Advice about a reversed lens

Started Jan 25, 2009 | Discussions thread
Joseph S Wisniewski
Forum ProPosts: 33,991Gear list
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You're controlling the wrong lens...
In reply to dlakier, Jan 26, 2009

dlakier wrote:

Hi,

Hi.

I have been playing with a reverse mounted 50 on my D50 for quite a
while now, and it has produced some neat images, but it was quite
tedious to keep manually adjusting the aperture after composing since
the camera could not do it.

I'm sorry, but on a D50, this "tedium" is just something you have to deal with. You always need to control aperture via the reversed lens, whether it's directly on the camera or reversed in front of a lens mounted on the camera. (or add an extra "inter-lens" aperture in between a pair of coupled lenses. That improves the results, and increases the tedium).

The only "solution" to the tedium is a gadget called the Nikon BR-6, which attaches to a reversed lens and lets you stop it down and fire the camera using a dual cable release. The only problem is that Nikon's dual cable releases cannot work with the D50 (or D40, D60, D70, D80, or D90). There is a mechanical dual release that works with the ancient D100, and an electrical release that works with D700, D300, D3, D200, D2X, D2H, D1X, and D1H.

So, I baught a 52 mm reverse coupling adaptor to allow me to stick
the 50 in front of another (normally mounted) lens and still get good
magnification. The only lens I have with a 52 mm filter thread is
the kit 18-55 lens. This makes taking pics much easier, and I get
quite nice shots. Here is a crop:

http://lh5.ggpht.com/_O84CCRGiV20/SXx-Zm0yeeI/AAAAAAAAPSw/HuUC1zwNa18/s800/_DSC2099-1.JPG

The problem is, that no matter what focal length I set the 18-55 at,
I get signficant vignetting. Here is an example with the 18-55 set
to 55:

http://lh5.ggpht.com/_O84CCRGiV20/SXx-Z4S5KvI/AAAAAAAAPS8/4DachPjlj8c/s400/_DSC2099.JPG

That is normal. Even with two lenses coupled, you need to keep the one on the camera wide open. You still control exposure and DOF using the aperture control on the reversed lens. But don't give up on coupling because of that, it still typically produces sharper, less distorted results than mounting a reversed lens directly on the camera.

That aside, the 18-55mm kit lens is a bit short for working with a reversed lens. I typically recommend at least 70mm. A 70-300mm lens is great behind a reversed 50mm...

Here is an even worse example when I accidentally did not have the 50
focused at infinity.

http://lh5.ggpht.com/_O84CCRGiV20/SXyBV2FlenI/AAAAAAAAPTw/evbU_hCdQNU/s400/_DSC2104.JPG

So, how do I improve on the situation? Here are some of the options
I have com e up with:

1) Try couple the 50 to my 18-200, but this will require a huge
step-down ring (72-52). This is cheap ($5), but I am worried about
the huge difference in front element size.

Don't worry, it won't affect the picture. I've used a reversed 50 in front of a 70-200mm f2.8, and that needs a 77mm coupler. Doesn't help your aperture problem, though. You still need to adjust that on the front lens.

Now, the 18-200's front
element is not really that big, there is a bunch of plastic next to
the lens, so it might work, especially at longer focal lengths. I
could get even more extreme and couple it to my 80-200 but that seems
like a bit much.

Actually, it's a better choice than the 18-200. Less distortion.

2) Buy another 50 (cheap used manual one) for $75.

The best way to control aperture on a pair of face to face 50mm lenses is the "inter-lens aperture". You set both lenses wide open, and mount an additional aperture mechanism in between them, in the macro coupler itself. I built one using two 62mm Cokin P-rings ($7 each) and an Edmund Optics aperture (about $60). And I built a coupler with a "Waterhouse Stop" holder from a pair of P-rings for the princely price of about $14. To use it, you slip in a number id cardboard sheets, each containing a round hole (the "Waterhouse stop") of various sizes. If you think your current system involves tedium...

The inter-lens stop is actually a good technique any time the ratio of the two lenses is less than 3:1, a 50mm in front of a 105mm or a 135mm, a 50mm in front of a 70-200 when the 70-200 is set to 150mm or less. You get the best sharpness...

3) Buy a used 55-200 for about $80. This could give me up to 4x
magnification...

Yes, but you still need to control the front lens...

4) Stop screwing around and buy a real macro lens for around $400-$500.

That's in addition to mastering coupling, not an alternative to it. A "real" $400-500 macro lens takes you from infinity to 1x magnification. (Miron pointed out that there are some that go to 1.5x). Coupling covers the range from 1x to 10x.

(a good bellows and an assortment of enlarger lenses and microscope objectives also covers the 1x to 10x range, but that's beyond the scope of today's discussion.

Or is this just a function of me being careful the 50 is focused to
infinity always?

Both front and rear lens get focused to infinity when coupling. Focusing is done by moving the camera with a device called a "focusing rail".

wizfaq

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Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com

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