Alf, here is Taiwan's Bigeye FD 85L to EOS conversion. While the text is Chinese, the pictures themselves should provide good reference for you.
Too bad this was not published before I did mine. I ended up with many tiny bearing balls fallen inside the focusing helical, and I had to completely disassemble the lens to take out all the balls. A magnet and a magnetize screwdriver was a big help here. I also took the chance to relube the lens.
Alf Beharie wrote:
Thanks Ron..I'll have to check that out.
ronchappel wrote:
If i understand this right you did always have at least one layer of tape between the last 2 elements?If so then the smearing is almost certainly gum from the tape-it should easily come off
Yes, but you should know that the coating itself has limited hardness. And I did press (lightly) and rotate the element to check for direct contact. So even after washing with ethanol the mark is still there.
ronchappel wrote:
I finally found my notes from when i measured the 5d mirror clearance:
EOS flange to mirror front (when mirror is up): 7.2mm
I also measured the mirror when it was partly down ,at a slight angle.At this point it has LESS clearance because the mirror is thick and so one edge naturally comes closer to the mount at that point.here it only gives 6.8mm ! (please note i cant remember what method i used to measure these.allow 0.1mm inaccuracy to be safe)
These numbers tally up well with actual testing.If i have my rear element set much more than 6.5mm back from the EOS mount surface,the mirror starts brushing it ...Show more →
Well, I also found that when the element approaches 7mm protrusion it would collide with the mirror of 1Ds Mk2. But I have seen remarks that the 1D series retracts the mirror towards the sensor when it is swinging up. When I manually move the mirror up there is really some backward movement. So this may be the real reason why 1D series is better than 5D in alt. lens compatibility.
ronchappel wrote:
First i must explain that my rear element holder has a slight forward extension which contacts the outer edge of the 2nd last element,stopping the glass parts of the two elements from touching.The point is-is this extension too long?
I use flange-less M39 to M42 adapter, and the 2nd element can pass through its opening well enough to collide with the 1st element.
ronchappel wrote:
After measuring the tape thickness i knew the gap had to be between 0.12mm and 0.24mm .
And due to the easily noticeable rocking motion i mentioned in the testing above ,it's most likely closer to the lower number.
So.. less than 1/4 of a mm gap! Pretty cool huh?
Since then i've had a little time to experiment with how far i can move the rear element forward and still achieve genuine infinity focus.
Sadly it seems to be no less than exactly 7mm -which is likely just a little too much for use on a 5D
When the brother visits with his 5D body this weekend i'll try it again but from past experimentation i'm guessing it wont work...Show more →
From my record, infinity can be achieved with 6.9mm protrusion when the element separation is slightly larger than 0.05mm (more than one layer of tape thickness but less than 2). YMMV
p.s, Just got the FD 55/1.2 aspherical, I am depending on the mercy of my 1Ds2 mirror again
Sorry, but 0.17mm simply would not cut it even for a 1Ds .
But setting the elements this close is potentially hazardous for the lens. When the lubricant drys or loose, the helical would have enough play to cause a "hard" collision. Or if the lens is rocking during a trip....
Last Saturday I opened a Contax 35/1.4 to relube the helical, because there was very significant play. When I focused the lens to infinity, I found that at wide open somethimes the zone B (a reference from 16-9.net) was sharp and sometimes it was not. So I tried taking an image while pressing the lens towards camera, and another while pulling the lens towards the subject. The sharpness at Zone B differed (pressing was much better) while Zone A and C I noted no significant changes. I disassembled and found the lubricant has hardened (but the focusing was always smooth). I relubed the lens, and the lens has no significant play now, and the sharpness at Zone B is more consistent now (after playing with the floating front element for some time )
ronchappel wrote:
haha! and i thought i was doing well to get the gap to about 0.17mm
I checked out your link to the contax compatibility list.Thats very interesting!
When i saw our comparative 7.2/7.3 measurements i had some doubts that the 1D could be better than the 5D,but the list seems to confirm your thoughts.I hope so anyway!
I'll try to find someone around here willing to let me try the lens of their camera
kf_tam wrote:
Alf, here is Taiwan's Bigeye FD 85L to EOS conversion. While the text is Chinese, the pictures themselves should provide good reference for you.
Too bad this was not published before I doing mine. I ended up with many tiny bearing balls fallen inside the focusing helical, and I had to completely disassemble the lens. But it may be a good practice to relube old lens.
Thanks K!....Are you able to read and write Chinese by any chance?...If so could you please try to contact him and ask him the exact dimensions of his custom made Copper fork bracket, which he has screwed onto the aperture dial...Heres a pic showing the fork on the dial:
While I can read Chinese, but as far as I read he doesn't own the lens. So if he didn't leave any notes, the information is lost. I will ask in his blog, but don't hold your breath.
In his text, he told he has carefully trimmed the dimension until
1. it fitted the aperture control lever.
2. its forward edge limit the aperture ring to not pass over F1.2 position.
3. its backward edge limit the aperture ring to not pass over F16 position.
