Lens filter: step-down adapter ring, or not?

[Redreflex]

Need your thoughts please...

On my two L lenses, I've currently got B&W 77mm UV filters with the occasional use of the 77mm circular polariser MRC. I've just ordered a 135mm f/2L, which would take a 72mm filter.

Should I:

1. Stick with 72mm filters (for those who agree these are useful!), i.e. buy a new filter, or

2. Get a step-down 77-72mm adapter ring (B&W has them - amazon, for an inviting $19.95). Whilst it may not be a good idea and I can imagine it would be incredibly annoying to repeatedly swap UV filters between lenses and leave a lens or 2 without a filter permanently attached (do most people always leave a filter on every lens anyway?), it would make sense to have an adapter for more infrequently used filters, i.e. in my case the circular polariser MRC filter. At over $150+ a pop, I'm not sure I want/need 77mm AND 72mm ones! So the adapter would get round that cost issue.

Suggestions very gratefully received!

[bvukich]

Get a 72mm UV for sure.  Having to move a UV between lenses will get old real quick.

For the CP it depends on how often you use it, and how small your fingers are.  If you are using the hood, there will be precious little room between a 77mm filter and the hood, and it will be annoying to get on and off.

[bvukich]

If you are using the hood, there will be precious little room between a 77mm filter and the hood, and it will be annoying to get on and off.

To clarify, that's getting the filter on and off.  It will be impossible to get the hood on/off with a 72-77mm adapter on.

[CR Backup Admin]

I would not jump to order a new polarizing filter for your 135mm.  If you only use it occasionally now, hold off and see if you take a lot of photos that would need one.  A hood, on the other hand is very useful.

A set of stepup and step down rings is pretty inexpensive and handy to have around, but I would not want to eliminate the possibility of using a hood.

[Redreflex]

If you are using the hood, there will be precious little room between a 77mm filter and the hood, and it will be annoying to get on and off.

To clarify, that's getting the filter on and off.  It will be impossible to get the hood on/off with a 72-77mm adapter on.

Thanks. Hood's essential for me, so adapter ring's out for daily use and 72mm's in. Very helpful.

I would not jump to order a new polarizing filter for your 135mm.  If you only use it occasionally now, hold off and see if you take a lot of photos that would need one.  A hood, on the other hand is very useful.

A set of stepup and step down rings is pretty inexpensive and handy to have around, but I would not want to eliminate the possibility of using a hood.

I may well get an adapter ring anyway as you suggest, for the occasional use of the CP, although not sure how much I'll actually need it for a 135mm.

Thanks again to both.

[Grummbeerbauer]

To the TO: I read your initial post twice now, I think what you are looking for, i.e., an adapter that allows you to use a larger filter on a lens with a smaller filter thread (this is what you want, right?), is called a step-up ring (see, e.g., here: http://www.stepupring.com/).

For UV filters (whether or not we "need" those in the digital age is another debate  ) I would definitely get fitting ones. For CPLs, the story is a bit different. I got myself a 82mm CPL (Hoya HD) because at that time I was planning to buy a lens with a 82mm filter thread, and I got a very good deal on the filter at that time.
I then bought step-up rings from 67->77mm and from 77->82mm, allowing me to use the filter with basically all my lenses, However, as other already said, this prevents my from using the standard lens hoods, which is IMO acceptable for wide angle lenses (where a lens hood cannot offer that much protection anyway), it could more significantly impact tele lenses. So for my 70-200 f4 IS (67m filter thread) I additionally got myself a 82mm screw-on lens hood. I can now use the 67->77mm step-up ring,followed by the 77->82mm step-up ring, followed by the CPL, followed by the screw-on hood, and can now very comfortably rotate the filter by simply rotating the screw-on hood.

But would I do it that way again?
While the purchase of the 82mm filter was actually a makeshift solution to compensate for my mistake of buying the 82mm CPL, I found it highly useful -- much better than trying to rotate a "fitting" CPL within the normal hood.
Of course if I had to do it again I would definitely go for a 77mm CPL now that I didn't get that 82mm filter thread lens -- using two step-up rings in sequence makes it yet even a bit more a PITA than using only one. That would allow me to use all my 77mm-filter-thread lenses (24-105, 17-55) directly with the CPL and use their standard hoods, although already a relatively deep hoods like the one for the 17-55 (which BTW I also use with the 24-105, since I am on a crop body) make it difficult to rotate the CPL with the hood on (some smarter lens vendors leave a small space in the hood on the belly side which allows you to rotate a CPL). If I could not live with rotating the CPL with the standard hood on (and smearing it all the time), I would get a 77mm screw-on hood for wide-to-normal angle lenses (which -- being not petal-shaped looks of course only half as cool as the original petal-shaped one ) and a longer hood for tele lenses to use with the 70-200 (+ step-up ring) just as I am using the 82mm screw on hood now.

[epsiloneri]

I have the same "problem" in that I have mostly 77mm lenses, and then this odd 72mm 135/2L. My solution, based on a principal successfully used by many politicians, is to simply ignore the problem and hope it never gets serious. So far I'm doing pretty OK, since I've never really felt the need to mount the CPL filter on the 135mm. Typically I use it for hand-held low-light and portraits. Should I feel the absolute urge to use the CPL with 135mm, I would probably just use my 70-200/2.8L, which takes 77mm filters. Not the same, but close.

