Raynox converters

[coolace78]

i have been reading about raynox macro converters and i have a few questions. i am using canon 450D with kit lens, 50mm f/1.8 and 55-250 IS.

1) i read about focusing problems. does auto-focus work with the macro converter? if yes, then with no USM, is there a problem with achieving focus on my lenses?

2) say i am 0.5m away from my subject, does the converter make my subject look 2.5x bigger when attached? does it allow me to focus on my subject when i am closer, say at 10cm away from it? (assuming 10cm is smaller than the min focus distance of the lens)

3) i read about cropping of photos, why is this necessary?

4) what kind of magnification factors can i expect with my lenses at max zoom, ie 55mm for kit, 250mm for telephoto?

5) i read about DOF control issues. does this arise cause the DOF is low as the converter allows me to focus at much closer distances to subject? will increasing aperture help with this problem?

thanks in advance on help provided.

 

[parampita]

i have been reading about raynox macro converters and i have a few questions. i am using canon 450D with kit lens, 50mm f/1.8 and 55-250 IS.

1) i read about focusing problems. does auto-focus work with the macro converter? if yes, then with no USM, is there a problem with achieving focus on my lenses?

2) say i am 0.5m away from my subject, does the converter make my subject look 2.5x bigger when attached? does it allow me to focus on my subject when i am closer, say at 10cm away from it? (assuming 10cm is smaller than the min focus distance of the lens)

3) i read about cropping of photos, why is this necessary?

4) what kind of magnification factors can i expect with my lenses at max zoom, ie 55mm for kit, 250mm for telephoto?

5) i read about DOF control issues. does this arise cause the DOF is low as the converter allows me to focus at much closer distances to subject? will increasing aperture help with this problem?

thanks in advance on help provided.

1.) Can autofocus but doesn't mean it is a good idea to do so. Manual focusing normally used in macro, we want to selectively focus on some details.

2.) Yes, allows u to focus much nearer. U lose infinity though.

3.) When one screws up composition.

4.) Dunno. But it's probably not practical to use long end of 250mm.

5.) If u used "increasing aperture" to mean raising the f-stop, then yes it will help to cover more DoF.

 

[coolace78]

1.) Can autofocus but doesn't mean it is a good idea to do so. Manual focusing normally used in macro, we want to selectively focus on some details.

2.) Yes, allows u to focus much nearer. U lose infinity though.

3.) When one screws up composition.

4.) Dunno. But it's probably not practical to use long end of 250mm.

5.) If u used "increasing aperture" to mean raising the f-stop, then yes it will help to cover more DoF.

thanks for ur quick reply.

1) if i select centre autofocus point only, then focus and recompose, does it achieve selective focusing? if not, then what is the difference between "focus and recompose" and manual focusing?

4) why is is not practical to use the long end of the 250mm? is the magnification factor too big to photograph anything useful?

5) yup, i was referring to raising the f-stop.

new question: how much does the converter affect image quality and are there better converters in the market, i.e. more expensive but gives better image quality?