A boring but useful topic. My original Sigma DP2 (non-Merrill non-Quattro) did not include its original lens cap. The original Sigma lens cap for the DP series was the LC-11. It has two clips to hold it against the lens barrel.
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| Sigma LC-11 |
Around this time Ricoh popularized the "self-retaining lens cap". This was mounted in front of the lens. When the lens was extended, it would push the doors of the cap aside.
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| Ricoh LC-1 |
Third party accessory manufacturers made similar caps for the Sigma DP series that bayonet onto the front of the lens. I believe the most popular one was manufactured by JJC. The ALC-2 "Automatic Lens Cap" is an extremely handy accessory and makes the camera feel a lot more portable. These are unfortunately hard to find today.
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| JJC ALC-2 |
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| Back of the lens cap |
If the lens extension is blocked the lens cap, the camera will raise a warning "Remove the front cap, and cycle the power."
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| Lens extended with the lens cap on |
Another alternative is to use the Sigma HA-21 hood and filter adapter with a 46mm filter for protection. Then lens is not so prone to flare so use of the hood is not as necessary.
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| Sigma HA-21 |
