Need info on Extension tubes

davev · August 15, 2005

I have read a few things about extension tubes, but haven't seen them in person.

I've read that you can buy them in a 3 piece set.

How much closer can the tubes get you?

Do you lose any stops while using them?

Can they be used with any lens?

Can they be stacked?

Anything you know about extension tubes will be helpful

The reason for this question, I have a Sigma 80-400os that the min. focusing
distance is 6 feet. Pathfinder has said that tubes would help, I'm just wondering
how much.

Thanks.

pathfinder · August 15, 2005

davev wrote:

I have read a few things about extension tubes, but haven't seen them in person.

I've read that you can buy them in a 3 piece set.

How much closer can the tubes get you?

Do you lose any stops while using them?

Can they be used with any lens?

Can they be stacked?

Anything you know about extension tubes will be helpful

The reason for this question, I have a Sigma 80-400os that the min. focusing
distance is 6 feet. Pathfinder has said that tubes would help, I'm just wondering
how much.

Thanks.

Hi davev. Extension tubes are simply 'tubes' that fit between the camera body and your lens - extending the lens further from the film/sensor plane and thus moving the close focus point closer to the front surface of the lens.

They typically come in matched sets of three - 12mm, 20mm, and 36mm. They can be mixed and matched together for a total extension of 12+20+36=68mm of total extension.
The Kenko brand set of tubes is $159 at B&H -- http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=375102&is=REG&addedTroughType=search

The instruction sheet that comes with the Kenko set has a table listing the image magnification ratio for a 50mm lens as 0.24 with the lens focused at infinity and 0.4 lens focused at 0.5 menters using the 12mm extension tube.

Using a 50mm lens, and all three extension tubes ( 12+20+36), the mag ration varies from 1.34 when the lens is focused at infinity, and 1.47 with the lens focused at 0.5meters.

As the lens is extended farther from the film plane, the effective diameter of the iris aperature is smaller, and hence there is an exposure factor that occcurs for 1.5 with the 12mm tube, to 6.1 with all three tubes. This efectively means that you need to plan on using flash as your light source. This can also make AutoFocus more difficult or impossible with stacked tubes and a slow lens.

If you are shooting with an EOS body, the exposure compensation is done automatically for you.

I have always thought that any lens can be used with extension tubes - they are a neat addition to telephoto lenses as I suggested to you about your grasshopper - but B&H says that EF-S lenses 18-55 f/3.5-5.6, 17-85 f/4-5.6, 60 f/2.8 macro are not compatible with the Kenko DG extension tubes. Not sure why this would be true, but that is what B&H says, so.......

Extension tubes can also be used in conjunction with a 250D or 500D +diopter macro lenses that screw into the filter ring on the front of a lens and act as a bifocal letting the lens focus closer. The Canon 500D comes in 52mm, 58mm, 72mm, and 77mm sizes. The 250D comes in 52mm and 58mm diameters. The 500d is a better choice to use on your Sigma 80-400 as the filter size is 77mm on your Sigma 80-400mm zoom.

If you search dgrin for extension tubes and Greaper( who has posted numerous shots done with extension tubes ) you should find some posts of interest.

Here are a couple of shots that included the 12mm extension with my 180mm macro lens - I liked these shots because the first one demonstrates the wear and tear, the hard life of a mature butterfly....and the second one a nice close up of a bee at work.

GREAPER · August 15, 2005

I have the three peice set of Kenko auto extension tubes for Nikon. I know they make them for Canon as well.

I often use all three stacked on a 28-80mm zoom.

Metering and TTL flash controls work fine through the contacts in the tubes.

Autofocus is about useless as your DOF is very shallow even at f/16 so it will hunt like crazy. I find the best way for me to achieve focus is to get close, then zoom the lens in and out for fine focus. This allows the zoom to act like a bellows

I often use the pop up flash on my D100, and it works suprisingly well, but it does sometime cause hotspots. A diffuser would help, but a ringflash, or a flash set up like Pathfinder uses, or a lightsphere, or something to give a softer more even light would be better. I am practicing with my flash off camera. but I need to make (or buy) a setup to control the flash's distance from the subject.

It is a fun way to get out with your camera and almost anything can look interesting when you can get that close.

Here are a couple I took with this setup.

davev · August 15, 2005

Thanks guys for the info.

Are the photos that you (both of you) posted full frames or crops?
I would like to get a little closer sometimes so I don't have to crop so much.

after the crop

before the crop.

Thanks again.

pathfinder · August 15, 2005

My images are almost always cropped to a certain extent, since I try to upload 4x5 ( or 8x10) ratio images to smuggy, so they can print on standard paper. Some of my images are 80% of the original frame, some are maybe 30%.
Closer is better, and filling the sensor is better, but with flying insects, that can be challenging to accomplish and I have to settle for what they (the bugs) will permit me.

I know the "I NEVER crop school" is always around to make us feel like lesser shooters, but for me, it is not about HOW it was shot, but WHAT does the Image LOOK LIKE!! Crop away as needed, I say.

pathfinder · August 15, 2005

Nice shots, Brian, a good demonstration that light and compostion make shots, not necessarily fancy equipment. Extension tubes are an inexpensive, but effective, way to explore close up and macro shooting.

davev · August 15, 2005

pathfinder wrote:

My images are almost always cropped to a certain extent, since I try to upload 4x5 ( or 8x10) ratio images to smuggy, so they can print on standard paper. Some of my images are 80% of the original frame, some are maybe 30%.
Closer is better, and filling the sensor is better, but with flying insects, that can be challenging to accomplish and I have to settle for what they (the bugs) will permit me.

I know the "I NEVER crop school" is always around to make us feel like lesser shooters, but for me, it is not about HOW it was shot, but WHAT does the Image LOOK LIKE!! Crop away as needed, I say.

I'm not opposed to cropping, I'd just like to do a little less of it, so if I wanted, I
could print a pic larger.

GREAPER · August 15, 2005

All three of the shots I posted are full frame uncropped images.

davev · August 16, 2005

GREAPER wrote:

All three of the shots I posted are full frame uncropped images.

Thanks Greaper.

Need info on Extension tubes

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