72XL center filter flare

[P. J. Hawke]

Although the 72XL is one of my favorite 4x5 lenses, there is one thing about it that drives me crazy: flare from the center filter, especially on overcast days. On clear days with the sun over my shoulder, I’ve never noticed any trouble, but overcast days are a big problem. Especially when using a lot of front rise (I generally shoot architecture), a soft but quite noticeable half-moon haze of pinkish flare appears in the lower half of the image.

I’m quite sure that this is caused by the filter – it never happens when I use the lens alone. I’m also quite sure that it’s caused by light being dispersed through the clouds above – I have tried suspending the ground glass cover over the lens, but then the light leaks in around the edges of the cover, leaving the same pattern with a flareless spot in the middle. Very irritating. It appears that I need some kind of lens hood that will completely shade at least the upper 180 degrees around the lens – without causing vignetting, of course!

I’ve seen discussion on the net about color shifts when using this filter, but none about flare. If anybody has had the same experience, or has any possible solutions to the problem, please let me know. I have read other threads about how difficult (or impossible) it is to shade this lens-filter setup, but I thought I’d ask anyway. As I prefer shooting in overcast light, this is a real concern. I’m even considering buying a 75mm lens instead so I can use a different center filter. The Heliopan and Hoya center filters that I use on other lenses do not have this problem. Any input would be much appreciated.

[Will Strain]

compendium shade helps - even with this lens.

[george jiri loun]

If you want to contact me off the list I can computer calculate a lens shade specifically for your lens and the format you use. You would need to make it yourself then.

[Paul Schilliger]

I have the same problem with a Schneider CF 3C Multicoated used either on the 47XL or on a Nikkor SW 65. I wonder if the silver mirrored finish is not the cause for this problem. It can produce light spots or even a half moon ghost image over a good part of the image. I'm not sure the compendium is enough. I use one but maybe not stretched to the limit. (Hi George!). It would be interesting to know if older CF with non reflective finish are subject to that kind of unwanted creative effect too.

[Donald Hutton]

I use a Heliopan slim center filter on my 72mmXL and haven't had any issues with flare. Drop me a line offlist if you'd like to do a comparison...

[Tom Westbrook]

Weird. I've never had issues with flare from the IVb CF on the 72 SA-XL. Here's an typical example: www.tomwestbrook.com/Photography/lf_lenses.html (http://www.tomwestbrook.com/Photography/lf_lenses.html) (about halfway down the page). It's two shots on an overcast winter day overlaid: one with, one without the CF. No rise was used on that shot, though.

I almost always use the CF with this lens--in fact I just leave it installed--and haven't noticed any flair on any image. I use monochrome film mostly, though. I don't have a real shade for it, but sometimes shade some overhead light with a gray card.

Maybe I'll try some color film the next overcast day we have just to see what happens. I'd be really ticked off if a $400 filter caused any flair.

[george jiri loun]

Hi me too, Paul ;-)

[Henry Ambrose]

I get occasional weirdness with center filters as well. I wonder why, other than user convenience, (like that has anything to do with large format photography ; >) they don't make them to attach to the rear of the lens?

[Bob Salomon]

Mounting filtres behind the lens will not only create a focus shift but will also affect the optical performance of the lens.

[Henry Ambrose]

That makes sense Bob, but why not take that into account when designing a lens that everyone knows will be used with a center filter? Using the filter improves the image but why not improve it further? Why not design in center filters for very wide lenses? Not doing so seems like making tires an option on a new car. For real wides you're gonna want the filter just like you'd want tires on your car.

Well maybe for front mounted center filters multi coating would help?

And why does the gradient on my center filters appear silver colored?

[Bob Salomon]

"That makes sense Bob, but why not take that into account when designing a lens that everyone knows will be used with a center filter? ""

Because lenses and center filters are not sold 1:1. Many people work around the need or like the result without the filter.

"Using the filter improves the image but why not improve it further? Why not design in center filters for very wide lenses?"

As the Linhof distributor we once asked this question. The answer was that center filters are harder to manufacturer then the front element of the lens itself. More rejected center filters are destroyed then would normally be acceptable. Since some people do no want a center filter and since many do not want to be forced to buy a center filter and since a center filter is far from inexpensive it would simply be a bad policy to force one on everyone. In addition the lens manufactturers like Schneider and Rodenstock offr either a 4.5 or a 5.6 lens. If the Center filter was built in they would then be offering a slower lens design. However their competiton like Nikon and Fuji both of whom do not manufacturer a center filter would then have faster lenses - albeit ones with more fall off. It would be a terrible marketing choice to let a competitors lens be faster because they did not correct their fall off while at the same time being cheaper due to their lack of the correction. As stated above many users do not see the fall off or can correcct it in printing.

[Paul Schilliger]

Speaking of lens design, are the Zeiss Biogon really that good with even illumuination across the field? Of course the trade off is the huge and heavy lens design and high price.

[P. J. Hawke]

Thank you all for your helpful responses.

Paul and Henry, I’m glad to hear that I’m not the only one who’s seen this. Paul, I wondered about the reflective finish as well. As I mentioned, I haven’t seen this with the 67mm Heliopan I use on my 90mm F8.0 Nikon, even with extreme rise applied. That filter does seem to me to be much less reflective than the IVb.

Tom, I’m interested to hear that you haven’t had the problem. This leads me to think that it might have something to do with the degree of rise applied. As I usually shoot architecture, I’m often applying a fair amount of rise, but I’ve seen this flare even when applying only a centimeter or so. Please do experiment with more rise and let me know what you find.

Don, thanks for the Heliopan 95mm filter tip. I didn’t know that it existed. Not many retailers seem to carry it. I’ll keep it in mind as my solution of last resort – needless to say, I’m not too eager to buy another $400 center filter. About a comparison, I’d like to do one, but unfortunately I don’t have a scanner that can deal with 4x5 film at the moment. When I get a hold of one, I’ll contact you for sure.

George, I will definitely contact you about designing a shade. That sounds like my best bet at the moment.

Thanks again to you all for your input.