I have to applaud Halley (of Halley's comet fame) for the incredible insight into how this could be used to determine the distance from earth to sun.
http://www.exploratorium.edu/venus/question4.html On Thu, Apr 27, 2017 at 11:03 AM, Gonz <[email protected]> wrote: > I used a similar setup a few years back during the transit of Venus. > It was an amazing thing to see. > > > On Thu, Apr 27, 2017 at 10:50 AM, Chris Mitchell > <[email protected]> wrote: >> From the NASA guidance on solar eclipses: >> >> "One of the most widely available filters for safe solar viewing is a >> number 14 welder's glass, available through welding supply outlets." >> >> Full guidance here https://eclipse.gsfc.nasa.gov/SEhelp/safety.html >> >> When we had a near total eclipse in my bit of the UK a few years ago, >> I used a reversed 50mm Pentax manual lens to project it. That worked >> pretty well. >> >> Chris >> >> On 27 April 2017 at 07:59, Richard Klein <[email protected]> wrote: >>> I wonder how similar the filters are to the glass used in welding masks? >>> Optical clarity probably isn't as important for welding masks. >>> >>> On Apr 19, 2017 4:13 PM, "John Sessoms" <[email protected]> wrote: >>> >>>> Update on my preparations (if anyone is interested). >>>> >>>> Stopped by my local Pentax dealer here in Raleigh. >>>> >>>> I got a Manfrotto 700RC2 fluid head that will take my existing mounting >>>> plates for my 3021 legs. >>>> >>>> He ordered an Astrozap AZ-1514 Glass full aperture Solar Filter to fit >>>> over the lens hood of my 300mm f/2.8 (124-130mm). >>>> >>>> https://www.astrozap.com/scripts/prodView.asp?idproduct=61 >>>> >>>> I hope to be able to start practicing safely shooting the sun by next >>>> week to see how much of the frame I'll fill & whether or not I'm going >>>> to need to use the 1.4x tele-converter. I want to have enough of the >>>> frame filled to get some detail on the sun, but loose enough to get the >>>> corona & solar prominences un-cropped. >>>> >>>> I'd like to have that lens on the K-1 because of the articulated screen, >>>> but I'll switch it to the K-3 if I find out I need the 1.5 crop factor. >>>> >>>> -- >>>> PDML Pentax-Discuss Mail List >>>> [email protected] >>>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>>> follow the directions. >>>> >>> -- >>> PDML Pentax-Discuss Mail List >>> [email protected] >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>> follow the directions. >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. > > > > -- > -- Photography takes an instant out of time, altering life by holding > it still. Dorothea Lange -- -- Photography takes an instant out of time, altering life by holding it still. Dorothea Lange -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
