Extension Tube

[lambchops511]

Sorry if no ebay links are allowed:

http://cgi.ebay.ca/Macro-Exten...VWQQrdZ1QQcmdZViewItem

Is that a good extension tube to work with a Canon 50mm 1.8 prime?

I think since I can't pickup a nice used body cheap, i will buy a new XTi body for around 500 and then pickup a 18-55 IS for 200 and then this extension tube with a 50mm prime. Sounds good?

 

[ElFenix]

no coupling with the lens whatsover, so it won't focus, it won't focus confirm, it won't meter, and it won't set the aperture.

i think fbb has the pro optic extension tube set

 

[lambchops511]

thats several times the cost O_O .

sorry for being noob

i know what focus is

aperture is like the size of part that absorbs the light

but what is metering?

 

[ElFenix]

Originally posted by: aznium
thats several times the cost O_O .

sorry for being noob

i know what focus is

aperture is like the size of part that absorbs the light

but what is metering?

i take that back, it should meter. if you set the camera to aperture-priority it'll do it. i've done it literally holding a lens out in front of the camera. so if it can do it with no connection between camera and lens, it should be able to do it with a tube.

meter is the camera measuring the light and suggesting an exposure. if you've got it set to aperture priority, it'll figure out the proper shutter speed to use based on the amount of light the meter is seeing.

however, you'll probably want the ability to control the aperture. that can be difficult with canon eos lenses as you can't set the aperture on the lens. i think the workaround is to set the aperture and then pull the lens off the camera, but i'm not certain.

the reason you want to control the aperture is that depth of field is miniscule at high magnification and short distances. stopping down the aperture will allow you to get more of the subject in focus.

 

[fuzzybabybunny]

Pretty much was Elfenix said. Without any electrical contacts between the lens and the body, there's no way to stop down the aperture for increased DOF unless you manually stop it down before each shot by pressing the DOF preview button and then twisting the lens off the body while the button is pressed. And then you'll be trying to focus a very dim image.

 

[jpeyton]

If you plan on using a cheap extension tube or reversing ring, pick up a cheap manual prime lens as well. The ones that have beefy aperture and focus rings for full manual exposure. They tend to be cheaper than newer AF primes.

 

[fuzzybabybunny]

Jesus, is this a moderator party or something???

 

[lambchops511]

LOL @ fuzzy

thanks for all the help guys!

jpeyton.....which cheap manual prime lens would your recommend then?

Thanks for all help again!

 

[fuzzybabybunny]

Originally posted by: aznium
LOL @ fuzzy

thanks for all the help guys!

jpeyton.....which cheap manual prime lens would your recommend then?

Thanks for all help again!

Ehhh.. I'd still recommend getting a set of real extension tubes with the electrical contacts. The reason is that you need to be able to stop down the aperture. The manual lenses will allow you to mechanically stop down the aperture, but this will really dim the image that you see through the viewfinder, making focusing very difficult.

eBay extension tubes: $20

Pro Optics: $80

Manual prime: $50? So $50 + $20 is already $70, and you won't be getting autofocus and you'll have to look at a really dim image to focus.

 

[lambchops511]

Originally posted by: fuzzybabybunny

Originally posted by: aznium
LOL @ fuzzy

thanks for all the help guys!

jpeyton.....which cheap manual prime lens would your recommend then?

Thanks for all help again!

Ehhh.. I'd still recommend getting a set of real extension tubes with the electrical contacts. The reason is that you need to be able to stop down the aperture. The manual lenses will allow you to mechanically stop down the aperture, but this will really dim the image that you see through the viewfinder, making focusing very difficult.

eBay extension tubes: $20

Pro Optics: $80

Manual prime: $50? So $50 + $20 is already $70, and you won't be getting autofocus and you'll have to look at a really dim image to focus.

good point . but if im going to spend 200 (80+100) ...... i might as well spend a little more to get a real macro lens? ie. 60mm macro

 

[fuzzybabybunny]

Originally posted by: aznium

Originally posted by: fuzzybabybunny

Originally posted by: aznium
LOL @ fuzzy

thanks for all the help guys!

jpeyton.....which cheap manual prime lens would your recommend then?

Thanks for all help again!

Ehhh.. I'd still recommend getting a set of real extension tubes with the electrical contacts. The reason is that you need to be able to stop down the aperture. The manual lenses will allow you to mechanically stop down the aperture, but this will really dim the image that you see through the viewfinder, making focusing very difficult.

eBay extension tubes: $20

Pro Optics: $80

Manual prime: $50? So $50 + $20 is already $70, and you won't be getting autofocus and you'll have to look at a really dim image to focus.

good point . but if im going to spend 200 (80+100) ...... i might as well spend a little more to get a real macro lens? ie. 60mm macro

Well, what exactly is a "real" macro? Is it simply an ordinary lens that has the ability to focus really close so that it can do 1:1 (1x) magnification?

So you buy a 60mm f/2.8 macro.

Compare this to an $80 50mm f/1.8 + $80 ProOptic extension tubes.

To get 1X magnification, the formula is

magnification = extension tube length / focal length

So to get a 1X magnification, you need 50mm worth of extension tubes and a 50mm lens. The ProOptics come with 21mm, 31mm, and 13mm tubes that can be stacked in any order. So the 50mm + 31mm tube + 21mm tube would get you to that 1X magnification.

The extra tubes will decrease the light gathering ability of the lens by about two stops, so 50mm f/1.8 becomes very close to a 50mm f/2.8.

So, 50mm f/1.8 + extension tubes can become close to a 50mm f/2.8 macro lens. For about $160. Plus you can pop off the tubes and use the 50mm f/1.8 by itself if you don't need macro. Or use the tubes on any other lens to allow the lens to focus closer.

The dedicated 60mm f/2.8... you're stuck with f/2.8. You always have the macro ability whether you use it or not. And it's more expensive.