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Old Apr 1, 2012, 5:15 PM   #1
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Default Canon FD 300 f4 L converted to K mount

Hi All,

Got a first chance to play with a lens I bought on a whim. It's a Canon FD 300 f4 L converted to K mount. I picked it up because the "L" version of lens has a stellar reputation.

Canon lenses are usually not good candidates for conversion to K mount since the register distance is over 3.5mm shorter for the FD mount than for the K, and the barrel of the lens would need to be shortened to allow the full focus range. This lens has a very deeply recessed rear element, so the conversion was possible. How well it was done made buying this a risk, but after seeing some samples from the owner who did the conversion and the subsequent owner who was selling it, I felt that the conversion was accomplished successfully. There were some problems with the aperture ring operation (no stop detents, and the aperture ring positions are no longer accurate), but since I would primarily be shooting this lens wide open, this would not effect my use much anyway. I bought it from a member on the PF marketplace for $225, so it was very inexpensive for this class of lens. Cosmetically, it was severely defaced by a long gone previous owner, but a little electrical tape makes it presentable. I've read that this lens retailed for $1900 when introduced in 1981!

With the K-5 I'd be using this lens with the F 1.7x AFA to get Auto Focus for birding. I currently use the FA* 300/4.5 with the AFA for handheld birding, so the question is how does the '80's vintage Canon L glass compare to the almost 10 year newer Pentax lens?

The FD 300/4 L is bigger and heavier -- about the same size as the K 300/4. It's also more suitable for the MF only since the focus ring travel is about 300 so considerably more precise than the FA* 300/4.5 whose focus travel is about 180. This is actually a disadvantage when using the AFA since it slows down the prefocusing needed to get within focusing range. The fully manual aperture doesn't matter much operationally since Pentax DSLRs can still be shot in Av priority with fully manual lenses.

Both lenses are sharp wide open, have ED glass elements to control PF/CA, and focus internally. The FD has an integral hood, but it's not as deep as the FA*'s which is separate, but can be stored on the lens reversed. The FD comes with an OEM removable tripod collar. The FA* does not have one, and there's really little room for one even if you can find one to fit. The FD can use drop in rear filters while the FA* can only use front mounted 67mm filters. The FD focuses to a min of @ 10 ft while the FA* focuses down to @ 6 ft.

The FD shoots well with the AFA on the K-5. I've only been able to get a few shots of birds. This one's at only a little over MFD, 10-12 ft. This shot has been cropped to vertical 8x10 from a landscape shot, corrected for some relatively minor PF/CA, sharpened a bit, and downsized in steps. It was shot in jpeg ***, sharpening and contrast turned down, f6.3 (wide open, corrected for the AFA), 1/250, ISO 250 handheld.

This is very similar to what I can get with the FA* 300/4.5. So why buy another 300/4 class lens that's bigger/heavier, slower to focus with possible limited resale value? I actually bought it looking to use it with the Q. This gives me a long, relatively fast lens that's easy to mount on my Wimberley Sidekick, with more precision and better feel in MF. I can have the Q tripod mounted with the FD for 1080mm (APS-C EQ) and have the FA*300/4.5 +1.7x AFA (510mm) handheld with AF for quick shots.

I only have had a few chances to shoot at birds with the Q/FD combo so far, as they were off somewhere else when I got to one of my favorite spots, but a Dark Eyed Junco stuck around for a couple of shots which gave me a good indication of what to expect from this lens.

Both were shot off a lightweight (2.5 lb) CF travel tripod and ballhead (12 oz) with the Wimberley Sidekick mounted, wide open, 1/400, ISO 125, jpeg *** with Sharpness and Contrast turned down. Both of these are only downsized in steps to 1024 on the long side with no other PP. I've included a 100% crop of a section of the second shot. Unlike some of my earlier attempts that I've posted with longer lenses previously, I was able to use the focus assist, so I'm certain I nailed the focus on these. These were shot from 18-20 feet from the subjects.

Bottom line, this lens is very good on the Q or a DSLR. Since FD to Q adapters aren't that expensive, some of these older premium MF lenses for other mounts should be a consideration if you'd like to shoot long with the Q. This particular model, I'd class as a hair above the M*/A* 300 f4 in sharpness, and considerably better in CA/PF control, even though these aberrations do show up pretty prominently in high contrast scenes. I'd place it pretty close to the FA*300/4.5 in sharpness wide open, but not as good in controlling CA/PF. I'd been looking at this lens as an possible for the Q for quite a while, and when the K converted lens became available at a very good price, I took a chance -- and am glad I did.


Last edited by snostorm; Apr 1, 2012 at 5:25 PM. Reason: added shot info
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Old Apr 3, 2012, 8:56 PM   #2
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Cool! That's very nice, especially with the Q.
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