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Old 06-06-2012, 09:29 PM
pax (Geoff)
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Question Is it too early to start talking about November?

Hi All,

I am just new in daytime sky photography and have joined the hype around today and November 14th. Hopefully I can pose some interesting discussion points, especially for those who are also in my position as true amateurs.

Today for me was a bit of a rush and did not work out how I wanted it. As I currently have a set of Cokin P filters and holder I wanted to try and utilise the holder to keep focal length and lock. Also the idea of screw or taped on filters didn't excite me. To this end my research led me to look at some shade 14 category welding glass (~3mm thick) which only arrived the night before, so I didn't have time to trim it to size, so I fitted it in one size and it hung over the top.

While I could see fine, the lens would not get a focus on the sun, so I was all shut out of getting shots, although I could look fine at the sun. Testing this evening on a halogen downlight gave me the same non-focus issue, although looking directly with my eyes showed no fuzziness or interruption of the light itself.

Given I don't want to go all the way to Cairns and have the same result, can someone advise if I should persist (obviously I will cut the glass to size), or go another route given the tools I want to use?

The other thing to consider to lens(es) for the trip. As I have nothing which is focally long enough to use, today I was stuck with my 70-300mm, but for Cairns I was thinking of hiring a 70-200 F2.8 and 2x TC. I thought this would be a better option than the 200-400mm because at the top focal length the aperture will be wider. This would give me the flexibility for a faster shutter or lower ISO, so "room to move". What are people's thoughts?

Thanks for your time in reading and not flaming my ignorance to hard. Asbestos does leave shards behind when removed.

Geoff
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Old 06-06-2012, 09:47 PM
Poita (Peter)
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Your best bet would be to get some solar film to make a solar filter for your lenses. It is inexpensive and won't affect focus and will give far far better images. I probably have an offcut you could experiment with.

I was at F6.3 today with solar film and the image was so bright that I had to stop it down more, so a fast lens isn't a must have. You may be better off with a cheap 80mm achro scope to attach the camera to.
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Old 06-06-2012, 10:26 PM
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MrB (Simon)
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Hi Geoff, were you attempting to use the autofocus or were you manual focusing?
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Old 07-06-2012, 08:27 AM
pax (Geoff)
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Quote:
Originally Posted by MrB View Post
Hi Geoff, were you attempting to use the autofocus or were you manual focusing?
Hi Mr B,

Manual focus after auto found nothing to lock onto.

Hi Poita,

That would be most appreciative, thanks for the offer and I'll be in contact.. I haven't really got into using scopes or had the interest which is why I wanted to restrict my tools to what I know which is lenses. Knowing us are stepping down from F6.3 is interesting. I assume you are using ISA 100 or lower.

Geoff
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Old 07-06-2012, 03:39 PM
Poita (Peter)
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It's just that an 80mm achro is cheap and gives a great view of the sun. You can get an F11 900mm scope for <$200, you would be hard pressed to find a lens that will offer that value. The. Just use it as a solar lens.
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