Help on kenko tubes

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TheLaird

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I am now even more confused than before. Setup 5DII, 50mm and tubes.

Issue #1 - how to focus
Do you actual focus using the focus ring or just put it at any setting and move the camera back and forth? It seems that since the DOF is so small, that it does not matter about focussing with the lens but just use the physical placement of the camera.I tried using the focus ring to no avail. I also expect AF does not work.

Issue #2 - F/stop
Does changing the aperature really give more of a DOF that is noticable? It seems to me that since the DOF is so small, it does not really matter. So stick it at f1.4 for light !

Issue #3 - focus stacking
If the answer to #1 above is you can use the focus ring, then I can concieve how to focus stack. However if it requires movement of the camera, how does this work?

Saying all that, I am hooked !! Please help me out so I can focus and get shooting.
 
I'm very much using the cheaper end of the scale, but ..

1) Move the camera, if you adjust the focus position of the lens, you actually also alter the magnification.

2) The DOF is very small, and I'm not sure how much of an effect stopping the lens down achieves... but at f/1.4, as far as I can tell, there is so little DOF as to have almost nothing in focus... Perhaps someone can answer that specifically

3) Move the camera as any other change, alters the magnification. The easiest option is to mount the camera on macro focusing rails on a tripod. The rail allows for very find adjustments in position, and therefore you can take shots in thin slices.
 
TheLaird said:
Issue #2 - F/stop
Does changing the aperature really give more of a DOF that is noticable? It seems to me that since the DOF is so small, it does not really matter. So stick it at f1.4 for light !
Click to expand...

I'm also just starting having bought a macro lens, and in terms of f stop with that you need to be thinking f16+ or in the f20's to get a usable DOF. I imagine the same or more will apply with tubes.

But yes, it does make a big difference.

Then for light, start thinking flash.
 
Rich R said:
I'm also just starting having bought a macro lens, and in terms of f stop with that you need to be thinking f16+ or in the f20's to get a usable DOF. I imagine the same or more will apply with tubes.

But yes, it does make a big difference.

Then for light, start thinking flash.
Click to expand...

But be aware that once you start using small apertures with extension tubes you may suddenly notice a number of small dark areas which weren't part of the pic.

This is DIRT on your sensor which can suddenly come into sharp focus when taking macro shots.

You can then clean your sensor using something like the Rocket Blower or else clone them out.

Anyway good luck with your macro - it's extremely addictive!

.
 
So I gather using extension tubes and a tripod are OK for items that are not moving. When trying to photograph flowers or insects, you cannot use a tripod as you need to move the camera to focus. Therefore you need light (and a flash and high ISO are options) to get a fast enough shutter speed when down at F14-22 range.

Unless I bring the flowers indoors of course ....... too much wind outside in the Highlands of Scotland !!
 
The tubes, as well as making the image appear larger also allow the lens to focus closer. This means even with a short tube on you will not be able to focus very far. You should use a high f stop to get better sharpness from your lens and also better DoF. You should not go beyond F16 with your camera or the image will be degraded by diffraction. Focus stacking is achieved by moving the camera around 2/3 of the distance of the DoF using a macro slide or other means. The stack can then be processed to align the photos and merge them together. I don't change the focus, just move the camera.
 
For moving subjects, I use a camera mounted flash with an adapter I made to bring the light around the lens... and bump the ISO to 400 to get a shutter speed of the flash sync speed.
 
TheLaird said:
I am now even more confused than before. Setup 5DII, 50mm and tubes.

Issue #1 - how to focus
Do you actual focus using the focus ring or just put it at any setting and move the camera back and forth? It seems that since the DOF is so small, that it does not matter about focussing with the lens but just use the physical placement of the camera.I tried using the focus ring to no avail. I also expect AF does not work.

Issue #2 - F/stop
Does changing the aperature really give more of a DOF that is noticable? It seems to me that since the DOF is so small, it does not really matter. So stick it at f1.4 for light !

Issue #3 - focus stacking
If the answer to #1 above is you can use the focus ring, then I can concieve how to focus stack. However if it requires movement of the camera, how does this work?

Saying all that, I am hooked !! Please help me out so I can focus and get shooting.
Click to expand...


Issue 1. When I use mine I set the ratio I want then I rock my body back and forward until I am in focus and the focus plain is where I want it, once I was shown it was easy to focus.

Isuue 2. Absolutely critical to change apperture to get as much dof as possible, also and external light source is critical to help with shutter speeds and DOF.

Just an example with my first outing with my 105vr a full set of tubes and a 1.4 tc lite with a r1 macro flash kit, hand held. iirc this gives you appor 2.7 magnification.

Exbury-9.jpg

d300 iso200 exp 1/200th sec F40
 
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