Home made camera lens solar filters (cheap!)

[WadeH (Wade)]

Into my final preparations for the Cairns solar eclipse in November.

I already have a F/A glass filter for the 200mm scope and have become the proud owner of a PST. Now its time for my 18-55mm and 55-250mm Canon lens's.

I didn't want to spend big dollars (c-$180.00) for 2x glass ones so research was done, what to do?

BAADER AstroSolar Safety Film from http://www.extravision.com.au/catalo...49286b63b90c77 at $35.00 for an A4 sheet was the go. Now for the frames. After looking at various methods (paper card cut outs seemed fiddly and another web site suggested taking a camera UV/protector filter apart and recycling this. Good idea but should be some thing better again. Had a talk with a very helpful fellow at http://www.digitalcamerawarehouse.co...FZBUpgodDzYAvg and he suggested using Stepping Rings $63.00 incl postage for 4 (used for attaching filters of various diameters to your camera lens), magnificent idea and 4x makes two filters .

So, after very prompt deliveries by all involved I proceeded to very carefully make my filters.

The pics mostly speak for themselves but the go was:

1. Match the correct rings to each other 58-67mm with 67-58mm in my case (whatever your lens diameter is first to whatever size outer ring you want as long as the first # on the second ring matches the second # on the first ring).
2. Mark and cut the solar film very carefully (you don't want any marks or damage which will let unfilter sunlight through) I used a cup with a 0.5cm extra diameter as my template.
3. Carefully place the film between the two rings giving a good amount of crumple to the film, this is how it is designed to work. Also do not directly touch any thing other than the edges which will be trimmed later.
4. Gently screw the two rings together until finger tight. This can be the awkward part.
5. Trim the edges if you wish to tidy the filter.
6. Check filter for holes and scratches before each solar session by holding at arms lenght towards the sunlight and observing for defects. (at arms lenght the light will be dispersed).
7. Protect by keeping filter (s) in a protective box.

Best thing is these two filters cost me only $75.00 and I still have over half the solar fim A4 sheet left.

Thats it, now to enjoy.

Above all never look directly at the sun without the appropriate protection whether it be Solar Glasses or the appropriate Solar Filters (sold by IIS and good Astronomy shops which we all know) . This can result in irreparable damage to your eyes and our sight is too precious to take chances with.

[leon]

Wade I see what you are doing and can see how this is a good way to take some lens shots, but do you think that the solar film could be a little smoother, and not so wrinkled.

Would not the wrinkles in the film give an uneven result.

Leon

[WadeH (Wade)]

Hi Leon,

BAADER film is actually designed to work wrinkled. Apparently any stress on the film reduces its optical properties somehow. This is off the instruction sheet that comes with the film.

I have looked through the finished product and there is no sign of the wrinkles.

Once I have had a chance to take a few pics I'll post them later.

[Regulus (Trevor)]

Excellent solution. But the test at arms length is important and I will bear it in mind cos of the possibility of a tear from the screwing motion when u join the stepping rings.
Thanks for the idea.

Trevor

[WadeH (Wade)]

Here is a quick snap shot taken using the above filter for my Canon D60 250mm focal lenght, F5.6, 1600 sec., ISO 100.

No editing or anti vibration. Very basic but gives an idea of the filter properties.

[sil (Steve)]

Stress on the film is because people tend to wrap it over the end of the lens and pull it back. I got a nice flat result by buying a "lens hood" which was basically a conical step up ring made of aluminium. I ran tarzans grip around the end of the ring and sat it glue down in the corner of the film to set. I left it alone for a few days, trimmed around 5mm from the ring, a little more glue and the trimming was folded back (not stretched) to the sides. When set a little black tape covered the sides to neaten it up and ensure no gaps for light leaks (though I was careful to make sure the glue on the front had no gaps, it completely sealed the end). Only cost me a couple of bucks for the ring. I use it regularly, film stays nice and flat (slightly slack at times, never tight though...thermal expansion of the aluminium I guess).

A few more bucks for a container to protect it (I used foam pads on the inside of the container whichs "holds" my filter suspended firmly so the film never touches anything). For my scope I found something suitable in the plumbing section of the local hardware store.

Probably the better solution would be two low-profile UV filters with a very carefully trimmed to size piece of solar film sitting between them. It would stay protected from dust and finger prints. Use a pair that are larger than the camera lens and use a low-profile step-down ring to ensure any light leakage at the edge of the film is blocked. Or paint a black border, or find a rubber O ring...doesn't much matter as long as there isn't any stray light coming in from the edges ruining the shot.

[leon]

OH, did not realize that, sorry, carry on

Leon