Macro Extension Tubes - Help...

[Remorhaz]

I have a question for those more knowledgeable than I, if someone can help me out...

I have a Nikon D7000 and the Tamron 90mm f/2.8 1:1 macro lens (amongst others 50/1.4, etc) but was thinking of acquiring something to allow getting even closer (e.g. I'd like to try something like eyes on a fly/spider, etc type shots - you know the ones )

So I was thinking of the Auto Extension Tubes and so my questions go:

- Is this the best way to go (extension tubes)?
- From what I can tell using all three tubes with my existing macro lens might get me out to around 1.7:1 - am I about right? is this enough? (I notice the go to lens for Canon users is that MP-E 65mm which allows like 5:1)
- Is it (much) better to get the auto versions of the tubes (which carry the electronic coupling for AF, TTL AE, etc) rather than the much cheaper ($15) manual only set?
- I've seen a few brands which support Nikon AF/AE including the Kenko ($160-300), Phottix ($95+), Opteka ($70+), Meike ($62+), etc - is the Kenko version that much better than the others? any NOT to get?
- Am I just dreaming? what else am I missing/forgetting?

Any help greatly appreciated...

[Mr Darcy]

I doubt that will get you as close as you are hoping.
I have the Nikon105VR and the Kenko Tubes
I can't comment on the other brands, but the Kenko ones work well. Remember there is no glass in them so you only need a good electrical contact and a reasonably rigid tube (all three Kenko stacked get a little wobbly when I use them with the 500mm Reflex.)
Personally I wouldn't consider the contactless tubes.

Here are some posts where I use them in concert:
viewtopic.php?f=17&t=35215 There are some photos of a $2 coin here taken with the 105VR & Kenko tubes
viewtopic.php?f=18&t=38314 Macros of funghi and a matchhead for scale.
viewtopic.php?f=5&t=37224 Comparison of 85/1.4 with Kenko tubes and the 105VR. Subject is an imperial ruler

The ruler in the second is graduated in 1/32 inch. (~0.8mm)
Unless the fly has a big eye, you will still be a ways off.

Also with the D7000 you will be running into diffraction issues if you stop down too far, so DOF will be a real issue.
Maybe you can join me in the Focus stacking experiments I am playing with at the moment.

Other options: reverse your 50mm in front of the 90. Use some electrical tape to hold them together and force the iris open on the 50mm with a pin or similar.
Get some magnifying filters to screw on the front of your lens
Use a teleconverter to increase the focal length of your lens. This will effectively get you closer. I sometimes use my 105VR with the 2x Converter to get me a 210mm macro lens. The add the tubes. It starts to get scary.
Combine several of the above.

You are welcome to borrow my tubes for a while. I hope to come down to the city soon. I need to return Cam's ultrawide I borrowed. Or you could come up.

[ATJ]

- Is this the best way to go (extension tubes)?

It tends to be the easiest and cheapest route. It also gives you flexibility. It won't give you the maximum amount of magnification possible. Reversing a lens is best for that.

- From what I can tell using all three tubes with my existing macro lens might get me out to around 1.7:1 - am I about right? is this enough? (I notice the go to lens for Canon users is that MP-E 65mm which allows like 5:1)

Sounds about right. The longer the lens, the less magnification change you get from a given length of extension. For example, a 36mm extension alone on my 60mm lens gets me to 1.7:1.

I rarely use more than 2 stacked and don't even do that very often. Each join leads to a bit of instability and with 3 stacked, the lens tends to droop. You'll need some way of mounting or holding it as that will affect the image.

- Is it (much) better to get the auto versions of the tubes (which carry the electronic coupling for AF, TTL AE, etc) rather than the much cheaper ($15) manual only set?

Once you get up to that level of magnification, you'll need to use flash to light the subject. Auto or manual won't make any difference to iTTL flash so you don't really need the auto.

