Wider than 72XL for 5x7?

[CasperMarly]

Is there a wider lens than the Schneider Super Angulon 72mm XL that will cover 5x7?

For those who have used the 72 XL on 5x7 - do you really need the center filter for normal images that include skies and/or larger continuous tone areas?

 

[Dan Fromm]

If you shoot color, you need a CF. With a 72 on 5x7, the corners will be 2.55 stops down from the center.

 

[CatSplat]

The No.000 Goerz Hypergon (60mm) is the only wider lens I know of that covers 5x7, but in terms of modern lenses of reasonable attainability the 72XL is probably the widest.

 

[138S]

really need the center filter for normal images that include skies and/or larger continuous tone areas?

YMMV, please check this explanation by Mr Rockwell that is full of wisdom: https://www.kenrockwell.com/tech/center-filters.htm

You may also check datasheet to see the fall-off amount depending on aperture yopur lens sports.

Super Angulons (IIRC) are Biogon design derivatives sporting a lower fall-off than the one calculated from the cos^4 rule, this is achieved by an optical hack named Tilting Pupil.

Using the center filter also has drawbacks, you are to loss several stops in the center/mid, and they are very expensive. The ideal situation is exploiting fall-off aesthetically, when possible.

Of course, in the hybrid workflow you may correct the image in Photoshop, etc.

If printing optically then you may partially correct the fall-off in the negative with the fall-off from the enparging lens. A negative with fall-off is thin in the corners burning more there, so the enlarging lens fall-off compensates that... so a hack is using an enlarging (W) lens that's short for the format, used at relatively large aperture to favor fall-off. Also corners can be dodged... or we can modify the enlarger's illumination.

So... having a lot of light (sunny landscape) if money is not a problem then the right CF may be a good idea.

 

[Dan Fromm]

Hmm. To hell with Rockwell, read this https://galerie-photo.com/center-filters-for-large-format-lenses.pdf for information on center filters. Schneider recommends their CF IVb for the 72 SA XL.

To find out whether you (that's you specifically, not self-appointed experts on the 'net) need a CF on a 72 SA XL when shooting 5x7, buy, rent or borrow the lens and see what it does in situations that are important to you. If you can live with the fall off, fine, wonderful. If you can't, save your small monetary units until you have enough to buy a CF IVb or equivalent.

 

[138S]

Hmm. To hell with Rockwell, read this https://galerie-photo.com/center-filters-for-large-format-lenses.pdf for information on center filters. Schneider recommends their CF IVb for the 72 SA XL.

To find out whether you (that's you specifically, not self-appointed experts on the 'net) need a CF on a 72 SA XL when shooting 5x7, buy, rent or borrow the lens and see what it does in situations that are important to you. If you can live with the fall off, fine, wonderful. If you can't, save your small monetary units until you have enough to buy a CF IVb or equivalent.

Dan, the information you show is of high value, still that Rockwell's page explains (bellow) that there are two kinds of center filters, one manufacturing way is more expensive than the other, IMO it is a quite interesting knowing why.

It can be added that owning a single CF is not a perfect solution as depending on aperture fall-off varies...

...if because of low available light and the CF we have to open more then fall-off increases, then a choice is removing the filter and stopping more to get less fall-off in that way.

https://www.kenrockwell.com/tech/center-filters.htm

 

[Dan Fromm]

It can be added that owning a single CF is not a perfect solution as depending on aperture fall-off varies...

...if because of low available light and the CF we have to open more then fall-off increases, then a choice is removing the filter and stopping more to get less fall-off in that way.

Two comments.

They're all somewhat approximate but all CFs of the same rating and thread size front and rear are functionally equivalent. However, R'stock says that their newer 2x as now recommended for Apo-Grandagons works better than the old 2.5x that was first recommended for those lenses.

Your second comment is simply mistaken. The reason R'stock and Schneider recommend stopping down at least 2 stops from wide open when using a CF is that mechanical vignetting is a problem unless the lens is stopped down as they recommended. A CF corrects for cos^4. A CF can't correct for mechanical vignetting. Stopping down will reduce mechanical vignetting, does nothing for cos^4. In short, if its darker than you like, you're stuck.

 

[138S]

Your second comment is simply mistaken. The reason R'stock and Schneider recommend stopping down at least 2 stops from wide open when using a CF is that mechanical vignetting is a problem unless the lens is stopped down as they recommended. A CF corrects for cos^4. A CF can't correct for mechanical vignetting. Stopping down will reduce mechanical vignetting, does nothing for cos^4. In short, if its darker than you like, you're stuck.

Dan, of course, as we close 2 or 3 stops then fall-off stabilizes, but from f/8 to f/11 we may have 1 stop missmatch.

This is the grandagon 45 but the other focals covering sheets are similar.



...but know let's see a practical situation where the CF is a pitfall, here (The Subway, Zion Park) velvia exposure takes 15 min


https://benhorne.wordpress.com/2009/11/16/my-zion-subway-experience/

Then with CF we have to use a large aperture if not wanting troubles, with no CF we may get a better shot.

My statement was a bit exagerating, as that effect is from max aperture to f/11 or f/16, depending on the lens.