Photochimps.com

Go Back   Photochimps.com the Photo Site for Photographers of All Skill Levels > Photography Discussions > General Photography Discussions
Home FAQ's of PC Forums Gallery Contests Register Members List


Reply
 
Thread Tools Display Modes
  #1  
Old 10-21-2014, 01:25 PM
Jim Jones's Avatar
Jim Jones Jim Jones is offline
"Ye ole' wise one" & Contributor

 
Join Date: Mar 2004
Location: Chillicothe, Missouri
Posts: 4,842
Default Solar Eclipse

The second solar eclipse for this month is this Thursday afternoon. Googling for October solar eclipse leads to sites with a variety of information. One such site is http://www.skyandtelescope.com/astro...2014-10062014/. Other sites have more detailed information on some aspects of the event. Weather permitting, I'll probably use crossed polarizer filters to block most of the light for a digital camera. These filters won't block the dangerous heat, so capping a big telephoto lens between shots is advisable. Do enough experimenting to work out any problems well ahead of time. Exposing for a solar eclipse is easier than for a lunar eclipse. First, there is plenty of light -- too much, really. While a tripod is convenient, it isn't needed for anything more than pointing the camera in the right direction while the photographer tends to other business. Second, the exposure is much more constant than for a lunar eclipse. No exposure compensation is required for the entire event.

Don't look at the Sun through the camera's eyepiece. It isn't necessary, and may be dangerous. Blind photographers are certainly handicapped! Even moderate, but permanent, damage can happen to camera or eye quickly. I'll mount a white cardboard disc around a digital camera's telephoto lens's base, and center the shadow of the lens on that disc to center the sun in the frame. If you plan to make multiple exposures on one frame of film, a very small pinhole over the lens, or positioned about where the diaphragm is located, lets you position the sun on the camera's ground glass. A pinhole telephoto of any focal length can be improvised for interchangeable lens cameras. Black PVC pipe 7 or 8 feet long makes a convenient pinhole telephoto that will about fill a 35mm camera frame. The longest I ever used was about 24 feet long for larger sheet film, but it was rather awkward to use. Almost any camera lens will produce a sharper image.

Feel free to post questions here or email me at jjones@greenhills.net if you have questions.
Reply With Quote
  #2  
Old 10-23-2014, 04:12 AM
winger's Avatar
winger winger is offline
Administrator

 
Join Date: May 2004
Location: southwest PA
Posts: 4,247
Default

If I have clear enough skies, I might try multiple exposures on one piece of film. Any advice on using my Chamonix? How do I get it about at infinity - just focus on something on land then aim it at the right part of the sky?

I only have iso 100 4x5 film at the moment, too.
__________________
Bethe

www.ewfisher.com
Reply With Quote
  #3  
Old 10-23-2014, 03:02 PM
Jim Jones's Avatar
Jim Jones Jim Jones is offline
"Ye ole' wise one" & Contributor

 
Join Date: Mar 2004
Location: Chillicothe, Missouri
Posts: 4,842
Default

First, never look through a camera or telescope at the Sun unless you have a proper solar filter properly installed. You need a solar filter or a good substitute to keep from really blowing out the exposure. Fortunately, some time ago I bought a 72mm adjustable ND filters for the ancient, but sharp, Vivitar 400mm f/5.6. The filter can be dialed from ND2 to ND1000. At maximum density it gives good exposures of the sun on a D3100 at f/8 at 1/4000 second and ISO 200. The images seem rather unsharp on the camera's monitor compared to lunar photographs without any filter. Also, there is a very strong blue color shift. Adding a red filter resulted in an unpleasant mauve image and further loss in sharpness. There seems to be color fringing with the variable ND filter which also increased when the red filter was added. Some available variable density ND filters are limited in their range so people can't use them at extreme densities with disappointing results. When photographing the transit of Venus a few years ago, I used ordinary polarizers crossed, and encountered some odd effects towards the edges of the image.