My advice: make sure you really want/need a CPL for your 135mm/2.0L before going through the trouble of getting a step-up ring or dedicated filter. If you feel the need to use a protector, it makes no sense at all to share it with your other lenses using a step-up ring. You would probably increase the likelihood of damaging your lenses while exchanging protectors.

[neuroanatomist]

If you are using the hood, there will be precious little room between a 77mm filter and the hood, and it will be annoying to get on and off.

Precious little is an understatement.  I tried it myself with my 135mm f/2L and B+W 72→77mm adapter with a 77mm filter on it.  As stated, the hood will not fit over the 77mm filter.  With the hood installed, there was really no way to thread on a 77mm filter inside it - it could be dropped in, but there's just not enough clearance to screw it on inside that hood.

I should point out that this is not true for all lenses with 72mm threads - I have the 85mm f/1.2L II, and often use a 3-stop ND filter with that lens.  My filters (except UV) are all 77mm or 82mm, and with the 72→77mm adapter, the hood for the 85L can be installed over the mounted 77mm filter.  Also, the 200mm f/2.8L II (which I had, but sold after getting the 70-200mm f/2.8L IS II) is quite similar in design to the 135L, but for that 72mm-filter lens, the hood can also be installed over a stepped-up 77mm filter (the 200/2.8 uses an 83mm hood, vs. the 78mm hood for the 135/2).

Like epsiloneri, I have never felt the need to mount a CPL on my 135L - it's just not needed for the type of shooting I do with that lens.  However, it occurs to me that I'll probably want to use an ND filter with that lens, for the same reason I use one on the 85L - outdoor portraits in bright light (or with strobes) where I want to open the lens up.  It hasn't come up yet since I bought the 135L in January, and it's been too cold for outdoor portraits - but spring is here, so I may have to get a 72mm B+W #103 for outdoor work with the 135L.  In fact, since I bought the 35mm f/1.4L at the same time as the 135L, I now have the complete 'holy trinity' of L primes - and they all use a 72mm filter.  So for me, I think a 72mm ND would make sense.  But still, for a CPL almost anything I'd be likely to shoot would be with a narrower aperture, so I'd likely use a zoom with a 77mm thread for those shots.

[AKCalixto]

Buy step down adapter ring to use with 77mm filters that you will not use often on your 72mm lens.  Buy 72mm filters that you will use often.
Ring downside: 
- Hood is not possible with adapter rings
- Filters and ring sometimes get stuck. Buy a filter wrench. It is cheap and can save your "day".

[endigo]

IMHO
Switching filters defeats half of the purpose of the filter, to protect the lens. While the filter is off the lens, the lens is vulnerable to dust, and scrapes and bumps when switching lenses or if the lens cap comes loose.

[skitron]

Shelling out for a really good filter the correct size is worth it to me just so I can leave it on and not risk cross threading the lens itself. I don't know how others feel about stacking a CP onto a UV but if they're good (like B+W MRC) seems like a non issue as long as no vingette. I'd rather cross thread two filters (even good ones) than ruin the threads on an expensive lens...and the less times I have to thread it on the less chance I screw it up.

[TexPhoto]

U/V filter or no is a long standing debate with no real right answer.  I go without myself.  I've ruined 3 lenses in 40 years, but those have slept with fishes, or smashed onto rocks, and a U/V filter would have done nothing to save them.

I think the step down ring is a good idea, especially for the polorizer.  Might not work with a hood, but it might, 72-77mm is only 5mm. 

[ronderick]

For clumsy people like myself, an additional UV filter for any new lens is a good idea. While it's no proof against dropping the lens, it's quite useful for fending off the occassional scratch and random collision...

Even for the more expensive filters (like BW), I think it's worth the investment since replacing a filter is less trouble than replacing the front element of a lens.

[dougkerr]

2. Get a step-down 77-72mm adapter ring

I think you are speaking of a 72-77 mm step-up adapter ring. (The description, both numerical and verbal, goes in the direction of lens size -> filter size.)

Here's an example:

http://www.bhphotovideo.com/c/product/98873-REG/General_Brand_72_77_72mm_77mm_Step_Up_Ring_Lens.html

Best regards,

Doug

[neuroanatomist]

2. Get a step-down 77-72mm adapter ring

I think you are speaking of a 72-77 mm step-up adapter ring. (The description, both numerical and verbal, goes in the direction of lens size -> filter size.)

The terminology does vary, which is an unfortunate confusion.  For example, even though B&H helpfully calls the B+W 72→77mm (lens-to-filter) adapter a step-up ring, Ace Photo Digital, and many other vendors, call the exact same item a step-down ring.  In this case, B&H is actually mislabeling the product - the manufacturer's website (Schneider Optics, the parent company of B+W) calls it a stepdown ring, with the description, "Allows you to attach a 77mm filter to a lens with a 72mm front thread," and consistent with that, the box that mine came in was labeled "Reduzierung" (German for "reduction").