little help please! - extension tubes

[mattsnoise]

This is probably cringe-worthy but because they were only £10.80 on ebay, I bought a set of unbranded extension tubes just because I could, and to have a play with. What I haven't really done, is looked into exactly how I should be using these, I've tried them with both my lenses this morning (Canon 18-55 and a 55-250mm) and had a little bit of fun with them in the house (I'll take them outside later) just to see what they can do.
I've established that you have to be almost with the lens touching the object for it to be in focus which feels really weird, and I keep having to judge the distance with my fingers as I'm conscious of knocking the end of the lens which I really don't want to do. The other thing I've noticed is that you get a really great depth of field, more so than I would without them - I have no control over the aperture whatsoever because these aren't the Canon ones with the elements running through them - I was just wondering, if you set the aperture before adding the extension tubes, will it remain at what you've set it or does it revert to some sort of default? (I ask this because it would maybe provide a way round the depth of focus issue, it would be much better to have less depth and more of the image in sharp focus)
Also - and the answer to this may well be get a tripod - with 5-6cm of tube and then a 55-250mm lens on the end, its is very, very difficult to stop wobble effecting the photo no matter how I try to stabilise my arms or the camera - any tricks on this front?
Thanks in advance!

 

[SamHH]

The longer the focal length, the less magnification you will get but the more working distance (distance between lens and subject). Try using different focal lengths to get the best compromise for any given photograph.

You can stop the lens down by setting your desired aperture (without the extension tubes attached), pressing and holding the depth-of-field preview button, then removing the lens and re-attaching it with the extension tubes. The problems are that you have to repeat this process every time you want to change the aperture and the viewfinder will be darker because the lens will be stopped down permanently, not just when the shutter is opened. If you can afford them, extension tubes with the electrical contacts make things much easier. There are third-party ones that are much cheaper than the Canon ones.

Regarding the camera shake, you may find that you need a shutter speed far faster than the usual 1/focal length rule. Use a fast enough shutter speed and the shake won't be a problem. As usual, to get a faster shutter speed you either have to increase the aperture size (at the expense of depth-of-field), increase the sensor or film sensitivity (at the expense of noise or grain) or add more light from a flash.

Using a tripod can be a solution for static subjects. Because even the slightest movement can vastly alter the framing and focussing though, you really do want a very sturdy tripod and head with smooth movements that lock down tightly. If you're dealing with a tripod that starts to move whilst you're adjusting it, things can get very frustrating.

For moving or likely to move subjects (like insects), forget using a tripod in my opinion.

 

[dtartagonidis]

I think you've bought the wrong tubes. They're maybe for Canon mount, but because there are no pass-through conections, your camera will not comunicate with the lens, thus dissabling AF and apperture control. Without apperture the depth of field will be too shallow (depending on the lens used). Yes, you can set the apperture, remove the lens, attach the tubes and re-attach the lens, but soon you'll get bored and fed up.:bonk:
Have a look at Kenko AF tubes, they're virtualy the same as canon's, but cheaper.

 

[mattsnoise]

The Kenko tubes are still cheaper but not quite as cheap as these ones
For the sake of £10 I'll have a fiddle with them over the next week and see what I can get out of them - thanks for the help!

 

[mattsnoise]

I've also read about these close-up or macro filters that provide magnification and a therefore a macro effect like with the extension tubes - given that these sit on the other side of the lens would they be another relatively cheap alternative and provide decent results without the faff?

Any opinion welcome.

 

[SamHH]

I've also read about these close-up or macro filters that provide magnification and a therefore a macro effect like with the extension tubes - given that these sit on the other side of the lens would they be another relatively cheap alternative and provide decent results without the faff?

Any opinion welcome.

Yes, they give you more magnification without interrupting the communication between the lens and camera.

As for relatively cheap; the cheap ones, yes; the expensive ones, no. Obviously, the cheap ones will degrade the image quality more than the expensive ones and whether any given filter will provide good enough results for you I don't know.

 

[squishy]

Look into the raynox DCR-250 and DCR-150 supplementary lenses.

They should get you to 1:1 on the 55-250mm and they're surprisingly good optically. I used one on a bridge camera for 2 years and got some nice results.


To stop your lens down, you can do the DoF preview button trick. Basically, you set the required aperture (usually between f/8 and f/14 for macro), then hold the DoF preview button while dismounting the lens.
Just a little disclaimer, canon don't recommend doing this.

 

[mattsnoise]

Those Raynox lenses appear (on initial inspection) to be quite good judging from reviews.
Would these be a better option - in terms of not degrading image quality as much as a cheaper close-up filter (I've seen then from about £40) ?

 

[squishy]

I have no experience with the cheap close up filters, but several people I know have tried them and most have either never used them again or binned them.
Some of them still use them though. I think it depends on whether you buy good ones or bad ones, but you have no way of telling how good it's going to be over the internet.

However, everyone I know who uses them is very pleased with the raynox lenses, and I was very impressed with mine.

My 2pence .

 

[artyman]

This is a shot taken with the el cheapo tubes on a 100mm lens. Don't stop down too far else the viewfinder becomes too dark for focusing. You will be on manual focus and find it easier moving back and forth to focus rather than twist the lens. Just takes practice.

 

[mattsnoise]

I though it would be worth concluding that I may just have bought the Raynox DCR-250 and it is completely different in terms of ease of use compared to cheap extension tubes - will take a little bit of getting used to but that'd merely an excuse to go and use it
Thanks everyone!