Borescope specs

[Walt Fricke]

10 or so years ago the Snap-on 5500 or something like that, at 7-800 dollars, was maybe the choice for shops for a bore scope. Then Harbor Freight came out with one for under $100 (no real ability to save pictures), and under $200 for a better model.

Nowadays, Snap-on has what looks like a better package - the scope probe attaches to a box, and the box attaches to the display so you don't have to stick your head way into the engine bay to see the display. Their 6600 or whatnot is still priced up there. Harbor freight about the same, and they still have the probe attached to a sort of gun with the display.

But for under $30 you can get just the probe, a small intermediate piece, and as much USB or other cable as you might want to use a huge computer monitor, a laptop screen, a tablet, or a smart phone (some, anyway) as your viewer. Those I have consulted on this agree that these are, indeed, a better mousetrap for shop use - bigger, clearer pictures, video if you want, and you can keep lots of scope pictures if you want easily. Don't even have to pull out an SD card for transfers. There may even be one which connects with Bluetooth, though that removes the value of the computer like device as the power source.

If you look at what Amazon has to offer under borescopes you will finds lots listed. Frustratingly, the sellers don't list a consistent set of specifications.

The Snap-on version has a screen resolution (if that's the right term) of 640x480. No self respecting user of a computer would want that low a screen resolution. I'm typing on a screen which is 1680x1050, and the 19" second monitor beside it is 1280x1024. I'm guessing that the typical laptop has a somewhat smaller set of numbers, but not down in the 640 range. I associate that, probably wrongly, with DOS and the early 1990s.

What I am looking for includes how good the camera part is (I thought these were fiberoptic, but I was way wrong - these use a miniature video camera) its camera pixel count. Many say they are 2 megapixels. That seems plenty large for a bore scope for automotive purposes (mine include checking inside engines for parts not allowed for class racing, which may be more subtle than finding foreign objects or looking for scored cylinders). But, naturally, not all models list the megapixel ability.

Just what resolution (if that is the right word) is as high as will do any good on, say, a 15" screen? I assume that a resolution needed for a huge wall mounted TV screen or the like is overkill for a smaller screen. Though having pictures with more pixels in them means parts can be blown up more than those with fewer. How does the camera pixel count relate to being able to match the native resolution of lap top screens?

It appears that the standard camera is 5.5mm in diameter, and is surrounded by six LEDs. Some are white, some tout blue a being better. The total width of the head is thus wider, but won't all of these fit within a 12mm spark plug hole?

Then there is focal length - at least in the sense of how close to something can the camera get and still get a good picture? One which otherwise seemed likely (and I ordered one just to see, as they are so relatively cheap) listed this as 3-6cm. 3cm is about 1.2" 6cm is 2.4". Both seem perhaps a bit limiting. Others tout a half inch near limit, which seems OK. Many don't mention this.

Another spec is angle of view, which seems to run from about 55 degrees to 66 degrees. Are these differences enough to worry about?

3' (or one meter) seems about as short as any of these are for the probe length (all are flexible, but generally stiff enough to hold a shape I think), but some only come in 3 meter or longer lengths. Longer is good for looking inside plumbing in or outside a house, and probably doesn't really matter for automotive purposes, but maybe it does?

What else matters? Do any of these come with software which is so poor as to be a problem once you plug the USB end in?

Anyone have a favorite they have used which I should consider for my purposes? There are several lists out there in Google land which purport to compare bore scopes or endoscopes (not the medical variety). Most of those are the kind with the little self contained screen, some of the sort of pistol configuration Harbor Freight carries. I don't care about any of those, just the kind you plug into a screen on a separate device.

[Spenny_b]

Hi Walt,

I'm no expert on borescopes but I can perhaps share my experience to add some weight to your thoughts...

I bought an eBay device for use with iPhone and iPad, and I guess for the money (about £50 iirc) it's ok - it did the job I needed it to do, which was some preliminary inspection work to see of there was anything obvious amiss with my engine before plunging for the tear-down option. And for this, it did give me good enough resolution to see the condition of the bores and piston tops.

But...would I want to use this on a more frequent basis than I have so far? No.

