taken w/ Nikon P7700, on a horizontal tripod arm ]
Yashica ML 28-85mm f/3.5-4.5 Macro - Test shot
A pre-cleanup test shot on a Sony NEX-F3. The heavy haze buildup has effected contrast, color rendering, and has softened the focus. Note the overall blue-ish cast to everything pictured, even though the camera was set to Auto White-balance in a scene lit entirely by daylight. (RAW conversion only, no post processing)