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? 

[ebiggs1]

Actually is is a wonder you got it to work at all.  You have two issues that may be interferring with each other.  Not enough light and too close.

Consider, macro lenses have very shallow depth of field (shallow area of focus) very close up. Using F/11 or F/16 to get most of small subjects in focus is a good idea. Conversely, if you do only want a small area in focus, say just the head of an insect, use a wide aperture of F/2.8 or F/4.  But that creates a very difficult situation for the camera.

If the light is not enough, your camera will not focus.  Whether you are using a macro or a normal lens doesn't matter.

You really didn't give a whole lot of info here but I suspect it is too dark and you are too close.  I am not a big fan of Tokina lenses either and it could be the problem, also.

[itsskatrina]

Sorry, I was in the bathroom, i thought it was enough light, i guess not. I wasnt close to the mantis, the tokina lense is heavy esp with the tubes attached so i have the worst camera shake..... But most times when im trying to focus i have to get a lil close or back up to see where it is that i need to be for it to perfectly focus but then when it is focusing it wont takr the picture still,

But I was curious as to what marco lenses you would suggest? Thank you so much 🙂

[Skirball]

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@itsskatrina wrote:
Sorry, I was in the bathroom, i thought it was enough light, i guess not. I wasnt close to the mantis, the tokina lense is heavy esp with the tubes attached so i have the worst camera shake..... But most times when im trying to focus i have to get a lil close or back up to see where it is that i need to be for it to perfectly focus but then when it is focusing it wont takr the picture still,

But I was curious as to what marco lenses you would suggest? Thank you so much 🙂

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I use a Canon 100mm macro lens.  It's a great lens, but I know nothing about the Tokina that you have.  Regardless, you have a lens, yet it sounds like you don't have a tripod or a flash.  I wouldn't worry about lenses until you get the other two - if you really want to get into macro photography.  The flash doesn't have to be anything fancy, just something that you can get off-camera and position in front of your subject instead of relying on the one on the camera.

Tripods are a difficult thing to recommend; other than the age old advice to buy the best you can afford.  I was given that same advice, yet  I recently just bought my fourth tripod; I swore after buying my third that I wouldn't ever need more.  My needs as a photographer changed and I had to upgrade.  The problem is, you never know what you're going to be shooting, if anything, down the road.  Paying $500+ for a tripod is tough to swallow for more beginner photographers.  A cheapo will suffice, for now, if that's all you want to spend.  But I guarantee that if you stick with it you'll be upgrading down the road. 

[itsskatrina]

Wow you paid $500+ for a tripod? What kind did you buy? & I do have too actually, I lost the small piece that attaches the camera to the pod, forgot what it's called, I haven't gotten the chance to buy a new one, and. I also have the lil small one with the crazy legs that can hang from trees and stuff, I think it's called the money tripod or spider or something like that? I will def be ordering that piece tho. 🙂

& I will also be checking out the canon 100mm lense ! 🙂

[Skirball]

Actually no, I should have been more specific.  I meant the tripod/head combo.   I got the new Manfrotto 055 tripod, in aluminium which is only $250; compared to the carbon fiber which are $400.  I was considering one of their 057 series tripods but I just couldn't stomach the cost, and I needed to purchase a geared head which was already putting me at the $500 mark for the set.

That said, I upgraded from a Manfrotto 190, which I loved.  The tripod served me well and will probably continue to do so for many years.  It's only shortcoming for me was the height, or lack thereof.  That's why I bought the 055, but now that I did, I'm amazed at the jump in quality and performance of the 055.  You don't realize what you were missing until you experience it. 

[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

[jrhoffman75]

My guess is that it is just too dark for the auto focus system. Plus, when you are that close to an object the flash won't illuminate it; it will shoot right over it.

[Skirball]

The lighting is an easy one to address.  In the second pic you didn't get the lighting in front of the subject, in the third it looks like the flash didn't go off at all.  Properly lighting macro is difficult, as there's not a lot of room to get your light inbetween your lens and subject; especially with extension tubes.  If you're using the camera's flash I'm surprised you got it to light at all.  Most either use macro-specific ring lights, or just external flashes with baffles set up to reflect light in front of the subject. 

As to focus: as many mentioned it's quite dark for AF to work, and you're subject is definitely close to being "too close" if not past that.  That's the purpose of the extension tubes, to allow you to focus closer.  That said, macro photographers mostly use manual focus (or automated focus stacking).  As you're probably finding out, the depth of field is extremely small, so you really need to choose exactly where you want your focus point, not rely on the camera to choose it for you.