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Axel
31-Mar-2013, 04:31
As posted here (http://www.largeformatphotography.info/forum/showthread.php?101798-Paris-calling-!)... one question regarding my new Sinaron 55/4,5 MC (green stripe, Copal 0 shutter) :

I bought it to recover some wide-angle possibilities with 6x9cm shots. I don't mind a little illumination fall-off, in fact I quite like it, but if it goes down one stop or more, then no. I don't use any with my Schneider Super-Angulon 75/5,6...

Rodenstock center filter necessary ?

Bob Salomon
31-Mar-2013, 07:06
Probably. It depends on you. All wide angle lenses will have fall off. That is physics. For any Apo Grandagon (including yours) you will need the 2.5x Rodenstock CF, not the 1.5X version. Both are made in 67mm and since all Apo Grandagon lenses are no longer manufactured the 2.5X CF will most likely be discontinued in the near future. So be prepared. Shoot and test know while the filter is still easily available new.

Axel
31-Mar-2013, 07:37
Thank you Bob.

I'll only be using the 55mm for 6x9cm ; on 4x5", the 75mm is large enough for my taste.
Will be doing tests tomorrow on 4x5", then cropped to 6x9cm with a cache and will see if necessary. The price of it (!) makes say that !

Dan Fromm
31-Mar-2013, 08:01
Axel, on the one hand Bob's "probably" is right. On the other, I shoot a 47/5.6 SA on a 2x3 Graphic (no decentering movements to speak of, absolutely no swings or tilts) and don't feel the need for a center filter.

Axel
31-Mar-2013, 08:10
2x3 is... inches ? (sorry for being European ;-)

With the 55mm, I will be using shifts, generally up - architecture demands it.

Fall-off like this (http://www.axeldahl.com/adn/book/archi/FC2012-01.jpg) I have no problems with (I even like it) but more I will ; that image is a 75mm on 4x5" with a large upward shift.

If I get no more than this with the 55mm on 6x9cm, that's fine. Otherwise... I guess I will have to shed the 500$.

George Hart
31-Mar-2013, 08:11
I have this lens for 6x9 use and I have never felt the need for a centre filter. I guess when I have taken it to the limit of its image circle I've been shooting mainly b&w, and a bit of natural vignetting often looks good on that format. If you are likely to need to use the full image circle on transparency film, it may be worth testing to see if a centre filter is necessary for your type of shooting.

Axel
31-Mar-2013, 08:16
Thanks George - if I could avoid that one bit of expense, it would be great !

No more Ektachromes here (I think there's only one lab left in Paris processing E6), only Portra 400 (4x5" or 6x9cm).

Dan Fromm
31-Mar-2013, 09:05
Axel, what I call 2x3 (inches) is shorthand for 2.25" x 3.25". The 6x9 you're used to is a very poor metric approximation to the actual format, which is (ta da!) 2.25" x 3.25".

And I shoot mainly E-6. You'll really have to try your lens out with a roll of E-6 to find out whether you can tolerate the darkness in the corners with the largest shift/rise you're likely to use.

Axel
31-Mar-2013, 09:14
Yes, it is an approximation... shorthand if you like :)
About 5,7cm x 8,25cm ? The closer to 8,xx and not 9, the happier I'd be.

Why the test on E6 and not C41 ?

Dan Fromm
31-Mar-2013, 09:38
Negative film has much more latitude, reversal film will give a more stringent test. If you intend to shoot color negative film, you should test with it.

Axel
31-Mar-2013, 09:46
ah - that's what I thought.
Yes, I only use C41 now.

Emmanuel BIGLER
1-Apr-2013, 07:58
Hello from France and welcom to the club of ultra-wide angle lenses for 6x9 / 2"x3" !

Taking into account that your lens is, with a probability of 99.9%, optically identical to the Rodenstock 55 mm Apo Grandagon, the following official data sheet is relevant, read page 36 and apply a factor 55/45 on the X-axis of the "Fall-off in illumination" chart :cool: (given for the 45 mm, but the apo grandagon 45 and 55 are of the same optical formula)

http://www.rodenstock-photo.com/mediabase/original/e_Rodenstock_Analog_Lenses_27-42__8226.pdf

At 45 off-axis (distance off-axis = focal length, total angle of 90) the light fall-off is about 1.5 f-stop. This is significantly less fall-off than you would expect from a basic cos^4(theta) law (-2 f-stops at 90), because those lenses somewhat compensate "natural" fall-off by a clever application of some amount of pupillar distorsion

I own both lenses, apo grandagon 45 and 55, and I have used them is 6x9 cm and 6x12 cm. I have no centre filter for those lenses and have never needed them in 6x9 with the 55 mm. But in 6x12 with some rise or shift or with the 35 or the 45 it is easy to see the effect of this "natural" light fall-off.
From my experience you can probably use the 55 in 6x9 without centre filter.
Rodenstock has those centre filters on catalogue, they are described on page 41 of the same document
-2.5 f-stop / 5x filter thread 67 mm filter diameter 86 mm.

Axel
1-Apr-2013, 08:27
Bonjour Emmanuel !

I have read the Rodenstock pdf but graphs do not speak much to me - never was good at math :(

I'll have my tests developed tomorrow ; with the 55mm, I made a straight shot and one with a 2,5cm down shift ; plus one with the 75 and the same amount of down-shift for reference.
From what I saw when doing them, fall-off (in 6x9) seemed equal to the slight effect I have with the 75mm on 4x5".
Wait (hope) and see.

Axel
5-Apr-2013, 06:25
Test made.

2x3" : indeed no signs of fall-off at all with (moderate) or without V shifts !

4x5" : sans shifts, there is some but it remains perfectly manageable in post-production ; with shifts, of course, it becomes clearly visible.


Glad I can skip the 500$ center filter expense !
Thank you all for your help and advice.