Filter for drop in holder

I've got a 300mm f2.8L IS lens and it came with a drop in gel filter holder. I'd like to replace it with a drop in holder that takes 52mm glass filters. That's no problem. I'm looking at the B&W filters and they come in slim (UV Haze 010 (MRC) Multi-Resistant Coating Glass Filter Slim) and regular width (UV Haze 010 (MRC) Multi-Resistant Coating Glass Filter) versions, with the slim being more expensive. Now I'll buy the slim version if I have to but I'd like to ask if anyone has used the regular thickness filter in the drop in holder?

Why put a UV filter into the drop-in drawer? Makes little sense to me. Now if you had said CP......

What kind of filter do you THINK goes in there?

There HAS to be a filter in that slot and I'd much prefer an excellent quality multicoated glass filter that I can clean, rather than the fragile acetate filter that it came with. A Skylight would be just fine as well, but what does your cryptic CP stand for?

I believe that would be circular polarizer.

DaveG wrote in post #4571196
What kind of filter do you THINK goes in there?

There HAS to be a filter in that slot and I'd much prefer an excellent quality multicoated glass filter that I can clean, rather than the fragile acetate filter that it came with. A Skylight would be just fine as well, but what does your cryptic CP stand for?

i did not know it was just a acetate in there but with it being so close to the camera i doult it will make the image degrade -but you do have me thinking about it lol
Rob.

Yup I've got one of those. It's the two cent piece of plastic within my $4000 lens that I'd like to take care of.

GyRob wrote in post #4571418
i did not know it was just a acetate in there but with it being so close to the camera i doult it will make the image degrade -but you do have me thinking about it lol
Rob.

With your lens lineup I would think that you have at least three of those acetate/gel filters. A fresh piece of acetate can be cut and remounted and while there's nothing horribly wrong with that I would suggest that there's a better answer in something like a B&W glass multicoated UV filter.

The holders that come with the lens will only hold the acetate or gel filters so that needs to be replaced as well if you - or I - want to mount a glass screw-in filter. This of course brings me back to my original question of whether I can use a regular thickness filter in that holder or if the slim version of the filter is required. The glass is exactly the same in either B&W filter but the slim version is more than 50% more expensive, and I'm cheap! So I want to spend only what I have too.

The big lenses that have rear filter slots come with a piece of glass in that slot. It should be left in place. If you want to use a filter, like a CP (circ. polz.) for example, you replace the glass with the filter. UV's are usually for protection to guard the front of the lens. Nothing to guard in the slot.

gasrocks wrote in post #4571484
The big lenses that have rear filter slots come with a piece of glass in that slot. It should be left in place. If you want to use a filter, like a CP (circ. polz.) for example, you replace the glass with the filter. UV's are usually for protection to guard the front of the lens. Nothing to guard in the slot.

Yes it is Glass i just checked -iv never taken it out of my lenses before .
Rob

gasrocks wrote in post #4571484
The big lenses that have rear filter slots come with a piece of glass in that slot. It should be left in place. If you want to use a filter, like a CP (circ. polz.) for example, you replace the glass with the filter. UV's are usually for protection to guard the front of the lens. Nothing to guard in the slot.

The Canon's - at least the 300 f2.8L IS - come with an acetate gel and in a specific gel holder. It does not come with a piece of glass, or a holder that will take a screw-in glass filter. My old Nikkor 300 f2.8 had a 39mm L37C (Nikonese for UV) filter in a holder, and I liked that a lot better.

Although there is nothing to guard - as you say - in that slot, the acetates get dirty, especially if you are swapping them out to use a Polarizing filter, and they are almost impossible to clean properly. Thus my desire to replace the acetate with a great glass filter.

Just out of curiosity (never owned one myself), why do you have to have anything at all in the filter holder?

GyRob wrote in post #4571554
Yes it is Glass i just checked -iv never taken it out of my lenses before .
Rob

On the B&H site this is what comes (among other things) with the Canon 300mm f2.8L IS : ... "Drop-In Gelatine Filter Holder" which I presume would hold a drop in gelatine filter.

I bought mine in Canada and that's what it came with as well. When you took the filter holder out did it reveal a 52mm glass screw-in filter? If your lens is older and of the non IS type then it would have taken 39mm screw in filter (like my old Nikkor 300), and THAT may well have been standard at that time. If it isn't a screw-in filter then I'd suggest that you are looking at a gel not a glass filter.

Grentz wrote in post #4571618
Just out of curiosity (never owned one myself), why do you have to have anything at all in the filter holder?

Because it says in the 300's instructions that you must.

Have you tried shooting without anything in it?

From a quick google, it looks like some lenses really do not need a filter in the holder even though they say they do. The issue seems to be with autofocus/focus to infinity so if you can focus correctly without a filter it seems like you would be just fine.

I dunno, in my mind I would play with it a bit and see what the results are like before dropping $XXX on a filter.

Well, if it is designed to hold a glass filter, then it shoudl have a plain peice of glass in it at all times to not change the optical path, whatever. Leave it out and I've heard about dust getting into the lens also.