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Old September 22nd, 2002, 02:08 PM   #1
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PD150 minimum focal distance

Hey there,

I've been trying to pull some extremely close-up shots with the PD150 (shooting 1" LEGO men and trying to get them from the waist up). I've found that the PD150 can not seem to pull focus on anything closer than 6" to the lens. The same focus problem manifests when I zoom in to the object and try to pull focus on it. Can anything be done about this? And can anyone explain why this problem exists?

I remedied the problem by using the TRV900 which can focus on objects about 2" away from the lens, but I'm wondering if anything can be done for the PD150 in this area.

Thanks.

:)

-Dan
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Old September 22nd, 2002, 03:03 PM   #2
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Dan,

Try adding more light. Saturate the scene with light. You should be able to focus very close with the PD150, provided you're zoomed all the way out to the wide end of the lens (but no way can you focus that close toward the tele end, no matter what camera it is). Good luck,
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Old September 22nd, 2002, 03:45 PM   #3
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Dan

what about a simple diopter lens adapter? (ie. closeup lens set). They are very cheap, a +1 or +2 should get you close enough.

Barry
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Old September 22nd, 2002, 04:05 PM   #4
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Dan,
I think, what you want is a fullscreen image of a small object. You can come close in focal distance when you zoon all the way out, but this will not solve yr problem, and the object will not show significantly bigger than by zooming in and shoot from the longer distance. The only way to get fullscreen images from objects having about 1/2" to 3" dimensions is by using an adapter lens with +/- 6" focus distance (about 9 dioptry) in front of your cameralens. No doubt that you can come close whit the TRV900 (and also with a zoomed out PD150), but did you get full screen with your (half) lego man? I doubt...
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Old September 22nd, 2002, 04:56 PM   #5
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Thanks for the advice folks. I was shooting the LEGO man with about 500 watts of halogen light on him, but I can kick it up to 1000 watts and give it another go. Failing that I'll take a look into the diopter lenses. BTW, I can almost touch a LEGO man with the TRV900's lens and keep him in focus, which is why I was surprised that the PD150 had troubles.

-Dan
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Old September 22nd, 2002, 08:36 PM   #6
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I too was a bit disappointed with the close distance capability of the 150. Especially since my Hi-8 will focus on dirt on the UV filter. A good Plus 1 or 2 diopter aux lens will probably solve your problem. Once in a while you can find a decent set of 1,2, & 3 diopters for a reasonable price.

Place the camera in manual mode and crank the f-stop down until just before the aperature leaves close. That is as good as it is going to get, no matter what the level of light. You shouldn't need to kick up the wattage. Since everything is still, you can drop the shutter speed to compensate. I wouldn't go above 3db of gain. Maybe 6.
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Old September 23rd, 2002, 04:34 AM   #7
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Dan,
Using more light doesn't really focus your lego man (the heat could well weaken it! So take Mike's advise and lower the shutter speed instead) but only the DOF becomes higher because of the high F number, which again can end up in some sharpness reduction(diffraction). What I have on my VX1000 (9-59 mm/ 1m+ shortest object distance when zoomed all in) is a 150mm (D~6.7) coated achromat. With this setup I get full picture (width) for objects between 9 and 90 mm. To find out what diopter(s) you really need, measure the near point distance when zoomed all in and measure the object dimensions. If you also know what dimensions you want you can calculate the magnification power(MP). The diopter you need is given by D= (MP-1)/nearpoint distance in meter. If you need large MP , achromat lenses is maybe a must..
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Old September 24th, 2002, 07:29 PM   #8
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While I'm not 100% sure, minimum distance is relative to the focal length (zoom).

At wide, you should be able to get right on top of it and I mean right on top of it. If zoomed tight, you need to be farther away.

At least that's how other cams have worked.
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Old September 25th, 2002, 12:49 AM   #9
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Min foc dist, Long

I'm not sure about this, but I'm sure some dual GL2/GL1 + pd150/vx2000 testers can set this one straight for the record: I thought that the PD150 lens, zoomed in all the way long, allowed closer minimum focusing distance than the Canon 20x (at equivalent focal lengths for an equal image size). True?
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Old September 25th, 2002, 01:02 AM   #10
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- correction of my post above

Oops, as soon as I posted that w/a big question mark floating in my head, I remembered what I meant to say, was --that the significant difference was that the Sony lens had a faster Aperture available at the long end than the Canon (at equiv focal lengths).

I have no idea about any diffs in their min foc dist's at a given focal length.
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Old September 25th, 2002, 03:50 AM   #11
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The initial question/problem was getting a fullscreen picture of a small object. Zoom factor, minimal focus distances, highest F number, all have their inpact on the min object dimensions which renders a "full" image. It would be better to just define the smallest object dimensions for which you can get a focussed full picture. This is 9cm horizontally for VX1000 (at +/-100cm distance, all zoomed in) and remains about the same when zoomed out and getting close.
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Old September 26th, 2002, 10:48 PM   #12
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Using a pd100, I can, at wide, focus at about the distance of the lens hood, roughly 1". It took a roughly 1" object to fill the vertical axis of the frame and hold focus. Going to guess the 150s on par. I think I could have used a small amount of zoom before things go out of focus, but Wide of near-Wide is what you should try.
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Old October 11th, 2002, 02:59 AM   #13
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Hi Mike,

I'm using a PD150 and have NO problems with close focus. In fact, I can read the names of the states on the back of a $5 bill. I find minimum focus to be as close as I can get the object to the lens. Have your lens set in full wide position then move your object as close as you want, even 1/4". At this range you have to get creative with your lighting. If you have objects in the background use manual focus.

Good luck,
Dennis
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Old October 11th, 2002, 03:32 PM   #14
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In adition to the lighting problem one gets a strong ( and unnatural) perspective for 3D objects. A diopter lens solves both problems because one can back of for the same object/image ratio.
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