Is extension tube = extension tube ?

<error> · Jun 14, 2015

To explain : I have a Canon D40 with the 60mm macro lens. I shot macro in manual mode, so AF is no issue. I would like to shot at around 100mm, but don't have the money right now to buy another lens.

So my question is : If I go extension tube, is there anything I should pay attention to?

2nd question : I thought I have seen that TPF has an Amazon affiliate link where each buy there sends some money over to this fine forum. True?

With some spring sun from the South of France: Thanks!

tirediron · Jun 14, 2015

Yes, quality. You can buy extension tubes from eBay for <$20. Don't! My brother bought a set and the mount was so poorly milled he wound up having to get them cut off of his camera. The brand that I would recommend is Kenko; they're available on eBay, Amazon, and most bricks & mortar shops. They're well made and have the necessary contacts to transmit exposure & focus information from the lens to the body, which many cheaper ones don't.

As for an Amazon affiliate, I'm not aware of such. There are many Amazon adverts that run on TPF, but I don't believe there's a specific affiliate link.

480sparky · Jun 14, 2015

If you put a 60mm on an extension tube, it will still be 60mm.

If you want to shoot at 100mm, you'll need a 1.7x teleconverter.

Buckster · Jun 14, 2015

When I put extension tubes on my lenses, including my 180mm macro lens, it allows me to get closer to the subject with the lens and still stay in focus, than I can without them. In effect, this allows me to get even tighter shots of subjects without cropping. And because there's no glass in the extension tubes, there's no optical loss involved with it.

Bottom line: Extension tubes make a great addition to your gear for shooting tighter macros.

Kenkos are the recommended extension tubes because they do have the contacts and a good reputation for fitting and working well.

I've no knowledge of an Amazon affiliate link around here.

Overread · Jun 14, 2015

Remember a typical macro prime lens gets to a magnification ratio of 1:1. This means the 60mm and 100mm and a 180mm macro lens will all focus to that same maximum magnification ratio of 1:1. As such the frame content and composition and amount of magnification for each is nearly identical*. What does change is the amount of background blurring that goes on; the longer focal length lenses render backgrounds more blured than shorter focal length lenses.

*you will see slight variation in copy to copy and lens to lens as part of manufacture; but in all honesty you won't see that difference outside of side by side test shots.

Yzerwing · Jun 14, 2015

Overread said:
Remember a typical macro prime lens gets to a magnification ratio of 1:1. This means the 60mm and 100mm and a 180mm macro lens will all focus to that same maximum magnification ratio of 1:1. As such the frame content and composition and amount of magnification for each is nearly identical*. What does change is the amount of background blurring that goes on; the longer focal length lenses render backgrounds more blured than shorter focal length lenses.

*you will see slight variation in copy to copy and lens to lens as part of manufacture; but in all honesty you won't see that difference outside of side by side test shots.

Maybe a quick definition of magnification ratio? I am not certain on how that works or what 1:1 really means...... thanks

Overread · Jun 14, 2015

Sure - 1:1 means
Size of the image reflected on the sensor by the lens : Size of the subject in real life.

So at 1:1 the image reflected on the sensor is identical to the size of the subject in real life. This means that if you know the physical dimensions of the sensor you can then measure how big the subject is on the digital/print version and estimate the size of the subject in real life. Of course this is generally crude for photography since lenses are not made to 100% exact construction; so there is a tiny bit of play in real world situations which means if you want accurate measuring it helps to still have a ruler or similar object in the frame to measure against.