Macro lens 50mm vs 105mm

[urycyon]

I need a good 1:1 macro lens for photograghing snakes.
I know that the Sigma EX 105 macro will allow me a greater operating distance, but it is more expensive. The thing i need most is decent depth of field. Which one will afford the greatest range in depth of field, the 50 or longer focal lengths? Any tips?

[CyberDyneSystems]

Okay treading thin ICE,. as I understand it.. for the same size image, the telphoto will give greater DOF as you will be farther away. The further away from the lens you are the greater the depth of feild (if all else remains equal) so by using a 105mm to get the same magnification you can increase the DOF.

[Roger_Cavanagh]

With close-up/macro photography DOF is a function of subject magnification and aperture. So the focal length of the lens is not relevant for a given magnification.

If it was me wanting to take pictures of snakes, I'd look for all the working distance I could get. :)

Regards,

[iwatkins]

.. me to. Do Canon or Sigma do a 1000mm macro ? :)

Seriously, having recently had a play with the Sigma 50 and 105 macros, the 105 is on my Xmas list as for the same shot the 105 gave me a better operating distance but DOF was very similar.

Cheers

Ian

[psk4363]

Got to say that I have the Sigma 105EX (which on the 10D performs like a 165mm lens) and I think it's a superb piece of optics. It gives you good depth of field, 1:1, and a reasonable working distance. Highly recommended.

Hope this helps,
Barry

[MediaMagic]

psk4363 wrote:
Got to say that I have the Sigma 105EX (which on the 10D performs like a 165mm lens) and I think it's a superb piece of optics. It gives you good depth of field, 1:1, and a reasonable working distance. Highly recommended.

Hope this helps,
Barry

What is the working distance of the 105EX?

I'm also looking at the sigma lenses for macro stuff. Macro is strictly something I'm interested in as a personal hobby, so I think I might give Sigma lenses another try. I'm another one who has had some terrible past experience with Sigma, but, I'm willing to give them another chance with the EX line. I've been eyeing the 105ex and the 180ex. I take it the 180 will give a 1:1 at a greater distance from the subject? I've heard only great reviews of the 105, but nothing about the 180.

My interest is in photographing spiders and insects. Will the 105 allow me to be far enough away to keep from spooking the little critters?

Thanks,
David

[EXA1a]

Roger_Cavanagh wrote:
With close-up/macro photography DOF is a function of subject magnification and aperture. So the focal length of the lens is not relevant for a given magnification.

If it was me wanting to take pictures of snakes, I'd look for all the working distance I could get. :)

Regards,

Read the above a second time - that's VERY important to know when you wanna shoot macro. And don't believe anybody who talks about a "good DOF" for a particular lens. That's bull*. At a given magnification it's completely independent of the lens construction and just a matter of aperture.
But be carefull: a smaller aperture does not only give you a greater DOF, it also decreases sharpness through light bending (I don't know the English word for the physical phenomenon that light does not go straight when meeting an edge...) in the small aperture hole.
Practically, at a 1:1 magnification the optimal aperture for 35mm is around f22. From f22 on you lose resolution while DOF increases. At higher magnifications this optimal aperture drops dramatically (to f8 at a 5:1 and f4 at 10:1 magnification).

--Jens--

[urycyon]

Hmmm, well I can't quite afford it yet, just bought a used 24-70 EX to partially replace my 300D kit lens.
I prefer the close focal distance of the 50 for the snakes, you have to position them and be ready to grab them if they try to take off, but for lizards and other wildlife the 105 would be better. Also the 105 might be easier to artificially light.

Thanks for the tips.

If I get a 15 EX, a macro lens, and someday a 50-500 EX, I should have about all the focal choices I need. Now I just need to get rid of my consumer lenses.

[iwatkins]

David,

The minimum focusing distance for the Sigma EX Macro lenses is as follows:

50mm = 18.8cm / 7.4 inches
105mm = 31.3cm / 12.3 inches
180mm = 46cm / 18.1 inches

These figures are from the Sigma specs.

Cheers

Ian

[urycyon]

Adorama posts a minimum focusing distance in macro for the 50 at 1.6 inches, but does not give this for the 105.
Distance this close would have to be required for the lens to achieve a 1:1 ratio.

[iwatkins]

Well, someone must be right :)

Figures quoted here (http://www.sigma-imaging-uk.com/a_pages/macro.htm) at the Sigma site in the UK. Whether they are correct or not, who knows ?

Your best bet is to go and try the 50mm if you can. If that gives a decent operating distance then no reason not to go for that.

Cheers

Ian

[MediaMagic]

iwatkins wrote:
David,

The minimum focusing distance for the Sigma EX Macro lenses is as follows:

50mm = 18.8cm / 7.4 inches
105mm = 31.3cm / 12.3 inches
180mm = 46cm / 18.1 inches

These figures are from the Sigma specs.

Cheers

Ian


Hi Ian,

Okay, I take it these numbers are for the lenses as related to standard 35mm film. If I understand it correctly, this means that a 1:1 Macro achieves the ratio of lifesize on the film at the minimum focus distance. So, on the 10D with the smaller sensor, the minumum focus distance should actually give the appearance of 1.6:1 or the appearance of greater than lifesize ratio (even though it will actually be life size, the smaller sensor would give the illusion of being larger than life because of the crop blah blah factor as compared to 35mm). These focus distances should be multiplied by 1.6 to get the appearance of 1:1 focus distance (same view as a 35mm) using the smaller sensor.

Is this correct? if not, how exactly does this translate to the 10D?

Thanks!
David

[aquace21]

iwatkins wrote:
The minimum focusing distance for the Sigma EX Macro lenses is as follows:

50mm = 18.8cm / 7.4 inches
105mm = 31.3cm / 12.3 inches
180mm = 46cm / 18.1 inches



If you wished to photograph insects, I'd advise getting at least the 105mm. You'll need the working distance. Do note that the figures above are the distances from the subject to the film plane or CMOS. You should be worried about the working distance instead, which is the measurement from subject to lens tip. The 105mm should have a working distance of approx 15cm.

DOF is the same for whichever lens you use. Only the perspective is different. E.g., for 180mm, the background looks 'blurrer' due to the fact that its perspective is narrower.