Trouble in focusing with macro lens... Help!

[SimonSKL]

I have a Canon Rebel Xsi camera and recently purchased a Canon EF 100mm f2.8 USM macro lens hoping to capture some great coral shots. I am a novice in macro photography but I have tried every technique and recommendation that I read and researched but I still can't get a sharp focus on the corals close-up.

I used a tripod, manual focusing, delay shutter, different picture styles, different shutter speeds and stops but I just couldn't bring the corals in focus unless I moved back 3-4 ft from my tank. But then the corals will be too small for a closeup shot.

Here is a shot of my tank from about 3 ft away.

Here are a few closeup shots of the corals all out of focus. The zoos are about 6 inches away from the glass.

At first I thought I have a defective lens so I took some closeup shots of something outside the tank. Here is a shot of an air plant 3 ft away.

Here is a close up from about 1ft.

I can clearly see the pores on the air plant in the close up shot even at 10X the magnification on my computer screen. So I don't think I have a defective lens.

One thing I suspect is causing the problem is I have a corner tank and the front glass is a quarter circle. Will that cause such a distortion that I can't bring corals in focus in close up shots? Any help and suggestion will be appreciated.

 

[BlueCorn]

Your coral shots aren't out of focus, that's motion blur. Either the camera or the coral (or both) is moving.

 

[SimonSKL]

Doug, The camera was on a tripod and I used the 2 second delayed shutter to capture the shot. The camera definitely was not moving. I have to admit I didn't turn off the PHs and return pump so the corals could have been moving. Even with the corals moving should I be able to bring them into focus in my view finder? I was not able to do that. Thanks!

 

[Dino]

You're likely to have a tough time focusing through a curved glass front. Its one of the reasons I want to get rid of my bow front when I can and go back to a regular flat sided tank.

 

[SimonSKL]

Dino, this is what I am afraid of. I think the curved glass creates a distortion like adding a curved filter lens making closeup focusing impossible

I wonder if anyone with a bowfront or curved glass have any suggestion to overcome this.

 

[BlueCorn]

Doug, The camera was on a tripod and I used the 2 second delayed shutter to capture the shot. The camera definitely was not moving. I have to admit I didn't turn off the PHs and return pump so the corals could have been moving. Even with the corals moving should I be able to bring them into focus in my view finder? I was not able to do that. Thanks!

The curved glass is almost certainly giving you grief. There is definitely motion as well. You might try turning on mirror lockup if you haven't already. Especially on a cheap tripod, just the act of the mirror swinging up for the shot can impart motion. I also know, from my own experience, that the floor in my tank room will vibrate if I walk on it; i.e. don't be moving around while shooting.

 

[thepenalty]

...the curved glass...

Sounds like your problem.

 

[Misled]

Yep, from one corner tank owner to another. It doesn't work well. The glass creates too much distortion. Your eyes don't pick it up without using the lens, but the lens will pick it up every time. Best to shoot top down with a box.

 

[SimonSKL]

Following Doug and Misled's suggestions I took some pictures thru an acrylic box from the top. I wouldn't call this a success, just improvement as I was not able to use manual focusing and a tripod. I had a hard time keeping the camera steady while trying to keep the box semi-submerged. Still I was amazed how well these pictures turned out.

Are those flat worms covering the coral. Are they harmful to the coral? If yes, what should I do to get rid of them.

More flat worms on this Montipora dig.