Camera wont take picture, hard time focusing?

[itsskatrina]

I shoot with the Canon Rebel T3i. Sometimes when taking marco (tokina marco lens with intention tubes) photography my camera (or lense) will not or can not focus on the image (in my case my praying mantis) I am shooting inside the house so lighting isnt the best but I also had my flash on aswell. Some of the pictures were coming out good but some were coming out without the flash and dark. I dont understand why this is happening. Also when I'm focusing i'm using my eye piece and the camera or lense is struggling to focus, going in and out of the subject. its like a hit or miss and im becoming very frustrated. For example check out the second & last picture, both pictures i was using flash. Im really dissappointed that the second one came out dark..... help? 

[TCampbell]

Although don't flinch too much at the price tag.  I have a number of tripods and heads.  

Thom Hogan, a photographer who usually shoots with "that other brand" camera, has a blog... it's actually an interesting perspective:  http://www.bythom.com/support.htm

To sum up...  if you need a solid platform (and you do), then everytime you buy an inadequate tripod (for whatever reason) and then have to buy a replacement... you can just keep adding those price tags together.  Eventually you hit the point where, had you just bought the really expensive tripod to begin with... you'd have saved money.

When shooting macro at minimum focusing distance, depth of field (the range at which objects appear to be in acceptable focus) can get EXTREMELY thing.  I have a photo of a coin laying on a desk.  The surface of the coin is tack sharp.  The desk it is sitting on is soft (no longer in sharp focus)... in just that tiny amount of distance.

There's a technique called "focus stacking".  There are applications that just do focus stacking.  But it's also a built-in feature of Photoshop (part of photomerge).    The photographers change the focus just a very tiny bit at a time.  Serious macro photographers will buy something called a focus-rail.  This sits on the tripod and you mount the camera to the rail.  You take a shot, adjust the rail just a milllimeter or two at a time (it has index marks), take another... repeating until you've completely photographed the object from front to back... then you stack the images to get an image where the entire subject is focused.

I don't do enough macro to justify having a rail.  I have done this with the focus ring.  To do this, I wrap a piece of masking tape around the focusing ring on the lens.   I focus the lens to the nearest focus distance, then put a mark on the tape (using a Sharpie).  I focus to the farthest focusing distance and add another mark.  Now I carefully photograph the object from front to back using the tape and the two marks ... moving it just a very tiny amount each time ... until I've moved the focusing ring from the first mark to the second mark.

[ebiggs1]

"But I was curious as to what marco lenses you would suggest?"

Anything that has the Canon brand name on it.  Avoiding 3rd party lenses helps avoid issues.

Also remember with extension tubes on it and a wider aperture, you DOF will be paper thin.  It is extremely easy to move in and out of focus if either you or the subject moves even the smallest amount.  I am talking 1/16 of an inch or even less.

Good luck