How to focus with a Fotodiox?

Discussion in 'Canon EOS' started by glenn_carroll, Feb 10, 2012.

  1. Hey I just bought this to get good macro photography with a standard telephoto lens:
    As you can see, it comes with three different extensions, 7mm 14mm and 28mm. You can use them all or separately. However, since the lens cannot communicate with the body, I am unsure how to focus. I know I cannot control the aperture, but I figured you could still focus somehow. I've tried it out and it is a blurred mess whether the object is 1 foot away or 1/2 inch away from the lens. I have a 24-105m f/4 L.
    Also I have no idea what 7mm 14mm and 28mm mean. Do you automatically have a good idea of how far the object needs to be from the lens based on whehter you are using the 7mm ring as opposed to the 14mm ring?
    Any insight on this would be fantastic. No, I dont want to spend 1,000 on an extension tube to be able to control the aperture. Thanks
  2. SCL


    You focus manually. If you are out of range for a given ring, you just move your camera (generally on a tripod for macro work) closer or further away from the object until it sort of comes into focus, then you finish off manually focusing. The extension #s mean the additional extension of the lens from the sensor. The lower the number means less extension, and you can be further from the object you want to shoot.
  3. Start with the 7mm ring, zoom at 105 and focused to infinity, then just move back and forth to see where focus is, it will be quite close, around 10"s.
    The set is of limited use with your zoom though, all three stacked will probably be unusable as the point of focus will be inside the lens! But they are a bit of fun.
  4. No, I dont want to spend 1,000 on an extension tube to be able to control the aperture. Thanks​
    I don't understand this comment. Without aperture control your lens will be stuck wide open. Your depth of field with maximum aperture at macro distances will litterally be paper thin. Most of the time you need to stop down the lens some to get at least a usuable amount of depth of field. Without aperture control it is going to be extremly difficult to get anything close to "good macro photography".
    You can get a set of Kenko extension tubes that will communicte electrically with the lens keeping auto focus and electric aperture control for a cost of about $180, not thousands. I have a Kenko set and they work perfectly. Amazon also sells a set Pro Optic extension tubes that do have electric aperture control for only $30 more than the Fotodiox brand you purchased.
    Keep in mind an extension tube is just a spacer between the lens and camera. There are no electronics in them. Only a set of electrical contacts that move the camera signals to the lens. Extension tubes don't consume any electricity, don't have any lenses and don't have any moving parts (other than the lens mount spring loaded locking pin).
    I would return the set you purchased and then buy a set that does allow aperture control. Without aperture control you will likely be disappointed in your macro images.
  5. jpk


    You can get a set of Kenko extension tubes that will communicte electrically with the lens keeping auto focus and electric aperture control for a cost of about $180, not thousands.​
    I've bought Kenko for around 60$, on Amazon similar set is even less expensive
    Since your tubes has no electric connection between lens and body, you can try another solution:
    1. Connect you lens directly to camera body.
    2. Set desired aperture, 11 for example.
    3. Press the depth of field preview button.
    4. Keeping it pressed disconnect the lens from the body - aperture should stay closed to previously set value.
    The biggest disadvantage of this method: focusing with the lens stopped down to 11 is really difficult... :)
  6. thanks guys. Steven F, I was reading another forum about this fotodiox and someone suggested getting a really expensive one that was able to control the aperture. As far as I'm concerned, this is just a dag-um spacer and there's no reason it should cost much of anything. molded plastic. But I really dont mind spending $50 or so if it grants good macro photography and allows me to avoid getting an entirely different lens.
    Jack, thanks for that. I was wondering if there was some way to turn the thing off without it defaulting to wide open
  7. Hey steven F, you say that if I use this then my DOF will be paper thin and the pic will look like garbage. Thats at f/4. Well if you go to this link below, you'll find some sample pictures of what people have put up there. There is one of green peas. It says they took that picture with an aperture of 1.8 with 36mm of extension tube @ a focal length of 50mm. If my settings would grant paper thin results, then those settings would have microscopically thin results, right? What do you think... I'm all confused. The picture of peas looks pretty good
  8. Glenn,
    I think the picture you are talking about was taken with the 50 1.8 but not likely at all to be shot at 1.8.
  9. Glenn, Depth of field is dependent on the lens aperture, focal lenth of the lens, and the distance between the lens and subject. You can use this depth of field caculator to determine the how much you will have. while it is possible to get a good shot with the aperture wide open it typically is easier with the aperture stopped down some. The picture of the peas was taken at F8 according to the Exif data.
  10. Narrow dof can be used to good effect in macro work, here is a 50 mm f1.4 lens with a 12mm tube shot at f2.5.
    The problem with using retrofocus lenses, and zoom lenses, is the subject to sensor distance (focus distance) can be so small the subject to front element distance (working distance or length) can be zero.
    There is a workaround for getting the lens to stop down, but it is clunky and not very effective.
  11. This looks like Chinese Restaurant Macro.

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