Alf Beharie wrote:
Thanks K!....Are you able to read and write Chinese by any chance?...If so could you please try to contact him and ask him the exact dimensions of his custom made Copper fork bracket, which he has screwed onto the aperture dial...Heres a pic showing the fork on the dial:
kf_tam wrote:
While I can read Chinese, but as far as I read he doesn't own the lens. So if he didn't leave any notes, the information is lost. I will ask in his blog, but don't hold your breath.
In his text, he told he has carefully trimmed the dimension until
1. it fitted the aperture control lever.
2. its forward edge limit the aperture ring to not pass over F1.2 position.
3. its backward edge limit the aperture ring to not pass over F16 position.
Thats why knowing the dimensions he ended up with is very important...I dont fancy having to cut umpteen of these forks out of copper sheet, all with slightly different dimensions, till I find the size thats correct for the job. Lifes too short!
kf_tam wrote:
Sorry, but 0.17mm simply would not cut it even for a 1Ds .
But setting the elements this close is potentially hazardous for the lens. When the lubricant drys or loose, the helical would have enough play to cause a "hard" collision. Or if the lens is rocking during a trip....
That's very usefull definitive info,Thanks!
As mine has a stopper built in it will be safe to adjust them closer.
Not sure it helps or not,but you may want to try acetone (in tiny amounts!) or mineral turps to remove that mark.Don't worry,i've used both on my lens with no problems.One thing i've noticed over the years is that alcohol type lens cleaning fluids are almost useless at removing gum or grease.
Hopefully it's not a permanent mark!
It's also interesting what you said about the 1Ds mirror moving backwards slightly.I'd heard that some cameras do such things and did wonder if that may possibly explain things
Alf Beharie wrote:
Thats why knowing the dimensions he ended up with is very important...I dont fancy having to cut umpteen of these forks out of copper sheet, all with slightly different dimensions, till I find the size thats correct for the job. Lifes too short!
Its interesting WHERE he's mounted that one.The square plastic bump it wraps around makes it easy to duplicate the position.
The gap between the tabs is critical but relatively easy to get right.
The length is not so hard either-just make them too long and trim to size last.
Unfortunately the positioning of the gap between the tabs is super critical and really tricky to get right(so the diaphragm is exactly fully open @ f1.2).Obviously you could mount it by elongated holes for adjustability but it wants top be a reliable setup.Personally i've never been able to make such small screws work well with enlarged holes !
Added to that is the issue of how you get it the right distance away from the ring-you need adjustability that way also!
Personally i feel its far easier to use stiff wire 'tabs' instead.Just bend em to shape! Only the tips of them contact the lever so it's so easier to get right.
Still annoying tho...
This part is one of the issues which make the conversion difficult.
Yes, it is annoying but it is a challenge as well.
If it would be that easy, everybody had a converted one ;-)
Alf Beharie wrote:
Thats why knowing the dimensions he ended up with is very important...I dont fancy having to cut umpteen of these forks out of copper sheet, all with slightly different dimensions, till I find the size thats correct for the job. Lifes too short!
Well, Jeff (Bigeye) has kindly replied that he didn't leave behind the dimensions, but it should be easy to measure the approximate dimensions that is required if you examine the lens, and trim the size slightly to fit your need . Some patience is required, though.
Well, my attempt just fullfills requirement 1, the aperture ring can turn slightly pass f1.2 and f16. But I wouldn't loss any sleep for these, anyway.
I nearly finish converting the FD 300/2.8 SSC fluorite to M42 mount (mainly for astronomical imaging), And I did make the aperture lever three times until I got it right. I lost a lot of sleeping time for this .
ronchappel wrote:
Not sure it helps or not,but you may want to try acetone (in tiny amounts!) or mineral turps to remove that mark.Don't worry,i've used both on my lens with no problems.One thing i've noticed over the years is that alcohol type lens cleaning fluids are almost useless at removing gum or grease.
Hopefully it's not a permanent mark!
Thanks for the advice, I should try some acetone tonight.
kf_tam wrote:
Well, Jeff (Bigeye) has kindly replied that he didn't leave behind the dimensions, but it should be easy to measure the approximate dimensions that is required if you examine the lens, and trim the size slightly to fit your need . Some patience is required, though..
Oh well, guess I'll just have to experiment with the dimensions.
I nearly finish converting the FD 300/2.8 SSC fluorite to M42 mount (mainly for astronomical imaging), And I did make the aperture lever three times until I got it right. I lost a lot of sleeping time for this .
It would be interesting to know how the FD 300/2.8 SSC fluorite compares to the Tamron SP 300mm f2.8 LD IF (60B)?
Alf Beharie wrote:
Oh well, guess I'll just have to experiment with the dimensions.
Good luck
It would be interesting to know how the FD 300/2.8 SSC fluorite compares to the Tamron SP 300mm f2.8 LD IF (60B)?
But who would buy the Tamron when the Canon FD 300 f2.8 L and SSC Fluorite can be had for the same price or less? My Fluorite is very slightly scratched and is only US$377, and a L with a slightly fungus spot is heading my way for just US$517. And recently two very good quality 300/2.8 Fluorites were sold for just US425 and 5xx. Poorer condition Nikkor AIS 300/2.8 ED lenses were sold for US600~800. Tamrons were also selling for about US600-900.
