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headhunter23

adding zoom function or suggestions for camera with adjustable zoom

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I have a couple friends that wants to view out a secondary camera on one of my birds. Have been thinking it would be cool if he could use a camera with zoom to look around. Wondering if theres an adapter or something for the kx191 or 171 to add zoom to the camera's? If not, are there any other relatively good reasonable camera's with zoom somewhere between 1-10x maybe a little higher... Have looked around, $650 is a bit steep.

Thanks for responses ;)

Ivan.

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The only way I have thought of doing it is to use two cameras, one with a wide lens and one with a narrow then switch between them.

Terry

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I have seen one (can't remember where) that used a mechanical linkage between a 180 degree servo and the lens somewhat like the pan servos on the cameras. Seems like the zoom would be somewhat limited though unless the lens threads were fairly coarse. At any rate, it may be a starting point.

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Wow, didn't think it was this difficult to find. Another option would be to take a regular camera that's very light to begin with and strip it down to just guts, and you end up with onboard recorder with 10x zoomish... still pretty heavy compared to an addition to the kx171.

Ivan.

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I've never seen lenses with that much zoom in board lens format. And there's a reason, because with the focal lengths you'd reach you'd also require adjustable focus, and those cams don't have any kind of support for AF...

The lighter you could do with that is one of those, if you can source it from somewhere (I think there's a shop selling them, could find the address, but it's around 350€):

http://www.mintron.com/HTM/PRODUCT/CAMERA/.../MTV-54G10H.htm

They're quite good and light (80gr), take 12V and the zoom can be easily controlled (2 wires, one for wide and the other for Tele, ground each to activate). AF is maybe just a bit slow, and as with all zoom cameras the widest angle isn't very wide.

But frankly I doubt you'd want a 10x zoom on a flying model, unless you have a REALLY stable heli or quadro that can hold its position and attitude while you look around, or even from 2x on the image will just be jumping around too much and your friends who aren't used to it either will just end throwing up ;)

Oh, and your aircraft would need to have ZERO vibration too. At 10x zoom common motor vibration is enough to make a point of the image jump all across the frame.

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Hmmm so screwing with more mounts to reduce vibration... perhaps will buy one to test out first before buying second, still more money than I was hoping, as with conversion, it's ... wow, $530. Btw just reading the specs, am I mistaken? Wouldn't this be 20x zoom not 100x? 10 plus 10... I've never seen it multiplied.

Ivan.

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I've never paid any attention but, do any of the cameras we commonly use have any provision for electronic (for lack of the proper term) zoom? My Coolpix has a 4X electronic and a 10X manual zoom..

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You mean digital zoom? Most camera's the digital zoom is a useless software gimick for the camera's. Optical is pretty much what ya want, I flick off all the digital on my camera's although this hv100 hd camera's digital zoom works, but what's weird is there's a drift at that range that the camera looks like it's compensating even on a tripod. Kinda a strange thing....

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Wouldn't this be 20x zoom not 100x? 10 plus 10... I've never seen it multiplied.

Nono, it's always multiplied. You zoom in 10x optically, then after that you zoom into that another 10x, so that's 10x the original 10x = 100x.

There are board cameras with digital zoom, I had one that would do 2x and 3x. It was pretty high resolution so 2x was still quite ok, but 3x would start to look more like a bunch of pixels.

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I have used the Sony LANC protocol (http://www.boehmel.de/lanc.htm) to control some of their cameras digitally. A microcontroller interface can convert between the servo signal and the camcorder protocol to perform zoom operations. However, I have haven't seen LANC on any lightweight cameras. But I am getting interested in these smaller hi-def cameras.

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Bugger... still looks like hacking a regular p&s is really the only way to get a light weight zoom function and 3x seems to be all that's worth zooming... unless platform was vibration free. Not likely. :o

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And you should very carefully choose your P&S too. I'd go with one of those new models with a 24mm or so equivalent at the wide end as you'll most likely have more use for that than for the tele end.

