How to focus a macro lens

[nirmal]

Hi,

 

I'm just beginning to get into macro photography of flowers and such.

I recently bought a Nikon 105mm macro lens. This question is really

about focusing this lens on a particular object... I'm not sure if

this is the forum to ask this question. So, my apologies if it isn't.

 

Suppose, the f-stop I have chosen is f8 and have mounted the camera on

a focusing rail. Now... when I move the camera back and forth to

focus on an object, does the viewfinder show what will be in focus at

f8 or do I have to hold down the depth of field preview button for

that? I tried both and it seems to me that I DON'T need to hold down

the depth-of-field preview button to see what is going to be in focus

at f8.

 

Because, if I choose f22 as the aperture for an exposure and I press

the depth-of-field preview button, I see almost nothing. Focusing

would be very hard if I have to hold down the DOF preview button at f22.

 

Please help. All help is much appreciated.

 

Thanks,

Nirmal.

[al_kaplan1]

In a perfect world you could tell the depth of field in your Nikon's finder. The optics in the finder and the fresnel lens under the ground glass make this hard to do, plus as you've discovered, the finder gets dark when you stop the lens down. You still have to judge the sharpness at the shooting aperture, dark as it may seem. Nothing in this world is easy.

[richard harris]

John Shaw's tip for focusing at small apertures using DOF preview is to stop the lens down slowly and gradually while looking through the viewfinder and holding down the DOF preview. That way you give your eyes time to adapt to the darker finder.

[eric_palmer1]

To help your eye adjust even more, drap a cloth over the back of the camera to exclude more ambient light.

 

Use a shutter release cable if you are not already to avoid camera shake at slow shutter speeds and large f stop settings.

 

Enjoy this lens. I have one and love mine. I use mine as a macro for flowers, bugs and spyders. It also makes a fine portrait lens for tight facal shots.

 

Cheers,

[nirmal]

Thanks for the answers. I mentioned in my posting that "it seems to me that I DON'T need to hold down the depth-of-field preview button to see what is going to be in focus at f8".

 

I suppose I'm asking why the DOF seems the same when I look in the viewfinder while not pressing the DOF preview button and while pressing the DOF preview button.

 

Thanks

[todd peach seattle, washi]

<i>

"it seems to me that I DON'T need to hold down the depth-of-field preview button to

see what is going to be in focus at f8"

</i>

<p>

Depending on how you have your F100 set up and what you're shooting, there may not be much difference. If you're shooting at near 1:1, the wide open effective aperture is around f/5.6, so stopping down to f/8 is a pretty small change.

[craig_bridge]

In addition to Todd's answer, your eyes have an adaption property that diminishes with age. In looking through the finder with a bright screen found in most AF bodies, you can "see" images that are in focus in front of and behind the focusing screen. The longer you stare at something, the greater the more trouble you have telling where the image critical focus is wrt the focus screen plane.

[stemked]

Hi Nirmal.

 

I don't know exactly what you are photographing or what kind of effect you are going after, but unless you REALLY want a very limited DOF you will normally in macrophotography be looking at stopping your lens down further than f8 (I'm normally shooting f16 of f22 unless I'm really going for a dramatic effect of a small subject). Keep in mind that it is *generally* better to have out of focus effects behind your subjects rather than in front of your subjects. Yes, it can also provide a dramatic 'popping' out to have out of focus items in front of your focused subject, but you have to do this with a lot of for-thought otherwise the closer in out of focus subjects become ugly distractions.

 

No doubt DOF is tricky to use especially if the subject is already somewhat dark. Sometimes, frankly, it just isn't possible. If your lens has the marks on it for hyperfocus or you happen to be using a camera that has a hyperfocus feature you can use this as another way to control your macro image. Focus first manually and then, using the marks on the lens for a given f-stop, refocus the lens now placing the subect at the min But as another poster noted the difference between f5.6 and f8 isn't going to be generally all that dramatic.

[Ed_Ingold]

There are tables to show the depth of field - basically, you don't have a lot to work with (<1/4"). John Shaw, and others offer some advice:

 

Move around to get the major objects in a plane, parallel to the film plane. The focusing helix isn't very effective at ratios closer than 1:4, so a focusing rail is the best option. You can easily rack the camera forward and back to optimize the focal plane.

 

I don't find the DOF button very effective for checking subject focus. However, it is very useful to check the effect of f-stop on the background.

[Ed_Ingold]

There are tables to show the depth of field - basically, you don't have a lot to work with (<1/4"). John Shaw, and others offer some advice:

 

Move around to get the major objects in a plane, parallel to the film plane. The focusing helix isn't very effective at ratios closer than 1:4, so a focusing rail is the best option. You can easily rack the camera forward and back to optimize the focal plane.

 

I don't find the DOF button very effective for checking subject focus. However, it is very useful to check the effect of f-stop on the background texture.

[Ed_Ingold]

I apologize for the duplicate response. I made a mistake confirming the message.

[nirmal]

Thanks, everyone for answering my question.

[peter liebert]

I love this lens as well and would add that a bright flashlight is often helpful when focusing in the dark field of a stopped-down lens.

 

I would not do this with most creatures, but flowers, etc. work well. Clamp (or even rubber band) the light to your tripod and you won't need to grow a third arm, though I wouldn't discourage it :-)

 

I once jerry-rigged a very simple foot-operated on/off switch so I wouldn't have to take my hands off the camera/lens to turn off the light to shoot/meter, etc.

 

-Peter