[mattb123]

I'd like to be better prepared for the Venus transit than I was for the Annular Eclipse so I need to get moving on this stuff now. For the eclipse I used my M 100mm on a Vivitar 2x TC because that was as long as I could go with a 49mm filter thread. My 10 stop ND filter is 49mm so that was what forced me to shoot it that way. I used that ND filter plus a circular polarizer for the eclipse.

This time around I'm thinking I want to use my A* 300mm either with or without the 2x TC (but probably with). I don't have any filters for that lens. It's bigger than all my others (77mm I think - anyone know for sure?). I can't really spend hundreds for a big ND filter so I'm trying to come up with lower cost alternatives.
I have the following ideas but I'm open to others so let me hear it if you think of anything else.

1. Buy some solar filter material and make a beer coozie or similar mount to go over the end of the lens
2. Buy a new lens cap and drill a ~49mm hole in it to mount my existing ND & polarizer filters. Maybe glue an old UV filter with no glass on it for the threads.
3. Buy some solar filter material and put it between the TC and the lens. I could do this with less filter material but from what I have read there is a possibility it could melt in there.

What do you guys think? Anyone else planning on trying to shoot this? What's your setup?

[Alliecat]

Some hints from Sky & Telescope...
General article on what to look for... (click "preview" under "not a subscriber" if applicable).
You can get fairly inexpensive solar filter film; Baader is often recommended. You might be able to find a dealer who will sell you a little piece rather than a whole filter or package. When I bought my telescope they stuck a piece in the cap for me; I don't think it cost that much.
Good luck... I'm expecting fog...
If by some miracle this corner of the Maritimes gets a cloudless fogless June day, I'll stick my camera on my 70mm refractor with an adapter. I think I recall this makes it effectively a 700 mm lens, at f11. I have taken a couple of passable sun pix this way in the past.

[mattb123]

I was going to buy some filter material from eBay but the guy only has 2.5" squares and 77mm is just over 3".
Anyone care to weigh in on the idea of mounting a 49mm filter on an old drilled out 77mm lens cap? I'm not too concerned with vignetting unless it's obscuring a large portion of the image. At 300 or 600mm I don't think the sun would fill the frame anyway.
The other option is that Baader filter material but I can only find a A4 sized sheet for $88 or a 2.5" piece for $30 on eBay. I guess I could do the lens cap idea with that 2.5" Baader filter too. I'm hesitant to spend $88 on a sheet unless someone wants to go in on some. Anyone?

Edit to add:
Or how about this? I buy the 2.5" filter material and put it between the TC and the lens. Would it melt from the concentrated sunlight? I'm actually very tempted to try this idea.

[mattb123]

Ah, found a 6" piece of filter material cheaper than the 2.5" the other guy was selling. I'll see what I can do with that.

[pixelsaurus]

Or how about this? I buy the 2.5" filter material and put it between the TC and the lens. Would it melt from the concentrated sunlight? I'm actually very tempted to try this idea.

Bad idea. Solar filters have been devised to keep the heat out of the optical system. They work by reflecting light and heat back at the sun. If you put this stuff inside the optics and it fails, you run the risk of frying the camera. Too bad if you are looking through the camera at this point.
Why shouldn't you look directly at the sun

[Ex Finn.]

Bad idea

+1.
Costs must have gone up on BAADER filter visual #5. I bought my A4 size just some time ago for $40 something.
As far as setup, my refractor telescope and baader #5 visual in a DYI holder made with materials from Lowe`s (one gallon bucket, black paint) and Michael`s craft`s store (self adhesive felt).
And then there is the weather factor always, I hope it will be clear for the portion that is visible from east coast.

[mattb123]

Thanks. The $20 6" piece should do the trick. I'll make a holder with a can cooler or cardboard. Weather could be a factor but statistics are on my side. Lots of clear skies here.

[RioRico]

I just shot the annular eclipse (my first heliography) with a Cosina(?) 300mm lens and a 3x TC. Sol never filled more than maybe 1/12 of the APS-C frame. Were I planning to shoot the transit (which I'm not) I'd use my 1000mm mirror with a 2x TC -- and a much better tripod than I have. The mirror's front diameter is ~115mm / 4.5in so a piece of SolarFilm wouldn't be too expensive. But I sure can't afford the right tripod. And from what I've seen, Venus in transit looks rather like a flyspeck. So I'll pass on this one. Yeah, I know, next one is in 105 years. I won't hold my breath.

[mattb123]

If I had that lens that is probably what I'd do too. But I don't.

[Mark Castleman]

I took my photos of the eclipse using a solar filter over the end of my Pentax 300mm. I had the camera on a tripod so that I could shoot at ISO 100 and then cropped the images as needed afterward. The key with a solar filter is that it reflects a very large fraction of the light, including UV and IR. An ND filter will let through more IR which can heat up your optics.

[Ailuropoda]

My first experience with observing solar phenomenon was with cardboard that had a section cut out of it, roughly 20% of the area. It was far from centered. There were also three sheets of mylar on it and we were projecting onto an index card. It was my highschool chemistry teacher's setup. Cloud cover kept getting in the way and we gave up. It's been a long time since I dabbled in this sort of stuff, but you should be able to obstruct a considerable amount of the front element and centering isn't too important when it is close enough.
I haven't really put much thought into my own setup yet. For the time being, I'm personally leaning toward cake and online streaming. It's not on a good day for me.

[pixelsaurus]

For those will telescopes/binoculars, these are easy to make http://cdn.transitofvenus.org/docs/Build_a_Sun_Funnel.pdf

[reeftool]

An inexpensive "ND" filter to cover the front of a rather large lens would be a welding helmet lens, available for around 10 bucks. It's not optical glass but I've seen some pretty impressive photos posted on occasion with this setup. I've heard stories of glass breaking inside lenses and telescopes aimed at the sun and the heat can fry your camera innards. Use live view. Cameras are replaceable, eyes aren't.

[RioRico]

An inexpensive "ND" filter to cover the front of a rather large lens would be a welding helmet lens, available for around 10 bucks. It's not optical glass but I've seen some pretty impressive photos posted on occasion with this setup. I've heard stories of glass breaking inside lenses and telescopes aimed at the sun and the heat can fry your camera innards.

I wonder if this experiment has been tried, and if so, where we might find the results: Take 3 cheap long lenses, with their bases sealed and a thermometer inside each. On T1, put a sheet of SolarFilm. On T2, a 950nm IR filter. On T3, a sheet of welding glass. Put them on a tracking mount. Aim them at Sol. See which heats up the most, and how fast.

[reeftool]

I wonder if this experiment has been tried, and if so, where we might find the results: Take 3 cheap long lenses, with their bases sealed and a thermometer inside each. On T1, put a sheet of SolarFilm. On T2, a 950nm IR filter. On T3, a sheet of welding glass. Put them on a tracking mount. Aim them at Sol. See which heats up the most, and how fast.

I was reading Astronomy magazine a few weeks ago while waiting in the dentists office and there was a whole article about the glass in eyepieces cracking and sometimes blowing out due to heat buildup in telescopes aimed at the sun with the so called "safe" solar filters and the writer did just that. They heated up to dangerous conditions relatively fast. The mag was a couple of years old and I don't remember the exact issue to reference it. I would assume the same fate awaits cameras. The main theme of the article was that just because lots of people get away with this practice doesn't mean it's safe, despite the ad claims from the people who make and sell the filters.