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Hard to say, as there are many more characteristics that will come into play if you intend to use a P&S still cam as a live camera... firstly obviously you need one with a video out that works in recording mode (some only work in playback mode), then it needs to have a reasonable resolution and framerate (some have only a low resolution live preview and/or reduced framerate), then you need to hope that the exposure setting works well in preview mode (sometimes as it's only a preview and not meant to be recorded the exposure adjusts itself in ugly steps), same for autofocus, zoom needs to be usable during recording, etc... and all those are things that are not in the specs so besides trying there's not much of a way to know if a camera is well suited or not.

It often also varies between preview and while the cam is actually recording video to the card so it might be nice to know if you intend to record onboard too or not.

I've seen very nice footage recorded with a Panasonic FX35, which will record pretty high quality 720p video onboard, and if I remember well, the guy was flying using it as a video source. But that one doesn't allow operating the zoom while recording, and I don't know about its behavior when left "waiting" in preview mode.

You might want to search a bit, but I fear you'll be a bit on your own here. I have quite a bit of experience with using P&Ss with live downlink, but that was for framing still shots. None of those I've used so far would have satisfied me as an FPV camera.

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Yes, but those are fine to adjust on the ground, not really in flight. Or you'd need 2 servos, and some pretty complex mixing between zoom and focus as they're not "linked", i.e if you adjust zoom, focus will be thrown out requiring readjustment.

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I have the cousin to the fx, an ls70 which works great, not too worried about lag and such. As I wouldn't be flying with it, just friends and family able to look around etc. Thanks.

Mr. speed that was what I was looking for, too bad it doesn't auto focus... kinda strange not to have them linked to eachother...

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Yes, but those are fine to adjust on the ground, not really in flight. Or you'd need 2 servos, and some pretty complex mixing between zoom and focus as they're not "linked", i.e if you adjust zoom, focus will be thrown out requiring readjustment.

I was just reading through some old threads and thought I might have something to add here. I'm not an expert in optics, but it's my understanding that if the object you're trying to film/photograph doesn't move (and you don't move), you can zoom in/out on that object and the focus doesn't need to be changed. So, you can keep a constant focus as long as the distances don't change.

So, at the distances we're talking about, we're essentially talking about focusing on objects at distances of infinity. So, it would seem to me, that you can keep the focus constant (i.e. focused properly on an object 50+ feet away) and still zoom in and out. But, again, I'm not certain. But it would seem to me that the only problem is if the focus is actually changed when the lens zooms. If the lens works in a way that the focus is kept constant when zooming occurs, then it should work. I don't have experience with such lenses, so I can't say for certain. But this principle seems to work well with my standard camcorder.

Also, I'm not sure why zooming would be necessary. I think it would work just as well if you used a high mag (non-zoom) lens that was optimally chosen for your application. For instance, a 15mm fixed lens.

Another thing to keep in mind is that the depth of field is related to the f number/aperture and the focal length of the lens. The greater the focal length (magnification) of the lens, the lower the depth of field (i.e. less of the scene is going to be in focus). That's part of the reason why low focal length lenses work so well for our applications where you can't be bothered to mess with the focus. They have a high depth of field, so virtually everything you look at, at all distances, will be in focus.

http://en.wikipedia.org/wiki/Depth_of_field

So, if you're using a fixed lens with a high focal length (i.e. 15mm), focusing becomes more difficult. But there's another aspect to this. A lens with a high f number (small aperture) will have a greater depth of field than a lens with a low f number. So, if you want to use a fixed lens with a high mag, a way to offset the decreased depth of field is by choosing a lens with a small aperture. The lenses with the smallest apertures are pinhole lenses, which are typically used for security applications. But, I think they can work here too. Unfortunately, they aren't very common at long focal lengths, and their quality can be very variable.

http://www.mars-cam.com/optical.html

I've had some success with the V-PL150CS-12 by Marshall Electronics. It's a 15mm pinhole lens available from B&H for only $20. The quality seems to be good. And the focus is good from about 10 feet to infinity without the need for any auto focus. Also, from my experience, this can provide an optimal magnification for those looking for higher magnification views from a second camera. And I doubt any actual zooming is necessary. This lens works on CS and board mount cameras. The problem with cheap pinhole lenses is that the quality is often not as good as a standard lens, but I thought this lens was good. I can't recommend the Marshall 30mm though. I tried one and the quality wasn't very good. Also, these lenses are probably more rugged than standard lenses, and will be more resistant to scratches and dirt, because the actual glass is protected inside the plastic casing. Any water or mud (amounts within reason) should just roll off of it while still maintaining a high quality image.

