Infinity focus? FD lens on EOS with EF Life Size Adapter

Started Feb 2, 2013 | Discussions thread
OP TTMartin Veteran Member • Posts: 7,304
Re: Infinity focus? FD lens on EOS with EF Life Size Adapter

RS_RS wrote:

As a long-time user of the Life Size Converter, let me provide some information and correct some misapprehensions.

As pointed out, the LSC is a combination of a teleconverter and some extra extension. Roughly speaking, the TC power is around 1.4× and IIRC the additional extension is equivalent to about 8mm.

The LSC has extra pins on the same pattern as the Extenders, and the 50/2.5 has the extra contacts required to allow it to recognise the presence of the LSC. With the LSC in place, the 50/2.5 reports itself as 70/3.2, and focuses from ×0.25 to ×1, so infinity focus is lost. Phase-detect AF works. The 50/2.5+LSC combination is reported correctly in EXIF data, and is recognised separately for aberration correction in-camera or through DPP.

Extenders will not fit physically on the 50/2.5.

However, the LSC will fit any EF lens, but it does not fit EF-S lenses. Because of the extra extension, infinity focus is lost except possibly with some super-telephotos which focus "beyond infinity". Obviously lenses that are not Extender-enabled do not recognise the presence of the LSC, because there are no extra contacts to make that possible on those lenses. But it is also the case that Extender-enabled lenses do not recognise the LSC (at least, those that I have tried).

The 50/2.5 and the LSC are computed to work together, and image quality is good. When the LSC is used on other lenses, image quality is very lens-dependent and in many cases is poor to very poor, with particularly high levels of lateral CA. Phase-detect AF generally refuses to lock.

My advice: the LSC is a useful, if rather expensive, complement to the 50/2.5, and if you buy one for that purpose it may be amusing to experiment with fitting it to other EF lenses. If you want a 1.4× TC that works with EF lenses that do not accept Canon Extenders, buy a good-quality off-brand one, and certainly do not buy an LSC for that purpose.

Thanks for the informative and insightful reply.

I am awaiting a LSC ordered from that was listed as 'like new' with case for $150 shipped, which seemed reasonable to me.

All my long zooms are Sigmas and I have a Sigma 1.4X teleconverter to use with those.

I ended up getting the EF 50mm f/2.5 Compact Macro because I was looking for a metal mount EF 50mm f/1.8 on ebay. My searches kept bring up this lens too. I saw that this lens often sold for less than the metal mount f/1.8s. So that got me looking at Macro lenses. I'm not really into macro photography, but, thought it might be fun to try.

So, all of my lens purchase decisions include looking at pictures from the lens on Flickr. So I set up a comparison of the 4 macro lenses Canon has 50mm f/2.5, 60mm f/2.8, 100mm f/2.8 and 100mm f/2.8L IS. I decide myself the 50mm f/2.5 was better than the 60mm f/2.8. I then did a test with my wife, she didn't know which picture came from which lens. She picked first the 100 L lens, then a mix of the 50mm f/2.5 and 100mm f/2.8, slight lead to the 100mm f/2.8. And she also had the 60mm f/2.8 come in last.

I got the 50mm f/2.5 for under $200 on ebay (was attached to an old Canon film SLR).

As I already mentioned, the 50mm f/2.5 has a metal mount, it is much better constructed than the 50mm f/1.8, ones made after 2007 have a 6 blade aperture so they have a better bokeh. From what I've read it is the sharpest of any of the Canon 50mm lenses at all f/stops, including the 50mm L. The front bezel doesn't rotate when focusing, so it works better with a polarizing filter.

Of course it's a f/2.5 lens, so it is a full stop slower than the 50mm f/1.8, and it wont have as thin a depth of field as any of the other 50mm lenses.

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