The Canon EOS and Photography Forums

I have an FD500L converted to EOS mount and I would like to use a tele-extender with it, but, obviously, an FD extender won't work anymore and I wonder if the EOS version would be optically compatible with the old lens. I realize this is something no one else is likely to have tested, but, perhaps based on your knowledge of the optical designs of the two lenses types, you could take a guess, which, if positive, might then make it worthwhile for me to buy an EOS tele and try it.

The other possibility, is, of course to convert and EOS 1.4 tele to FD mounts, but I think the cost would be prohibitive for me.

Since having the FD/EOS conversion done on the 500L, I've had some second thoughts on how to do it a better way: I have an original "FD-EOS macro converter", the glassless one that doesn't allow infinity focussing, but does have a rotating switch that allows reasonably quick switching between wide open and shooting aperture. If I had realized it at the time, that converter should have been made part of the conversion, if possible, leaving the lens modified for infinity focus but with the FD mount intact on the lens (the tailpiece of the lens would be shortened more to make up for the thickness of the converter). This way only the camera side of the converter would be EOS, the other two mounts would stay FD and any old FD converters or tubes could be used with the lens and mount on EOS bodies via the converter.

It should be fine with the EOS 1.4x TC. I've used the EOS TC with the EF 500/4.5L and it was optically fine (no AF of course).  As far as I know the EF500/4.5L has the same optical formula as the earlier FD 500/4.5L so the EOS TC should work equally well with either one.

OK and thanks. Now that I'm seriously considering getting a 1.4xTC I have another follow-up question:

I usually try to use my 500/4.5L at f/8 (+1.5 stops), where sharpness is excellent. The 1.4xTC will make my f/4.5 lens into an f/6.7, do I still have to stop down 1.5 stops to get the quality I want (f/11)?

According to one of the articles I posted in the other thread, no.

I'd say maybe! I know that with a 2x on my 300/4L I get the best results at around f13, which is about 1.5 stops stopped down.

It really depends on the lens and the TC, but generally you will get slightly sharper images if you stop down a stop or so, assuming that the lens is well supported and that you don't get motion blurring from the slower shutter speed required.

I've been using the modified FD500/4.5L with the 1.4x extender on a 5DII for about a month pretty frequently for birds and found it to be a challenge to get the sharpest possible images, but one technique worked best of all: using Live View and the LCD with the 5x and 10x digital magnifier for focussing. A modified Mamiya MF magnifier hood provided an optimum view of the screen.

The depth of field with the 700mm equivalent combo was minute, even stopped down to f/6.7 or 8. With the magnified LCD screen it was quite obvious that the optical viewfinder was inadequate to do the job reliably (it also showed how much vibration I was inducing when I touched the camera on the window mount or tripod.) The absolutely sharpest shots required hands-off, remote release and patience waiting for the image to stop bouncing. One of the nice things about working this way, using Live View, is that the mirror is up and the camera makes much less noise when tripping the shutter only. Watching the screen immediately after a release showed no movement at 10x. This was all done with a large Studioball head on a home made window pod.

BTW: I have excellent eyesight after a cataract removal and a synthetic replacement lens in my eye and could focus quite well without the 1.4x extender on that lens using the optical viewfinder.

The birds I am working on are south-bound migrants and they arrive hungry and were actively feeding, so hands-off shooting didn't work until some of them settled-down for a nap. Trying to follow an active small bird like a sandpiper with the magnified LCD was a bit of a trick, but possible and necessary. I used a lot of shifting between normal, 5x and 10x views as the birds often ran out of the viewed area.

Using Live View, even intermittently, heats up the camera noticably. The area of the right grip on the back gets pretty warm! I shut off LV as often as possible, but didn't let the heat prevent me from shooting, if subjects were present.

Some odd notes: if LV was set for video and stills, it overrode the stills settings to low ISOs (I had to use ISO 1600 for most of my work) and correspondingly slow shutter speeds. Fortunately, setting LV to Stills Only solved that problem.
Also, with the extender in place, some short shutter speeds caused more or less of the bottom of the image to be cut off as if the shutter was still part closed (as in using flash at shutter speeds above the maximum synch speed). This did not happen with the 500 and no extender or with other lenses.

I haven't worked with a long lens since my FD600L fell when the shoulder strap broke and smashed the camera mount to bits (the F1 that was attached, which hit the concrete first, was undamaged). It's taken a while, but the skills are coming back (also, the new tricks are being figured out!)