Tag Archives: Maxxum

Cleaning the cat … 500mm reflex

I wanted to try out this oddity of a lens. I shoot a lot of wildlife, so a long focal length lens is handy. Even handier is a physically short and lightweight lens. I snagged this lens for a bit less than normal because there was obvious dust/stuff inside.

I first thought of just removing the front element by unscrewing the ring … but it would not budge. I checked the web, and others show a disassembly … Ok, doesn’t look that hard.

Tools – philiips screwdriver, cleaning stuff, and painters tape

First thing to do is get the tape out, set the lens to infinity focus and place a tape reference on the outside between outer focus ring and body.

TIP: try not to rotate anything during disassembly.

Next you need to take off the PCB board with the contacts. There are two screw holding it on and there is a spring underneath one side.

Next remove the screws from the mounting ring.

Pull off the mounting ring a bid and then maneuver the PCB through the hole to separate them.

The outer body is held on by the four screws.

Note that the PCB and chip are attached to this part, so try not to damage it … and it sits in a slotted area.

At this point you might want to get the tape out again and make more reference marks on any rotatable parts.

In order to remove this rotating focus collar you will need to remove some gears … make a tape reference to its position.

Tip: pull the lens while slowly unscrewing, and as soon as the two release place a tape marker. You’ll thank me when you put it back together.

Two screws hold the gears on.

Try not to lose any parts when you remove it … and also try to keep the lube.

Pull off the column.

Then just unscrew the two parts.

Clean up, and try not to scratch the mirrors.

 

 

Those tape marks will come in handy to make sure you correctly get the correct position of everything.

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Holy Schmidt-Spiegel Batman … its the Minolta 500mm reflex !!!

The Minolta Maxxum AF 500mm f/8 Relex lens was brought out in 1989, and is a Schmidt-Cassegrain catadioptric lens.

In 1672, Laurent Cassegrain designed a telescope using two mirrors to reflect incoming light to the eyepiece. This design corrected spherical aberrations and also made the telescope shorter. Later on the Catadioptric system was created, and his utilized both refraction and reflection … corrective lenses and mirrors.  In 1930 Bernhard Schmidt redesigned the mirror shape and added an aspherical lens to correct for coma, and astigmatism aberrations. The Schmidt-Cassegrain design is currently one of the most popular telescope design used today … and it also caused many camera lens manufacturers to use that also. Almost everybody made one (well not really), but Minolta was the only one to incorporate it into their Auto Focus system.

The Maxxum 500mm reflex is a stubby barrel of a lens. Due to the way it is designed it can produce donut or crescent shaped bokeh … which probably explains why this lens is not more popular. As I mentioned before, this is an AF lens which can support centre point focus … and since this is a gear driven lens, the body has a direct influence on AF speed. You’ve got one aperture size of f8 so it can cause the AF to hunt … IQ is pretty good on this lens … you just have to know how to work the bokeh … overall I really like this small handful lens.


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