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I have Canon EOS Rebel XS but can't not take picture from my tank very well.

It is bow front tank, anyone know what to do to improve the shot?

Thanks
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I bought a submersible housing for my Canon PowerShot so that I can just put the camera right into the tank for good closeup pictures. A ziplock bag might even work but thats taking some risk.

Only way is to go top down or through the side. You have to have the lens perfectly perpendicular to the glass to get a good clear macro. Unfortunately with curved glass this is impossible, which is why most people into photography don't by bow fronts or other curved glass tanks.

Best solution is make a top down camera box, it's a simple DIY project but don't use a Ziploc bag as I assure you this won't work.

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thank you for all comments
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Can buy a topdown viewer from RedCoral that works great for topdown shots.:mrgreen:

Just curious but couldn't a warped image be shaped flat with some good post processing? It's just geometry right?

Nope

You're right but it's not that simple.

We do this all the time in my industry (flattening lens distortion, warping CG images to fit existing lens distortion, creating 'clean plates' etc.)

Depends on how much distortion you have. I'm guessing you wont have the image info needed to 'unwrap' the distortion from a bow front, but you could take 2 or more images & then stitch them together (with a little warping into shape if needed).

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Or you could upgrade and sell me the bowfront!!:mrgreen::wink:

Its not really just warped, but rather the image is distorted :biggrin:

Sorry but I disagree, Theses are macro through a bow front.
http://i266.photobucket.com/albums/i...r/P3240002.jpg
http://i266.photobucket.com/albums/i...P3220003-4.jpg
I have more photos of angle shot going down the length of the bow and they turned out. The quality of glass ? What make of tank?

It will depend on the angle of the glass vs. the angle of the lens. Try to keep the plane of the film/ccd as parallel to the glass as possible to minimize distortion.

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ok, i tried all angle and could not minimize distortion. Anyway, I am picking up this http://www.newegg.ca/Product/Product...82E16830112033 so i can film it too :-) and take micro shot. Will see how it goes
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Do you use special lens?
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Disagree with what?? You can still take macros through curved glass but the results simply won't be as good. The effect is probably worse with SLR cameras due to the larger lenses they use.

Also your macros are good and I would even say excellent considering the camera you used but there is clear evidence of distortion which gets worse the further away from the center. You'll see this effect even with a larger DOF and is a result of the curved glass.

When I was doing my Master's thesis work, we videoed salmon using an underwater camera with a bowed lense. It took a special program to digitally "un-bow" the images or to flatten them out so another program would allow us to use the computer mouse to help size the fish without physicall handling them. I don't think that such a program is commercially available but for someone who was reallllllllly determined to do this, it may be possible. You would have to capture images of a grid with known spacing, then click the mouse on each intersection of the lines. Then through trial and error in programming the right algorythm, you could try to find one that spreads out the image until the grid is again flattened digitally.:mrgreen: Simple, no?

I think the lining up the camera lense to the plane of the glass is by far the better method than trying to digitally flatten the image using geometry or computer programming:biggrin:

It's actually much more complicated than that and still not possible to correct for the distortion resulting from a bow front.

All camera lenses are actually curved, especially fish eye lenses which are often added with another glass lens to many underwater housings for cameras. This allows for a wider viewing angle and more light intake. The difference though relates to how these lenses are curved and sized.

A simple curved lens will create distortion and blurring effects, often called aberrations, which get worse as you move closer to the edge. The difference is camera lens curvature, including those placed externally on housings or wide angle additions, is not constant but rather aspheric which vary like the shape of a parabola. This combined with setting the proper distance between elements and the lens size, type and radius reduces the effect of aberrations. What you are still left with is simple lens distortion which is easily fixed with various programs including photoshop.

Bow front tanks have constant curvature and a radius or shape which isn't designed for photography in anyway so even if you figured out the correct distance you wouldn't be able to eliminate the major aberrations which cause the blurring effects.

Also, the further the subject is away from the glass the more distortion. The curved glass and water will distort the image unless you position your lens as close to the subject as possible. Have the corals almost touch the glass and you will find that there is less distortion.

