FWIW, Rodenstock's literature recommends f/16 as the optimal aperture for the 75/4.5 Grandagon-N unshifted, and f/22 if shifts are used, based on the criterion "highest sharpness is achieved over the whole format with the depth of field being neglected".Originally Posted by r.e.
Thanks Oren.
If that statement is from a longer text that's useful, do you have a link at hand for it? It doesn't appear to be in the catalogue .pdf that I linked in post #40.
Only if handy.
Yes, you have to go to older catalogs to get the full wording. But I'm afraid there's nothing that provides any more insight. Here's the entire paragraph:
___________
Notes on the Recommended Working Aperture
In the table, the range given for the recommended working aperture is that in which the highest sharpness is achieved over the whole format with the depth of field being neglected.
The larger aperture applies to unmoved lenses, i.e. when the "format range" is used. The smaller aperture is recommended for shifted and/or tilted lens, i.e for the "movement range".
Depending on the reproduction ratio and the depth of the motif, the required depth of field may make further stopping down necessary. In such cases, the sharpness may be reduced due to diffraction - particularly in the center of the image circle.
___________
The Rodenstock catalogs show MTF at two apertures. As I'm sure you've already noticed, if you compare them you can see the tradeoff of center vs peripheral MTF as you stop down. But of course that's only two stops and only at a particular magnification. I know you know this, but for the benefit of anyone who's less experienced and might be reading this: for really critical applications there's no alternative to running one's own tests to find the optimum for one's subject matter, enlargement habits and photographic purposes.
Thanks very much Oren. I think that the additional text is helpful.
This is a follow-up to Bob Salomon's post #37 and my reply in post #38. Bob made the good point that a polariser on a lens this wide can be problematic. In my response, I said that I was interested in using one to control glare/reflections, not on the sky. That said, I think that the problem that Bob raises is potentially also an issue when a polariser is used as I proposed.
However, yesterday I saw a video that was quite encouraging. In it, UK landscape photographer Tom Heaton uses a Lee round polariser (mine is a 100mm square linear polariser) on a Canon full frame and Canon 16-35mm at 16mm. The subject is wet rocks in water on a beach on the UK coast. See the 8:34 mark, where he shows the effect without and with the polariser. The finished photograph is at 11:10. I should probably note that Heaton also used a Lee graduated neutral density filter and focus stacking (three shots) for this photograph.
All that aside, my main purpose in using a Lee polariser and/or Lee IRND filter is to see how the Grandagon 75mm plus centre filter reacts to filter stacking in terms of vignetting. At that, I'm just making do and will handhold the filter because I don't have a Lee 86mm adapter ring.
Without the centre filter, the Grandagon has a 67mm thread. Being standardised at 82mm for screw-in filters, without the centre filter I would just use my 67mm to 82mm step-up ring and screw-in filters. The problem of vignetting wouldn't arise with one filter, and probably not with two.
Last edited by r.e.; 19-Aug-2021 at 06:15.
I expect to receive the Grandagon 75mm lens this afternoon and the Rodenstock 67/86 centre filter tomorrow, in time for the weekend.
One reason that I've purchased this lens is that it will make it easier to make photographs in an historic and highly diverse New York neighbourhood. Some of these photographs will show a shop front with the shop owner in front of his/her establishment. Basically, environmental portraits. The practical problem is making these photographs without setting up a tripod on the street and playing chicken with the traffic. Not to mention that shooting from the street means waiting for the parking space in front of the shop to be vacant. In New York, this could be an eternity. As a practical matter, shop owner subject + traffic + parked cars = no photograph.
Some quick snaps with my iPhone and an app called Artist's Viewfinder demonstrated that a 75mm lens would solve the problem. The two snaps below were taken using the app and 75mm frame lines. They show that with a 75mm lens I can make the photographs from the sidewalks, which are about 5m (16') wide. I think that I can avoid distorting the human subjects by keeping the camera horizontal (that is, not tilted up or down) and keeping the subjects away from the sides and corners of the frame. I also concluded that the Grandagon will be generally useful for making urban photographs, not just in these circumstances. There's discussion about Artist's Viewfinder in this thread, What Scouting/Planning Apps Are You Using in 2021?
Judging from the first photo, I'm also going to need a broom
iPhone 11, Artist's Viewfinder, 75mm frame, black and white:
iPhone 11, Artist's Viewfinder, 75mm frame, colour:
The above photos should explain why I expressed interest in earlier posts (see the post just above this one) in using a polariser. One will be useful in dealing with reflections from shop front windows.
The other issue is camera height. In some cases, I'll need to get my camera either back further or fairly high off the ground to frame the shop front properly. I'll be able to determine this weekend whether the available rise on the Grandagon solves the problem. In any event, I plan to use a Miller CX6 fluid head, which is fairly tall to begin with, and if needed I can use a 150mm (6") riser. The first photo below shows my Arca-Swiss on the Miller. The second, albeit with a Blackmagic cinema camera on a ground tripod, shows the Miller head mounted on a 150mm riser.
Arca-Swiss 4x5 on a Miller CX6 Fluid Head:
Miller CX6 + 150mm (6") Riser:
Post continued below...
Last edited by r.e.; 21-Aug-2021 at 19:04.
Continued from post #46 above...
The rig in the photo below, with its small footprint, may also come in useful. It consists of a robust Gitzo Series 3 monopod and the RRS ground tripod shown in the last photo in the post just above. In that photo the legs are fully extended, whereas here they're at their shortest. I could use this rig without a tripod head (levelling a ground tripod is trivial), with a levelling base or with a conventional head.
Gitzo Series 3 Monopod + RRS Ground Tripod:
Last edited by r.e.; 20-Aug-2021 at 07:16.
I've now received both the Grandagon-N f/4.5 75mm lens and the Rodenstock 67/86 centre filter that a forum member has kindly leant me.
A comment about the lens...
I purchased it from forum participant @corallus. The condition of the barrel and glass is every bit as good as he described in his "for sale" post at Rodenstock Grandagon-N 75mm f/4.5
Judging from the serial number, the lens was made in 1993. Rodenstock added a green stripe to many of its lenses, including this one, shortly after, in time for Photokina. I've noticed that lenses with a green stripe are often described as the "new version". Subject to any comments that Bob Salomon may have, my internet research suggests that the addition of a green stripe on the 75mm was cosmetic. It looks smart visually, and helps brand the lens lineup, but doesn't reflect a change to the mechanics or optics of this particular lens.
I'll post some photos of my Arca-Swiss 4x5 with the lens and the centre filter over the weekend. The plan is to test field of view, available lens movement (especially rise) and the centre filter's effect on images.
There is no difference, save the stripe, between those lenses and the Grandagon-N MC that preceded it.
Earlier today, I came across the discussion in this 2016 thread about wide angle lenses, centre filters and fall-off. Well worth reading, I think. See Bob Salomon's post #13 and following: Help! Schneider XL Input
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