Mine uses WiFi - it creates it's own access point, to which you pair the iOS device. I know not why, but this is terribly intermittent. Once the signal drops, it's a case of starting all over. REALLY irritating when you've just about manoeuvred the lens into the position you need.

The focal length is exactly as you say - limiting. For our use, this is crucial, and I'd have to dig out the specs on mine to tell you what it is, but suffice to say, don't skimp on this bit. (I thought mine would be fine when I bought it, but in reality it's adequate at best @30mm). The viewing angle on mine is 66º.

The outer ring of LEDs are ok....the only occasion when you don't want them at full brightness is when using with the 45º mirror attachment, as it over exposes the image against the mirror-like cylinder walls! The rotary switch on mine is a little binary; it also acts as the on/off switch, so I have a feeling that this is intermittent and triggering the unit to "blip" causing it to lose WiFi connectivity (hence Prob #1)

On the plus-side:

- the diameter of the lens assy is great - fine for spark plug entry and everything I've thrown at it.

- the flexi-neck is also very good; rigid enough to hold position.

- one press of the units button forces the iOS device to capture the image, so you can generally "get" the pic you want without shake or inadvertently moving the frame.

- picture quality on the iPad was really quite good (I'll dig out some pics later)

The 45º mirror for 90º viewing isn't too bad, not sure if there are units out there with a selection of angles in their kit-of-bits; this would definitely be useful. Something approaching a 180º view would be excellent for head/valve shots - this may be wishful thinking though!

Having briefly used an industrial grade Olympus setup, it is a marked difference...with an eyepiece over the inspection tube, it's ok for cylinder inspection - but I've used my camera for rooting around in the engine bay (dropped nut) and crankcase - the Olympus would be no good for that. The Olympus had an infinitely variable twist and rotate head, very cool...but also cost a fortune to buy and maintain. It had a separate light box and fibre optic "hose" = massively expensive for bulbs and new fibres as/when they get damaged! Images also couldn't be captured.

If I were doing it again, I would go for a hard-wired USB device, definitely with a rigid neck and I'd invest more into something with a tighter focal length. I'm not sure if that's possible, I guess the majority of them use exactly the same CCD chips.

HTH
Spencer.

Edited to add...

Just searched my Inbox - I paid £55, and upon clicking the link, it's now down to £36! Typical. For $45, maybe worth a punt?

This is the one which I bought....

...with this spec...

Manufacturer Specifications
Model No: 99W2
Certification: CE, ROHS, FCC
Len pixels: 1280*720/ 1600*1200/ 640*480
Len Dia.: 8.5mm
Removable Tuble Dia.: 6.8mm
RemoveableTube length:800mm
Focus distance:30mm to 80mm
View angle:66
Frame Rate: 30fps
Security: Password Setup
Receiver distance: 20M
Accessories: mirror, hook, magnet
Powered by : 4 pcs AA batteries(not included)

[Walt Fricke]

Thanks, Spencer
Wireless, happily, is not something which is needed or particularly useful in the application I have in mind. If one were a shop owner, maybe the ability to have the picture show up on a big screen somewhere would be useful - some of the wheel alignment systems shops use benefit from something like this - no wires running around, big display the technician can see while adjusting the toe, etc. So I'll look on that as a sort of minus.

And good info on the focal length - sounds like the one I just ordered will have a problem that way, as 30mm is 3cm.

With these small cameras, what affects the focal length? Is this about the same as depth of field we used to think about with pre-digital cameras? Wider aperture = greater depth of field? Are these probe cameras charge coupled devices? Is it an optical lens over them which affects depth of field? Is the view angle related to "focus distance"?

Assuming some standardization of the probe camera enclosure diameter, there is a three mirror assortment out there for USD 10. Looks good in the seller pictures, anyway.

Shop guys worry about mirrors or other attachments falling off. If replacement probe cables (I think they tend to have a standard plug)are fairly inexpensive, one might think of gluing or otherwise affixing mirror attachments to probes, so you would change the probe based on what mirror angle was needed. Shops often worry about things we home brew guys don't - costing money and losing customers and reputation means a lot, while as a hobbyist we can just curse and spend more time. On this deal I have to think like a shop owner.

