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PostPosted: Wed Oct 14, 2009 4:33 am 
Insects. 8)


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PostPosted: Wed Oct 14, 2009 6:42 am 
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Weeeell, Graham: Those buggers wont sit still :twisted:
At least not the German ones I know...

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PostPosted: Wed Oct 14, 2009 7:31 am 
That's too bad. I thought I would have problems with insects and the working distance of my 60 macro but I was pleasantly suprised. It will cease to be pleasant once they actually do actually start moving. :roll:


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PostPosted: Thu Oct 15, 2009 6:31 pm 
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The Canon 500D with 77mm filter-thread arrived today.
First tests on my Sigma 400/5.6 APO macro show a magnification of 1:0.88=1.14x at closest focus distance (at which the lens alone goes to 1:3) and 1:1.25=0.8x at infinity.
Phew: This is exactly as I predicted/calculated a few posts back 8)
So I had calculated the effect of the shrink-factor of this lens correctly :D

With respect to resolution the Sigma+Canon combo was clearly suffering from low contrast at f/5.6 in my current artificial lighting set-up and improved markedly at f/8. At f/8 and smaller apertures it becomes comparable to the micro-Nikkor at f/4.5 which in itself improves a bit when stepped down to f/5.6 and keeps the contrast from then on.
I have to find a setup at the weekend where I can be sure that contra-light is not overly putting one lens at a disadvantage.
Apart from contrast it was hard to judge critical sharpness as the test-target so far is not optimal and focusing around 1:1 (even manually with magnified LiveView support) is super critical. But I did not immediately see any weakness from the Sigma+Canon combo

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PostPosted: Thu Oct 15, 2009 7:48 pm 
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Here's an image I shot tonight (with flash). Sigma 400/5.6 APO macro plus Canon 500D combo at f/8.0. Postprocessing included standard settings, no additional sharpening, only a little curves to optimize contrast.

Feather:
Image
Click through for the large original in all its pixel-peepable glory :wink:

As you can see at 1:1.2 (roughly) the fine structures of a feather are still not fine enough to tax resolution.

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PostPosted: Sat Oct 17, 2009 10:33 am 
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Just testing the Sigma 300/4.0 APO macro with the Canon 500D close-up filter.
At the closest focusing distance the magnification of the combo is 0.92x = 1:1.08. The working distance (front-lens to subject) is around 30 cm.*
At infinity you get 0.6x = 1:1.67 and 50cm working distance.
Again: This is as calculated.

The 300mm Sigma also showed pretty low contrast wide open (f/4.0) just like the 400mm at f/5.6. Both improve when stopping down to f/8.0 or f/11. But at magnifications around 1:1 - 1:1.6 the dof produced at f/4.0 or f/5.6 is barely usable. So this should not hold you back.
The biggest challenge at these magnifications is SHAKE! And the need to have the shortest possible exposure.
If you look through the viewfinder with my 400mm lens plus close-up filter mounted on my tripod you immediately see that this combo is much more prone to shake than e.g. the Sigma 150/2.8. The length and weight of the 400mm lens is the reason for this. If you want to shoot this combo freehand look out for some support of the front-lens - otherwise you have to go for 1/1000 sec, even 1/2000 sec minimum. And that at f/11. Can you imagine the amount of light and/or ISO you need to shoot :shock:
-----
*remember the Sigma 300/4.0 goes down to 1:3 all on its own at closest focus distance of 1.2m.

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PostPosted: Sat Oct 17, 2009 11:54 am 
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At longer focal length macro, I find a flash is very useful.

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PostPosted: Sat Oct 17, 2009 1:57 pm 
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Yeah, flash is the practical way to cope with the risks of shake in many macro situations!

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PostPosted: Sat Oct 17, 2009 6:18 pm 
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Went out with the Sigma 300/4.0 APO macro + Canon 500D combo this evening to look for mushrooms. What I want to show you here are some practical examples of what magnifications of 1:3 or 1:1.3 mean.

The first one was captured with the close-up filter and a magnification of around 1:1.3:
Image

The next photo is a capture of same mushroom without close-up filter. The lens alone goes down to 1:3:
Image

Following is a 100% crop of a photo similar to the last taken also at 1:3. It gives you a good feeling what 1:3 magnification means:
Image
Shot at f/8.0, 1/250 sec, ISO 720 with the aid of a monopod

Now for my kind of macro-photography 1:1 or even 1:1.5 is seldom necessary. I'm pretty happy with what I can get at 1:3. And I think, when you look at the 100% crop with the grains of sand you would not have bet that this is "only" 1:3, right?

What I find most annoying is the limited variance in magnification when you put the close-up filter to a fixed focal lens. This gets much better, when you put it in front of a zoom. So I'm really looking forward to using the Canon 500D close-up filter on a 70-200mm/2.8 zoom giving me a calculated range of 1:7 - 1:2.3 which fits neatly to the range the lens can do all by itself.

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PostPosted: Sat Oct 17, 2009 6:45 pm 
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Some additional remarks:

In that last crop with the grains you can see what little dof you get at 1:3 and f/8.0. Keep in mind that you need to stop down 2 stops to double the dof and that doubling the magnification (i.e. from 1:3 to 1:1.5) reduces the dof to a quarter, tripling the magnification (i.e. from 1:3 to 1:1) shrinks the dof by a factor of 9 :shock:
You would have to stop down to f/72 to keep the same dof as in the above shot. Not many lenses can do that :wink:

There's also the effect that larger sensors produce smaller dof. So if you really, really want some decent dof at magnifications close to 1:1 you should use a camera with a very small sensor like a compact,

If you ask now what focal length gives you 1:3 = 0.33x magnification with a 500mm close-up filter, here's the answer:
focal length of lens = focal length of close-up filter x magnification
which yields in our case
167mm = 500mm x 0.33

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PostPosted: Wed Nov 18, 2009 7:22 pm 
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Just mounted my 77mm Canon 500D close-up filter with a 77->72 step-down ring on my Nikon 18-200.
Results at 200mm and focus to infinity* yielded the predicted results: a magnification of 1:2.5! Very nice with the stabilization of the super-zoom helping a lot.
But when you focus the Nikon closer (up to 50cm) the incredible shrink-factor of this zoom prohibits that you get any larger magnification. In fact focusing the lens to 50cm reduces the magnification to about 1:3.4 :shock:

---
*remember: When the lens is focused to infinity the distance of the subject to the close-up filter mounted to the front of your lens is just 50cm :idea:

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PostPosted: Wed Nov 25, 2009 5:08 pm 
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I've opened a new thread and posted some comparisons to show you the quality of the Canon 500D close-up filter.
It is open for everybody to post his 100% crops shot with close-up filters.

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