iosa Loc: Fairbanks, AK

Early next month, there is a transit of Venus across the sun. In the hopes of getting some pictures of it, I have started assembling a solar filter for my camera. I purchased a #11 (welding) filter, and a 3" ID PVC cap. The idea is to cut a hole in the cap and fix the filter over the hole. The cap fits snuggly on the inverted hood for my Tamron 70mm-300mm lens.

So far, I've only drilled a small hole, about 5/64-inch, in the center of the cap. Before enlarging the hole, I tried it out just to see what there was to be seen. I was quite impressed. Pictures two and three are taken through the hole and 70mm and 300mm, respectively. The light is poor, as I didn't get around to trying this until about 11pm tonight (hey, it's Fairbanks. There is still *some* light out there). No cropping or other adjustments have been done on these pictures.

At this point, I'm thinking I can just fix the filter to the cap without further adjustment. Thoughts?

Supplies


'wide' angle


zoomed

oldtool2 Loc: South Jersey

Your best bet is to get a solar filter made for a telescope and use it. You can get them to fit the lenses of most scopes so I am sure you could find one to fit the hood you are using. I have one that fits onto the hood for my 400mm lens.

If you are showing that much light thru your present cover I think you are showing too much light and may end up frying your camera or damaging your eyes.

Jim D

Photoman74 Loc: Conroe Tx

:thumbup: Thinking out of box - remember if this fails it could lead to the step that succeeds.

wlgoode Loc: Globe, AZ

Call your state University ask for an astronomer and ask advice.

jerryc41 Loc: Catskill Mts of NY

Here are some links.

http://galacticfool.com/build-solar-filter/
http://joe-cali.com/eclipses/EQUIPMENT/solarfilters.html
http://www.jonathangazeley.com/2012/02/making-a-solar-filter/
http://www.astronomylog.co.uk/2010/06/24/how-to-make-a-digital-camera-solar-filter/

Camera dealers sell ready-made solar filters, too, but they're not cheap.

bawlmer Loc: Baltimore, MD

Don't hold me to this, but I believe a #11 glass is only good for protecting your eyes from an acetylene burning torch. To get proper protection for something like a welding stick, or in this case, the brightness of the direct sun, you're going to need something quite a bit darker.

Nikonian72 Loc: Chico CA

Both of your test photographs show Circular Aperture Diffraction http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/cirapp.html
Enlarging the hole (aperture) will reduce the distortion, but will require a more dense filter.

FAQ: What Filter to Use for Solar Photography?
http://www.uglyhedgehog.com/t-30562-1.html

toolmaker Loc: Albert Lea, MN. USA

A # 11 welding filter is enough protection for this. number 11 or 12 is used for wire feed welding and for tungsten inert gas welding so it is dark enough.
Dave
ave