26 Jan 2009 Partial Solar Eclipse


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weixing

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Feb 1, 2005
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#1
Hi,
There will be a partial solar eclipse on the coming 26 Jan 2009... first day of Chinese New Year. The timing will be from 16:30:00 to 18:57:52.

For those who interested to photo the solar eclipse using your camera lens, you can buy a ready make solar filter for your lens filter size. The other way is to buy a sheet of solar filter and DIY a solar filter for your lens. Since you only need a small portion of the filter (unless you are one of those "big gun" owner), a few of you can buy one and share, so should be the cheaper option.

You should be able to get those ready make solar filter for camera lens and those solar filter sheet from Astro Scientific Centre (located in Omni Theatre building at Singapore Science Centre). Not sure about the price, but I think those ready make solar filter for camera lens are not cheap. Not sure is there any other shop in Singapore that you can get a proper solar filter for camera lens. Below is a picture of my Thousand Oak Black Polymer solar filter sheet (around A4 size) that I got from Astro Scientific Centre last year (can't remember the price, but I think less than or around S$50):


Anyway, I don't think I'll want to bring out my telescope to photo this partial solar eclipse as I might just shoot from a tall, west facing building, so I'll just make a solar filter for my zoom lens. Below is an easier way of making a solar filter from a big sheet and install on your lens by using the UV (or protector) filter that most of us have on our lens. Do it at your own risk (I won't be responsible for any damage equipment or any eye damage):

1) Use a compass to draw a circular template from a hard cover paper of your lens thread size and cut it out. DO NOT use the compass to draw a circle directly on the solar filter as it might cause a hole in the filter and risk of damaging your DSLR sensor or your eye.

2) Use the circular paper template to draw a circle on your solar filter and cut it out. Remember to make a spare just in case your solar filter got holes on the actual day. Below is a picture of the circular template (left), the solar filter cut out (middle), UV filter (right) and my zoom lens (top):


3) Before you install and use the solar filter, make sure you check that there is no holes on the solar filter. You can check for holes by putting the solar filter in front of a bright light source and see is there any bright dots on the solar filter. If yes, it's mean that there are holes on the solar filter... throw it away and DON'T USE ANY SOLAR FILTER THAT HAD HOLES ON IT!!

4) Remove the UV (or protector) filter from your lens and place the solar filter on to the lens surface.

Install the UV (or protector) filter back on your lens. Please note that there is a small gap between the UV (or protector) filter and the lens surface, so the solar filter inside will move around (especially if your solar filter is not the exact size) when you rotate the lens, so make sure the solar filter cover the whole lens surface.


5) Check the solar filter is install properly by pointing the lens at a bright light source and look through the rear of the lens. No light should be seen. If yes, either the solar filter is not install properly, is too small or got holes on it.

Please take extra safety precaution when making the solar filter. Hope the above information are useful and happy shooting!

Have a nice day.
 

weixing

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Feb 1, 2005
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#2
Hi,
Below are a few test shot using my Canon EFS 55-250mm f/4.5-5.6 IS lens at 250mm on my Canon 450D:
1) My room light bulb (F5.6, 20s @ ISO 800):


2) Sun (F5.6, 1/500s @ ISO 100):


3) Same as above but 100% crop:


Have a nice day.
 

Octarine

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Jan 3, 2008
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#3
How many f-stops do you achieve by that? Thought of using my NDx400 filter for that purpose but I'm not sure whether it is enough.
 

weixing

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Feb 1, 2005
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#4
Hi,
How many f-stops do you achieve by that? Thought of using my NDx400 filter for that purpose but I'm not sure whether it is enough.
Not sure how many stop does this solar filter will reduce, but according to the manufacturer, this solar filters are coated to a neutral density of 5, which reduces the light about 100,000 times. Anyway, this solar filter is basically design more for visual, so it's might reduce more light than necessary for photography.

By the way, I checked the hoya website and seem like NDx400 filter can be use for this purpose ( http://www.hoyafilter.com/products/hoya/oef-07.html ), but best to test it first.

Have a nice day.
 

Octarine

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Jan 3, 2008
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#5
Not sure how many stop does this solar filter will reduce, but according to the manufacturer, this solar filters are coated to a neutral density of 5, which reduces the light about 100,000 times. Anyway, this solar filter is basically design more for visual, so it's might reduce more light than necessary for photography.
Thank you for the details. Not sure what this "neutral density of 5" means but cutting down to 1/100,000 is equivalent to nearly 17 f-stops (each stop cutting the light by 50%). Using a Hoya NDx400 (9 stops) and maybe an additional Cokin (4 stops) I think I can get quite close to that. I just hope I don't get too much glare by stacking filters.
Thanks again for the tip and the clarifications!
 

ckpy7677

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May 23, 2006
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#6
Hi, Thanks for sharing.....

Any idea have they started selling the solor sheet @ Astro Scientific Centre? Can get it anytime? Thinking of getting it tomorrow when i'm in Jurong area?

Cheers!!!!
 

weixing

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Feb 1, 2005
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#7
Hi, Thanks for sharing.....

Any idea have they started selling the solor sheet @ Astro Scientific Centre? Can get it anytime? Thinking of getting it tomorrow when i'm in Jurong area?

