p.18 #1 · lens repair, modification and disassembly guide thread
Does anybody have any suggestions as to how I might remove the trim ring (see red arrow) on this Sigma Art 20mm/f1.4 lens without damaging it?
I found a page that shows the lens hood is held in place by four screws underneath this trim ring and it claims it just press-fits into place.
The trouble is that I have this lens on evaluation and don't want to damage it in any way. But I would like to remove the hood so I can determine how large the image circle it projects is without the built-in hood limiting it. (Unfortunately, as it is, there's only 1-2mm of movement available, which makes this lens a non-starter for my purposes.)
p.18 #3 · lens repair, modification and disassembly guide thread
Maybe two sided duct tape, try one, then maybe two layers of it (so that it makes contact down into the rings on the trim ring) around the rim of a glass that fits but does not touch the glass, press it in firmly, and give it a pull? The tape works well for unscrewing them; a tug might work for a friction fit.
p.18 #4 · lens repair, modification and disassembly guide thread
2ndviolinman wrote:
Maybe two sided duct tape, try one, then maybe two layers of it (so that it makes contact down into the rings on the trim ring) around the rim of a glass that fits but does not touch the glass, press it in firmly, and give it a pull? The tape works well for unscrewing them; a tug might work for a friction fit.
Good idea, but it didn't work. Nor did anything else I tried, so I gave up and sent the lens back to Sigma.
p.18 #7 · lens repair, modification and disassembly guide thread
Regarding the OM 90/2 issue: zuiko.com is a good place to send it, John is an expert at OM stuff.
The 90/2 has a unique aperture actuation lever system, which is probably what is messed up. It's a long linkage that allows the front aperture ring to still actuate the aperture despite the massive barrel extension when the lens is focused down to minimum focus distance. I've had mine apart before in the past but don't have it front of me right now, but I do remember that piece being rather complex (and ingenious).
p.18 #8 · lens repair, modification and disassembly guide thread
After a couple years of putting it off and then a weekend of fussing, I have converted my G45 using an MC 55 1.7 body. Sadly, I damaged the cosmetics of the name ring b/c it was glued on and SO hard to get off. I seem to be missing a couple of tiny screws too but had enough to put it together. (Any ideas on the best way to get obscure tiny screws for an old camera lens?
p.18 #9 · lens repair, modification and disassembly guide thread
dkerins wrote:
Any ideas on the best way to get obscure tiny screws for an old camera lens?
off old broken camera lenses.
most of them are metric, though some of the newer contax g lenses might not be. you used to be able to buy them off smallparts.com, but they got bought up by amazon i think...
p.18 #10 · lens repair, modification and disassembly guide thread
Just saw this, did you get it fixed? I had an 80-200 that wouldn't focus past a few feet. But it was sharp otherwise at its focus point. On that one the front ring screwed off by hand. There were then 4 set screws, when loosened they affected how the elements moved for focusing. To fix, loosen them, set the focus scale. Then by hand twist the front element and chimp focus as you go until it's correct. Then tighten screws. Worth a shot.
brendans wrote:
Has anyone worked on the Contax zooms? I have a 100-300 that will only only focus to 5m or so and won't actually focus to being sharp--it's very glowy and soft. Clearly an element out of whack somewhere. I've worked on quite a lot of primes and have the tools to do it but have basically zero experience with zooms.
Thoughts on if it's worth opening it up and seeing if it's something obvious or is a zoom like this a lot more complex?
p.18 #11 · lens repair, modification and disassembly guide thread
Audii-Dudii wrote:
...
[Does anybody have any suggestions as to how I might remove the trim ring (see red arrow) on this Sigma Art 20mm/f1.4 lens without damaging it?
...
Did you find a solution?
On other lenses I take a very small screwdriver and pry it open. Perhaps a part of a plastic (!) dough scraper would be better here.
p.18 #12 · lens repair, modification and disassembly guide thread
Just thought I would share my CornerFix experience with my Contax G21 f/2.8 converted to LM using the Hawks DIY kit.
I had reasonable success correcting its colour smearing when using Capture One Pro with M9 DNG files (creating an LCC file correction), however the lens performance on M240 was much worse and I could not achieve satisfactory correction in C1 Pro. The situation was similar in LR.
I've just used CornerFix for the first time and I am getting acceptable corrections now. The CF lens profile was created using the G21 at f8, at extreme close range to give full-frame coverage using the ColorChecker Passport grey card, with +2 EV set, as suggested.
p.18 #13 · lens repair, modification and disassembly guide thread
lenticular11 wrote:
Just thought I would share my CornerFix experience with my Contax G21 f/2.8 converted to LM using the Hawks DIY kit.
