Are these brushings black plastic with a brass core at the center? If so, I have encountered them in the FDn 200mm f2.8 (2), FD 300 f2.8 fluorite (4!) and FDn 300 f2.8 L (only 1 but much bigger). They just seemed to have melt!
And Canon calls these "collar". They still presents in the EF lens (such as the EF70-200L or the 24/28-70L), but thank god the material has been changed (white in color without the brass core, maybe nylon or acetal polymer) to last longer.
Without the ability to make new one, I modified the collars in my fungus-ridden Tokina ATX 28-70 f2.8 to fit. In the case of the 300 f2.8L, I just used a heat-shrink tubing over the brass core, and it seemed to work.
I have been looking for the FD24 f2, and missed twice already . But the bokeh in your samples is making me to think twice .
BTW, I have converted a FDn 17mm f4, and the image quality at edge is surely better than the EF 17-35 f2.8L (owned one since 1997 and sold this year). At least it doesn't have horrible CA of the EF.
Best Regards,
Edward Tam
pengland wrote:
A word of caution on the the 24mm nFDs. I converted an f 2.8 version first and I can report that the design was identical. In both lenses there was a set of bushings that I have never encountered in any other lens. The bushings are tiny....maybe 4mm in dia. In both lenses these bushings were worn out or had broken down from old lubricant. The lenses were both functional as they were but there was some "lost motion" in the focus rings as well as a tendency for the focus to creep under certain conditions when gravity could take hold. I ended up machining new bushings from teflon that work great. ...Show more →
I think the important thing is enjoyment/cost ratio here. I openly admit that my knowledge of machining tools and practices outweigh my knowledge and abilities to be able to fully analyze the various lens attributes revealed in any given photograph. These FD lenses can be obtained cheaply....much cheaper than their EF counterparts in the majority of cases...and I really enjoy the challenge of converting and "rediscovering them" so to speak.
Threads like this one serve as a helpful guide in showcasing and picking out potential conversion candidates. Critical analysis is valuable indeed; but it does not always tell the full story. As we all know, this is due to limited test samples and testing errors and inconsistencies.
In the end, if I enjoy the pics these lenses help me to take I am delighted. If sharing my experiences can help others find enjoyment in these lenses as well, then that is an added bonus....Show more →
OK, just asking. Thank you, for the thoughtful reply.
Are these brushings black plastic with a brass core at the center? If so, I have encountered them in the FDn 200mm f2.8 (2), FD 300 f2.8 fluorite (4!) and FDn 300 f2.8 L (only 1 but much bigger). They just seemed to have melt!
And Canon calls these "collar". They still presents in the EF lens (such as the EF70-200L or the 24/28-70L), but thank god the material has been changed (white in color without the brass core, maybe nylon or acetal polymer) to last longer.
Without the ability to make new one, I modified the collars in my fungus-ridden Tokina ATX 28-70 f2.8 to fit. In the case of the 300 f2.8L, I just used a heat-shrink tubing over the brass core, and it seemed to work.
I have been looking for the FD24 f2, and missed twice already . But the bokeh in your samples is making me to think twice .
BTW, I have converted a FDn 17mm f4, and the image quality at edge is surely better than the EF 17-35 f2.8L (owned one since 1997 and sold this year). At least it doesn't have horrible CA of the EF.
Yes, those are the bushings I am referring to. They seem to just disintegrate. I considered using heat shrink tubing but the teflon bushings I fabricated did the job so I never tried it.
As for the spacer thickness....it's 1.33mm....and made of vinyl since it is light, inexpensive, impervious to corrosion, good in compression and easy to work with in the CAD driven laser cutting machine. I have others machined from brass that are 1.52-1.54mm that work fine also. The most time consuming part of producing the spacers was creation of the template in AutoCAD. The dimensions have to be entered precisely and a few "beta" samples created before a perfect template is established.
I will take a couple of pics with the spacers in action and post them later on.
Pengland,
The vivitar has very similar look to my kiron 24 f2. I believe they are the same made but not sure about the "RL" brand.
Since you have both, would you say the canon is much better then the vivitar (minus close focus)?
Thanks,
P
With the limited comparisons I have done I would say the Canon has the edge on IQ but due to the issue with the "disintegrating" bushings or collars it is well behind the Vivitar in terms of build quality. Perhaps this problem is limited to a few lenses or a few within certain lots built by Canon. I can only relay what I have found in two samples of different Canon FD 24mm lenses (f2 and f2.8). I can't comment on how common this problem is.
Imagine focusing on your subject and leaning slightly forward. At the moment you press the shutter release the moving lens group "slips" a fraction of a millimeter toward the subject because of the gap between the bushing and the corresponding groove in the helicoid and due to the effects of gravity. It can be noticeable enough to result in a perceptible little 'clunk" and at wide apertures it is enough to throw your subject out of focus.
The lens can be operated to compensate for this by always carrying out the final focus adjustment in a rotational direction of adjustment that ensures loading of the bushings at the point of shutter release but this is highly inconvenient and inefficient.
kf_tam wrote:
But the bokeh in your samples is making me to think twice .
This is the funniest thing I've read yet. Most lenses this close will give smooth bokeh and the one shot at further distance shows the bokeh that Paul always complains about.
Sorry, I meant pengland shots, not yours. I like both your and pengland's shots. This lens looks great and the fact that you got it super cheap makes it even better. At medium distances I suspect this lens will exhibit the same bokeh that you often complain about. I guess we'll see.
I suspect you may be right, but I'm not really going to be so picky about bokeh at 24mm. The speed will be nice to have, but I am planning to use it stopped down more often than not.
Thanks to Nick (pengland), I have now completed the conversion of this little gem (more on that later).
I managed to find time to shoot a few more test shots. Unfortunately not outdoors yet, but I plan to take it for a walk later this morning.
Here it is at f2 on my 5D, to test for distortion and corner performance. Hard to determine the real resolution at ISO 1600 (1/20th, hand held), but I think this is pretty impressive, nonetheless, for a 24/2 wide open.
cogitech wrote:
That makes sense, since I was holding the camera to my face with my right hand and holding the lens near the camera with the other hand. To focus, the mountless lens had to be held about 3-4mm away from the camera mount flange, so some tilt and shift was inevitable (I'm not that good). Sort of like Anden's Franken-tilt, but without the lens pouch "bellows".
Not quite though. Lensbabies aren't tilt-shift lenses and have no correction for aberation. A hand-held lens would have a mimic'd tilt or shift (or both) effect applied, through virtue of being unsecured, but it would never have a lensbaby effect by virtue of higher quality optics. Unless of course, if you reversed the polarity and added blur before reversion to original polarity in Photoshop. :P
Really, in the first example, you're getting a really sweet example of Scheimpflug.
Interesting. I like. Seeing that I can't do this conversion myself atm, are there people out there that will do the FD to EOS conversions for me? If so, at what price?
. But the bokeh in your samples is making me to think twice 
.