Chan Garrett

I am new to close up and macro. I plan to use my Canon RP for this. I also have a Canon 100mm Macro lens with the EF mount. When I attach the EF lens to my RF mount RP, does the converter also have the effect of an extension tube?

randave2001 Loc: Richmond

No they do not. An extension tube does not have lens elements in them, they are just an empty ring. The EF adapter, on the other hand, has optical elements built in that compensate for this.

agillot

NO , as long as you can focus at infinity , it does not .

olemikey Loc: 6 mile creek, Spacecoast Florida

To my understanding and from usage ( I hope my explanation attempt makes sense) any device (tube/adapter) that increases the distance between lens and sensor (without a corrective lens element) would indeed change the Field Of View, if it increases the flange distance it will act as a zoom would, multiplying the image size to some degree. I use this trick with zooms (adding manual/auto extension tubes) to effectively increase image size that hits the sensor....it is helpful with small birds, but does change the range of "in focus", meaning loss of infinity - if shooting in a setting where that is of no concern (example - you need focus from 5 to 20 feet or somesuch, extension tube would give this, while increasing the size of the image hitting the sensor). depending on tube/adapter length it could cause some light falloff. As always no "free lunch" with equipment comprimises.

Chan Garrett

As I sit here looking at my adapter, there are no optical elements in it. I can put my finger through from one side to the other.

CHG_CANON Loc: the Windy City

You're thinking is almost accurate about the adapter being like an extension tube. But, a true extension tube moves the lens beyond the flange distance of the native lens mount. For Canon EF, that is 44.0mm. So, from 44.1mm and further, the extension tube changes the lens's ability to focus to infinity as well as changing how close it can focus onto subjects closer than the 'normal' minimum distance.

The EF to RF adapter just places the EF / EF-S lens to the required 44mm distance so the EF lens performs as 'normal' when mounted to a DSLR, but now operating on a mirrorless EOS camera with a native flange distance of 20mm.

Chan Garrett

Thanks for your response. I have a lot to learn about macro and look forward to experimenting.

Mark Sturtevant Loc: Grand Blanc, MI

I was about to say what CHG-CANON said, only I don't have the actual distances at hand.
Since the camera body supports focus bracketing, I believe your adapter will also support that feature and so you can do super fast focus bracketing with your 100mm lens. This is a thing I would like to do ... one day.

amfoto1 Loc: San Jose, Calif. USA

No. The lens mount adapter is merely a spacer.

A Canon EF lens is designed with something like 44mm back spacing. That's the point at which the lens at infinity is designed to back focus onto the film/sensor plane.

An RF lens is designed with 20mm of back spacing, if I recall correctly. Once again, this is where the lens at infinity is designed to back focus onto the image sensor.

So the EF to RF adapter is essentially a 24mm spacer, to move the lens with the longer back space focus out to where it needs to sit for the image to properly focus onto the image sensor.

In addition to any electronic lens to camera connectivity that needs to pass through, there also is the diameter and design of the bayonet mounts themselves which are adapted,. But this is somewhat secondary to repositioning the lens appropriately.

And, NO, lens adapters like this DO NOT have any optics. Note: There are some that require "corrective lenses", when trying to adapt a lens with a slightly shorter back focal distance onto a camera system with one that's a little longer. An example would be putting a Canon EF lens with 44mm onto a Nikon F mount DSLR that's designed for 46mm. But NO OPTICS are need in an EF to RF adapter needed here.

There ARE lens adapters that accommodate drop-in filters.... polarizers and neutral density typically. But these are filters that do not effect the optical formula and focus of the lens.

If you are looking to push your lens to even higher magnification, you still need separate macro extension tubes. Those will move the lens even farther from the camera, so the the lens can focus even closer and render even higher magnification. Macro tubes ALSO do not have any optics. You can either get EF mount tubes and position them between the lens and the EF side of the EF to RF adapter... or you can get RF mount tubes and position them between the RF side of the adapter and the camera. It really doesn't matter which. EF mount extension tubes are quite widely available, including top quality such as Canon's own, Kenko, and others. Canon's are sold individually and only come in two sizes: 12mm and 25mm. Kenko and most others sell sets of three, which typically include 12mm, 20mm and 36mm sizes (some brands vary a little). RF mount macro extension tubes are not yet as common. In fact, Canon doesn't even make them yet. There are Kenko, Viltrox and some other brands though. They come in sets of two tubes. There's a lot of variation in the sizes, but something like 12mm and 20mm or 10mm and 16mm is typical. One advantage of getting RF mount macro extension tubes is that they would be usable both with the adapted lens and with any RF mount lenses you have now or get in the future. EF tubes would only be usable with the adapted lens(es).

With the adapter installed, your lens will be able to focus to infinity at one extreme and focus to 1:1 magnification at the other end of it's focus range. If you add extension tubes as well, it will be able to focus closer, with higher than 1:1 magnification, but will not be able to focus to infinity.

Incidentally, Canon calls their teleconverters "Extenders"... not to be confused with macro extension tubes. As teleconverters, Canon's RF 1.4X and RF 2X Extenders DO contain optics that change the optical formula of the lens. They also increase magnification, but they do so by changing the lens focal length.

Macro extension tubes make lenses able to get closer to subjects, shortens the lens' minimum focus distance to render higher magnification, but have no effect on the lens' focal length. Teleconverters on the other hand, do not change a lens' minimum focus distance. They instead render higher magnification by changing the lens' focal length. Usually, but not necessarily, teleconverters are used for higher magnification of distant subjects. However, they also can be used for higher magnification of close subjects. Macro extension tubes, on the other hand, are only useful with close subjects.

Chan Garrett

Thank you for your very helpful explanation. Everyone who responded had something to contribute. I feel I now understand what has been said to me.

dpullum Loc: Tampa Florida

No glass so it is in a sense an extension tube. "The Canon EF-EOS M Adapter is very solidly built, but it is a very simple device with no glass,"
https://www.the-digital-picture.com/Reviews/Canon-EF-EOS-M-Adapter-Review.aspx

DWU2 Loc: Phoenix Arizona area

Sorry, but an EF to RF adapter has no glass.