That said, I got the auto ones so the AF works - not that I use the AF to focus for the shot, but rather I use the it to get in the range and then focus by rocking forward or back. I usually shoot macro with the D300 and it has an AF-On button. The camera can be set to only focus from the AF-On button rather than the shutter button. By using the AF-On button, I can shoot one handed (with the camera on a monopod) and focus with that one hand.

- I've seen a few brands which support Nikon AF/AE including the Kenko ($160-300), Phottix ($95+), Opteka ($70+), Meike ($62+), etc - is the Kenko version that much better than the others? any NOT to get?

I'm very happy with my Kenko tubes and I've not heard anything bad about them.

- Am I just dreaming? what else am I missing/forgetting?

Most likely and probably.

[Mr Darcy]

Auto or manual won't make any difference to iTTL flash so you don't really need the auto.

Except that if you are using them with a G type lens, you need the contacts to control the aperture.

I rarely use more than 2 stacked and don't even do that very often. Each join leads to a bit of instability and with 3 stacked, the lens tends to droop. You'll need some way of mounting or holding it as that will affect the image.

If I have to do it I try to shoot vertically to solve this problem. Gaffer tape should also work well. The trial with the 500Reflex was just to see what would happen. I wouldn't recommend it as a practical scenario.

[phillipb]

A set of bellows would be my preferred method, assuming you can still get your hands on some.

[Remorhaz]

Thankyou everyone for your very useful info

Auto or manual won't make any difference to iTTL flash so you don't really need the auto.

Except that if you are using them with a G type lens, you need the contacts to control the aperture.

Pretty much what I was thinking - I don't care so much about the AF (I expect to MF anyway) and I do expect to use added light (my LED macro ring light + SB900). My issue is I think maybe all my lenses are gelded. My Tamron 90 has no aperture ring, my 50/1.4 also (and it would be a nightmare to reverse - it's very large - has 77mm front thread) - actually looked at the whole lot - all 9 current lenses have no aperture ring I used to have the 50/1.8D but sold it when I got the Sigma 50/1.4

Also with the D7000 you will be running into diffraction issues if you stop down too far, so DOF will be a real issue. Maybe you can join me in the Focus stacking experiments I am playing with at the moment.

Was planning to do that too (although was unsure how I might control the different shots - I have no rails, etc so was going to try the handheld move slightly forward and backward and shoot and hope that auto alignment would work somewhat

Get some magnifying filters to screw on the front of your lens

Yep - saw some conflicting comments on the Raynox DCR-150 and DCR-250

Use a teleconverter to increase the focal length of your lens.

I went to try that too I have the 1.4 TC which I've not actually used yet - however I can't mount the Tamron in front of it - the glass at the back of the Tamron sticks out

You are welcome to borrow my tubes for a while

That would be great - if you don't mind - thanks

A set of bellows would be my preferred method, assuming you can still get your hands on some.

Less than $50

http://www.linkdelight.com/L7C-Lens-Mac ... -Lens.html
http://fotodioxpro.com/index.php/camera ... d7000.html

but I assume I'll have the same gelded lens problem as with the non auto extension tubes - i.e. I'd have to buy a lens to go with this


and going back to the rails topic I just found these for not very much (2 way rail for $15 and 4 way for $37):

http://www.linkdelight.com/K4G-2-Way-Ma ... entax.html
http://www.linkdelight.com/K1O-4-Way-Ma ... amera.html

[biggerry]

I have a PK-13 extension tube, bought on teh cheap for 20 bucks or something from foto resiol, the cheapest and easiest way to get past 1:1.

As mentioned elsewhere, comparing to the canon lens is bit fruitless, you will not get close to that level in terms of mag. or quality.

check this thread from yonkos ago, its a tick

http://www.dslrusers.com/viewtopic.php?f=18&t=39100&p=411767#p411767

and

http://www.dslrusers.com/viewtopic.php?f=18&t=37820&p=400875#p400875

i am prolly gonna be around your side this week and was thinking about dabbling in some more fungi fantastico..may crack out the extension tube for a play then.

[Remorhaz]

i am prolly gonna be around your side this week and was thinking about dabbling in some more fungi fantastico..may crack out the extension tube for a play then.

