Schneider CF IVa/b on 72XL, how different?

[Daniel Geiger]

I have a Schneider 90XL with CF IVa. I will be getting the 72XL shortly and wonder how noticeable the difference is with a IVa (filter factor 3; "optional with less correction" for 72XL according to Schneider data sheets) vs. IVb (filter factor 4; ideal for 72XL). I shoot chromes, and do find the 90XL without CF often objectionable with respect to light fall-off, unless the brighter center is a design element of the shot. This is to say, I seem to be picky re fall-off.

Given that this is a $500 question, there is also part of the answer. Anyone with side by side experience? Thanks.

[more photography]

I am interested in this too - any experience from those who own both lenses.

[Daniel Geiger]

Dear MRF,

It's been a while since I posted the above. In the meantime, I have both the 72 and the 90 XL lenses, and just a couple of weeks ago got also the 72 XL CF. I had used the 90 CF on the 72 (same thread), and there is a noticeable fall-off towards the edge, whereas with the 90 and 90 CF, there is no perceptible fall-off. Although I have not used the 72 with 72CF, I expect that it will also render the image pretty uniform in brightness.

As I shoot exclusively color chromes, being off by 1 F-stop in part of the image is very significant. May be less so for B&W. Occasionally, the image lends itself to having the center brighter than the surroundings, occasionally by 3 or 4 f-stops, occasionally by only 1 f-stop, but I think mostly I like to have an even illumination across the image.

The 3 and 4 f-stop exposure correction is very significant, so only very still objects work even in bright daylight, or you work with very shallow depth of field. But also consider that for best results with the CF, the lens should be stopped down 2-3 stops from all open, i.e., f/11-16. Sunny-16 gives you a 1/60s in good daylight.

One problem that persists is the simultaneous use of CF and Pol filter (-5 or 6 stops! mind you). Ideally, I would like to use the pol on the rear element and the CF on the front, but the rear element does not have a filter thread. You can mount a Pol with the Lee push-on adaptor for the 72/90XL, but the Pol has a 105 thread whereas the CF has a 95 thread. Then one would have to use step-down rings. All of those elements progressively increase the distance of the CF from the main lens, and as the CF density is an angular function, one messes with the CF characteristics, and coverage of course as well. So for the time being it is either/or, but not both.

Anyone who knows a rear adapter for the XLs?

Daniel

[Don Hutton]

I've used both the 4a and 4b on the 72mmXl. If you use extensive (and that is a bold term for that lens!) movements, you will see fall off even with the 4b. How objectionable is it? Only you can be the judge. Personally, I didn't see a big enough difference between the correction of the 4a and 4b to warrant the expense - both are not perfect with a lot of movement and the $500 less expensive imperfect solution suited me... I'd shoot the CF you have and make your own mind up. For most shots, I'd expect you to be very happy with the 4a.

[Eric Leppanen]

You can mount a Pol with the Lee push-on adaptor for the 72/90XL, but the Pol has a 105 thread whereas the CF has a 95 thread. Then one would have to use step-down rings. All of those elements progressively increase the distance of the CF from the main lens, and as the CF density is an angular function, one messes with the CF characteristics, and coverage of course as well. So for the time being it is either/or, but not both.There might be another option: use a Lee FK-115 press-on holder (a special order item) with a 4x4" square polarizer (either Lee or Tiffen) in the nearest-to-the-lens filter slot. The holder would fit over the installed CF, and hold the polarizer very close to the CF glass. I don't know how many filter slots could be supported (if any) without vignetting, if you are interested I suggest you talk to John Adler of Lee USA for more info. Admittedly this is a lot of hardware for one lens, but it might work.

[Nathan Potter]

Daniel, you might want to be cautious about using a behind the lens filter with the two wide angles you mention. I think I remember a post where Bob Salomon of HP Marketing recommended against this. I had some trouble, IIRC, several years ago with a 75 mm Nikon fitted with a rear glass CC filter. It seems to me that the extreme off axis rays have a longer refractive path thru the filter corrupting the peripheral image. Maybe some others can chime in on this possibility.

Nate Potter, Boston MA.

[more photography]

Hi Daniel

thanks for the update - just ordered a 72Xl and CF for now, I an mot after a 90XL any time soon, unless it is required, having both 110Xl and 72XL, Iam hoping that will be enough.

As Eric suggested, Lee do a 115 filter with a dounut to accomodate diam of 110, which i think that is the ext dia of the CF, however not sure if can still attach 105 mm thread Pol such as Lee or B+W to it , I think this will work - I will check with Robert White in the Uk as they very knowledgable about Schnedier Cf and Lee filters.

I shoot chromes too and will be trying B+W as some stage.