- This topic has 2 replies, 1 voice, and was last updated 12 years, 5 months ago by
.
-
Posts
-
Posted by Nick Hudd at 08:10 on 2012 Jun 04
Apologies that this is duplcated under "Venus". Does anyone have advice about safe observing at sunrise please? I have a solar filter, and know how to project, but both seem inappropriate for observing this transit. For a few minutes direct low power observation? For photos, straightforward telephoto use of the camera? Help! Nick Hudd
Posted by Martin Mobberley at 10:05 on 2012 Jun 04
Nick,Under *NO CIRCUMSTANCES* should you ever observe the Sun directly withoutthe appropriate solar filters. The chances of permanent eye damage arevery high indeed and even experienced observers have damaged theireyesight in the past. The Sun brightens rapidly as it clears thehorizon and you cannot see the IR/UV radiation so have no idea whatdamage is being done. Many have made these mistakes before…..The BAA observer J.Hedley Robinson’s accident is just one example.Projection is the only 100% safe method and a black cloth overobserver and screen will help increase contrast in such dimconditions. As far as photography is concerned the usual safe solarfilters should be used. If the image is too dim, try longerexposures. If the image is still too dim you should blank offthe visual viewfinder with tape and not use it, just looking atthe LCD screen if you remove the filters. Looking thru a visualviewfinder at the Sun will also trash your eyesight. If you justlook at an LCD screen in such a situation, you may wreck the camerabut not your eyes………..The bottom line is, NEVER, EVER, observe the Sun direct thru anytelescope, or with the naked eye, or thru a camera viewfinder, evenwhen it’s close to the horizon.As I say, even experienced observers have damaged their eyesighttrying this in the past….. It’s either projection, or observingwith solar filters, or photography while watching an LCD screen ora separate monitor. Martin>Apologies that this is duplcated under "Venus". Does anyone have advice about safe observing at sunrise please? I have a solar filter, and know how to project, but both seem inappropriate for observing this transit. For a few minutes direct low power observation? For photos, straightforward telephoto use of the camera? Help! Nick Hudd <
Posted by Grant Privett at 01:09 on 2012 Jun 05
Much safer to project on to a screen and then photograph the screen. If you make sure you have a clean screen and a decent depth of field (higher f ratio) you can get a decent image even though you will not be perfectly on axis. You can later rescale the image as necessary to restore the Suns shape to circular. I used this approach very successfully in 2004.Why take risks when theres no need to? You only get one set of eyes.
- You must be logged in to reply to this topic.