Extension Tubes

Extension Tubes

Extension tubes are tubes without any optical elements that you place between the camera and lens of an interchangeable lens camera. They extend the lens so it can focus closer, giving the lens macro capabilities. Some have full automatic couplings so the camera can continue to be used in all its auto and program exposure and focus modes. Some lower priced ones have no couplings, so the camera needs to be used in manual.Extension Tube Set
Tubes are often sold in sets of three. The set illustrated above has 13mm, 21mm and 31mm extensions, and these can be attached in any combination giving a total of seven different extensions:

  • 13mm
  • 21mm
  • 31mm
  • 34mm (13mm+21mm)
  • 44mm (13mm+31mm)
  • 52mm (21mm+31mm)
  • 65mm (13mm+21mm+31mm)

Camera with Extension Tubes
Here a set of three tubes can be seen attached to a Nikon digital SLR camera.

extension tube example photoThis photograph of a British one pound coin was taken using a nikon camera with a 55mm lens set to infinity and an extension tube added. The smaller coin on the left is with the 13mm and the coin on the right is with the three tubes attached giving 65mm extension. The lens was at f/2.8 to show how shallow depth of field is.  When using tubes you either need to use a very small aperture or shoot the subject parallel to the CCD or film plane. Here the coin was at an angle so only a shallow strip across the centre is sharp.

Advantages of using Extension Tubes
Low cost macro
No optical degradation
Compact

Disadvantages of using Extension Tubes
Limited magnification variations
Fiddly changing between magnifications
Taking lens off increases risk of dust intrusion

We have a selection of extension tubes in different camera fittings

 


Fungus on Photography Lenses

Fungus spores are everywhere, but they only germinate in humidity and they thrive on dust.

A lens that has a dose of fungus has it because it has dust inside (and all lenses have some specs of dust even if they’re hard to see), and it’s been kept in a humid/warm environment. Fungus likes dark, damp places with warmth. Fungus generates spores which look to feed on dust, but the amount of dust in most lenses isnt enough for the fungus to spread.

When you clean a lens you move the dust around and push it into the edges. If the lens is then stored in a humid environment it’s more likely to encourage fungus growth. The fungus wont spread from lens to lens but it may appear in other lenses if the conditions are right for it.

So it’s best to store your lenses in a dry place in good light with minimal humidity. Also use them – the UV in sunlight kills fungus.

Fungus on rear elelemt of a Pentax 135mm lens

The above photo shows one patch of familiar fungal veins. This is on a rear element and is hard to spot without scrutiny. 

The best way to check for fungus is to shine a bright light in through the front or rear. A mini torch such as a Maglight is ideal.

Can fungus spread from camera lens to lens?
Does lens fungus spread from one lens to another? It’s a common question. Much is written about the subject on the internet…and views are mixed – some saying yes it does spread so you should isolate the infected lens and some say no, don’t worry about it.

Fungus on lensThis lens has lots of fungal attack ont the front element that’s creeping out to the centre. At present this could be used without any real loss in quality.

Using infected lenses
You can often clean fungus off the lens elements providing it’s not etched into the coating. If it’s on the inner elements you’ll need to strip the lens down but only attempt that if you’re competent with mechanical items as they’re not always as simple to take apart as they look.
If the lens is stored well once fungus is found it’s unlikely to spread.
Lenses can be used and results will vary depending on the level of contamination. A small colony here or there is hardly likely to affect anything while a more severe case will cases a dramatic reduction in contrast and sharpness, especially when shooting into the sun.

bad condition lens

This lens is badly affected and will result in lower contrast photos that lack sharpness and have a diffused look.

For those who want more info check out this informative web page: All about lens fungus


Teleconverters

A tele-converter is a budget accessory that will increase your photography options. The most common one is a 2x converter that doubles the focal length of your lens. Your 50mm lens becomes 100mm, your 70-300mm zoom becomes 140-600mm.

Vivitar Teleconverter Vivitar made a number of converters through the 70s and 80s.

Teleconverters are ideal for photography such as sports and wildlife.

Advantages:

  • increased magnification
  • light weight
  • cheap

Disadvantages:

  • light loss
  • quality degraded

Several teleconverters converters for sale here


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