Having said that, the lighting will be different as well if your lights aren't fully covering the front part of the tank.

This is what I disagree with. "Impossible" I guess the level of quality in photographs is in the eye of the beholder. I thought these were good pics through curved glass. But I guess you are talking about professional quality photos through curved glass. Which I would now nothing about. I figure a 400$ camera can take a decent photo through curved glass than an expensive camera shouldn't be a problem. We were talking macro through curved glass right?
The camera is a olympus 1030sw point and shoot. no special lens. It take what I think are good macro shots.:noidea:

I was only saying it's impossible to line up a lens perpendicular to a curved surface which is a true statement. Of course you can still physically take the picture but you will get distortion and blurring effects which you can't correct for no matter what camera you use. You don't need to be a professional to eliminate these aberrations you just need straight glass ;)

So here are a few more pics through curved glass. They taken roughly 3 to 4 " away from the glass. Please feel free to critique them no offense will be taken This is only a discussion. I might add I am now using a considerable better camera.

http://i266.photobucket.com/albums/i...r/IMG_1398.jpg

http://i266.photobucket.com/albums/i...r/IMG_1188.jpg

http://i266.photobucket.com/albums/i...r/IMG_1629.jpg

http://i266.photobucket.com/albums/i.../IMG_17531.jpg

Nice pictures and camera, that 50D and 100mm is quite the upgrade.

I'm not a huge fan of the flash but it worked well for you. I noticed you used a fairly small aperture but your DOF is still a little limited, perhaps you could try focusing on the center of the subject. Also in the interest of the thread perhaps you could try take a few top downs with that nice new camera for comparison. Plus you should take a few at a true 1:1 ratio (macro).

Sphelps I'm confused how did you know the camera I was using? And I'm puzzled buy the 1:1 ratio. I think it is 1:1 ,I'm using the Canon EF 100mm f/2.8 Macro lens. Or am I suppose to be like 1" from the subject? All tyhe photos are at different manual settings I've been experimenting.
Copperband was f/16, 1/250, iso 100
Mush was f/5.6, 1/20, iso 500
Y Tang f/9, 1/250, iso100
Ric was f/9, 1/125, 100
Here are a few top down through custom photo tube

http://i266.photobucket.com/albums/i...r/IMG_1751.jpg

http://i266.photobucket.com/albums/i...r/IMG_1769.jpg

http://i266.photobucket.com/albums/i...r/IMG_1770.jpg

http://i266.photobucket.com/albums/i...r/IMG_1803.jpg

Incredible Pictures o.c.d.!

Wow! Very nice :mrgreen:

Thanks, Carmen and Leah I'm still figuring out this camera so hopefully they get better. I'm going to post some Fluorescence pics I took in a new thread you might like those.

Magic! Haha, jk. All digital cameras store data in each photo called exif data. This contains all the information about the picture including camera model, focal length, shutter speed, aperture, and so on. I can simply extract that data from any image with a simple plug-in on my computer. It's a nice feature to have because if you see a picture on the web you like, you can find out how it was taken, great for learning! If you don't have a plug-in or a program and don't want one you can use one of many online extractors. One is camerasummary.com

The 1:1 ratio is the definition of a macro/micro shot. If you look on your focus ring you'll see, along with the distance, a ratio (usually the closest focusing distance). If you focus on a subject at point you're at the 1:1 ratio and taking a true macro shot.

I apologize for not explaining this better but I simply assumed you knew all this because your pictures are that good! The best advice I can offer is for you to try and see what you can do without a flash. Top down will give the best results and you may need to use a tripod of some sort to steady the camera. You'll want a long exposure and a small aperture along with a low iso. You'll need to turn off all circulation to prevent your subject from moving but by doing so I'm sure your results will be even more spectacular.

Ahh, now I get it that's what they mean. I'm glad you like the pics. Thanks for the info and I'm going to look into a info extractor. I'm always wondering what settings pics are at. Thanks Shelps

Very nice pictures o.c.d. !!!