-M42 mount .A nice option but abit tricky finding room for 2nd to last elements to fit inside the M42 thread.It can be done i think...
- Nikkor mount.Sounds good but from discussions earlier in this thread there may be no hope of using it on nikon bodies (not enough room)
- Contax mount,Oly mount.These could be good but i have no knowledge about them
- EOS mount/EOS-M42 mount.A sensible option but very difficult to make screw holes through them, because you inevitable have to go through the trickiest part of the mount!I got around this by threading holes from the inside instead.
B)Spacing issues.
- Some like the nikkor mount may give infinity focus issues.
The EOS adapter i used could have been mounted further back with a small spacer,but in the end it only effects close focus ability by a very trivial amount.I preferred simplicity and strength so mounted it directly to the chassis
C) Mounting the rear element
- Using an EOS-M42 adapter for a mount is one of the easiest options because the threaded hole in the back gives a very convenient mounting area for the element holder
D) Aperture adjustment (and calibration)
-Most of us use some kind of hand formed sheet metal which is then attached to the aperture adjustment ring somehow.
For this conversion i decided to try stiff wire instead.It runs all the way around the inside of the aperture adjustment ring which it is glued to.The ends are then formed into the right shape to engage the diaphragm lever.It works extremely well and looks neat but it did take awhile to get to the right shape...
I first decided to try this method because the plastic aperture adjustment ring on the lens looked way too flimsy.The wire reinforcement makes it much stronger
-Calibrating the aperture to the clickstops on the dial can be difficult with sheetmetal parts.Using the wire method makes it easy to get things just right
cogitech wrote:
Another option is to use a C/Y-EOS adapter as the new mount. All you need to do is use a Dremel to remove the circular piece that holds the rear element in the old mount. The circumference fits perfectly inside the C/Y adapter (once the internal flanges have been Dremeled off the C/Y adapter). With the circular piece from the old mount fastened inside the C/Y adapter, you simply thread the rear element in.
cogitech wrote:
Another option is to use a C/Y-EOS adapter as the new mount.......
I do recognize the convenience of this method, but 2 gotchas:
1. This method will not allow the mounting of a AF-chip, because the FD L rear element housing will protrude 2mm out from the back face of the C/Y-EOS adapter (if proper placement is required), effectively taking the place of the surface that the AF-chip needs on the bayonet back.
2. The 2mm offset of a properly placed rear element & housing will start to interfere with the focus screen front cover at the top of the mirrorbox and the larger diameter of that 2mm offset could cause problems.
cogitech wrote:
Another option is to use a C/Y-EOS adapter as the new mount.......
I'm also curious to understand how the original screws are used to secure a new C/Y-EOS adapter, or any other adapter for that matter, to the lens body. The FD L lenses use a unusual "self threading" wide pitch panhead screw that is just long enough for the original thin FD back. Panheads can't be used with a 1.5mm thick adapter because a flat bottom hole deep enough for head clearance would make the wall too thin.
The precursors to the FD L lenses used a regular thread and different "bolt pattern" so it is a little easier to use the original screws or get flatheads with the same threads. The old breach lock and new nFD are different.
I understand that there is a difference (I think you might have mentioned it before) between the breachlock 85/1.2 SSC and the NewFD 85/1.2 L with respect to the screws, but I also know that Dmitry used the same method that I did (to mount the rear element) when he converted the NewFD 85/1.2 L. I suspect that the method I describe works with each lens, but then the adapter is secured in different ways for each.
Regarding the gotchas above:
Only the rear element needs to be set back, not the entire assembly. This avoids the problem of the assembly bumping into anything and also allows one to attach a chip, if desired (I did not, as I hate blinking lights in my VF).
The rear element can be very safely secured in a position further back in the threads of the assembly; there is a lot of adjustment room there. I remember the previous debate about the accuracy of this, and I'll simply state again that performance does not suffer from doing it this way. The threads are so fine and mate so well that the element remains level throughout its travel in the threads. Much more importantly, the old assembly must be mounted perfectly flat and level within the new mount to avoid any tilting of the rear element with respect to the entire lens.