I had reasonable success correcting its colour smearing when using Capture One Pro with M9 DNG files (creating an LCC file correction), however the lens performance on M240 was much worse and I could not achieve satisfactory correction in C1 Pro. The situation was similar in LR.
I've just used CornerFix for the first time and I am getting acceptable corrections now. The CF lens profile was created using the G21 at f8, at extreme close range to give full-frame coverage using the ColorChecker Passport grey card, with +2 EV set, as suggested.
the LR flat field plugin seems to work great for me on the a7 for those using lightroom.
also, i had a batch of conversion rings made for the g21 (this time in anodized black) designed to actually fit on an m camera or TAP adapter. my previous conversions didn't take into account how close and large the lens release button is on some cameras and adapters since i was just using the hawk's adapter. anyway, i have a couple extras so let me know if anybody is interested in the rings themselves or having me convert a lens for them.
the 21, 28, and 35 in my conversions place the aperture ring too close to camera body to work with the TAP adapter, so i also have a file to 3D print a smaller diameter aperture ring that is compatible with TAP (not as pretty though)...
p.18 #15 · lens repair, modification and disassembly guide thread
Hi Sebboh,
I've admired your G90 conversion for a few years now and I finally got the Leica Zooan and G90 to do this conversion and I have a question - there is a ribbed skirt on the base of my zooan that seems to be attached to the L39 mount. I've taken out the set screws that hold the tube with the DOF scale, as well as the ribbed tube that rotates the helicoid. But I don't see any way to remove the ribbed skirt at the bottom of the zooan. Looking at your conversion the skirt isn't there, and it needs to be removed to recess the L39 threads into an adapter.
How did you get rid of the skirt that surrounds the L39 threads? Did you just take a grinder/dremel to it? Or is there a way to get it off?
Thanks for any help you can provide!
Steve
sebboh wrote:
for the donor helicoid i used a leica zooan helicoid, which can be found cheaply on ebay. it fits the size of the g90 wonderfully (though not the color), is very smooth, and has 350 degrees of rotation. unfortunately the distance scale will be off as it is designed for a 135mm lens.
[snip]
now you have a fully assembled lens with real manual focus helicoid and an m39 mount. unfortunately it won't quite reach infinity with the m39 mount, so i recessed the m39 threads inside an e-mount to get infinity. i used an e-mount to m-mount adapter that attaches the m-mount via set screws in the throat: http://c2.staticflickr.com/2/1663/25431170335_085efe3f7f_o.jpg
i took out the female m-mount and stuck the m39 mount through the e-mount throat. i then drilled holes in the m39 mount so i could hold it in place with the three screws in the e-mount: http://c2.staticflickr.com/2/1695/25312836582_42592a5dcc_o.jpg
i haven't seen any optical issue with those exposed screws but i'll probably cover them up with flocking... ...Show more →
p.18 #16 · lens repair, modification and disassembly guide thread
sychan wrote:
Hi Sebboh,
I've admired your G90 conversion for a few years now and I finally got the Leica Zooan and G90 to do this conversion and I have a question - there is a ribbed skirt on the base of my zooan that seems to be attached to the L39 mount. I've taken out the set screws that hold the tube with the DOF scale, as well as the ribbed tube that rotates the helicoid. But I don't see any way to remove the ribbed skirt at the bottom of the zooan. Looking at your conversion the skirt isn't there, and it needs to be removed to recess the L39 threads into an adapter.
How did you get rid of the skirt that surrounds the L39 threads? Did you just take a grinder/dremel to it? Or is there a way to get it off?
i believe that skirt is just glued in place, though there may be a single set screw holding on (it's been a long time since i took it off). I remember trying a few different things and then discovering it just snapped off with a little pressure...
p.18 #20 · lens repair, modification and disassembly guide thread
sebboh wrote:
i believe that skirt is just glued in place, though there may be a single set screw holding on (it's been a long time since i took it off). I remember trying a few different things and then discovering it just snapped off with a little pressure...
No luck trying to snap it off by hand, or with pliers, or by trying to wedge a screwdriver in there (without trying so hard that I mark up the barrel). No sign of a set screw on that skirt. I think I'm going to pickup a new dremel cutting where and see about cutting it some and then try to pry it off again.
Incidentally I noticed that the outside diameter of an L39 to M bayonet adapter is 40mm, and the inside diameter of an Sony E mount bayonet flange is 40mm, so I can probably get a tight friction fit if I grind off the flanges on the outside of the M bayonet and put it inside the E mount flange - getting an L39 to Sony E mount adapter. If I pull it off (or fail miserably) I'll let people know how it goes.
Those aperture rings look good - if I'm lucky with the G90 maybe I'll work on some other conversions and contact you about them.
