This is the story of how I hacked a telephoto lens into a really useful macro lens.
WARMING: I CAN´T BE HELD RESPONSIBLE FOR WHAT YOU DO TO YOUR LENSES, FOLLOW THIS INSTRUCTABLE BY YOUR OWN RISK.
But first a little background on why I did the things I did (sorry if it is to long).
Step 1: The Story
When I first got my DSLR it came with the standard 18-55mm lens, and I started noticing that I loved to picture wild life but my lens didn’t had enough “zoom” in one side, and also didn’t serve much as a macro lens. The thing is that photography is a hobby for me and I didn’t want to spend lots of money in it, and since I have a Nikon D3100 I ended up buying an old AI 80-200mm telephoto lens. It’s a really old lens; I had to use it always in Manual because the camera doesn’t have aperture control over the lens. This was really good for me because I had to teach myself how to shoot really fast in manual without measuring.
Me being a DIY guy, I ended up making an extension tube to cover my macro needs. And the Instructables is over here https://www.instructables.com/id/Macro-Tube-with-f-.... But I still wanted a little more range of magnifications.
Since then I have grow a lot and the poor telephoto lens wasn’t keeping up with me. It had a lot of aberrations even in high f-stops, so I began to look for a new telephoto. Then I got my hands on a Nikkor 70-210mm AF, which give me measuring and better quality photos.
So I decided that I didn’t need two telephotos of the same range, what I needed was a macro lens. And that’s where my journey begins. I started to look around the web for articles about how to turn a lens in to macro, and all I found was reversed rings and extension tubes. But I wanted something more, so I adventure myself into disassemble the lens and taking a close look in its construction and the individual lenses.
Step 2: Disassembling
Be very careful when disassembling, work in a clean table (I use a desktop with paper so I don’t miss a thing), put the screw back where they go after you take the parts away (you may see this in the following pictures), have a good light source, and it is better to take pictures as you are disassembling so you can go back and reassemble without trouble or missing a thing.
If you are going to take the lenses out of their cradle use gloves and pay special attention in the way the lens is position, because if you invert it you will loose quality.
Step 3: The Sections
I noticed that (at least) this lens can be taken into 3 different sections. A first section, in the front part of the lens, that functions as the “focuser”. A middle section with the zoom mechanism and the last section is where aperture is.
In the first section there are two lenses that have positive magnification.
The second section consists of two sets of lens that move, of two lenses each one. One of this sets move in a linear way, while the other one move in a curved trajectory. Also, the set in the curved trajectory have a negative magnification and the other one a positive.
And lastly the third section consists in a series of 4 lenses, one before the aperture (with a positive magnification) and 3 after the aperture all in one cradle. These last 3 lenses together don’t produce a magnification.
Step 4: The Hack
After I made this analysis I decided to make some experiments. What I did was to partly reassemble the lens without some of the lenses in different combinations. After a few arrangements I noticed that I was having great results if I removed the set of negative magnification lenses of the middle sections, as well as the last 3 lenses.
With the combination of lenses selected I did one more modification. Since the set of lenses I kept in the middle section was the one in the curved trajectory I was “losing” zoom power, so I decided to put this set in the linear trajectory. The only thing was that the distance from the screws to the end of the cradle was longer than the original cradle of that trajectory, so it would collide with the aperture section. To fix this I just put the cradle, without the lenses, in my lathe and worked so it would be the same as the original.
Step 5: The Results
With all the hacking done, I disassemble again all the lens so I could clean it up. I put on latex gloves, made a mixture of window cleaner (with ammonia) and Hydrogen peroxide, and grab a couple of microfiber cloths. I cleaned up the lenses as I was reassembling the lens, trying to keep everything as free of dust as possible. And that’s it. Here are a few of the photos I took with this lens alone (The first one is an reference one of the screw next to a AAA Battery). The first macro photo of the screw is at f 4.5 thats why it is all blury (normal for a hacked lens), and the second one is at f 22. Thanks :D!!!