Cheers!!!!
Hi,
They usually had the solar filter in stock... I saw it last week when I was there.

Have a nice day.
 

weixing

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Feb 1, 2005
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#10
Hi,
Can we use IR filter?
NO! Never look at the sun through an IR filter even the IR filter looks black... IR filter let IR pass through easily, so basically all the IR from the Sun will "heat" your eye at full power. Not sure will it damage your DSLR sensor (due to the IR blocking filter in-front of the sensor), but I think it'll damage your eye (and may be damage the IR blocking filter in-front of the sensor)!

any idea how much will that be?
I didn't check the price the last time I went there, so not sure how much does it cost.

Have a nice day.
 

#12
Hi,

NO! Never look at the sun through an IR filter even the IR filter looks black... IR filter let IR pass through easily, so basically all the IR from the Sun will "heat" your eye at full power. Not sure will it damage your DSLR sensor (due to the IR blocking filter in-front of the sensor), but I think it'll damage your eye (and may be damage the IR blocking filter in-front of the sensor)!




Have a nice day.
I've got those eclipse viewing glasses, silver film ones.
 

weixing

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Feb 1, 2005
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#13
Hi,
I've got those eclipse viewing glasses, silver film ones.
There are few type of solar filter, so it's safe as long as it's design for solar viewing.

Below are 2 article on safety solar viewing:
1) http://www.skyandtelescope.com/observing/objects/sun/3304056.html
2) http://eclipse.gsfc.nasa.gov/SEhelp/safety2.html

Please read it especially if you are first time solar observer.

By the way, in the above articles, it's mention that photographic neutral density filters are not safe... just wonder why the hoya filter website put the photographing solar eclipse as one of NDx400 application?? :think: Anyway, since I can't find the Hoya NDx400 filter transmission graph to check, it's best not to use those photographic neutral density filter.

Have a nice day.
 

Octarine

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Jan 3, 2008
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#14
Thanks so much for this information and warning! I'll better get the filter you have recommended. The NASA guys know their subjects.
 

GilbertGoh

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Aug 16, 2005
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#15
Hi,

There are few type of solar filter, so it's safe as long as it's design for solar viewing.

Below are 2 article on safety solar viewing:
1) http://www.skyandtelescope.com/observing/objects/sun/3304056.html
2) http://eclipse.gsfc.nasa.gov/SEhelp/safety2.html

Please read it especially if you are first time solar observer.

By the way, in the above articles, it's mention that photographic neutral density filters are not safe... just wonder why the hoya filter website put the photographing solar eclipse as one of NDx400 application?? :think: Anyway, since I can't find the Hoya NDx400 filter transmission graph to check, it's best not to use those photographic neutral density filter.

Have a nice day.
not too sure about NDx400,
but Cokin NDX is designed for solar eclipse. i would suggest people first time shoot to try their setup againist an light bulb first. remember the sun is much stronger.
 

weixing

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Feb 1, 2005
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#16
not too sure about NDx400,
but Cokin NDX is designed for solar eclipse. i would suggest people first time shoot to try their setup againist an light bulb first. remember the sun is much stronger.
Hi,
I'm not sure whether the Cokin NDX filter also block the IR or just dim down the visible light.

Below is quote from the NASA eye safety during eclipse for safe solar filter:
"A safe solar filter should transmit less than 0.003% (density~4.5)[1] of visible light (380 to 780 nm) and no more than 0.5% (density~2.3) of the near-infrared radiation (780 to 1400 nm)."

Below is quote from the NASA eye safety during eclipse for unsafe filter:
"Unsafe filters include all color film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters. Most of these transmit high levels of invisible infrared radiation which can cause a thermal retinal burn (see Figure 24). The fact that the Sun appears dim, or that you feel no discomfort when looking at the Sun through the filter, is no guarantee that your eyes are safe."

Have a nice day.
 

#17
Guess if you really want to photograph the eclipse, better spend some money and buy the correct filter. because its our own eyes. otherwise just experience the eclipse while collecting ang pows:).
 

Aug 16, 2005
1,078
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Singapore
#19
Hi,
I'm not sure whether the Cokin NDX filter also block the IR or just dim down the visible light.

Below is quote from the NASA eye safety during eclipse for safe solar filter:
"A safe solar filter should transmit less than 0.003% (density~4.5)[1] of visible light (380 to 780 nm) and no more than 0.5% (density~2.3) of the near-infrared radiation (780 to 1400 nm)."

Below is quote from the NASA eye safety during eclipse for unsafe filter:
"Unsafe filters include all color film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters. Most of these transmit high levels of invisible infrared radiation which can cause a thermal retinal burn (see Figure 24). The fact that the Sun appears dim, or that you feel no discomfort when looking at the Sun through the filter, is no guarantee that your eyes are safe."

Have a nice day.
i would want to continue this. lets shoot the eclipse and show the result ok?
 

Aug 16, 2005
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Singapore
#20
Guess if you really want to photograph the eclipse, better spend some money and buy the correct filter. because its our own eyes. otherwise just experience the eclipse while collecting ang pows:).
NDX is not cheep. if i am not wrong. i got it for almost 100+
 

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