Lens caps - a stupid question?

The push on caps that I got with my 210mm Caltar are worse than useless, they don't stay on at all. Can I ask a stupid newbie question? Can I just use standard lens caps from Canon/Nikon whatever or is there a reason why they won't fit?

You sure can. While some of the newer Schneider press-on caps are pretty firm, most press-ons are not. Personally, I like Canon caps as the squeeze buttons don't protrude past the edges of the cap so they won't hang up of other items in the bag. Only about $5 each and they are only available in limited sizes, but the sizes they do have cover most of my LF lens needs -- 52mm, 58mm, 67mm, 72mm, 77mm and 82mm -- and step-rings take care of the few non-standard front threads I have. Covering the rear is more problematic, so I tend to use the press-ons for them.

Cheers,

I have tried squeeze caps on my LF lenses and did not like them. They always seem to pop off in my lens bag. I have purchased push-on caps at B&H that work great. Pretty sure it was their Kaiser brand cap.

I like the Nikon pinch caps (new style) so long as the front element is back 3-4mm from the rim (some wide angles are not). I also use a short screw in metal lenshood (S&W on eBay) not as my primary lenshade but as a first round defense -- it protects the lens if you drop it, keeps the dust down, and provides some minimal shading. With the Nikon caps you can leave the shade screwed in all the time.

Of course the SK Grimes custom caps are the best but $$$. Flat metal screw-in caps are the most secure of all (if the front element is set back!).

Finding a good lens case - either Rubbermaid or a Gnass case or something, helps prevent the lenscaps from being the sole protector of your lenses -- keeping the caps from pressing in is the big thing you need to avoid.

In a pinch, a cheap UV filter is a great cap ;-)

The metal screw in caps are cheap and solid, but slow.

A squeeze cap came off a lens when it was in a Gnass case in my backpack. Luckily I had left a filter on the lens, and the only damage was to the filter coating.

After that experience I decided to insure my lens elements with S.K. Grimes; $25 for the rear, $35 front caps. Expensive, but after a couple of very close calls they not only protect my lenses, but my peace of mind.

My solution was to order a bunch of Schneider press on caps in 77mm size which is the size of all of my filters. A step up ring on the front of each lens holds the cap and helps to protect the lens as well. The best thing is that each lens is ready for a filter if needed without at least one of the threading jobs. The rear elements all have their original caps. If you do need an odd size cap- a good vintage camera shop or repair shop will usually have a box of them someplace and a really good shop wont charge you for one or two.

Cut off maybe a two inch length of electrical tape and cut it in half horizontally (i.e. so that you have two thin strips of tape three inches long). Attach some of the tape around the inside rim of your existing lens cap until you have enough of a build-up to make the cap fit tightly. I've done that with several old Schneider caps that I wanted to use just because I like the leather material and the blue velvet interior but that were a little too big for the lenses on which I wanted to use them. The tape has worked fine for years and of course by using more or less of it you can customize the fit to your liking.