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01-29-2008, 10:35 AM   #1
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Remote photography of a solar eclipse

I wish to program a digital camera to take several pictures with different exposures using interval. But as far as I understand, no camera has this possibility.


Any ideas?

Harald

01-29-2008, 12:08 PM   #2
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I would consider doing several things, since pointing a camera at the sun would probably destroy it.

This also assumes you don't have a K20D

First, Look into either two polarizing filters back to back, in order to create a huge (value wise) neutral desnsity filter or a filter made of welding goggle material (for an Arc welder ) They scale these in a numerical scale, and I am not sure this relates directly to neutral density scaling. you want I think either 9 or 11 (gas welding is #5 and is not dark enough).

Second, make a small circuit, which you program to trigger the camera every so many seconds / minutes or purchase an interval timer if you are not technically inclined

Third be very carefull

The other alternitives are to make a pin hole camera and photograph the image that way, by projecting the image of the eclips on a wite board, or to keep exposure constant, and take photographs of the impact of the eclips, over time.
01-29-2008, 12:57 PM   #3
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You can also shoot thru a solar filter. These can be either glass or silvered mylar. Many shoot thru a silver "space blanket" that has been at least doubled (two layers of material). Some use three single layers.
Pentax used to make an electrical timer that might work in conjunction with the bracketing feature. It is a pretty rare item. How remote are you going to be from the camera? There are wireless triggers that will work 100 ft away. Wish I was shooting a eclipse. Sure you know this but for others never aim camera and lens at sun unprotected or look thru unprotected camera. You could end up needing a new hobby.
thanks
barondla
01-29-2008, 01:15 PM   #4
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I'm sure we all have seen thousands of pictures with the sun in the frame, and apparently all those cameras are still functioning after the shot.

I think as long as you're not keeping the shutter open for long, there is no danger to the sensor. The risk of sun exposure is mainly of damage to your eyes, or melting the microlens on the sensor due to heat. But I reason that leaving the camera pointed at the sun could damage the AF sensors, loose the oil on the blades, I don't know. You could be the first to try it! :]

I'm not sure I understood your question clearly, but what you want (bracketing on intervals) could be done with the Remote Assistant (K10D, or K100D with 1.0 firmware). As long as you can take the lens cap off, take the pictures, then put the cap back, I would have no worries.

01-29-2008, 03:34 PM   #5
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How remote do you need? Most cameras need to be hooked up to a computer to do this (USB serial). I guess could could always use do VNC or some kind of funky USB over Ethernet. As for camera damage, if you use the right filters the camera should be fine. I remember using a pin hole and a piece of cardboard when I was a kid to do this. I've also read that the glass used in welding goggles/shields make it safe for the human eye which should be good enough for a consumer level DSLR.
01-29-2008, 09:06 PM   #6
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NASA & Solar Eclipse - Previous Thread

There is a previous thread in this forum discussing this very topic (shooting solar eclipses). In it, I offered a link to a NASA (USA government space agency) website suggesting focal lengths and which filters to use before, during, and after the total phase. The website also provides an exposure guide, a link to a list of solar filter manufacturers, and links to other related websites.

It also offers some good advice concerning eye safety which contradicts several comments made so far in this thread. Most notably, you should not attempt to use polarizing filters, neutral density filters, or other common photo filters to photograph the sun. A properly designed solar filter or similar material (#14 welder's glass, for example, not just any welder's glass) is required.

stewart



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Last edited by stewart_photo; 01-29-2008 at 09:17 PM.
02-06-2008, 11:36 AM   #7
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As I have some experience taking pictures of a total solar eclipse, I know about the filters. But as far as I understand it is still not possible to take photographs programming a camera for interval with different exposures, let me say 1/1000, 1/250, 1/60, 1/2, 1 second, 5 seconds, 10 seconds. Using a Computer and USB connection, it is not possible to take pictures with different exposures. Maxim DL is a astronomical program to connect a camera to a telescope for remote-photography by the stars and deep sky, but as far as I understand it is not possible to program exposures of 1/1000, 1/500 or 1/60 second.

I would be grateful if there are somebody with knowledge how to make your own program and interface or with experience about MAXIM. Diffraction Limited

Harald
02-06-2008, 12:23 PM   #8
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You can get blind!

[QUOTE=Lowell Goudge;165886]The other alternitives are to make a pin hole camera and photograph the image that way, by projecting the image of the eclips on a wite board/QUOTE]

Let me assume that you don't use a telescope with solar filter. Because if you did, you would have posted your question in an astrophotography forum.

Ok then, do not expect that great images anyway. You will definitely be disappointed if you expect something close to published solar eclipse photography. They are all done with telescopes.

If you are ready to accept a lower quality, this "pin hole camera" trick a a very good suggestion. Normally, special solar eclipse pin hole cameras are sold close to such an event and they are cheap.

If you really want to shoot directly you will need a strong telescope. Note that a 300mm f/2.8 tele gathers 100 times the amount of light compared to a 30mm f/2.8, so you need a 99% solar filter securely mounted to your lens to compensate. This means that the viewfinder is plain black until you find the sun. If you try to adjust the camera w/o filter and then shot, note that you won't see any results anymore because you got blind within a fraction of a second. Period. You have been warned. Simply dont try. This is why people doing it right use a finder scope to adjust and a motor mounting compensating for rotation of the earth.

You may, of course, shot at normal lengths (50mm or so). But then the pin hole camera gives a better image.

Again: Do not try to point to the sun and only then put the filter for the shooting. You will end up blind if it was a tele lens. If you do it via LiveView, you won't be blind but your sensor will ;-)

02-06-2008, 04:21 PM   #9
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Well I don't know how does camera act when in bulb mode but I assume that it is quite easy to make a little simple gadget to fit your needs.

1) Use solar filters as mentioned before
2) Switch to bulb mode
3) Connect this little gadget to cable release socket

About circuit - the key Idea is to switch camera in bulb mode thus giving possibility to control shutter speed. Normally Bulb is used in long exposures so you can't expect to get a 1/2000 s exposure in bulb unless it is controlled by electronics (you need a sub 1/2000 s pulse to trigger the shutter this quick). So lets assume that there are no limitations in how short a trigger pulse can be in Bulb mode (I hope its true). So if it is that way only thing you need is a preprogrammed microcontroller some power source, few external parts and 2,5 mm stereo jack and a wire. Preprogram microcontroller to tirger camera like you want and it will do it. Simple 8-bit microcontrollers can work with 4 - 20 Mhz clock speeds so there is no problem to achieve 1/4000 s pulses.

Project should cost less than $10.
02-06-2008, 04:58 PM   #10
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QuoteOriginally posted by barondla Quote
You can also shoot thru a solar filter. Many shoot thru a silver "space blanket" that has been at least doubled (two layers of material). Some use three single layers.

thanks
barondla
You should also be very careful if you intend to look at a solar eclipse through any kind of contraption that has not been tested for U.V. absorption. If you use welding filters, those are completely safe (#9 and up preferred). You can also get those silver instead of green, so they won't change the color as much.
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