Raynox DC-250 magnification question

[dpastern]

Anyone got any idea what sort of magnification I can get using the Raynox DC-250 + 50mm + 68mm of Kenko tubes? I know there'll be softness at the edges, and probably some vignetting as well it wouldn't surprise me, maybe even some light drop off as well, and central sharpness will probably drop a few notches, but I'm curious.

Dave

[LordV]

Seems the dcr-250 is +8 dioptre =1000/8 focal length = 125mm.

Think therefore the total mag of this system assuming it's a non macro 50mm lens
=( 68/50) + (50/125) = 1.76 :1

Brian V.

Ps Dave - would be interested in knowing if this calc is approx correct. I'm assuming you can treat an add-on dioptre like a reversed lens for the calc.

[dpastern]

Thanks Brian. For the smallish increase in magnification, I couldn't justify buying the Raynox - was hoping for aroudn 2.5x - 3x (on the cheap) to play with. I'm watching a mpe-65 on Fleabay, might see how that goes.

Dave

PS where did you get the 1000 in the 1000/8 equation from?

[LordV]

Thanks Brian. For the smallish increase in magnification, I couldn't justify buying the Raynox - was hoping for aroudn 2.5x - 3x (on the cheap) to play with. I'm watching a mpe-65 on Fleabay, might see how that goes.

Dave

PS where did you get the 1000 in the 1000/8 equation from?

The 1000 is just how you change dioptre values into focal lengths - assume +1 dioptre = 1000mm focal length.

As a general rule for magnification, dioptres work best on longer focal length lenses and ext tubes on shorter focal length lenses.

Brian V.

[dpastern]

Ah thanks Brian. As usual, a wealth of knowledge.

Dave

[orionmystery]

The 1000 is just how you change dioptre values into focal lengths - assume +1 dioptre = 1000mm focal length.

As a general rule for magnification, dioptres work best on longer focal length lenses and ext tubes on shorter focal length lenses.

Brian V.

Interesting. Didn't know that before but now i do :).

Brian, think you're spot on about the magnification. 68mm of tube on a 50mm should give 1X. DCR250 on an SP90 give 1.7X.

Dave, you could get an MSN202 with a 25 diopter. It gives you 3X when coupled with a 1:1 macro lens. The bokeh was terrible though :(. I can show you samples if you'd like to see them:)

[dpastern]

Cool - yes please. Although, if I win this mpe-65, I won't need it ;-) Well, unless I really want to do *silly things* like mpe-65 + 1.4x TC + 2x TC + 68 mm tubes...man, that'd be wicked!!!

Dave

[orionmystery]

Cool - yes please. Although, if I win this mpe-65, I won't need it ;-) Well, unless I really want to do *silly things* like mpe-65 + 1.4x TC + 2x TC + 68 mm tubes...man, that'd be wicked!!!

Dave

Here you go, Dave :) http://photography-on-the.net/forum/showthread.php?t=598920

[dpastern]

Not too bad Kurt - some softening at the edges and really shallow DOF, but not too bad.

Thanks!

Dave

[johnkermit1]

i like the dcr 250, it is the only thing i use with my S3.
i think you would have fun with it, but good luck on that mpe!

[dpastern]

Well, the MPE went and I didn't bid on it - nearly a grand 2nd hand. Hell, I can get it new for $1400 or slightly less, stuff that. I'll wait till my Mark IIn is paid off (first week in new year) and my mastercard is paid off (mid February). Then I *might* consider a MPE, all depends on what Canon does with its next 1 series cameras. If I don't like em, I'll be moving to Nikon and of course, the mpe-65 doesn't exist for Nikon.

Dave