I briefly considered also shooting a sequence on one sheet of film, but with unfavorable weather forecast yesterday, did no testing. Rather than swap the ND filter, I might have improvised a solar filter. One way is to completely expose B&W sheet film, develop it for maximum density, and mount it inside the camera close to the film plane. It might take more than one sheet to achieve enough density. A camera and lens that can be precisely focused on infinity without using the ground glass facilitates such photography. One can focus without the filters. lock everything down, and add the filters. They won't cause significant focus shift at small apertures. Sometimes such a filter can be loaded on top of a sheet of raw film in the holder. To prevent possible damage when using a filter inside the camera, cap the lens with a metal cap between exposures. A tin can can be cut down to do this.

Some films, T-Max for example, might have a smooth enough surface to work as a filter in front of the lens. It is also good for visually observing the Sun. At least two sheets together are recommended. Don't use color film for this: it might block visual light, but not the destructive heat rays. I've heard of people using heat and light blocking sheet plastic coated with metallic film as a solar filter, but others discourage that.
Reply With Quote
  #4  
Old 10-23-2014, 03:39 PM
winger's Avatar
winger winger is offline
Administrator

 
Join Date: May 2004
Location: southwest PA
Posts: 4,247
Default

Thanks, Jim! I think I have a few sheets of exposed film that I use to test my fixer - maybe I'll stick a couple in developer and use those as filters. I'll have to improvise a lens cap, too, since I don't think I have a metal one that fits my LF lenses. Will the 135mm work? Or I could try the pinhole camera.

Though at the moment, the clouds may hinder anything anyway. It's supposed to clear up somewhat, but I'm not sure if the timing will work.
__________________
Bethe

www.ewfisher.com
Reply With Quote
  #5  
Old 10-23-2014, 10:17 PM
Jim Jones's Avatar
Jim Jones Jim Jones is offline
"Ye ole' wise one" & Contributor

 
Join Date: Mar 2004
Location: Chillicothe, Missouri
Posts: 4,842
Default

For this purpose a lens cap doesn't have to fit; it can just hang onto the lens.

I may have used a somewhat longer lens than 135mm when photographing a sequence of a lunar eclipse on one sheet of film years ago, but don't remember. The 135mm lens will make an image of the sun a little over 1mm in diameter.

It's hazy and overcast here at the moment. Oh well, I ought to be getting a few prints framed to deliver to a group exhibit tomorrow. It's not going to be much of an eclipse, anyhow.
Reply With Quote
  #6  
Old 10-24-2014, 12:00 AM
Jim Jones's Avatar
Jim Jones Jim Jones is offline
"Ye ole' wise one" & Contributor

 
Join Date: Mar 2004
Location: Chillicothe, Missouri
Posts: 4,842
Default Solar eclipse

Just after my last post the sun appeared intermittently, but this was the best I could do in its rare appearances. Nikon D3100, ISO200, old Vivitar 400mm f/5.6 at f/8, 1/640 sec, Vivitar NDX variable neutral density filter adjusted to near its maximim of ND1000. The unsharpness and color fringing is not apparent in photos taken with this lens without the ND filter. The small spots near the center of the Sun's disc are sunspots. Time was 5:37:05 p.m. CST. This image is full frame and unedited except for resizing.
Attached Images
File Type: jpg DSC_7164a.jpg (135.3 KB, 4 views)

Last edited by Jim Jones; 10-24-2014 at 12:08 AM..
Reply With Quote
  #7  
Old 10-24-2014, 05:04 AM
davidb davidb is offline
Senior Member

 
Join Date: Mar 2012
Posts: 763
Default

I like this photo very much. Somehow it looks as though you are in a plane up in the clouds taking the picture.
__________________
-------
David
Reply With Quote
  #8  
Old 10-24-2014, 03:19 PM
winger's Avatar
winger winger is offline
Administrator

 
Join Date: May 2004
Location: southwest PA
Posts: 4,247
Default

I agree with David - nice shot. Nicer than a textbook-pretty type shot, too.
I ended up not even trying. It cleared up here then got cloudy again. I think it cleared up during the eclipse, but by then I was inside making dinner. Oh well. Next time?
__________________
Bethe

www.ewfisher.com
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 12:41 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2018, vBulletin Solutions, Inc.