50mm Macro Life Size Adapter/Converter

[RichardD]

I own the 50mm f:2.5 macro lens.  This lens will focus to 1/2 life size but to get to life size Canon states that I need to buy their unique adapter which costs an arm and a leg.  What is the advantage of using the Canon adapter/converter instead of using s simple extension tube?

Thanks.

[Skirball]

---

@RichardD wrote:

I own the 50mm f:2.5 macro lens.  This lens will focus to 1/2 life size but to get to life size Canon states that I need to buy their unique adapter which costs an arm and a leg.  What is the advantage of using the Canon adapter/converter instead of using s simple extension tube?

Thanks.

---

The advantage of extenders ("teleconverters") is that they can be used for more than close-up work.  They effectively increase you magnification, but at the cost of image quality and light (the 1X costs a stop of light, I believe the 2X costs 2).  But you can turn a 200mm lens into a 400mm.

The extension tube on the other hand just moves the lens element further from sensor.  If you imagine a projector, move it further from the screen and the image gets larger.  But the screen (sensor) stays the same size, so the image in effect gets enlarged.  Extension tubes have no glass elements, so there's no loss of image quality.  You do lose light, since part of the image falls outside the sensor.  And most of the cheap extension tubes don't have wires for the electronics so you loose all communication between the lens and camera (read: no autofocus).  But it lets you focus closer than the minimum focusing distance of the lens.  That's how you get a higher magnification.  The downside is that you have to get really close to your subject.  You also lose the ability to focus to infinity, but that doesn't effect most macro photography.

That said, for what you're doing, I'd just get extension tubes.  If you're going to plunk down a couple hundred dollars I'd get a 1:1 macro, like the 100mm, not an extender.

[RichardD]

I think that I have failed to make my point regarding the adapter that Canon recommends for use with this particular lens.  I understand the difference between teleconvertors and extension tubes.  That is not my question.  Specifically, Canon makes an adapter that is designed to be used with the 50mm F:2.5 macro lens.  This adapter is matched to that lens and, as far as I know, to that lens alone.  It is not advertised as being a teleconverter but rather an converter that allows this particular lens to record images at life size or 1:1.  This adapter does have some glass in it and certainly does look like most teleconvertors. Canon lists it on their website as the "EF Lens Life-Size Converter" and is priced at $210.  So, my question is why do I need a special life-size converter for this lens when all lenses can be focused closer just by using an extension tube? 

[Mykolas · Accepted solution]

Richard D,

It is true that you can change the focusing distance of the EF 50mm f/2.5 Compact Macro lens by simply adding an extension tube to it.  To achieve anywhere close to life size magnification (1x), you would need the EF 25 II extension tube. 

The disadvantage is that you do not quite hit the target of life size magnification with an extension tube and you are adding an extra 25mm to the focal length, which changes the working distance.  The Life-Size Converter allows you to achieve 1x life size magnification while keeping the working distance and focal length shorter, which is great for copy stand work or photographing large, flat artwork.

[RichardD]

Thanks for responding to my query. 

[TCampbell]

The 50mm compact macro is about $299 (although there's a $30 rebate at the moment).  The life-size converter is another $269 bringing the total to about $570.

An alternative is the EF-S 60mm f/2.8 Macro USM.  This is $469 (although there's a $50 rebate at the moment).

I had the EF-S 60mm for a while and was well-pleased with the performance of this lens.  But the "catch" is that the EF-S lens is for use on Canon bodies that have APS-C sensors.  If you have a full-frame camera, the EF 50mm compact macro and the life-size converter can be used on a full-frame body (although on full-frame bodies, most folks tend to want 100mm or longer focal lengths on their macro lenses.)

[RichardD]

Thanks for your input, Tim.  I use the 50mm on both apc and full frame bodies and I have been extremely pleased.  The 50mm on my apc camera effectively makes it an 80mm lens which turns out to be ideal for how I use the lens.  My query into buying the Canon converter versus using an extension tube was more of an academic curiosity than anything else.  I really have no need to photograph anything at 1:1 but I have used extension tubes in the past to enhance the close focusing capabilities of my lenses and so was wondering why extension tubes were not recommended by Canon.  A Canon rep posted a response which you may or may not have read but his explanation seemed plausible to me.

Again, thank you fro your input.

Regards,

Richard