Extension tube with close up filter...?
If the question is: "can I put an extension ring at one end of my lens and a close-up filter at the other" the answer is yes. But what would be the point. Their effect are similar, the extension rings are cheaper than a quality close-up lens (especially with large diameter ones), and will work on all your lenses (even if they have more effect on short ones).
Most modern digital cameras allow close-up photography without the need to purchase additional gadgets. You should check your camera’s manual before you buy gadgets for close focusing.
That being said, camera lenses are usually optimized for distant and near subject distances and are compromised when tasked to work in close. Close-up work is generally considered under 3 feet (1 meter) subject distance. Many camera lens combinations restrict close focusing. For these cameras, it will be necessary to buy close-up gadgetry.
The simplest of such gadgetry is the close-up lens (sometimes mistakenly called a filter). These are supplemental lenses that mount directly ahead of the usual camera lens. These close-up lenses work just the way reading eyeglasses allow farsighted people to read. In fact, you can go to the drugstore and buy a pair of reading glasses and try them with your camera by merely holding one of the lenses over your camera lens. The quality will be less than decent but such a test will give you a preview what a close-up camera lens will do for you. Camera close-up lenses are labeled in the same way reading glasses are categorized. This is a “+” sign ahead of a number like + 2 or +2.5 etc.
The number just another way of expressing focal length.
+1 = 1 meter (39.3 inches)
+2 = 500mm = 19 ½ inches
+3 = 333mm = 13 inches
+4 = 250mm = 9 ½ inches
How this works: If your camera is set to infinity ∞ and you mount a +3 close-up, your camera is tricked to a working distance 13 inches to about 9 ½ inches (333 to 250 millimeters). Close-up supplemental lenses work! Good ones are “achromatic” a two lens color error free sandwich.
Next extension tubes sometimes called rings. You dismount your camera lens, install an extension tube and then re-mount your camera lens. These act as spacers that reposition the lens more forward of its regular position. This adds distance lens to sensor and allows for superb close-up work. The drawbacks are; your normal camera lens is not optimized for close-up work, however, likely it will function just fine. The typical extension tub is a simple spacer that will abolishes electrical and camera mechanical control over the lens. When used, you are required to make all lens adjustments manually. Sophisticated extension tubs are available that maintain camera to lens linkage, they are not cheap.
The typical camera lens is optimized to work a world with different subject distances and image them, by focusing, onto the flat surface of film or digital sensor. When tasked to do extreme close-up work it becomes compromised. Since the rear lens elements of a standard lens is designed to project on a flat surface, for close-up work, the lens is often mounted reversed. A reversing ring is sold for this purpose. In other words, when doing extreme close-up work using extension tubes, we reverse the lens to optimize it for close-up work. Again, all connection lens to camera body is lost so you are on your own when it comes to lens settings.
After all this what is best for close-up work. Answer – a “macro” lens. This is a distinctive lens design, optimized for close-up work. These lenses maintain lens to body communications so automatic lens settings are maintained. This is your best bet to do super close-up work.
By the way, combining a close-up lens with extension tubs is possible and are free to experiment. I think it won’t give you any improvements worth the effort.