Here and there I’ve read in the internet that mounting Canon’s 500D close-up filter in reverse gives you better image quality. So, I tried it…
Even though I own a nice 105 mm macro lens, I don’t always carry it with me: There is a physical limit to what you can put in your backpack! However, when I don’t, I always make sure I have a quality close-up filter for my telephoto zoom lens.
The trick I always do to get good image quality is to stop-down the lens a bit and also keep the lens focused close to the infinity mark. Zoom lenses are great for macro photography because you can change the magnification without having to move your lens (and tripod) forward or backward. Nikon used to make a true macro zoom lens but it is long discontinued now, and used ones for sale have become very, very rare.
So, what happens if you reverse mount the filter? Some people unscrew the lens holder and mount the filter backwards, but I simply mounted it with adhesive tape for the experiment. What I found out is that, with slow lenses like the popular Nikon AFS 70-300 or the AFS 80-400 (about f/5.6), mounting it one way or the other does does not make a big difference, and it is always advisable to stop down the lens a bit. However, when I tried it in my Samyang/Rokinon 135 f/2, where I cannot get a sharp close up image with the filter unless I stop down to at least f/4, reverse mounting it does make the images I get at f/2 almost as good as the ones I get by closing down one or two stops. Now I can have this lens’s beautiful Bokeh in the macro range!
All is not good news though: the flatness of field does decrease a lot by mounting the 500D filter in reverse. Now, this might not matter for three dimensional subjects but it’s something to keep in mind should you need to photograph flat objects.
To sum up: Do use top quality close-up filters to save weight… and get as close to using a true macro zoom as you can. Just stop down a bit and don’t try to focus your lens too close. Experiment to know the limits of your equipment. If you have a slow lens or if you need to photograph flat objects, do not bother mounting Canon’s 500D filter in reverse. In this case, you will be stopping down your lens anyway.
Canon’s 500D is a great close-up filter and a good purchase… and it is a Nikon user who says it!