EEVblog #278 - Elmo Visual Presenter Teardown - Page 1
Forum section: electronics / general

author: IanB
author_rank: Super Contributor
timestamp: May 15, 2012, 02:05:29 am
content: A modern version of an old classic. Back when I was a schoolkid in the 70's the projector version of such things was common. Look up epidiascope. Evidently rendered obsolete by digital cameras.

author: IanB
author_rank: Super Contributor
timestamp: May 15, 2012, 02:31:49 am
content: I don't get why you talked about using it for soldering, but didn't actually try that out on video?

author: BobC
author_rank: Unknown
timestamp: May 15, 2012, 03:40:14 am
content: The camera is what's known as a "chassis camera", and is a common form-factor in the surveillance industry. The big players in this segment are Sony, Hitachi and Panasonic. If you search for "HD chassis camera 16x" you will see the top candidates for this capability.Nearly all of these cameras connect with a standardized 6-conductor flex cable that provides +12V + GND, analog video + ground, and an RS-232 pair. Most cameras also have a second flex connector for 8-10-bit-parallel clocked digital video suitable for feeding to an encoder.Neither the protocol over the serial link nor the clocking of the digital data are standardized, but none are difficult to use.Unlike most consumer high-zoom pocket cameras, the front element in chassis cameras doesn't move, meaning the focus range depends on the zoom position. These lenses typically focus closest at the widest zoom setting, many of them getting down to 1 cm! Try bringing the head down while the zoom is full wide, and I think you will be very surprised at how much effective zoom you will get.For best results, use 2 light sources, one on each side of the camera, separated far enough apart so each can be aimed down at an angle of 45 degrees relative to the center of the camera's field of view. That will give you maximum intensity and contrast with minimum glare.

author: EEVblog
author_rank: Unknown
timestamp: May 15, 2012, 06:08:34 am
content: Quote from: IanB on May 15, 2012, 02:31:49 amBecause I could see what the zoom levels and update rate was like with real components. The act of soldering under it was kinda pointless, and it's hard to capture the shot anyway. If I get better zoom and some video capture then I'll try some actual soldering.Dave.

author: EEVblog
author_rank: Unknown
timestamp: May 15, 2012, 06:09:47 am
content: Quote from: BobC on May 15, 2012, 03:40:14 amTried it, no joy. It won't focus much closer than the distances shown in the video.Dave.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 15, 2012, 06:45:41 am
content: These things are not only used for education. They are a common accessory for video conference systems. Much better to have one instead of trying to hold a piece of paper into the main camera.

author: Rufus
author_rank: Super Contributor
timestamp: May 15, 2012, 07:07:45 am
content: It is a discontinued model but still available discounted to around $2500us.There is a used one on ebay.au BIN $450.I think it best used for its intended purpose. Shame to trash it because it isn't really obsolete or useless.

author: david77
author_rank: Frequent Contributor
timestamp: May 15, 2012, 07:16:15 am
content: I think this thing could come in handy for your video blogs if you figured out a way to capture the video in good enough quality.You could obviously use it for:- Testing and probing on PCB's- Soldering while recording video- Pointing out stuff on datasheets- Get rid of your whiteboard, use pen & paper instead

author: Psi
author_rank: Super Contributor
timestamp: May 15, 2012, 08:36:51 am
content: Might pay to check if there's any hardware feedback on the camera height.If there is it maybe software limiting the focus when the camera is low.You could easy test it by trying to focus on an object that's raised up off the bed while the camera is at its top position.

author: ejeffrey
author_rank: Super Contributor
timestamp: May 15, 2012, 10:20:28 am
content: Quote from: Psi on May 15, 2012, 08:36:51 amWhy would they do that? That doesn't make any sense.

author: Psi
author_rank: Super Contributor
timestamp: May 15, 2012, 11:23:42 am
content: Quote from: ejeffrey on May 15, 2012, 10:20:28 amBecause it was never intended for that kind of closeup work.It's for documents and live demonstrations.Or perhaps to speed up auto-focus at close range.Or maybe to sell another model for closeup work.Or maybe it kept trying to auto-focus on lens dirt at close range.Or who knows, i stopped trying to expect product design to always be logical a while agoTest everything, assume nothing

author: Rerouter
author_rank: Super Contributor
timestamp: May 15, 2012, 11:28:43 am
content: yeah i also have to agree its likely there is some level of feedback in the arm(s) to tell the system where it is,

author: ejeffrey
author_rank: Super Contributor
timestamp: May 15, 2012, 12:58:34 pm
content: Quote from: Psi on May 15, 2012, 11:23:42 amIf this were a feature to speed up focusing or avoid focusing on the wrong thing (like the top of your pen if you are writing on a piece of paper), it would use the opposite logic: the focal distance would be restricted when the camera is at the highest position, and allowed to focus to short distances when the camera was close to the platform.If it were crippled to segement the market it would be cheaper, simpler, and harder to circumvent to just limit the closest focal distance to 40 cm in software. There is no reason to have that controlled by the height of the articulated arm.This wouldn't be the stupidest misfeature I have ever seen in a product, but it is hard to see how your proposed mechanism even makes sense by marketing weasel logic.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 15, 2012, 01:39:21 pm
content: That's a Samsung digital overhead projector. I have considered using it as a PCB inspection tool, but it uses up a lot of bench space.

