Adafruit USB Microscope Focus

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npiguy
 
Posts: 5
Joined: Sun Nov 20, 2011 1:21 pm

Adafruit USB Microscope Focus

Post by npiguy »

Recently, I succeeded in getting a working $80 USB microscope from Adafruit and I am delighted with its performance/price ratio. As an experienced person would expect at this price level, the mechanical workings are what one would expect to see in a toy. That's fine, and not a deal breaker for me. I expect cheap zoom optics to have substantial focus shift as the zoom setting is changed, but not quite as much as my scope demonstrates. I asked Adafruit to have a look at their in house unit to see if it behaved similarly, and my request was denied as being "outside our area of expertise". So, I am left unable to ascertain if my unit performs like it does because Adafruit shipped the unit to me without any padding, of if "They all work that way". So, I post my question here in the faint hope that another scope owner 1)stumbles their way to this post, and 2)is willing to engage in the daunting research task that overwhelmed the expertise available at Adafruit. So what follows is a repeat of that complex request:

Please set the zoom on your scope to 90x, focus on the tip of your finger, and tell me if your finger tip is inside or outside of the clear plastic cone. No measurement necessary, just fingertip inside or outside. Period.

Pretty advanced Rocket Science, eh? So, does anyone out there have the expertise to tackle this advanced research for the public good? I was told that words were confusing, so I post some pictures, each of which is said to be worth a thousand words. I substituted a penlight battery, as I needed my fingertip to take the pictures. In each picture, the scope is in sharp focus with the end of the battery. The first picture is of what I unsuccessfully requested from Adafruit, and what I am asking of any reader of this blog who has one of these scopes. Namely, where does the unit focus at 90x? In or out of the clear plastic cone. Yep, looks like it's in. That's really all that I wanted to know about other scopes.

The next pic demonstrates the focus at 230x (the unit I got has more than the 20-200 range specified by Adafruit). Notice that the focus is outside the clear cone. This forum allows a max of three images, so I can't upload the 20x pic. which also shows the focus outside the cone, similar to the 230x pic.

Finally, there is a scan of a crude plot I made of what is happening with the focus on the unit I got. Regardless of damaged or not, I am delighted that zoom settings below 20x move the focus all the way out to infinity! As a result, my unit makes very nice macro photos. Set to the zoom that gives infinity focus, the scope has a focal length equivalent to a 125mm lens on a 35mm camera ("normal" focal length of 50mm), making it a short telephoto. It makes a dandy web cam! The approximate zoom settings giving these effects are on the plot. The only "calibration" on the scope for these settings is a small black box (inked in on the plot), which gives a focus 2" outside the cone.

To repeat, if anyone out there has one of these scopes and is willing to take on the daunting task of setting the zoom at 90 and moving the scope back forth until their fingertip is in focus, I would appreciate your posting of this difficult-to-obtain information.

If this post generates a reply which indicates my unit is unique in its focus characteristics, I may try to get an undamaged unit from Adafruit, but I doubt that I will submit myself to any more hassle with this particular purchase. As in the note I scrawled to myself on the plot, there is a really easy work around for this problem- cutting a half inch off of the clear cone. Then, the 78% of zoom settings which now require you be able to cram your subject inside the clear plastic cone, will be as usable as the 22% of settings where this is currently not required. This is very easy for me as I have a complete machine shop.

Since the pictures that Adafruit published were taken at 20x or "200x", they most likely did not stumble upon the problem with zoom settings in between. Or, maybe, my unit took a damaging hit in transit and I have the only one which focuses that way. I will have no way of knowing which assumption is correct unless someone having this scope tells me where their unit focuses at about 90x.

To repeat, I like this scope, focus issues and all, and will keep it in any event. If there is no response to this post (given the probabilities, very likely) I will throw mine into the lathe and soon have one which can be focused on a surface at any zoom setting. Unless I discover that my scope is unique (as in damaged), I will post detail on my work around for this focus issue. Be clear that there is no zoom issue if you plan to use your scope only at 20x or 230x. I say that this product is well worth the minor work it will take to modify it to work well at any zoom setting. I may even do the work in a way which does not require a machine shop, so that as many others who wish to modify theirs can do so by following my work around post.

Finally, I want to be very clear that my affection for Adafruit Industries lives on despite my frustrations about having my simple information request denied. I very much admire Lady Ada's business model and social focus. How can a guy not love to see a young BANNED with vividly dyed hair, a lip ring, and a Masters from MIT, running a high tech electronics business! Oh my! I'm an old techno-geezer who is absolutely delighted to see the young people who are being drawn to this new paradigm of simplified microprocessor dev tools, cheap open source hardware, and intense person-to-person support. It's all good! Very good!
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230x.JPG
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adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: Adafruit USB Microscope Focus

Post by adafruit »

hi npiguy,

thanks for posting in the forums, this is the best way we can assist you and others as we chatted about over email and our recent phone call. we received the camera you reported as not turning on and it worked on our test machines. the camera you now have is another new one we sent at our cost and we also refunded you shipping on the one you sent in. we sent a photo of the one you sent in working - we're using it now. sounds like the new one you have is working, that's great news. on to your question!
npiguy wrote:Please set the zoom on your scope to 90x, focus on the tip of your finger, and tell me if your finger tip is inside or outside of the clear plastic cone. No measurement necessary, just fingertip inside or outside.
at 90x our finger tip is slightly on the inside.

hope this helps, and we've also completely refunded you purchase, including the other item in your order - enjoy! let us know if you want another exchange based on this information we've provided. we hope this helps resolves this issue and thanks again for posting up so we could assist you and others.

thanks!

npiguy
 
Posts: 5
Joined: Sun Nov 20, 2011 1:21 pm

Re: Adafruit USB Microscope Focus

Post by npiguy »

I appreciate your prompt reply. With that little question answered, I know that they're all that way, and a picture of my response should be below. Presto! 100% of zoom settings now available. I discovered that the lens retracts easily if pushed, so I cut the entire cone off. You see, my interest is more about seeing what I'm doing than inspecting what I've done. No cone means more room to work, less chance of melting it with my hot air rework tool.. 'Just looking for more flexibility than the old 10-20x A-O stereo scope I've used the last 4 decades.

If I can find an easy way to alternate display of the video frames, I''ll be buying another of these scopes and a $59 pair of Nvidia shutter glasses to see if that setup can enable good enough vision to work with. If it works, I'll post it. Who knows, scope sales might double.

Gosh! I explicitly wrote that I was not requesting a refund for either item, so you are providing service way over the top. Thanks!

Happy Bob at N.P.Instruments
Attachments
TheFix.jpg
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