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Old Oct 15, 2003, 8:25 PM   #1
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Default Macro lens on Digital Rebel/10D

I have a question about macro lenses and extension tubes on dSLRs and I'm getting more confused by the otherwise excellent book I'm reading on close up nature photography.

The book says that an extension tube will allow me to focus on objects much closer than 'normal'. But in talking about a 50mm lens it says that the working distance ends up being about 4 inches. That's too close for what i want to do. it also says that the same amount of extension on a 100mm lens will no give as much magnification but will keep the working distance longer.

Most digital SLRs have a smaller than 35 mm imaging chip so a 1:2 magnification is going to be more like 1:1.5 due to the magnification effect. Is that right?

Secondly - the effect of the extension tube will be the same as on a film camera. Right? 25mm on a 50mm lens on my d300 will give me the same focusing distance as on a film camera. It won't be like 25mm extension on an 85mm lens.

thirdly - my 75-300 zoom with macro - it will have the same focusing distance on my dSLR as on film? I think so, and the limited amount of experimentation seems to confirm this.

This leads me to a question of options -

where I've lost a lot of shots is with my 28-105 zoom with the subject (butterflies) being too close to focus on.

The options are - getting a Sigma 50mm macro lens, getting a 50mm normal lens and a set of extensin tubes, getting a 100 mm macro lens, getting an add-on macro filter lens.

opinions? bear in mind that I like taking some macro shots but don't want to invest too much in it. I'm saving up for a brighter long zoom lens.
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Old Oct 15, 2003, 9:59 PM   #2
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i think canon's 180mm macro lens gives a 1:1 ratio at about 19 inches from the film/sensor plane. i think that is about 12 inches from the front of the lens. i think the 100mm macro gives 1:1 at about 5 or 6 inches from the front of the lens. are those distances too close?

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Old Oct 16, 2003, 7:39 AM   #3
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The extension tubes work wonderfull, but only if you can get quite close to subject. However with a while set total 68mm and a 135 mm focallength you can take a distance of 50 cm and still have a ful lframed peach (as example)
The macro lenses itself, no experience than holding them and drooling over them in the shop.
Macro filter is another option, quality of photo will significant lower at edges of photo, but you can stay at same distance with such magnifier glass.
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Old Oct 16, 2003, 9:34 AM   #4
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I asked a very similar question to one of the best nature photographers in the UK (George McCarthy.) His basic statment is that the optics of Macro lenses are so superior to normal lenses that if it matters, get the macro lens. You won't be disapointed. Extention tubes serve a purpose, but they don't "replace" a macro lens.

I have had the same problem with butterflies you have. The close focusing distance of my 100-400 (the lens which is usually on my camera when out and about) is annoyingly far. I get good shots, but finding the right distance can cause you to loose it. So I will probably get a tube or two (they are too cheap to deny)... and if I find I really like Macro, I'll get one of those some day.

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Old Oct 17, 2003, 4:50 PM   #5
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I have been experimenting with macro tubes up to 65mm with my Tamron 28-200 lens, (on the 300D). To my suprise I am able to get reasonable macro results at a distance. Another benefit is that I do the coarse focusing with the zoom and fine (final) focus in manual, using the manual ring on the lens. If I have the shutter button partially depressed I even get the red light + beep to say it is focussed!

With the kit lens I have been using close up filters but the result is not as good ie: you lose focus distance (it seems, don't know why).

I've just got my 50mm 1.8 lens and have yet to try the macro tubes with it.
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Old Oct 17, 2003, 4:51 PM   #6
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Double post. Sorry
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