My Planning for the Venus Transit

[Fermenter]

I am planning to observe the transit of Venus from the east coast of the United States, so the beginning of the transit at around 6-7:30pm EDT. I own a Meade LXD-55 6" Schmidt-Newtonian F=762mm f/5 refractor. I would like to use the telescope to make a projection of the sun however. My understanding is that I don't want to point the telescope at the sun without limiting the amount of light that can enter it because it can damage the secondary mirror onto which the primary mirror concentrates the light.

So my question is what do people recommend doing with this telescope for this event. Should I buy a special solar filter that goes over the aperture of the telescope greatly reducing the incoming light. Should I use a piece of cardboard with a small circular hole off-center to cover the aperture, and if so any recommendation on a safe size?

I think my plan is to build one of those funnel rear-projection screens so many people can watch the transit at the same time. This just seems safer than putting eyes to an eyepiece.

Any guidance is appreciated. Thanks.

[Qualia]

Second the need for help.

I was planning a similar thing with my f/10 refractor, but was worried I'd damage the thing. Would it be better to buy something like this and not worrying about messing up the refractor?

Solarscope FR Solarscope Standard

[Graham Darke]

You could make a mask with a 2 inch diameter hole in it to stop down your scope. That should still let plenty of light through for projection. If you do this, make the hole off axis. The other alternative would be a full aperture solar filter and you could then insert a webcam into your focuser and display a live image on a laptop so that a group can watch. You can record the event and watch it at the same time if you do this option.

I'm planning on watching the event on the east coast too but the east coast of England! Good luck and clear skies.

[spaceboy]

Baader Planetarium AstroSolar Safety Film

[Qualia]

Thank you, Graham & Spaceboy.

Would it be absolutely foolish to observe the sun, full aperture solar filter included, with the naked eye?

[Fermenter]

Thanks. Yeah, I don't think I'll be able to do the webcam thing, but I've been thinking about building the "Sun Funnel" described here: Safety

I'm still digging through that site and trying to figure out how best to do it within my budget. If I get a solar filter for the telescope, is it safe to view straight through the eyepiece?

Qualia, refractors don't have a mirror onto which the sunlight is concentrated, that's why that document I linked is designed around refractors and why I came here to ask about my reflector.

[spaceboy]

As long as you buy the visual solar film you should be able to make a filter cell up to an A4 sheet in size and visually observe the sun through an albeit square scope Only kidding. I think the largest aperture you can get out of the sheet is 8". Baader sell larger sheets but it becomes very expensive.

[Qualia]

Thanks a lot, Spaceboy, for the speedy and informative reply. Great stuff.

[Eastridge]

Here is my plan for what it's worth, any comments welcome.

Have bought baader A4 solar safety film with a view to making a filter to go over the 2" hole the scope has with it's end cap still in place. Given could well be cloudy I could'nt justify the cost of bigger sheet to cover whole of scope and don't believe need whole 10" apeture anyway.

Have bought some cheap eclipse glasses from 365asto to help get scope into postion etc. So finder will probably not be used and will be removed or taped up to aviod use in error. I will try positioning before the big day so that if I find it difficult I can make a filter ring for the finderscope as well.

There are only 2 of us so mass viewing isn't a need. Whoever isn't at the scope can be using the 'glasses' as I understand it is visible, if tiny, with the naked but protected eye.

[spaceboy]

You do know you need to be on the East coast or really high up to see it don't you ? I say this as you don't get much more west coast than Devon. I have a little 60mm refractor which I use (came free with a mount ) . Dust caps on scopes usually give you a stop down of 50mm aperture so although the frak is small it actually has more aperture than the bigger stopped down newt. It is portable and can be mounted on a camera tripod. Uses next to no Baader film so I have plenty spare should I need it.

[Mr TamiyaCowboy]

yup made two filters for my dob and newt, used astrofilm.

have a 114mm and a 76mm, both run full aperture filters.

as for full aperture and eyepieces, i have no troubles using both my 114 with a 2x barlow and 25mm eyepiece. gives a nice view.

the 76mm with a 2x barlow and a 25mm eyepiece gives stunning crisp clear views. DSLR prime focus is also fairly easy with live view, but my 350D lacks this so i have to focus via cameras veiwfinder.

focusing is key and scope placement. focusing is very fine you need to back and forth focuser till you get the crisp image showing.

scope needs to be placed away from houses and roads/tarmac areas. best area been said to be a grass field. this will help with a steady focused image.

remove finderscope or cover with some baader film, this stops any accidents, to be honest just remove it. another safety tip, keep eyepieces with caps on and safe in the shade somewhere they to have a lens and will magnify the sun. best safe than sorry.

Always Check your filter Before using with the scope. hold it up to the sun and view through it, check for splits / cuts and-or pinholes that may have formed.

i have been solar viewing with both my large newton and my smaller table dobson. it has opened up a whole new area of photography for me.

[Eastridge]

Yeah space boy, intend to go east, north or high depending on where weather forecast indicates best chance of getting a clear sky. But thanks for pointing out just in case.

[spaceboy]

I'm lucky that I get to use the in-laws holiday home on the East coast. Getting out of bed a 4:30am is a bit early in the morning for me so at least if it is a wash out with cloud I can be back in bed in 5 minutes

[petermarknimmo]

Just got to hope its clear now.

[Capricorn]

Just found out that the sunrise is ~4:40am here.

Going to be a hell of a choice to make. Stay curled up in warm bed, get up about 4:00 to drive to somewhere to see the last minutes of the transit.

[Scott]

ok I'm a wimp but i'm gunna watch it on the evening news. i'd never put my eye to a 'scope unless it was a proper solar scope so even with a solar filter i'd still be watching it on a laptop screen at silly o'clock so i think i'll wait.

[JoLo]

Here in the central US I will get about an hour of the transit prior to sunset, then it will rise for my fellow telescope geeks in the UK.

Second the motion on the homemade filters using Baader film...I made filters for my 106 and 65 refractors, the finder scopes, and for my camera lenses.

I gotta tell you though, the solar funnel is very cool. I put it together for $15 US, including shipping on the Datex projection sheet. The only other items needed is an old EP, a gas funnel you cut to length, and two hose clamps. I put it together in less than 10 minutes (the filters took me about 45 minutes each).

With my AT65 and the 10mm Plossl that came with my first Orion Dob, the funnel projects an image of the sun about 4" wide. Great for groups, highly recommended.