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Old May 9, 2008, 7:39 AM   #21
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The rectangular opening is not uncommon. My old Minolta 75-300 and 28-105 (contemporaries of your 100-300)had similar openings and worked fine on my KM5D.
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Old May 9, 2008, 7:44 AM   #22
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That shouldn't have anything to do with it and if the AF screw and Focus Ring turn together from close to infinity without binding, I'm not sure what may be wrong with it. Are you sure it won't Manual focus on the camera either? Do you see change in the image occuring throughout the focus range without any binding of the focus ring with it mounted on the camera (with the camera's AF/MF switch in the MF position)?


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Old May 9, 2008, 9:45 AM   #23
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OK. That eliminates that theory. The good news is that my other lenses work fine. I guess its just the lens.



Thanks,

Glenn
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Old May 9, 2008, 9:48 AM   #24
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When iI turn the focus ring I see the screw turning al I turn the ring. On camera, the item does change but never to focused. The lens also hunts alot before deciding that its focused.



Thanks,

Glenn
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Old May 9, 2008, 9:58 AM   #25
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Hunting with a dimmer lens like that is normal if you're not using it outside in good light, especially if you zoom in any, since that type of lens loses a lot of light as you zoom in more. It's best suited for use outdoors in brighter lighting.

But, if you can't get a sharp image using manual focus (making sure you're not seeing camera shake, etc.) in good outdoor lighting, then there is probably something wrong with it internally (which is pretty rare with this lens, as you're the first person I can remember mentioning this type of problem with one).

You don't have any filters on it that could be degrading optical quality by any chance?

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Old May 9, 2008, 2:15 PM   #26
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Just came back from my local camera shop. They confirmed that the lens does not work. The theory is that someone took the lens appart but didn't put it back together correctly. There's a bonus. The camera shop had a Sigma 75-300 4 - 5.6 apo used for $270.00. I was surprised to find out that a 1.4 apo converter goes for $400.00.

Thanks for all the help. I read the discussions regularly. Maybe next time I will have a good question to ask.
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Old May 9, 2008, 2:42 PM   #27
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That's an outrageous price for that Sigma used. I would have probably went around $100 tops on it, for one in Excellent condition with hood and caps from a vendor like keh.com with a 7 day return policy (from invoice date) for testing it, plus a 60 day warranty. ;'-)

Plus, some of the older Sigmas like that one tended to have compatibility issues with digital (because Sigma reverse engineers the lens mount protocol and sometimes gets it wrong, since newer camera models sometimes use instructions that the cameras they were using for reverse engineering had not implemented yet. You'd have to try it to find out.

You can find some user reviews of it here (and this one does get very good reviews for a budget zoom):

http://www.dyxum.com/reviews/lenses/...asp?IDLens=342

The very newest Sigma model with a similar focal range and brightness, including improved "DG: coatings for digital so that you have less problems from flare, etc., is only $219 brand new from reputable vendors (and far less used), and it's going to have better 1:2 magnification for macros, too (it can focus much closer than some of the older versions that were only 1:4 macro). Here's an example:

Sigma 70-300mm f/4-5.6 APO DG Macro Autofocus Len for $219 at B&H

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Old May 9, 2008, 2:51 PM   #28
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What kind of converter for $400?

I assume you mean a 1.4x teleconverter. There are a number of diffrences between them, and they tend to go for *far* less than that for professional quality generic brands (Tamron or Kenko Pro versions, etc.). Here are some examples of Kenko TCs:

Kenko Teleconverters in Maxxum mount at B&H

Also, you can't use a lens that dim (down to f/5.6 on it's longer end) with many teleconvertors if the TC passes corrected Aperture Information to the camera when it's attached (some models do, some don't). That's because you lose one stop of light (only half the light gets through) with a 1.4x TC (making that lens an f/8 lens on it's longer end if trying to use a 1.4x TC with it).

Many cameras will refuse to Autofocus at all (they won't even try) when the aperture gets past around f/6.3 or f/6.7. Even if you use a TC that doesn't send corrected aperture information to a camera so that it doesn't know it's using a lens as dim as f/8, the camera is going to struggle trying to lock focus using a TC with a lens in anything other than the brightest light. I'd stick to lenses with f/4 (at the dimmest) or even better, lenses with f/2.8 throughout their focal range if you want to try using a TC with one, especially since a TC will degrade optical quality some, and you want to make sure you're using a Pro quality lens to start out with (versus a budget lens that's going to be a bit softer at wider apertures and longer focal lengths, since you'd need to stop down the aperture for best results with a TC, making a dimmer lens even dimmer for shutter speed purposes, even if you can focus with it).

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Old May 12, 2008, 3:12 PM   #29
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With the Minolta 100-300, whats the difference between APO D versus APO II?
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Old May 12, 2008, 3:28 PM   #30
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I think the main difference is the D designation, which means it incorporates Minolta's ADI (Advanced Distance Integration) feature, designed to send focus distance information back to to the camera for flash exposure purposes. I'm not likely to be using a flash very often with a lens that long, so that wouldn't be very important to me.

Some versions of the Minolta 100-300mm f/4.5-5.6 APO lens also had a different AF ring design and more. I think they all have the same optical design, and any of the APO versions of it should be excellent for a lens in this market niche, especially when compared to the budget grade Tamron and Sigma 70-300mm models.

Here are some links to both D and non-D versions of Minolta 100-300mm f/4.5-5.6 APO lenses, where you can see lens specs, user reviews from KM and Sony dSLR users, sample images from these lenses and more (just click on the lnks you'll see on the main page for each lens):

Minolta AF 100-300 F4.5-5.6 D APO 2681-110

Minolta AF 100-300 F4.5-5.6 APO (older non-D version)

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