Sigma 105mm F2.8 Macro
Aug 23, 2013 15:24:37 #
I am trying out this lens and I can only get it to go down to f2.8 when it is focused to infinity. Anything less it only goes down to f3.5. Anyone have this problem? Is this the same with the Nikon 105mm f2.8 Micro?
Aug 23, 2013 15:34:01 #
Aug 23, 2013 15:47:46 #
Aug 23, 2013 15:56:26 #
darkmanCANADA wrote:
Can anyone explain why?
It is possible, and I am going out on a limb here that with virtually all lenses the focal length is measured when the lens is focused at infinity.
As you focus closer, the focal length of the lens increases (obviously) and the aperture decreases.
Some Nikkor macro lenses use an internal cam to open the aperture up as the lens is focused closer. This however does not work when the lens is wide open.
So it may be that the Sigma lens is showing true aperture as it cannot be a f2.8 lens if focused at (say) 2 feet.
This would be a VERY strange way for the lens to indicate aperture.
Another possibility is that the lens is knackered.
Oliver.
Aug 23, 2013 16:11:17 #
Terra Australis wrote:
It is possible, and I am going out on a limb here ... (show quote)
Brand new, out of the box lens. Looked at a bunch of other forums and seems this is a quirk of the lens. It is being offered at a $160 rebate at the local camera store. So this puts it at $90 below the Nikon 105mm f2.8 Micro. I am going to play with it over the weekend and then try out the Nikon next week. Then I will decide.
Aug 23, 2013 16:13:54 #
darkmanCANADA wrote:
Brand new, out of the box lens. Looked at a bunch of other forums and seems this is a quirk of the lens. It is being offered at a $160 rebate at the local camera store. So this puts it at $90 below the Nikon 105mm f2.8 Micro. I am going to play with it over the weekend and then try out the Nikon next week. Then I will decide.
If it was only $90 less than the Nikkor I would not wast my time with it.
Aug 23, 2013 16:19:03 #
"If it was only $90 less than the Nikkor I would not wast my time with it."
Yeah what he said.
Yeah what he said.
Aug 23, 2013 16:22:23 #
Terra Australis wrote:
If it was only $90 less than the Nikkor I would not wast my time with it.
I don't see your reasoning. The regular price of the Sigma is $889 (without rebate) and the Nikon $809. The Sigma has a slightly better features:
Sigma 105mm f2.8 Macro
Focus limiter: Full, .0312-.045m, .045-infinity
Optical stabilization: Off, 1-horizontal & vertical, 2- horizontal only
Nikon 105mm f2.8 Micro
Focus limiter: Full, .50m-infinty
VR: On or Off
I chose to test the Sigma first because I already have a Sigma lens and I like the build.
Aug 24, 2013 06:15:52 #
darkmanCANADA wrote:
I am trying out this lens and I can only get it to go down to f2.8 when it is focused to infinity. Anything less it only goes down to f3.5. Anyone have this problem? Is this the same with the Nikon 105mm f2.8 Micro?
This is not a problem, but a rule of physics. The diafragm number is calculated as (distance focuspoint to sensor) / (width of the diafragm opening).
If you go to a shorter distance, this number will become higher as the focus distance becomes longer; you see your lens comes out.
So the full opening at infinity is 2.8, but going closer it becomes 3.5 and at 1:1 the focus distance is doubled, so the number becomes up to 5.6.
Only the number is changing, of course you still use your full opening.
Nothing to do with Sigma, every lens in the world has it. Even Nikon can't break the rules of physics. With a macro lens you see it clearer due to the enormous reach in distance. But take a normal 50 mm lens, put an extension ring of 50mm on it. It comes to 1:1 and you loose 2 stops.
Aug 24, 2013 06:42:52 #
Do you loose light with internal focus lenses like the Canon 100mm macro?the lens does mot physically extend, at least not externally.
Aug 24, 2013 09:19:22 #
External or internal , you will loose light as the lens focuses closer - but it is insignificant until you get to around 10 times the focal length of the lens.
Aug 24, 2013 14:40:09 #
You could do what I did when I was shooting with a Canon 5D and wanted a macro lens. I ordered both the Sigma 105 and Canon 100L from B&H to try them both out. I thought the Canon was slightly better on the Canon and returned the Sigma to B&H.
If interested here is a link to my un-scientific testing of both:
http://wingincamera.zenfolio.com/lens-test
If interested here is a link to my un-scientific testing of both:
http://wingincamera.zenfolio.com/lens-test
Aug 26, 2013 00:29:19 #
Aug 26, 2013 16:24:08 #
hikercheryl wrote:
No, it is not the same with the Nikon 105 Micro.
I went to the camera store again today. That this is the same on the Nikon 105mm f2.8 Micro. It is a function of the internal focusing of both lenses. This is not the case with the Tokina 100mm f2.8 where the barrel extends as the lens is focused closer.
Aug 26, 2013 17:54:25 #
I shoot with the Tokina 100mm on a daily bases.. It also goes to F/5.6 when focused to the closes working distance at 1:1. But the good news is it's only about $500 brand new and is as good as any lens you have mentioned so far. I've posted at least 1,000 macro photos if you want to take a look and see how sharp it is. It does not have the VR, but I use a flash and never need it anyway.
darkmanCANADA wrote:
I went to the camera store again today. That this is the same on the Nikon 105mm f2.8 Micro. It is a function of the internal focusing of both lenses. This is not the case with the Tokina 100mm f2.8 where the barrel extends as the lens is focused closer.
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