Extension Tubes + Dedicated Macro Lens

[wideangle]

Does anyone here use a dedicated Macro lens with Extension tubes? Is this an effective combination in getting even closer to small subjects, and is there any loss of quality and/or extra challenges in using extension tubes with a macro lens? Are there extension tubes to steer clear of, and are there ones that are more effective than others?

[OzzieTraveller]

G'day wideangle

While I don't today do the sort of macro work you are asking Qs about, I have done it in years past

Of your many Qs above ... Some Macros lenses come with an extension tube as part of the 'kit' - eg: the lens by itself may go to an image size of 1/2 life size and by adding the tube, you can reach life size.

It is quite common for a user with a macro lens to add 'some' extension to it occasionally ~ ie: the lens has its own extension via the focussing ring, but that can only go so far. So by adding some extension, you can get a greater magnification than without the extension

As with all things tho, the more extension you add, the larger the image size and the smaller the depth of field ~ so it becomes an ever more difficult issue to get a sharp image containing everything you are seeing

Extension tubes have a greater effect when used on short lenses (30mm - 60mm) rather than the long macros of (100mm - 150mm)

Hope this helps a bit
Regards, Phil

[wideangle]

G'day wideangle

While I don't today do the sort of macro work you are asking Qs about, I have done it in years past

Of your many Qs above ... Some Macros lenses come with an extension tube as part of the 'kit' - eg: the lens by itself may go to an image size of 1/2 life size and by adding the tube, you can reach life size.

It is quite common for a user with a macro lens to add 'some' extension to it occasionally ~ ie: the lens has its own extension via the focussing ring, but that can only go so far. So by adding some extension, you can get a greater magnification than without the extension

As with all things tho, the more extension you add, the larger the image size and the smaller the depth of field ~ so it becomes an ever more difficult issue to get a sharp image containing everything you are seeing

Extension tubes have a greater effect when used on short lenses (30mm - 60mm) rather than the long macros of (100mm - 150mm)

Hope this helps a bit
Regards, Phil

Thanks for your help Phil. I am interested to know why you say they have a greater effect on shorter lenses than a dedicated macro lens. My idea was that it would magnify with a Macro beyond 1:1

Regarding DOF, I see a lot of photos taken of things like fly eyes and surely these have been taken with a macro lens and extension tubes attached to get so close, and then techniques used such as 'stacking' photos of different f stops to achieve desired sharpness.

[OzzieTraveller]

G'day again wa

With ff/35mm users, when the extension equals the focal length, the lens is at 1:1 [dSLR users will have a crop factor to take into account as well] but ...

If you have a (say) 40mm lens and use 40mm of tubes, you will get to 1:1 ... however with a 120mm lens + 40mm of tubes you will only get to 1/3:1 -> so it leads to me statement regarding "Extension tubes have a greater effect when used on shorter lenses ..." - that's all I mean

As to digital-focus-stacking, that is introducing a new ball game, and comes down to the capabilities of the software etc etc

Regards, Phil

[Ross the fiddler]

I use a 25mm extension tube (Olympus EX25) with the 150mm Sigma macro lens as it gives me 30-35% more magnification with plenty of room to get closer with it. Extiension tubes are not very practicle on short macro lenses because they are already at a close focusing distance & since the tube only allows you to focus closer, the subject might be focusing at its maximum when touching the front lens. It all depends on the working distance at maximum magnification for that lens & how much closer it would be with the extension tube. For Olympus, they have compatabilty tables to show these details & there is probably details for other manufacturers lenses somewhere to be found.