Sindarin wrote in post #15176253
I have found the shorty forty to be an excellent lens, and very sharp at f/2.8. I have seen examples of people using it with extension tubes and getting great close-up images.
I know that canon has the 12mm and 25mm extension tubes that allow for aperture control and AF, but even the cheaper 12mm is nearly $100. Seems somewhat pricey for a hollow plastic tube with some electrical contacts...
The Canon ones, in contrast to anybody else's, are metal tubes, actually, and they bear the name Canon in addition .
One can buy a 3-set of non-electrical adapters for about $15. Are the Canon extension tubes necessary for the 40mm f2/8, since even manual focus is focus by wire?
Yes. Canon, or at least tubes which have electrical contacts.
Or is there a way to use the cheap tubes?
There is, but it is very limiting:
1) only at the distance prescribed by the tube, and hence fixed magnification
2) the aperture has to be set by pressing the DoF preview button while simultaneously pressing the button and unmounting the lens
3) focusing has to be done by moving the camera, tube(s) plus lens in its entirety
Also - do the extension tubes reduce the minimum focus distance?
P.S. I realize that a true 1:1 macro lens such as the 60mm or 100mm would be better. I won't have the budget for that for quite a while though, and would like to do some close-up photography before then.
Thank you in advance for your help!
The cheapest tube set with electric contacts is about $60 to $70 I understand. At least, it was that a couple of months ago, although prices may have gone up by now. Just check Amazon or the B&H site.
For a good set but more expensive, get a Kenko 3 tube set (plastic), and if you want metal the only option is Canon. However, with a 40 mm you could just get away with a 12 mm tube to begin with anyway.
As this lens has an MFD of 25 cm, a 12 mm tube at MFD will give you a new MFD of approximately 175 mm with 113 mm WD and a magnification of 1:0.55, or slightly better than half size.
A 25 mm tube 161 mm MFD, 86 mm WD, and magnification of 1:0.875. A 30 mm tube will provide you with 1:1 for this lens.
HTH, kind regards, Wim