Vignetting on 55mm APO Grandagon

[JPlomley]

So I thought I would try to save some money on filters and bought a 67-77mm step up ring (Heliopan) so I could use my B+W MRC and Singh Ray polarizers, all 77mm. After shooting a bunch of chromes in neutral position with the 55mm Grandagon, I observed vignetting.:mad: So am I better off buying 67mm slim mount filters, or EW designated filters (which I am not even sure if they are available for polarizers)?

[Rob_5419]

You do realise you need a centre filter for such a wide-angle lens?

Check out Rodenstock & Heliopans centre-filters designed for the 55mm Grandagon.

The slim mount or EW filters won't make a difference and your light fall off on your contrasty chromes will still be there. It's a wide-angle lens thing...

[Dave Aharonian]

I used to have this lens when I shot 4x5 and it was a pain in the a__ for filters. I have a B&W 67mm slim polarizer which still caused a tiny bit of vignetting. What did work was my Lee filter holder with the wide angle ring which sets the holder back further on the lens. No more vignetting, but as Rob says, there is a lot of fall-off with this lens and in many cases a centre filter is necessary. I didn't use the centre filter for b&w but for colour it was a must (at least for me!).

[Bob Salomon]

"Check out Rodenstock & Heliopans centre-filters designed for the 55mm Grandagon. "

The Heliopan CF is not for the Apo Grandagon series. It is for the other 67mm wa lenses and has the wrong density for the Apo Grandagon series.

[JPlomley]

Rob, I'm able to get around the CF issue thanks to Photoshop. I'd much rather have the 1.3 stops of extra light in the field to fight wind.

I'm surprised the EW filter would not work given that this is essentially what the CF is. I'm wondering if I should swap this lens for a 47XL with the larger image circle?

[Bob Salomon]

Do you have vignetting or fall off?

If it is vignetting then just step up to a larger filter. The correct CF filter for all of the Apo Grandagon lenses is the 170005 which is 67/86mm. That will not vignette. Neither will slim filters when mounted on the Heliopan 67 to 86mm step up ring.

If it is fall-off then you need the 170005 Rodenstock center filter for the Apo Grandagon. You can tell this center filter from the 170002 Rodenstock center filter for the 90mm 6.8 and the 75mm 4.5 Grandagon N lenses because the CF for the Apo Grandagon series has a marked factor of 2.5X while the 170002 is marked 1.5x. All other Rodenstock CF are marked 3x.

Both the 170005 and the 170002 are 67/86mm thread so you can't tell by looking at the size.

[JPlomley]

Bob, it is definite vignetting. I was thinking about the 67/86 SUR option, but good luck finding this anywhere. Of course, then I need to find 86mm filters, almost as rare as 105mm these days.

[David A. Goldfarb]

I generally use this lens with a CF and 4" gels or polyester filters on 4x5".

[Bob Salomon]

Bob, it is definite vignetting. I was thinking about the 67/86 SUR option, but good luck finding this anywhere. Of course, then I need to find 86mm filters, almost as rare as 105mm these days.

The 67 to 86mm ring is #123 from Heliopan. Special order and takes about 30 days. 86mm filters we stock as we do 95mm and 105mm. BTW, 67 to 95mm and 67 to 105mm step up rings are in stock. As are 95mm and 105mm filters.

[JPlomley]

Well, I do have a 105 Polarizer, but it is not a slim line. However, in going from 67 to 105mm, would this really be necessary?

[Bob Salomon]

Well, I do have a 105 Polarizer, but it is not a slim line. However, in going from 67 to 105mm, would this really be necessary?

No, you would not need a slim 105mm.
But as this is an extreme wide angle lens you would get banding in the sky if you use a polarizer and have a large expanse of sky. That is because areas of the sky are naturally polarized and an extreme wide will capture both unpolarized and polarized areas. Use a polarizing filter for those shots and the naturally polarized areas will photograph darker then the unpolarized areas of the sky.

[Rob_5419]

Rob, I'm able to get around the CF issue thanks to Photoshop.

:eek:

It's strange - I always find in my shooting, I'm trying to shoot slower and slower - sometimes the NDx16 has to come out and the wind can wreak all the havoc it likes.

The centre filter is kind of stippled with ND optical anti-matter (I'm sure there's a proper term for this!) which blocks out light in the centre, and radiates less of this darkening agent towards the circumference of the filter. Not sure the EW filters are like that all all - they're pretty much consistent and not graduated at all.

The image circle of the 47mm XL is great for 5x4, but be warned -the filter factor is worse at x1.5 stops extra. (I do like the colour rendition of the Grandagon compared to Schneider btw). For an extra 3mm of image circle, you will probably not get the vignetting from your IC expiring, but honestly - the light fall-off from the wide-angle design is just as strikingly awful when looking at chromes.

Bob - are you sure the Heliopan won't suffice? I know it wasn't designed specifically with the Grandagon, although user reports on the Heliopan are very favourable with wider angle lenses. The prob. is mostly supply. Heliopan are a smaller family outfit and like most Europeans, go off on holiday with the kids during August.

I'm surprised the EW filter would not work given that this is essentially what the CF is. I'm wondering if I should swap this lens for a 47XL with the larger image circle?[/QUOTE]

[Bob Salomon]

:eek:

Bob - are you sure the Heliopan won't suffice? I know it wasn't designed specifically with the Grandagon, although user reports on the Heliopan are very favourable with wider angle lenses. "

The Heliopan is very good. But not the best for the Apo Grandagon as the Heliopan has an exposure correction of 3x and the Apo Grandagon needs an exposure correction of 2.5x.

"The prob. is mostly supply. Heliopan are a smaller family outfit and like most Europeans, go off on holiday with the kids during August."

No, we have a very large inventory of Heliopan in stock. The one Heliopan filter that is in very tight supply is the Digital filter. The others are not a problem usually.

"I'm surprised the EW filter would not work given that this is essentially what the CF is. I'm wondering if I should swap this lens for a 47XL with the larger image circle?[/QUOTE]

Not if it is vignetting. That is mechanical in this case and a 47, 45, 38 or 35mm would have even more vignetting as they cover more.

[Rob_5419]

Oops - sorry - that last bit is quoted from JPlomley ...I messed up the editing...

[JPlomley]

Think I found a solution. I contacted S.K. Grimes and they can make me a slip on ring with a 77mm front that will get my polarizers as close as possible to the front element (without touching of course). This should solve the vignetting problems altogether and allow me to use my favorite Singh Ray slim mount polarizers.

[JPlomley]

Thought I would try one last approach so purchased an 86mm Helipoan SH-PMC slim line polarizer to mount on my CF. I can't believe it, but it vignettes. I am really surprised given how remarkably thin this filter is. Looks as if I am going to need to contact S.K. Grimes after all.

[JPlomley]

Actually, I am thinking I might flip this lens and get a 47XL instead. The extra image circle will probably negate the vignetting I am observing.