author: siliconmix
author_rank: Frequent Contributor
timestamp: May 17, 2012, 09:37:18 am
content: i want one

author: Rerouter
author_rank: Super Contributor
timestamp: May 17, 2012, 10:36:24 am
content: mike, you one looks like it could easily be compacted to 1/3rd the size, (semi idea for most board inspection, however like dave it would come down to what you could do with the camera arm

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 18, 2012, 03:48:40 am
content: I actually plan to put it on a small cart so it can be wheeled out of the way when not in use. I initially thought to make it fold up, but then I realized that I would need to clear the area to use it anyways.At this point, I use a cheap security camera with the lens adjusted to focus closer. But that digital overhead projector (got it for free because someone threw it out) gives better images and has a very nice automatic brightness lighting system built in.

author: T4P
author_rank: Super Contributor
timestamp: May 18, 2012, 06:45:02 am
content: Quote from: NiHaoMike on May 18, 2012, 03:48:40 amWell yeah security cameras don't make terribly good cameras...

author: Fraser
author_rank: Super Contributor
timestamp: May 18, 2012, 11:10:42 pm
content: I'm sad enough to have a collection of these things .....It started with just an Elmo L1-n mobile unit that I thought could be useful for PCB inspection. I now have a lot of these types of document camera/visualizer. They were cheap so I couldn't help myself ! They can be bought quite cheaply on the used market as many people have little use for them. The cameras can range from superb (like the Elmo) to total trash CMOS low res webcam like devices fitted to the likes of Avermedia offerings. Flexcam's are another variant for the lab. The zoom is mechanical movement.... you move the camera head closer to the object and refocus the close-up lensThe lens structure on the electric zoom and focus desk units is optimised for the 0.5m distance ..... the chassis cameras usually have a standard medium to long focus range. The manufacturer then places a removeable No.2 close-up lens in front of the objective lens. A No.2 CU lens is a single element with a focus distance of around 0.5mFor longer focus distances the manufacturer normally advises to remove the additional lens and the camera then behaves like a normal autofocus electric zoom CCTV camera. If you want to go closer....buy a set of close-up lenses. They are cheap and range from No.1 to No.10 usually. Mine cost around $10 for a used set in a case. You can use a bracket to hold additional CU lenses in front of the built in CU lens or you can swap out the built in CU lens for a higher No. unit. The higher the CU No. the greater the magnification and the closer that it focuses. Its just like being long sited and needing reading glasses for close work ! In fact I first experimented with reading glasses on one of my units. With a higher No. CU lens you can move the head down to the new focal distance but that will be it, you can't change that distance unless you use a variable CU lens. I bought one for a few dollars as they are not popular these days. Its basically a variable close up from No.1 to No.10 or so. Variable CU lenses eat light so more illumination may be needed. If you google close-up lenses you will find plenty of detail on the focus distance for the various No.s from 1 to 10.In my 'collection I have the Elmo P30 and P30S models. They have a good reputation and I like the performance. With one of my HP Companion LED micro projectors I can project an 0603 onto a wall and it is enlarged to massive proportions which can be great for fault finding solder bridges, cracked tracks and solder joints. You can also store the image for future reference or a report. Video and image capture bolt ons for standard microscopes can be very expensive. Note. The Videolab / Ken A Vision Flexcam was designed to also couple to the eyepiece hole of microscopes and is provided with all the required optical adapters. You can have CCIR video or USB to PC video transfer for the output. The later units provide higher resolution and te USB version is the Flexcam iCAM.Dave- the remote control that you need is the ELMO RC-VHQA.I found new ones on eBay so that is a good hunting ground with them costing around $15-$20. The RC-VHLA will also work but differs in the area of SD/camera/input selection. Other features work OK.Aurora

author: elmohandis
author_rank: Contributor
timestamp: May 24, 2012, 01:35:37 pm
content: Quote from: EEVblog on May 15, 2012, 06:08:34 amHey DaveIn your last videos regarding the BK precision 8500, when you were zooming in on the OPAMPS, the video feed was quite usable for soldering.You said you used a macro lens. What was the distance between the camera and the board at that time? Do you think the camera+lens combo that you have is suitable for SMD soldering ?Regards