Post by thread:[OT] The secret to taking sharp pictures of circui

Picbits Sales <sales <at> picbits.co.uk> writes: > Another good way is to bung it on your flatbed scanner if it has decent > optics and can focus at objects further than its own glass. I have bad experiences with scanners used for this. Even a photo left in its 3mm glass frame (too old to remove) was scanned out of focus and I had to pry it out. Brand name scanner, 1200 real dpi and still ... Depth of field is extremely closely related to lighting and numeric aperture. Usually scanner optics don't have anything resembling a diaphragm so they use the full aperture and good bright color-true light is expensive and short-lived so you get *very* shallow depth of field. Please do not confuse contemporary led-lit full row ccd sensor scanners with 1kW xenon-lit photocopiers and ancient flying spot scanners which *did* have respectable depth of field because of loose optics, small numerical aperture and oodles of light. Point in (lower) ... cheek: http://www.youtube.com/watch?v=h_grO7H2FD8 (warning grainy content: http://mefeedia.com/entry/how-to-photocopy/13905392) Peter

>> Another good way is to bung it on your flatbed scanner if it has decent >> optics and can focus at objects further than its own glass. > > I have bad experiences with scanners used for this. Even a photo left in its 3mm > glass frame (too old to remove) was scanned out of focus and I had to pry it > out. Brand name scanner, 1200 real dpi and still ... > > Depth of field is extremely closely related to lighting and numeric aperture. > Usually scanner optics don't have anything resembling a diaphragm so they use > the full aperture and good bright color-true light is expensive and short-lived > so you get *very* shallow depth of field. > > Please do not confuse contemporary led-lit full row ccd sensor scanners with 1kW > xenon-lit photocopiers and ancient flying spot scanners which *did* have > respectable depth of field because of loose optics, small numerical aperture and > oodles of light. Point in (lower) ... cheek: > > http://www.youtube.com/watch?v=h_grO7H2FD8 > (warning grainy content: http://mefeedia.com/entry/how-to-photocopy/13905392) The copier on that clip has no need for large depth of field... Perhaps you are talking about this model? http://www.youtube.com/watch?v=ppyq7LWtbyY Djula

{Quote hidden}> Date: Wed, 25 Mar 2009 03:58:59 +1300 > From: spam_OUTapptechTakeThisOuTparadise.net.nz > Subject: Re: [EE] The secret to taking sharp pictures of circuit boards > To: .....piclistKILLspam@spam@mit.edu > > > Olin made the comment that they aren't applicable to small, inexpensive > > cameras. Yes, that is mostly true. I have seen people hack a large view > > camera back to allow the use of a smaller (dSLR I believe it was) as a > > pseudo-digital back. At one point there was, and may still be, a > > comercial product available to do this. Also seen these sort of optics > > hacked onto a flatbed scanner so that the scanner became the optical > > sensor. But for the most part, it is pretty much just a novelty to > > convert a view camera in this maner. > > For distances well below infinity (parallel light) you can get good results > with a bellows unit that mounts the lens separate from the camera. Moving > the lens away from the camera body shortens the maximum focusing distance > (unless the lens has been designed to focus "past infinity" which is rare. > > Amazingly capable DSLRs which you can do this with are now down to well > under $US500. Not in the same class as point and shoot, but accessible > enough for the suitably keen in many cases. Second hand DSLRs are even > cheaper and many film SLRs are close to free. Bellows units from days of > yore can be very cheap on occasion. > > I think you may be confusing the bellows extensions used for macro work on SLR/dSLR with a true shift capable lens. That said, I wonder if you could modify such a unit. The next problem after that is having sufficient image circle on on the lens so that you can shift and work away from center. At magnification greater than 1, this does become somewhat easier as the lens can start to be a good distance away from the camera. Switched topic tag to OT as we are, in my opintion, drifting away from the original intent of "cheap" camera and straight-up shots... Rob

Be careful BG or you may be labeled as "silly" by Olin. MA {Quote hidden}> On Mar 24, 2009, at 2:28 PM, Benjamin Grant wrote: > > this is now a very long post with many people interested, so, per > usual olin > if you're not interested, stop responding. However, as a.) people > consistently post subpar pictures of circuits and b.) people have > had a lot > of interest in this post, the fact that you are disinterested is > largely > irrelevant. My congratulations on your discovery of macro mode prior > to > vitaly, i'm not sure what other response you'd like to your post. > > On Tue, Mar 24, 2009 at 4:23 PM, Olin Lathrop <olin_piclistKILLspamembedinc.com > >wrote: > >> Vitaliy wrote: >>> I just wanted to mention the macro mode, which is available in most >>> cameras (even the very cheap ones), >> >> I bought the camera I did for the office largely because it could get >> really >> close in macro mode. >> >>> but is often overlooked when >>> someone is taking an up-close picture of a circuit board to >>> illustrate >>> a problem. >> >> Maybe you just discovered it, but frankly, macro mode is well known >> and the >> obvious choice for taking pictures of small things. To me this is >> in the >> "blatantly obvious" catagory, and I think for most people too. >> >> WFT Electronics Denver, CO 720 222 1309 " dent the UNIVERSE " All ideas, text, drawings and audio , that are originated by WFT Electronics ( and it's principals ), that are included with this signature text are to be deemed to be released to the public domain as of the date of this communication .

well, fortunately for me i have been labeled as a future mcdonald's employee by Olin, so I've moved beyond worrying about sir Olin's opinion. On Tue, Mar 24, 2009 at 6:02 PM, Michael Algernon <.....picKILLspam.....nope9.com> wrote: {Quote hidden}> Be careful BG or you may be labeled as "silly" by Olin. > MA > > > On Mar 24, 2009, at 2:28 PM, Benjamin Grant wrote: > > > > this is now a very long post with many people interested, so, per > > usual olin > > if you're not interested, stop responding. However, as a.) people > > consistently post subpar pictures of circuits and b.) people have > > had a lot > > of interest in this post, the fact that you are disinterested is > > largely > > irrelevant. My congratulations on your discovery of macro mode prior > > to > > vitaly, i'm not sure what other response you'd like to your post. > > > > On Tue, Mar 24, 2009 at 4:23 PM, Olin Lathrop <EraseMEolin_piclistspam_OUTTakeThisOuTembedinc.com > > >wrote: > > > >> Vitaliy wrote: > >>> I just wanted to mention the macro mode, which is available in most > >>> cameras (even the very cheap ones), > >> > >> I bought the camera I did for the office largely because it could get > >> really > >> close in macro mode. > >> > >>> but is often overlooked when > >>> someone is taking an up-close picture of a circuit board to > >>> illustrate > >>> a problem. > >> > >> Maybe you just discovered it, but frankly, macro mode is well known > >> and the > >> obvious choice for taking pictures of small things. To me this is > >> in the > >> "blatantly obvious" catagory, and I think for most people too. > >> > >> > > > WFT Electronics > Denver, CO 720 222 1309 > " dent the UNIVERSE " > > All ideas, text, drawings and audio , that are originated by WFT > Electronics ( and it's principals ), that are included with this > signature text are to be deemed to be released to the public domain as > of the date of this communication . > > -