extension tube & close-up filter

[EiRiK]

whats the difference between extention tubes and close-up filters?
both useful for macro pics but are there any distinct functional differences between them?

 

[EiRiK]

come on... so many EXPERTS here...
no one can explain this to newie like me?

 

[roygoh]

I am not an expert, but would like to share what I know...

When a subject is closer then the minimum focusing distance of a lens, this means that the lens is not able to focus the image onto the film plane, but the image is instead focused onto a plane that is behind the film plane.

There are 2 ways to get around this.

1. Use a closeup filter. This bends the light rays before they enter the lens, to enable the lens to focus the image onto the film plane.

2. Move the lens further away from the film plane, so that the image is now focused on the film plane. This is achieved by using an extension tube.

The pros and cons, in my opionion, are:

1. Closeup filters are more convenient to use than extension tubes.
2. Closeup filters are generally cheaper than extension tubes.
3. Close up filters are smaller and lighter than extension tubes.

So what's so good about extension tubes? My guess is that when you use close up filters, you are adding more glass in the optical path, thus degradation of the image quality.

When you use extension tube, you are simply adding more air into the optical path, which in theory should not degrade the image.

Some teleconverters have removable optical elements, such that they can also function as an extension tube with the optical element removed.

- Roy

 

[EiRiK]

whats the difference between extention tubes and close-up filters?
both useful for macro pics but are there any distinct functional differences between them?

i posted this question in the GENERAL section, but only got 1 answer(appreciate it though)... want more opinion...

 

[tsdh]

Originally posted by EiRiK
i posted this question in the GENERAL section, but only got 1 answer(appreciate it though)... want more opinion...

The one answer in your previous post is good enough.
So, what else you want?

 

[roygoh]

Originally posted by EiRiK
i posted this question in the GENERAL section, but only got 1 answer(appreciate it though)... want more opinion...

Sigh..if you really appreciate my answer you should have expressed that in your original post and not come over here to ask the same question again...

 

[chriszzz]

Originally posted by roygoh

1. Closeup filters are more convenient to use than extension tubes.
2. Closeup filters are generally cheaper than extension tubes.
3. Close up filters are smaller and lighter than extension tubes.

So what's so good about extension tubes? My guess is that when you use close up filters, you are adding more glass in the optical path, thus degradation of the image quality.

When you use extension tube, you are simply adding more air into the optical path, which in theory should not degrade the image.

- Roy

A reasonably accurate answer. More specificically, since a close up filter is screwed to the front of the lens, metering and AF still works. But the quality depends on the filter. It is thus important to buy good quality close up filters. But no matter how good, since they are not matched to the lens (ie, not specifically made for a particular lens or series of lenses ), abberations and softness at the edges will probably result. It's not a good idea to stack close up filters because quality degradation becomes more pronouced as you add more filters. Another advantage is that it can be used on digital cameras or on cameras with non-interchangeable lenses as long as focusing is through the lens ( eg, on a Canon G3 ). A disadvantage is that you can only use it on lenses that have the correct filter size.

Extension tubes sits between the lens and the camera, so depending on the tubes and your camera body, you may lose autoexposure or AF, or both. Quality is generally good, probably only second to a real macro/micro lens. As Roy pointed out, no extra optical elements are added, so you don't lose quality.

The advantage is that you can stack extension tubes without affecting image quality. In fact, you can buy a set of extension tubes of different sizes, and mix and match them to get your desired extension. Another advantage is that you are not limited to lenses of a particular filter size, so the same tubes will work whether your lenses have a 52mm filter size or 72mm filter size. A disadvantage is that you can only use this on a SLR.

Hope this helps.

 

[EiRiK]

hey, no offence intended dude...

just wondering why so many people reply to pointless threads and BS here... yet when i ask a genuinely technical and inquisitive question, i only get 1 reply...

as i said, i really appreciate your answer. but true to the nature of forums, i think i am entitled to expect more information and then draw my own conclusion.

 

[Adam Goi]

Threads merged due to cross-posting.