[Costa P]

Hi Walt,

Your question got me thinking....so I found myself Googling to read up on the ins-n-outs of borescopes and stumbled on some helpfull info:

Choosing a Borescope

Field-of-View

Field-of-view may be very wide, wide, medium, or narrow. Think of it as a cone coming from the borescope tip, so that anything within the cone is visible. The field-of-view of the ************ borescope is approximately 37°.
Field-of-View should be dictated by the distance from the distal end of the borescope to the subject, for your application. The wider the field the lower the magnification, and vice versa. If you have plenty of space to move inside the cavity, but want to see both detailed close-ups and big picture views you might choose a 67° moderate wide angle. If the space is more confined but you still need to see most of it at one time, try a 90° extreme wide angle. On the other hand, if you can't get close enough to show the detail you need, a 30° telephoto might be required.

Magnification

Microscopes and loupes have very limited depth of field — they are only in clear focus at a single distance, so the magnification is also fixed. A borescope, however, has a very large depth of field — often from infinity down to an inch or less — that makes them easy to use without constant refocusing. The closer an object is to the lens of a borescope, the greater the magnification. To calculate magnification you must know the distance of the subject from the lens. The same principles apply to rigid or flexible borescopes.

Hope this helps a bit

[Walt Fricke]

Costa - well, now I know what industrial quality can do - articulating tips, lots of stuff, and 10K+ USD prices. However, the digital photo format for these is 640x480, so maybe my thought that bigger is better here is misplaced?

No snow in SA, is there?

[Costa P]

Originally Posted by Walt Fricke

However, the digital photo format for these is 640x480, so maybe my thought that bigger is better here is misplaced?

I suspect the 640x480 resolution may be a result of the current available technology for tiny camera CCD image sensors which can be packaged into the small borescope end.

Originally Posted by Walt Fricke

No snow in SA, is there?

Nope. We've been cooking in mid 30 deg C temps the last couple of days

[Walt Fricke]

Could be. I'm seeing higher specs for some of these low cost ones, but the industrial Hawkeye in the USD 2.6-9K range (high end allows tip manipulation) lists digital photo size of 640x480. Their ad shows a guy inspecting jet turbine blades. I could maybe go to USD 500 for something which is distinctly better than the Snap-on in some useful way, but not to that level. But chasing higher resolution may not produce a benefit.

But my humble Netbook with its 10.1" screen has a native resolution of 1366x768. My assumption is that you give up something if the resolution of the source is less than that of the screen, and you get nothing extra if it is larger.

[porterdog]

A co-worker twigged me to this today; I bought it immediately. For $20, how bad could it be?

https://phoneendoscope.com/

[Walt Fricke]

I've found ones basically like this down to $5!

Where the camera is listed as 1/9th inch, it seems this is a 0.3Mp camera, and only supports 640/480 resolution.

Where the camera is listed as 1/6", then the spec might be 0.3Mp or 640/480 for an Android or other smallish screen, or 1.3MP or720p or 1280x720 for a laptop or larger. 7mm seems to be the narrowest head for these.

However, how about a head like this?



Of course, that is an order of magnitude more expensive - $350. But airplane mechanics are starting to use those. They list the old standard 640/480 as their resolution, but it may be that more isn't needed?

[gtc]

I've used a usb borescope with 640x480 (VGA) resolution to look at the top of my pistons. It was sufficient, but not great. I'll post an example of the photos if i can find one.

2 MP (1600x1200 ?) would have been much more useful for seeing details inside the cylinder.

[Walt Fricke]

Graham - some of the scopes which claim a 2 megapixel camera list the 640x480 VGA resolution for small screens like Androids, and a much larger one (varies) for laptops and above.

If a screen only has so many pixels, maybe its resolution simply can't be any better than that? So it just ignores the extra ones?

There can be some tricky advertising - I found one which showed a second, larger, resolution, but added "interpolated." I take that to mean the graphics program can just use the same camera pixel twice, so there really isn't any improvement in the picture? Made me wonder if others were not so careful. You can get one of these for $5!