If you don't want to use a pinhole lens, you can use a standard 16mm, although the depth of field will probably be a little lower. I'm not sure what impact that would have, but my guess is that a standard lens would work as well. Just focus to an object 100ft away, and the depth of field will probably be suitable.

And, as someone else mentioned, too high of a magnification will amplify any vibrations to the extent that it becomes unwatchable. None of these mini-cams have image stabilization, as far as I know. Also, too high of a mag and you'll have difficulty with situational awareness (because the lens has no zoom). You'll have trouble knowing exactly what you're looking at. It may be sharp and in focus, but you can still lose perspective of exactly where you are. So, there is a sweet spot in terms of magnification for a second camera (assuming no zoom). That sweet spot will depend on the individual and the stability of the rig. The first camera for FPV purposes, of course, should have a low focal length lens.

Edited by ginger_marianne

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it's my understanding that if the object you're trying to film/photograph doesn't move (and you don't move), you can zoom in/out on that object and the focus doesn't need to be changed. So, you can keep a constant focus as long as the distances don't change.

But it would seem to me that the only problem is if the focus is actually changed when the lens zooms.

You got it. A proper lens has mechanical linkages that will move the focus lens so that it follows the zoom's moving parts to always keep focus the same. On those mechanically simplified zoom board lenses, there's no such linkage, so when you move the zoom lever you also need to move the focus one to keep the focus right. But those were not made to zoom in and out, just to make it easier when you install your fixed security camera, you adjust the "zoom" lever to frame how you want it and then focus, and never touch it again. It just makes it easier than changing lenses until you find the right one.

Also, I'm not sure why zooming would be necessary. I think it would work just as well if you used a high mag (non-zoom) lens that was optimally chosen for your application. For instance, a 15mm fixed lens. [...] The first camera for FPV purposes, of course, should have a low focal length lens.

The OP's point was to add the zoom cam as a 2nd one for "passengers", not to fly with it. That way the "pax" could just look around like they want and zoom at some things if they want to see them more closely. So, not necessary, just fun and entertaining for the viewers ;)

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The OP's point was to add the zoom cam as a 2nd one for "passengers", not to fly with it. That way the "pax" could just look around like they want and zoom at some things if they want to see them more closely. So, not necessary, just fun and entertaining for the viewers ;)

I realize that. My point is that having a moderate mag fixed lens with a high depth of field for the second camera may actually be a better choice for a second camera than having a zoom lens. I think zoom is of little utility. If you pick a fixed lens that's say ~3x camcorder equivalent magnification, it may provide the best result. Much higher magnification than this and vibrations may negatively impact the video quality. Much lower than this isn't of much use either unless you get really close up.

People overuse the zoom on their camcorders (because they can). At the distances we're talking about, I don't see any point to zooming. Just magnify everything by a fixed amount. It's easier and it works.

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Yes, but that means if you fit a fixed length lens with a certain FOV.. then you obviously don't have the wide angle anymore!

You don't necessarily want a 10x zoom, but being able to go from a wide 90° to some more moderate ~40° does give some viewing flexibility in a meaningful way...

I prefer wide angle, but wouldn't mind being able to switch to a narrower field sometimes to have a look at some detail...

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Yes, but that means if you fit a fixed length lens with a certain FOV.. then you obviously don't have the wide angle anymore!

You don't necessarily want a 10x zoom, but being able to go from a wide 90° to some more moderate ~40° does give some viewing flexibility in a meaningful way...

I prefer wide angle, but wouldn't mind being able to switch to a narrower field sometimes to have a look at some detail...

To each his own. I like detail. At long ranges, 15mm isn't exactly close up. At 1000 feet, you're still looking at an area about 250 feet wide. It's about a 20° FOV, about like putting a camcorder at 3x. For someone who likes detail (like me) but doesn't want to fiddle with zoom/focus, it's a good compromise. For people thinking of using a modified small camcorder, remember that the widest angle for most camcorders is about 45 to 50°, not much wider than the smallest FOV you would use.

Of course it's not suitable for an FPV cam, but it could work fine for a second cam (for people who want to see more close up).

Edited by ginger_marianne

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