I am only explaining this as an alternative method, not the best method. I'll let those who are converting their lenses themselves decide which method to use. All I can say is that it worked extremely well for me and, as I have said before, the results speak for themselves. Time and again I have shown samples, including 100% crops, of both the sharpness and amazing CA control of my copy. If my method introduced some sort of optical issue, we would see it.
If you disagree with this or remain unconvinced about the performance of my lens, then simply ask me to show more samples and crops. I'd be happy to oblige. Snide remarks about my "snapshots" will do nothing to enlighten those who wish to convert this lens. It only tells everyone here about your character and intentions, to attempt to insult someone like me by calling my photography work "snapshots." If you think I am insulted, just consider my work again and then try to imagine how I might perceive attempted insults.
You'd be better off posting the work you do with your converted 85/1.2, than trying to insult mine. After all, despite our mutual interest in the lenses themselves and the technical aspects of conversion, wouldn't you agree that the most important point is to use them?
Anyway, I think there is room for more than one method. Each has it's pros and cons. Let others choose which will work best for them.
cogitech wrote:
Anyway, I think there is room for more than one method. Each has it's pros and cons. Let others choose which will work best for them.
I agree and this is my #1 motivator, to understand all methods for the benefit of me, and others, if they are interested. If I want to know what the con is of a method described here, it is in no way meant to be a personal attack.
Case in point, is the placement of the rear element of this lens. You are changing the orientation of the original lens. From my work, there is at most 1.5mm of space between the rear element and the rest of the lens assembly, at infinity. If you move the rear element back for more mirror clearance, the main lens assembly has no room for infinity focus. Your method sacrifices infinity focus, right? You've never really said that, except upon my questioning of the fact. The pro is more mirror clearance, the con is lack of infinity focus. Confirming an IQ change is way beyond my capabilities, right now. I am sure there is a consequence, although no one has seen it, yet. As you say, let others choose which will work best for them.
I happen to believe that I don't see the full story of IQ in jpegs for LCD screens. I call them snapshots without ever mentioning your name, and you get offended? What's that all about?
I happen to strive for maintaining the original performance and function of my lens conversions. If I question a procedure to understand if I've missed something, you get offended and defensive? This is a recurring theme and not just directed at me.
When I said "move the rear element back" I meant back towards the mirror box, not the reverse. Using the threads, it is possible to adjust the rear element back, beyond the threaded assembly. The assembly can stay flush with the mount, avoiding mirror box issues and allowing addition of a chip, while the rear element extends slightly into the mirror box.
I have not tuned mine to infinity (I've readily stated that several times), but this is due to laziness more than anything else. Others have reached infinity using my method, including Dmitry, convert1, etc. So, my method does not sacrifice infinity, I just didn't care enough to bother. 50 feet is enough for my uses of this lens. I could get infinity, as I said in another thread:
"by simply discarding the internal shroud from the equation (it is sandwiched between the barrel and mount, remember) and then simply turning the rear element in its threads so it does not touch the internal group at infinity.I haven't felt the need to do so yet, and prefer to keep the internal shroud in place. Also, I enjoy the benefit of a slightly closer min. focus distance."
You know as well as anyone here who your comments were aimed at. 100% crops tell the whole story, and I've shown them.
Hi cogitech
I tried PMing you but not sure that worked.I looked through some past threads both here and on the manual focus forum but couldnt find any (working) links to example photos.Do you still have any online?
Thanks
Ron
ronchappel wrote:
Hi cogitech
I tried PMing you but not sure that worked.I looked through some past threads both here and on the manual focus forum but couldnt find any (working) links to example photos.Do you still have any online?
