24mm f1.4: front element; possible contact with filter

[a.r._landstrom]

The front of the element on this lens sticks out alarmingly close to the plane

of the filter threads. Any precautionary experiences regarding filters & the 24mm?

[HarryBaker]

I had the same worry and asked questions. After reassurance I have a filter on without it touching the glass. I got my lens s/hand and am less than impressed with it. It's OK above f2 but at wider apertures is very unsharp. It's OK on my 5D but really doesn't autofocus on a 350D. Others have reported this. Compared with an f1.4 CV lens on my M8 it is a very poor lens.

[bueh]

I have a filter on my lens and the front element does not touch the filter glass. I find the lens very usable below f/2 (especially when compared to the EF 50mm f/1.4 USM), but unless I need maximum light or minimum <abbr title="depth-of-field">DOF</abbr>, I shoot at f/2.2 or so.

[tim_bonzi]

You can check for clearance by clean cutting a small (.5" x .5" or a bit smaller) piece of lens tissue, take the filter off, place the lens tissue on the front element of the lens, screwing the filter back on normally, then move the assembly around and see if the lens tissue moves freely beteween the elements. You may want to rack the focus on the lens back and forth, too.

[james_taylor11]

"It's OK above f2 but at wider apertures is very unsharp."

 

Wow, I love this lens wide open. I agree it gets sharper at 2.0, but I find 1.4 very usable.

 

"The front of the element on this lens sticks out alarmingly close"

 

I felt the same way when it arrived. I put a filter on it and it doesn?t seem to have any problems.

 

JT

[a.r._landstrom]

Thanks, everyone. I'm reassured.

 

The lens behaves oddly at 1.4. A lot of the softness reported wide open with the lens must be attributable to focus problems, because it *can* be quite sharp at that aperture. But it often isn't. AF with the 20d is hit or miss, and points off-center, sometimes well off-center, are surprisingly sharp for the aperture, while the center is obviously soft.

 

The purple fringing is also pretty spectacular - the tops of black fence posts against overcast sky have come out entirely violet and translucent.

 

None of these are deal-killers. Didn't expect a f1.4 WA to be perfect, and I'm confident AF will be better on more recent bodies.

[keith_lubow]

I have the same problem with my FD 17mm. Filters, when tightened all the way down, contact the front element. When I first got the lens, it actually bound the focus somewhat due to the pressure on the glass. I thought I would need to repair the lens internally, but I just removed the filter and it focused like new. I slipped the retaining ring from an unused filter down into the filter threads of the lens to act as a spacer. This keeps filters off of the glass, but unless it is a super slim type filter, it heavily vignettes the very corners of the pix.

 

Quite honestly, I would just take off the filter and use a lens hood for protection. I have never once damaged the glass of a lens that had a hood attached, and I am fairly careless and rough with my cameras. I have scratched the front element of a lens when a filter shattered, however.

 

Keith

[john_r._fulton_jr.]

No problems at f1.4 with my 24mm. 'Must be a focus problem that some folks have. (Using a

Leica M you become a bit spoiled with the M's precision focus when shooting wides as

opposed to the Canon AF somewhat loosey-goosey focus with wides.)

[a.r._landstrom]

John, what body do you use with the lens?