Hello.

I think this question could have been placed in either the canon section as well as the Advice for beginners.

My questions is this:

I am interested in purchasing a macro lense for my existing canon camera so that I can take some close up shots. I am considering purchasing the EF50mm f/2.5 compact Macro. Now, my knowledge is relatively limited.

What does the 2.5 mean? I know it refers to the aperture size but thats all i know. What does this mean physically? Some macro lenses are available with f1.8 what difference is there?

I also wanted to know what specification determines the distance from the lense to the object while still being in focus? Because i have seen specifications for this lense, closest focusing distance is 0.23m. I however went to check this lense out and wanted to find out just how close i could get and it seemed to be much less than this. Am i confusing these two values?

If i were to get an extension tube as well, what does this do? does this mean i can reduce the distance from the lense to the object? or does this mean that i can stand further back while still having increaed magnification?

is this lense good value? and what can i expect to pay for this lense?

Thank you so much, I hope to hear from you soon, Emmet

-- Emmet Poon (emmetpoon@hotmail.com), February 21, 2002

Answers

.23m refers to the distance from the subject to the film plane, not to the front of the lens, so it will seem closer than that. If you are interested in full life size macro, (this means the subject is the same size on the film as it is in real life) you may want to consider Canon's 100mm macro lens. The 50mm needs a special converter to get to full life size, and the cost of the lens and converter together doesn't really save that much money compared to the 100mm. Also, the newest 100mm macro from Canon has a faster focus motor, along with internal focus so the size of the lens doesn't change when you focus. These features make it a better choice if you intend to use the lens for general purpose photography as well.

-- Brad Hutcheson (bhutcheson@iname.com), February 22, 2002.

Emmet,The 2.5 is the maximum aperture of the lens, ie the setting at which it will let in the most light. But at settings like this the depth of field (the amount of the picture in focus) is very small, and so for close up work these wide apertures are not that important, more likely you'll need to be shooting at f11, f16 or f22. How close a lens focusses is determined by how far it can move from the film plane. You'll notice that as you focus the lens closer it gets longer (ie further from the film). The lens specification for closest focus should be correct at 0.23m. This is also how extension tubes work-they take the lens further from the film. With an extension tube you will get closer to the subject. Whether or not the lens is good value depends on how much you use it. If you do lots of close up work then yes. Best wishes, Steve

ps If you're going to shoot live subjects like insects, you might need something a bit longer like 100 or 200mm macro.

-- Steve Phillipps (steve@redvixen.freeserve.co.uk), February 22, 2002.