Thanks
Ron
Ron,
You've had a PM sitting unread in your Inbox since Sep 22, 09, 07:18 PM
cogitech wrote:
....I have not tuned mine to infinity (I've readily stated that several times), but this is due to laziness more than anything else. Others have reached infinity using my method, including Dmitry, convert1, etc. So, my method does not sacrifice infinity, I just didn't care enough to bother. 50 feet is enough for my uses of this lens. I could get infinity, as I said in another thread.....
If your method is to place the rear element any amount of space away from the sensor, than the original position, then you do indeed sacrifice infinity focus. As the rear element moves away from the sensor, the main lens assembly has to be moved toward the sensor to get infinity focus. Since there is as little as 1mm space between the rear element and the main lens assembly, there is no room for adjusting for infinity focus, using your method.
If you move the rear element away from the sensor, from the original position, you will sacrifice infinity focus. The elements will touch.
If the others get infinity focus, it will be because they have placed the rear element very close to its proper placement.
Sorry to be so tough on you, but your self described "laziness" and "not caring enough" attitude implies you really don't know what your talking about, and will attempt to prove your point with multiple 100% crops of shallow depth of field shots.
I don't know how many times I have to say it. I'm not moving the rear element away from the sensor. I am moving it closer to the sensor by turning it back in its threads. You seem to think the entire assembly needs to be moved back. It doesn't. Only the element does.
Now, currently, my rear element is not ideally placed for infinity focus because I chose to do it that way. I could achieve infinity focus, just as the others did, by turning the element in its threads (toward the sensor) and then removing the rear lens shroud which is currently sandwiched between the new mount and the base of the lens. This would bring the entire lens back to where it should be. I choose to keep the rear shroud in place and I am more than happy with 50' of focus. Not everyone would be.
I know exactly what I am talking about. Stop insulting my intelligence.
EDIT: Removed street language due to another member's request.
Mainly due to threads like this on web that I've just bought a FD85L , and will convert it to EOS mount for my 1Ds II. From my rough measurement, the 1Ds is capable of accepting 6.7~6.8mm protrusion into the EOS flange before the mirror issue occurs. It seems not enough to attain infinity focus, but my rough estimation suggests that the rearmost and the next element still has about 1.4mm separation. By tweaking the position rearmost element and the focus ring I may attain a useful focus range.
I start disassembling the FD mount, but unfortunately I couldn't get the retain ring of the rearmost element to unscrew . Despite having soaked wet with ethanol for several minutes, the ring seems to stay put.
Can anyone kindly confirm that one should turn anticlockwise to unscrew it? Or the other way around? I will wait one day before going the totally destructive method (by destroying the surrounding metal plate). Thanks in advance!
I also had to cut the surrounding metal plate since the ring was sitting too tight.
I used a high speed cutter wheel on a Dremel and cut all the way through from one side. I could "bend" the rear element free, afterwards.
I can't tell for sure now which direction the element should turn, but I guess it is anticlockwise.
m-a-x wrote:
I also had to cut the surrounding metal plate since the ring was sitting too tight.
I used a high speed cutter wheel on a Dremel and cut all the way through from one side. I could "bend" the rear element free, afterwards.
I can't tell for sure now which direction the element should turn, but I guess it is anticlockwise.
Hi m-a-x,
Thanks for trying to help .
I end up using a hand file to remove the back plate and the lens, by filing at the corner until the back plate is separated. Of course the lens was covered with tape first .
The back plate with the lens is glued to a flangeless M39-M42 adapter, and then screwed in to the rear of a M42 adapter. Parts of the thread on the M42 adapter has to be removed to allow the movement of the aperture control lever (highlighted below).
Some parts of the aperture control lever is removed, and outer (black plastic) and inner aperture control ring (silvery metal) is modified to re-establish the aperture control.
I followed the method of Taiwan's BigEye, and file down the original nFD's mount ring to provide a mounting surface for the M42 adapter. I have tested my technique with a nFD85mm f1.8 first.
.