Tell me if you do - I'll see if I can make it too

[Mr Darcy]

I have dropped off my tubes with Cameron. He knows they have your name on them.

[biggerry]

i am prolly gonna be around your side this week and was thinking about dabbling in some more fungi fantastico..may crack out the extension tube for a play then.

Tell me if you do - I'll see if I can make it too

I have dropped off my tubes with Cameron. He knows they have your name on them.

tomorrow, either lane cove or botanical gardens...leaning towards lane cove.

[Matt. K]

Extension tubes are the way to go. Why? Because they contain no optics and so don't degrade the prime taking lens. I believe that when the extension, measured in millimetres, equals the focal length of the lens then 1:1 magnification is achieved. (This is from memory so is not gospel). Problems.....lack of DOF and very long exposures. These problems can usually be solved by shooting at smallest F stop and using a sturdy tripod.

[Mr Darcy]

Because they contain no optics and so don't degrade the prime taking lens.

when the extension, measured in millimetres, equals the focal length of the lens then 1:1 magnification is achieved.

Interesting comment Matt, and it would explain ATJs point that their effect decreases with focal length. But I do wonder how this is measured in the real world. It would have to take into account the closest focus of the lens in question. a 50mm macro lens (lets say closest focus 50mm without tubes) but stacked with three tubes bringing focus down to 10mm would not achieve the same magnification as a 50mm normal lens with closest focus of 300mm before tubes. Surely?

[Steffen]

Actually, the magnification is 1:1 if the lens extension is exactly twice the focal length. In general the magnification is calculated as:

Code: Select all

m = (a' - f) / f

Where a' is the lens extension (distance between lens centre and film plane). Depending on the lens design it's often not obvious where the centre of the lens is, some lenses have two centres, and with some lenses the centre even lies outside the physical dimensions of the lens.

With reasonably simple designs (only one centre) one doesn't need to know where exactly the centre lies, because the magnification relates directly to the sum of lens extension and subject distance (measured from the centre point):

Code: Select all

a + a' = (m + 1/m + 2) * f

For example, to achieve a magnification of 2 with a 50mm lens one has to place the subject 225mm away from the film plane and bring the rig into focus by extending the lens.

Unfortunately, many macro lenses (such as the 60mm Micro-Nikkor) are complex designs and actually change their focal length during focussing, so things aren't that easy. However, with simple a 50mm or 35mm Tessar, or the 55mm f/3.5 Micro on a bellows this works well.

Cheers
Steffen.

[Mr Darcy]

Thanks for that explanation Steffen.

So the lens extension is not taking about the extension tubes, but about the distance of the centre of the lens to the film plane. i wonder if this is the same as the nodal point which is taken to be the optical centre of the lens for panorama work. That is fairly easy to work out. And yes sometimes it is actually outside the physical lens itself. Though I have no idea how they achieve this.

Surely though, with tubes or bellows, you don't need to worry about lens complexity as this will have to do with the mechanism of altering focus within the physical lens. If you alter focus by moving the physical lens you should be able to treat it as a "black box" simple lens albeit of a focal length not necessarily the one printed on the side.

Hmm. I wonder if you could make a bellows that works as a CPU lens? It shouldn't be too hard. Just run the contacts along a coiled wire down the outside of the mechanism.

[Matt. K]

Thanks Steffen
Can always count on you for the technical stuff. It's been awhile since I had to do the mathematics and I always give the red wine first preference.

[Steffen]

Oh, same here, I'm getting rusty on most of the things I used to know and nothing beats red wine. Moreover, I learned my physics and optics in German, so I'm sometimes not quite sure about the correct English terminology. Greg, "nodal point" sounds about right, I guess that's what it's called.

A lot of wide-angles lenses have whacky designs, otherwise they wouldn't be possible on SLRs. At infinity focus the lens extension is exactly the focal length – any lens wider than 45mm or so would be out unless they managed to move the nodal point behind the lens (or required permanent mirror lock-up, like with a couple of the early Nikkors).

Cheers
Steffen.