Macros

[Tim Vaughan]

Hello all, I am a beekeeper, and I am doing some studies that require good macros. I have a G3, and I am constrained by my DoF. Here is a photo I took this week. You can see portions of the ant and the honeybee it is attacking are out of focus. The max f value I can get out of my G3 is f8, and I need to get much better than this.

http://www.pbase.com/image/28466111

My question for the board is this. Can I achieve a significantly better DoF by upgrading to a Canon Digital Rebel? And if so, what sort of macro lense you all recommend?

Thanks and regards
Tim

[karusel]

That close, you won't get much more DOF with any lens/setup as far as I can tell. Should anyone know how, please tell me...

The compact cameras are (in)famous for their lack of shallowness of DOF, SLR's need to be stopped down much further to achieve the same DOF.

[cgratti]

SLR's need to be stopped down much further to achieve the same DOF.

What do you mean by Stopped down???? Please explain, I am a noob and was just wondering...

[Tim Vaughan]

I understand that you can stop some of them down to up to f/32?

[Scottes]

What do you mean by Stopped down???? Please explain, I am a noob and was just wondering...

Stop down: to set the aperture to a smaller setting, ie; going from f/4 to f/5.6. This would result in more Depth of Field, since the smaller the aperture the larger the DoF.

[Osmium]

Have a read through this:

http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml

And you'll find a lot of folks here:

http://www.fredmiranda.com/forum/board/45

who should be able to help you.

[Lamplight]

If the smallest aperture you can currently stop down to is F8, then a DRebel with just the kit lens will go significantly lower. Then you could buy a macro lens and really go nuts. :D

[Tim Vaughan]

Osmium, I've briefly read through the links you gave me, and have registered on the forum you recommend. You obviously understand this subject, and I wonder what your opinion is of the question I asked. Will it be worth it for me to upgrade from a G3 to a Rebel Digital? Or should I save my money and wait till I can afford something better?

Thanks very much.

[Tim Vaughan]

Lamplight, what lense do you recommend?

Oss, the forum you recommended is somewhat messed up, and seems impossible to join.

Regards and thanks.

[Lamplight]

I only mentioned a macro lens after seeing Myrmecos' wonderful shot here:

http://photography-on-the.net/forum/showthread.php?t=31116

I would love to try some shots like that eventually! :)

[Tim Vaughan]

Thanks, Ben

I guess I'll have to blow my honey account and get this lense, there's more to life than a savings account.

Very best.

[Digital Prophet]

I am sorry to put in my thoroughly unknowledgable thought. But would a tele-macro lens maybe help? I have a 70-300 telemacro and I seem to get an ok FoD. Then again I really am not entirely sure how to use it correctly ( I have noob-itis).

Just a thought.

- Digital Prophet -

[Osmium]

The reason I pointed you at that forum is that the people there are far more expert than I am at macro photography.

That said, if I re-phrase your original question to: Given the photo example posted, would I have been able to take the same photograph with greater depth-of-field if I had been able to use a D-Rebel setup instead of a G3?

You'd have to do the math, but the sensor on the Rebel is larger than that on the G3. Therefore the required magnification of your subject to get the same photo is higher (see below). Therefore at f8 the DOF would be more shallow. Stopping down would at one point give you the same DOF and stopping down further would give you greater DOF. You'd have to calculate the numbers. You could then work out if this is "significantly" better.

Then there's the question of magnification. Let's say that ant is 3 or 4 mm long. Then it's occupying about half the frame width of the G3 (7.18mm). So we're seeing about 1:1 magnification. To fill half the frame of the rebel (22.7mm) you'd need a magnification of approx 3:1 (3x). A "standard" macro lens of whatever focal length will normally give you 1:1 magnification. So you'd either have to use a macro lens with extensions or bellows or the Canon MP-65 lens to achieve that magnification.

Now I've exhausted my knowledge. You'd get a far better response from the macro gurus on the forum... so...

As to registering on the forum: Near the top of the page that the link points to is "Login | Register". Click register, fill in the required info, wait for your password in an email then off you go!

[Edit: I had my ratio around the wrong way - 1:3 is 1/3 3:1 is 3x]

[Scottes]

Yes, a longer telephoto macro will help, but most (any?) zooms won't get to 1:1. A 180mm macro would get a lot more DoF than a 100mm since you'll be further away from the subject.

[Digital Prophet]

True, mine only gets to 1:2 in macro mode. Not that I am entirely sure what that means. It just seemed to me that maybe the answer wasn't a matter of being physically closer, just a closer view.

- Digital Prophet -

[Scottes]

1:2 means that the subject on film is half the size of the actual subject. This is always measured from 35mm film frame size, so a subject 36mm long would end being half as wide as the resulting image. (Digital crop factors make this seem larger.) 1:1 would fill the frame.

A telephoto macro allows more working distance - you're further from the subject - so the resulting depth of field is larger compared to a shorter lens at the same aperture.

[cowman345]

Taken with a 10D, which is close enough to a DRebel. Canon 100mm f2.8 macro lens:

http://www.davecollinsphoto.com/images/photos/gallery1/012.jpg

DOF is always a problem. This shot was taken stopped down to at least f22 with direct sunlight and diffused flash from a 420ex off to the side as fill.

-dave-

[Osmium]

Tim, you might also like to check out this:

http://www.mplonsky.com/photo/article.htm

especially since most of his pix are created with the G3. Might make you think twice about upgrading...

[Osmium]

I was loathe to put this up because I couldn't find the reference - but I'm pretty sure it's right:

According to something I've read somewhere :roll:

Depth of field varies directly with F-number and inversely with the square of the magnification. I checked the f-number part with a set of tables I have on hand. Everything else being equal, if you change the f-stop from f8 to f16 you get twice the depth of field. The magnification part I haven't been able to check - I'm sure the gurus here will correct me if I'm wrong, but I think it's right...

So, in the example above, going from G3 setup to DRebel setup. The magnification is increased by 3 to get the same picture. Therefore the depth of field is reduced to 1/9th of the DOF you get with the G3 setup if both are at f8. So to compensate, you'd have to change the fstop from f8 to f72!!! To get the SAME DOF!

Ok. Go to it folks... tear me to shreds!! :D