Due to the "difficulty" of mount conversion, the FD 300/2.8s are the best bargain for EOSers (with conversion ability) .
p.s. For all the money I spent on the two FD300/2.8s, I could also buy a single EF300/2.8 non-IS with malfuntions (a failed USM or loosen internal element). But I judged the risk was too high for the price.
It would be interesting to know how the FD 300/2.8 SSC fluorite compares to the Tamron SP 300mm f2.8 LD IF (60B)?
I've used the Tamron 60B as well as the FD 300/2.8L, and both versions of the EF 300/2.8. The Tamron is a nice sharp lens, but the canon is noticeably better. Images from the Canon just have a crispness and sparkle you don't get with the Tamron.
I could'nt find any 300mm f2.8 lenses on ebay UK for under £500, so when I found a camera shop in London selling a Tamron SP 300mm f2.8 LD IF (60B) in good cosmetic condition and with mint optics for less than £350 I snapped it up!
The Tamron SP BBAR 2x teleconverter is a very good match for the SP 300/2.8 LD IF and it does'nt noticably increase CA. I did try a Nikon TC-300 2x TC on it and the CA it produced was terrible so I returned it and stuck with the BBAR.
The most usefull piece of info I found in the whole article was how he made a fork actuator bracket that screws onto the aperture dial and moves the Iris actuation lever, as can be seen here:
Tonight I set about making one myself which is'nt as easy as it looks. In fact its an extremely skillfull bit of engineering.
To make it I first had to make some suitable copper sheet and I did this cutting a 1 1/2-2" length of 15mm copper tube down one side, annealing it with a blowtorch, opening it out with pliers and then hammering it flat.
Then I marked the required outline on the sheet and with great care and precision I accurately cut out the shape with a pair of tinsnips. Some carefull filing was necessary to get the outer radus of the brackets securing flange to perfectly match the inner radius of the aperture dial.
Next I needed to drill two tiny holes through both the fork bracket and the aperture dial. The two holes in the bracket were then drilled slightly larger than in the aperture dial to give clearance for the securing screws to pass through freely whilst tightening into the aperture dial underneath. The screws I chose were tiny (about 1-1.2mm, corse threaded and about 3mm long. This turned out to be too long so I had to grind them down to about 2mm long using a custom jig and an angle grinder.
Then using a machine vice I accurately bend each fork leg at right angles to the securing flange. At this point I added an improvement over the orginal design...I bent about 1.5-2mm of the end of each fork arm back outwards at right angles (towards the middle of the lens) to ensure a positive catch on each side of the Iris actuation lever.
I gradually snipped the copper away on each side of the securing flange of the bracket to get the aperture dial to stop in the correct position when I noticed that only one side of the bracket was actually acting as a stop!
It turned out that the left hand side of the flange sets the f16 stop position and the f1.2 position was set by a cutout on the aperture dial itself. So using a file I gradually filed this cutout a bit longer until the f1.2 position was set bang on.
Then it was a simple case of screwing the backplate on to keep the aperture dial in place and the lens now stops down and opens up perfectly with a lovely snappy action!!!
Next job is to fit an SA mounting plate to it. Thats going to be a bit tricky too as a quick test showed that closest focus distance is reached with the rear of the lens about 40-45mm away from the mount on the camera...WTF!!!!!!
Alf Beharie wrote:
...... At this point I added an improvement over the orginal design...I bent about 1.5-2mm of the end of each fork arm back outwards at right angles (towards the middle of the lens) to ensure a positive catch on each side of the Iris actuation lever.
Yep,good move!
Alf Beharie wrote:
...........Next job is to fit an SA mounting plate to it. Thats going to be a bit tricky too as a quick test showed that closest focus distance is reached with the rear of the lens about 40-45mm away from the mount on the camera...WTF!!!!!!
Closest focus?thats abit confusing .it's natural for lenses to focus closer as you move them further from the camera.To test it you will need to set the lens to infinity and see if it can focus on a distant subject.That's the only accurate way of doing it.
Is the fixed rear element set the right distance from the sensor plane?It's important to get that right first.The rear edge should protrude 7.4mm INSIDE the camera,measured from the camera mount surface.If it's less than 7mm you will only be able to focus close.
Alf, sounds like a nice aperture thingy you made.
What you wrote about close focusing distance is a bit confusing.
Adhering to the approximate 7mm which Ron mentioned above, the space between the front part of my EF mount (M42 adapter) and the lens mounting part (the one with the three screw holes which sits in the middle of the aperture actuating ring) is about 2 mm. These ~ 2 mm are filled with the original EF part which was there before, modified to that thickness.
40-45mm distance is definitely not the distance to achieve infinity focus.
Are you sure you have the proper fixed rear element? It sounds like what you have is not working properly in the "optical formula" for the FD85L. Could it be that you have the element for some other lens?
.
!
. Some patience is required, though.