Tag Archives: Minolta

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.


eBay … Autocord.

Hmm, was just hunting eBay for Minolta Autocords … I don’t know why I keep looking for these cameras … and I notice that the price has been really jacked up.

I just saw one that commented on a fugly one that it has great patina ? Really ? It really is need of a thorough CLA … and it has the classic bent focus knob … way too much $$$ for a starting price.

I wonder if this has anything to do with my blog … hmmm, maybe I am thinking too highly of myself … but I do constantly see that my Autocord posts are still the most actively viewed ones.

Yes, it is a great camera … but not worth that much (that some of these people are asking), its almost like Rollei prices.

FYI: for those that want a great TLR, you should hunt for a Ricoh Ricohmatic 225 … it has a great lens and can still be found cheap (most of the time). I still keep my eye out for one with the Color-Back 225 35mm film adapter kit.


The living dead

“It is not more surprising to be born twice than once; everything in nature is resurrection.” ― Voltaire

I thought I would post an image with all three of the cameras that I have worked on so far.

All three are now in working condition. Actually I have gone through four Autocords, three 35’s, and two chrome 50mm’s … these just happen to be the last ones that I have now off the bench.

The Minolta Autocord has new grey Griptac leatherette from Cameraleather.com. The Minolta-35 has some nice brown leatherette, from eBay seller camera-shop-pl, that I custom cut. The Canon IIF didn’t need a recovering.

I will say that restoring/repairing is quite satisfying … cameras are supposed to take pictures, so having one that is just a broken mantel piece does not fit well with me. I would like to restore all the cameras that I have, but sometimes you just can’t … some things are just broken beyond repair or replacement parts no longer exist (though that leads to buying more cameras).


Minolta-35 – the shutter and speed gears

If the slow speed is not so good then you will need to pull out the insides. This also provides access if you are bold enough to do a shutter curtain replacement … which requires a lot of boldness.

You will need to have the some of the top items removed, so look at my previous post about removing the top.

Tools: slotted screw drivers, spanner wrench, q-tips, Ronsonal,

First take off the bottom plate.

Remove screw by tripod socket.

Unscrew the lock screw over the door lock dial with the spanner wrench (or tweezers).

Pull off lock dial

There will be a compression washer underneath.

Note that the part on the inside will fall out in the body.

Remove screw (I think on Ver. B there may be more than one).

Pull off the bottom plate.

 

 

I decided to unscrew the other two parts under the door lock, though it is not necessary.

 

 

From the front of the body there will be four screws that need to be removed.

The two on the bottom my look odd … in my case, the head was shaved down on one side so that the bottom plate would fit properly. Looks like a slight design opps as they did not make the lower body wide enough account for the size of the screws.

 

Open the camera back.

Remove all the screws that hold the cover plates on.

Ver. A has only one screw on the right plate.

The large cover plate is take off by lifting the left side to allow the right side to pivot away from underneath the film takeup spool.

Remove the last screw (on the top left).

 

 

 

Finally back to the bottom, remove the two screws.

 

 

Now you can pull out the insides.

This image is the rear view.

The shutter release gears and high speed gears are all located in the top portion.

Give this a good wash with Ronsonol.

 

Looking at the front side you can see the slow speed gears located in the bottom. Ronsonol and exercise … you can press the little lever on the right side of the gears.

Put the winding knob and shutter pin back in so you can work all the mechanisms.

You can view the condition of the shutter curtains. The material used on the Minolta-35 does not age well if the camera has been left unused for a long time. The curtain material gets stiff and will form to the rollers. When this happens it causes resistance that will either throw off the timing or cause the shutter not to close properly … or worst case, torn curtains when some idiot just winds the hell out of it.

Each curtain has a take spool and a spring loaded roller that the straps are attached to.

One day I may talk about replacing a cloth shutter … right now I will leave this subject alone.

The rest of the body shell showing the self timer gear box.

You can put some Ronsonol on that to clean it up … and also on the focus actuating arm.


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