Lens question

The Flounder · 02-09-2013, 06:00 PM

Ok. this is more geared towards video than photography but I figure this is the best place to get advice.

I have a Replay XD 1080 that I want to add a zoom lens to. Replay sell a lens adapter that will give me 37mm threads instead of the current threads that are on there. I am looking for something with a 2-4x zoom to pick up those longer range shots.

I have a friend who tried a basic 4x camcorder lens and he said it gave him a tunnel effect but not much for zoom.

Hints, tips. suggestions?

Thanks

Luckless · 02-10-2013, 10:18 AM

Remember the difference between "Zoom" and "Magnification" as they are most commonly used. A 10mm-40mm lens gives you 4x 'zoom', but fairly limited magnification. The narrowest angle divided by the widest, biggest number divided by smallest. You can go wide angle with the 10mm, then 'zoom' in to 40mm, which in most systems isn't hugely telephoto and won't magnify something far away for you.

A 100mm-200mm lens is only a 2x 'zoom', but will give you a far narrower field of view to bring you closer to the action. A 100mm-400mm is again a 4x, but is vastly more magnification than the 10mm-40mm lens example above.

Sadly I'm not familiar with the camera system you're using, but you may want to look up Field of View calculations to help give you a better idea of what different lenses are going to do for you. Good luck.

The Flounder · 02-10-2013, 11:11 AM

Quote:

Originally Posted by Luckless

Remember the difference between "Zoom" and "Magnification" as they are most commonly used. A 10mm-40mm lens gives you 4x 'zoom', but fairly limited magnification. The narrowest angle divided by the widest, biggest number divided by smallest. You can go wide angle with the 10mm, then 'zoom' in to 40mm, which in most systems isn't hugely telephoto and won't magnify something far away for you.

A 100mm-200mm lens is only a 2x 'zoom', but will give you a far narrower field of view to bring you closer to the action. A 100mm-400mm is again a 4x, but is vastly more magnification than the 10mm-40mm lens example above.

Sadly I'm not familiar with the camera system you're using, but you may want to look up Field of View calculations to help give you a better idea of what different lenses are going to do for you. Good luck.

Very useful information. I have little to no knowledge of lenses and how they work. It looks like I will be learning plenty before this is through.

Luckless · 02-10-2013, 11:56 AM

Yep, lots of interesting stuff to learn. Sadly video and photography became consumer products, not merely professional equipment, so a lot of details have become heavily muddied by marketing which in turn means you have to learn more to avoid getting hoodwinked. But if you're at all geeky then it is a fun subject to learn anyway.

I think I might have to look into the system you're using, because I'm a geek and this stuff is interesting.

uv_halo · 02-19-2013, 02:13 PM

I've recently done similar things.

Action cameras (GoPro, Contour, Replay, etc) are all wide angle cameras. In these cameras, the lens in front of the center is designed to capture light from the sides (approximately 65deg out to each side from center). So, if you slip a telephoto lens over the front of it, it will image the insides of the telephoto lens body with the net impact being the tunnel effect.

The only way I'm aware of to get around this is to replace the factory lens with a narrow FOV lens and then you could slip a telephoto conversion lens over it. However, most action cameras are designed in such a way that you cannot remove the lens (Greg Hastings told me this was the case in the R7 ReplayXD). The only current camera system I know that can have the lens changed is the Contour Hero series.

The Flounder · 02-19-2013, 03:17 PM

I haved talked to Greg about the problems he encountered with the tunnelling on the Replay when he tried putting a lens on it. I spoke with the folks at Replay as well and the only sulution they came up with was a multi-element lens. I am not sure if a larger optic on the front would help with light gathering enough to offset this problem or not. I have found a few options I am going to try (I found a few stores with decent return policies)

I have taken my Replay apart and the lens is threaded on but it looks like there is some epoxy on there as well. If I could figure out what they used to epoxy it in place I may be able to remove it. The next problem if I could get it apart would be finding something to replace it with.

Not giving up on the idea just yet.

Thanks for the input.