Showing posts with label second exposure. Show all posts
Showing posts with label second exposure. Show all posts

Welders Glass ND Filter

Penulis : Admin Ashish Chaturevdi on Sunday, 11 December 2011 | 12:59

Sunday, 11 December 2011

I was reading online about a cheap alternative to a Neutral Density (ND) filter to use for photography. An ND filter is basically sunglasses for your camera. It decreases the amount of light that gets through, thus allowing you to keep the lens open longer. Neutral density filters can cost as much as $400 for a really nice one.

The cheap alternative is to use a welders glass. They type of glass that welders for eye protection against the bright light created during welding. So i went to Lowe's and bought one.
Welding Glass for Sale At Lowes, Home Depot, Hardware Store

Lowes lens dark, welders glass, for sale

Then because my new camera only has a small lens i decided to cut the glass down to about 2" x 2".
DIY, how to make an ND Filter, cut glass

And make a type of "dark housing" to fit over the camera lens. I used a piece of PVC pipe and
a permanent marker to color it black.

cut welding glass, darken case to prevent light, glare

Then glued it together.

assembled homemade ND filter

I used a rubber band to hold it onto the camera and some cloth on the edge so it wouldn't scratch anything.

completed ND filter for point and shoot camera, homemade, diy, New ND Filter design, homemade, make, weld glass, homemade, diy, nd filter on camera, Neutral Density
The two main problems with using the welders glass is that it is not as high a quality as an ND filter and that it has a green tint. This is what the image looks like right out of the camera. This was a 64 second exposure during the day.


RAW ND filter photo, green tint, welders glass

But in Photoshop this can be corrected, mainly by adjusting White Balance and Tint.

photoshop corrected RAW photo with ND filter

That design was not the best, it was too big and heavy. So i tried to simplify it.


I started with the same 2" square piece of glass that i cut from the larger glass. But then i used pliers as a kind of glass nippers and slowly broke off corners until it was round.
New ND Filter design, homemade, make, weld glass, homemade, diy, nd filter on camera, Neutral Density
I sanded and filed the sharp edge. Then just as before i glued it to a PVC pipe i colored black, inside and out. But the key difference is this time is that i glued a foam ring to the inside of the PVC.
assembled ND filter housing, foam, ring
point and shoot nd filter, homemade, make, diy
I sanded the foam down until i could slide it onto the outer lens, but with just enough pressure that it wouldn't fall off.homemade, diy, nd filter on camera, Neutral Density

I plan to use it when i'm in Tennessee to take pictures of some waterfalls.


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Star Pictures

Penulis : Admin Ashish Chaturevdi on Wednesday, 30 November 2011 | 04:53

Wednesday, 30 November 2011

Before i crashed the kite and broke the camera i took these pictures of stars from the roof of my garage. They were 50 seconds exposures (which was a bit too long, 30 or 40 would have been better) and this time i did not use the dark frame subtraction so there wasn't a 50 second wait time in between each picture. Although there was some dark patches in the pictures, probably due to the lens.

Again this was done by combining several pictures that were taken over about an hour. Half way through some clouds blew in and screwed it up a bit.
Here's the original, untouched picture taken over the first 30 minutes. star trails, canon CHDK, long exposure
Here's the other original picture over the entire hour.
star trails, canon CHDK, long exposure, star, sky, night
I Photoshopped them look better. star trails, exposure time, star, sky, night
I just randomly pointed the camera toward the sky, you can see that i almost got the North Star in the upper right hand corner.
This one i used a purple lens filter effect how to increase exposure using CHDK
For better results i need to use a better camera, on a night with no clouds and in an area out in the country where the stars are really bright.
star trails, night sky, long exposure
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