Part 2 – Installing and Testing the Lens

In Part 1, I researched my options for replacing the cracked internal lens on my GoPro Hero2 HD. I decided to replace it with a Sunex DSL377 lens. Part 2 is about installing and testing the lens.

Continue reading to see how it went…

Removing the Broken Lens

After taking apart the case, my broken lens came out pretty easily. I didn’t have to apply any heat or force. However, the mount that the lens screws into was cracked. To make sure the new lens would be secure when screwed in, I reinforced the cracked mount with a piece of cellophane tape wound tightly around the outside. Here is a youtube video on removing a GoPro Hero2 lens.

After removing the old broken lens, there was not much glue residue left inside the camera. I gently tapped the back of the camera while holding it facing the ground to free any debris. The sensor is exposed after removing the lens and anything that gets on the sensor will appear in the video. Unfortunately, there were still a couple of tiny specs on my sensor. I am sure most folks would say never touch the sensor with anything, but I used a cotton swab to gently clean off the specs. After that, I put a piece of cellophane tape over the mount to keep stuff from getting on the sensor.

Sunex DSL377

To read the details of why I bought the Sunex DSL377 , see Part 1 of this post, but here is a summary of the reasons:

• Relatively inexpensive
• Less wide angle (104 vs. 170 degrees)
• Less fish-eye effect
• Designed for a 1/2.3″ or 1/2.5″ sensor
• IR Filter

I received the lens quickly from Optics Online and it was carefully packed.

Securing the Lens

I have read where others have used glue to secure the lens inside the mount. Glue is a pretty permanent solution and could only be done after focusing the lens. I decided to go a different route and wrap the threads of my lens with Teflon tape for a secure mount. This way, it stays secure while I focus it and it is also easy to remove.

Focusing the Lens

These lenses are focused by screwing them in or out until the desired level of focus is achieved. The easiest way to do this would be to attach an rca video cable to the video out port on the GoPro and attach it to a television or monitor while focusing. Unfortunately, I don’t have one of these cables. I do however have a cable that attaches the GoPro to my FPV video transmitter. I hooked it up and tried to focus it through my FPV goggles. Since the FPV rig doesn’t transmit in HD, it was hard to get an exact focus, but I was able to get it close.

After that, I recorded some video on the camera’s SD card to see how it looked. I was close, but not in perfect focus. Next, I made some marks on my lens and the GoPro case to track different levels of focus. I made one mark at the current position and one to the right and left of the current position. I then took some video while gradual moving from the right mark, to the middle mark, then to the left mark. I spoke into the microphone saying “right”, “middle” and “left” while I screwed in the lens. After watching my “focus video”, I liked the focus level between the right mark and middle mark. So, I moved it there and left it.

You can change the quality of the following youtube videos by clicking the gear icon.

Test Flight One – Lens Vibrations

Here is my first test flight with the new lens:

It may be hard to see on youtube, but there are some tiny vibrations that make it impossible to watch in HD. The Sunex lens is much longer than the original GoPro lens and extends out past the black plastic piece that surrounds the original lens. This black plastic piece is what secures the original lens with a gasket. I decided the front of the Sunex needed to be more secure to eliminate these vibrations, but it just doesn’t fit together like the original.

After not much thought, I decided to go back to my trusty cellophane tape. It is the equivalent of duct tape when dealing with tiny cameras. I secured the lens to the plastic piece on the GoPro by tightly wrapping them with the tape. It may seem rigged, but when cellophane tape is tightly wrapped around the two cylindrical surfaces, it makes a solid bond.

Test Flight Two – Jello

So, after taping up the lens, here is my second video:

Hmm, not so good. You can see there is a really bad jello effect. With my lens firmly secured, I decided this was a result of the camera vibrating and not the lens. However, I had the GoPro mounted the same way as before it broke and I had never experienced any jello effect problems pre-crash. Here are a few things I considered:

• My quadcopter might be vibrating more due to the crash
• Narrower angle lenses show vibrations more than wide angle lenses
• Perhaps the GoPro lens is designed to absorb vibrations and this one is not

At this point, I had the GoPro attached directly to my quad with two sided foam tape, but I needed something different to dampen the vibrations more. Frankly, I was starting to wonder if my problem was fixable. After some searching, I found a video where hallstudio was using Velcro to attach his camera to his quad. Wow, he is a total pro! On the other hand, I still have loud motors blaring and propellers mucking up my vids. It was time to give Velcro a try!

Test Flight Three – Velcro Mount

After swapping out the sticky tape with Velcro, here are my results:

Much to my surprise, there was much less waviness and giggling. The Velcro dampens the vibrations from the quad while still keeping the camera attached. There may still be a slight jello effect, but it doesn’t bother me.

Video Quality

I like the video without the fish-eye distortion, though both certainly have their place. After comparing to some old pre-crash videos, I think the quality is better than what I was getting with the original lens. I need to do a more scientific side by side comparison. Alas, I have no original lens to do one with. The tone is a little more yellow/greenish, but interestingly, the tone seems to get better during the video. Either I am imagining it or the GoPro is making some kind of software adjustments.

Conclusion

I was pretty upset when I broke my GoPro lens, but hey, it was a learning experience. Perhaps, I should have just payed up for an original lens to replace it, but I wanted to see if something else would work. Bottomline, this new lens will require a little more work to get good results, but I am glad I bought the lens and made the camera usable again. The picture quality is great, but dealing with the vibrations is a bit of a pain.