Extension tubes

Wheels

Wheels

Julian Keeler
Messages
2,812
Name
Julian
Edit My Images
No
I was snapping away with my nifty 50 of with an extension tube to get real close up shots of some forget me nots at my parents today, I then thought about putting the tube on my 18-200. We put it all together and tried focusing manually on a nest in my parents neighbours garden, no matter what I did I couldn't get anything in focus. Are the tubes for just close up work? :thinking:
 
I'm no expert so someone may well correct me but yes, they reduce the minimum distance on your lens which is why you can use them for macro.
 
It's very simple really. The further you move the lens away from the camera body, then the closer the point of focus - just look at what happens when you move your lens from infinity to its closest focus!

If you put extension tubes (tubes that are just hollow tubes with no lenses in them) between the lens and the camera body, then you are moving the lens even further away thereby bringing the point of focus even nearer than the lens can normally focus.

It always amazes me how little grasp of basic physical optics many people have - I suppose it reflects the state of science education in schools these days.
 
Somelier said:
It's very simple really. The further you move the lens away from the camera body, then the closer the point of focus - just look at what happens when you move your lens from infinity to its closest focus!

If you put extension tubes (tubes that are just hollow tubes with no lenses in them) between the lens and the camera body, then you are moving the lens even further away thereby bringing the point of focus even nearer than the lens can normally focus.

It always amazes me how little grasp of basic physical optics many people have - I suppose it reflects the state of science education in schools these days.
Click to expand...

Must be just me being a dumb **** then
 
Somelier said:
It always amazes me how little grasp of basic physical optics many people have - I suppose it reflects the state of science education in schools these days.
Click to expand...
Plus the increased amount of automation in cameras, reducing the perceived need for technical knowledge. And the Internet lowering people's ability to think and research for themselves.

Jonathan (a grumpy old man)
 
I must have wrongly assumed that me asking the question was a way of researching.
 
Wheels said:
Must be just me being a dumb **** then
Click to expand...

Used extension tubes on my 100-400 to capture butterflies

Worked up to around 4m in distance, by zooming, it was effectively moving my focal plane in and out, focus/auto-focus was pointless.

Suggest you get to a wall, side on, and try looking through the camera whilst zooming in and out along the wall, this will help to get an idea of where your focal range will be with te tubes in.
 
coldpenguin said:
Used extension tubes on my 100-400 to capture butterflies

Worked up to around 4m in distance, by zooming, it was effectively moving my focal plane in and out, focus/auto-focus was pointless.

Suggest you get to a wall, side on, and try looking through the camera whilst zooming in and out along the wall, this will help to get an idea of where your focal range will be with te tubes in.
Click to expand...

Thank you I will give it a try later.
 
And there was I thinking that this was one of the friendlier forums, it would seem we are seeing some completely unnecessary remarks :thumbsdown:
 
Snapsh0t said:
Of course I have but I look things up first then ask if I can't find the answer. I don't expect to be spoon-fed.
Click to expand...

Let's hope u don't need some advice on anything, I will be the first to stick it up your a.rse.
 
Snapsh0t said:
Of course I have but I look things up first then ask if I can't find the answer. I don't expect to be spoon-fed.
Click to expand...

What a nice chap you appear to be, this is a forum, people go to forums to learn and enjoy a bit of banter not to be belittled. Why dont you pop along to DP, you'll fit right in there
 
SussexBlue said:
What a nice chap you appear to be, this is a forum, people go to forums to learn and enjoy a bit of banter not to be belittled. Why dont you pop along to DP, you'll fit right in there
Click to expand...

The stuck up git doesn't even know if I attempted to look it up. Not worth peein on if on fire.
 
This is a lovely read, perhaps no-one should ask any questions on here for fear of offending someone :bang: (if a question has been asked before, or annoys you, why not just ignore it people!?) :D

Despite the unnecessary comments, there's some good advice in this thread! Richard's post sums up how they work, and the wall trick is a good one to see whereabout you focus.

One thing though, if you have a set of extension tubes on the 18-200 and set it at 18mm, you'll be able to get quite extreme macro, but you'll have to focus so close that you'll probably block out all light.

I think a rule of thumb is something like to get 1:1 macro use the same amount of extension as focal length.... so a full set of tubes on a 50mm lens is about 1:1. If you use them on a longer lens, you'll be able to focus closer, but with a less extreme effect. Don't quote me on that though!
 
Last edited:
chris321 said:
This is a lovely read, perhaps no-one should ask any questions on here for fear of offending someone :bang: (if a question has been asked before, or annoys you, why not just ignore it people!?) :D

Despite the unnecessary comments, there's some good advice in this thread! Richard's post sums up how they work, and the wall trick is a good one to see whereabout you focus.

One thing though, if you have a set of extension tubes on the 18-200 and set it at 18mm, you'll be able to get quite extreme macro, but you'll have to focus so close that you'll probably block out all light.

I think a rule of thumb is something like to get 1:1 macro use the same amount of extension as focal length.... so a full set of tubes on a 50mm lens is about 1:1. If you use them on a longer lens, you'll be able to focus closer, but with a less extreme effect. Don't quote me on that though!
Click to expand...

Thanks Chris I had a play around against the wall today and got the idea of the focal point, as for using them with 18-200 for macro. Found a video this evening showing how to position a flash to compensate for blocking the light with the lens.
 
Snapsh0t said:
Of course I have but I look things up first then ask if I can't find the answer. I don't expect to be spoon-fed.
Click to expand...
For a guy who has only been here for 2 minutes, made only 15 posts and most of them rubbish you certainally have a massive chip on your shoulder which i would like to knock off.
 
Can we knock the personal threats out please folks.
 
You must log in or register to reply here.
Back
Top