Lightning detector for photography

@strongheart It sounds different, I never heard of a phone that can measure heat and any thermal cameras were super expensive.

Posted by: @strongheart

I think that a microcomputer or even a microprocessor is overkill for the job.  No matter that, the key component would be the LDD or photoDiode to trigger a transistor switch.
Would it need lenses?
Lightning season is coming up

I've been whining a lot about my piss-poor Internet.  I did see a Google search link that indicated someone had a project that without any MPU as you suggest.  Obviously, you have more/better hardware experience than I.  Unfortunately, I couldn't successfully get to that link. 

@zander - As far as a lens... I think what @strongheart is getting at is to reduce field of view going to the photo diode/resistor/whatever sensor... so it doesn't get triggered for lightning that isn't in the camera's field of view.  Me... looking for a cheap way...  I'd try just using some kind of cardboard box to act as a lens hood for the light sensor.  If the concept works, I'd make a nice 3D printed hood.

VBR,

Inq

@inq Some sort of lens hood around the sensor makes sense, but the FOV (field of view) should probably be close to human FOV. The sensor has to be calibrated to detect light that is many orders of magnitude brighter than ambient so it is extremely unlikely that stray light would trigger it. There are two scenarios for lightning shots, the well understood repeatable location like the Empire State or CN Tower etc. These locations can be shot with longer lenses cropping much of the human FOV and a smaller sensor window. The other style (and more common) is the nature shot, the great plains, and mountain vistas where wide angle lenses and human FOV's + are used (a typical shoot with 6 lenses will have 5 of them 50mm or less, 3 less than 20mm and one in the 1xx size). The sensor in this case needs to 'see' a larger FOV.

Lightning triggers are invaluable in daylight, but seldom used by pros at night. At night they calculate a base exposure using very low ISO so that exposure times are 10 to 30 secs or better still 10 exposures of 2 to 3 seconds.  If in a storm, just leaving the shutter open for long (in lightning terms) exposures will 'catch' the multiple strikes and side paths much more than a trigger can. In daylight this is not advised since the shutter speeds would have to be more like 1/30 to 1/250 of a second and we would wear out our shutters way too fast. Of course smartphones do NOT have mechanical shutters so that is not a consideration however the smartphone camera while a marvel of modern technology is still no where close to a sensor more than an order of magnitude larger and the same for lenses. It's great advantage is it is always with us. I have been a photographer for well over 50 yrs and I will be ditching all my action/waterproof etc cameras (all except the big DSLR) in favour of the newest iPhone available next April. For ad-hoc shooting it is now quite acceptable. If using a smartphone (at least an iPhone) then there is an app that does the work of capturing lightning strikes, it costs $2.79CDN and there is a free version.

Just imagine how difficult this was before digital. One or more film magazines with 50ft of B&W film. In many cases movie cameras were used but I also had add on motorized backs for 35mm and those 50ft film canisters. SO much easier today and now the quality is very good.

Posted by: @zander

Just imagine how difficult this was before digital. One or more film magazines with 50ft of B&W film. In many cases movie cameras were used but I also had add on motorized backs for 35mm and those 50ft film canisters. SO much easier today and now the quality is very good.

I don't have to imagine... I did it semi professional while I was in college for extra beer money and to take pictures of co-eds. 😉  I had several Nikons... an F2, F3, FM and all Nikkor lens - 24mm F2, 50mm 1.2 and 1.4.  55mm Macro, 105mm portrait, 80-200mm Zoom, 500 mm reflex.  Also did my own dark-room work with B&W.  I did not make the transition to digital DSLR.  No money in it since I was no Ansel Adams.

As far a Lightning... I found it far easier at night.  I could use the 24mm, using Panatomic-X (ASA 32) and really crank down the F-stop... 11, 16, 22, 32... etc.  I could do a manual open shutter... let lightning happen and then manual close shutter.  Got lightning every time on every exposure.  You could leave it open for tens of minutes and still have a dark background.  

But today... my phone makes this kind of stuff trivial...

VBR,

Inq

@inq 10's of minutes? What was the reciprocity adjustment for that? 

Posted by: @zander

@inq 10's of minutes? What was the reciprocity adjustment for that? 

Testing me, eh?  😋 

As you know, photographic reciprocity is to adjust extremely long exposures (usually longer than 1 second) in an attempt to handle chemical based film's non-linear light versus exposure curves.  Usually film was made to be as linear as possible in shutter speed ranges that someone can hand-hold without a tripod.  In long exposures, extra duration had to be added because the light-meters are assume linear behavior.  If the reciprocity adjustment is not done, the images tend to be underexposed and/or of low contrast.

The images I was going for were at such low ASA (32) and small aperture (F32) that light meter's would probably have calculated multiple hour exposures.  IOW, I didn't even use light readings, much less use a reciprocity adjustment.  The ten minute exposure would have resulted in a black image unless lightning occurred.  Think of it more like light-painting or firework photography...

@inq It's just that 10mins is really long. I thought you made a typo.

@zander - Which brings up a interesting point since you made me think about it.  There really isn't much need to trigger for a lightning strike IF one is able to just leave the shutter open. 

I'll have to study if there is some equivalent way to do that with my phone's camera.  I imagine you can with a DLSR... set low equilivent ISO/ASA, set small apertures and then just "keep" the shutter open till lightning strikes within it's field of view.  Close the shutter and admire your work.

Posted by: @zander

@inq It's just that 10mins is really long. I thought you made a typo.

As I described above, the time the shutter was open was really irrelevant... If I opened it and lightning struck (by happenstance) a second later, I could close the shutter.  If I left it open for ten minutes and had only one lightning strike, the images would looks the same... Ambient light was so minimal compared to the lightning, that in both cases the background was totally black.

@inq With DSLR's, the better technique is multiple shorter exposures, instead of 10 mins, 10 1 min exposures. Since it's digital, any 'empty' frames are simply deleted and any strike across multiple frames is stitched together in post with Lightroom or equivalent. This is the current technique for nighttime, the Pluto is still needed for daytime. Most phone/cameras should have an app if not built in to do intervalometer photography and there are devices that you can attach also. I just downloaded an app for my iPhone called iLightningCam 2. I just got the free version, I will upgrade for $2.79 later if it proves useful.