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PostPosted: Wed Jul 11, 2007 2:45 am 
I own a canon 18-55mm kit lens and a 70-300 IS lens. Before I save up the money to buy a macro lens, I might like to try using either a 500d or a 250d. I am not sure which one would be most useful, or even if the image quality would be downgraded to a point where it would not be worth spending the $130. Does anyone know of the image quality of these filters and/or the magnification they would have on either of my lenses (they are both 58mm thread, but I would use step up rings with a larger sized filter)? Any information would be of great help.


Vivian


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PostPosted: Wed Jul 11, 2007 6:58 am 
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The Canon close-up lenses belong to the very best (achromatic). Don't play around with others - I once did and was bitterly disappointed.
Use them on your 70-300mm. I suggest to get the 500D which limits the infinity-distance to 50cm and then you can still focus closer.
Stopping down a bit (say f11-f16) helps increase IQ and d.o.f.

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PostPosted: Wed Jul 11, 2007 6:36 pm 
My 70-300 as is has a min focus distance of about 5 feet. Does it mean that when I have the filter on the furthest I can be is 50cm, or is that the min focus distance?


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PostPosted: Wed Jul 11, 2007 6:57 pm 
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It is the maximum distance from the front-lens. And you should have roughly 2x greater magnification than without close-up lens.
The 250d has 4 diopters and gives you a max distance from the front-lens of 25cm and around 4x greater magnification than without it.

Some sample calculations show that your lens at 300mm and a distance of 5 feet should give a magnification of 2.5:1. But beware, you have to test this, because some zoom lenses reduce their focal-lenght as you focus closer. So shoot a pic from a ruler at 300mm and closest focus distance. Divide the width of the ruler that you can capture by 22.2mm (=width of the sensor) and you can find out yourself, what magnification you get.
If your lens+cam "sees" 55mm on the ruler then you're at 2.5:1 and your zoom has a real 300mm even when focussing close (congrats!). The 500d close-up lens should then get you to almost 1:1.

With the 250d you risk lower IQ.

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Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
D800+assorted lenses


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PostPosted: Thu Jul 12, 2007 12:43 am 
I have decided to go with the 500d. I don't want to buy something that hinders my photo performance.


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PostPosted: Thu Jul 12, 2007 6:17 pm 
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Did you test your 70-300mm for close-up-performance?!

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