Wide Angle Lens Physics and Infinity

Discussion in 'Classic Manual Cameras' started by chuck_foreman|1, Sep 25, 2021.

  1. Greetings Friends.

    Inspired by Bradley here, I have had a LF Speed Graphic with a roll-film back hanging around my shelves and felt it has been seriously neglected. Probably simultaneous to Bradley's foray, I had ordered the positive paper from Hamamn/Ilford in the belief this would instant instant gratification with less work. Dismayed with the the high contrast, the learning curve or lack thereof of pre-flashing, I wasted most of the box fooling around. Oh, and the images are reversed to boot duhh!! I realized with this much effort, film is likely cheaper and the curve is not too vertical.
    My camera is fitted with the 127 4.7 Ektar. Reportedly just barely covers 4x5 with no movements. As the Speed Graphic has very limited movements anyway, I suppose it's quite ok. I am still teething in LF with the Stearman tank. Prior to my foray but "on my mind" I saw a 90mm 6.8 Optar WA at a good price listed as good working order. I took the bait and after threatening to return as it was not in good order, I rcvd a partial refund and told to keep it. After some naphtha flushing etc, it fires well, but when opening the aperture, one of the blades is lifted or jammed and causes a puckering of a few millimeters of distortion in the shutter plane and hindering the shutter firing when opened. Closed down it is flat and fires well; the aperture blade only slightly out of place. Realizing it's now or never, I bought a 3D printed shutter board and now have mounted this lens on the camera. Using the GG black as a focus guide I am surprised at how little bearing on the rail bed there is when it "appears" to be focused. That is the lens is so far back ie close t to the focal plane that it barely can move further. ( Is this for your WAs the same Bradley?)

    I read often that with Wide Angle lens focus is less critical. Does this mean they are inherently, due to their construction in focus across a longer distance? Is it an illusion like depth of field wherein the human eye perceives sharpness? And to what extent the wider the angle affects this, as we move towards distorted images ie fish eye etc . Or is the acceptance angle the critical part? I suppose there is a very equation oriented reply that is above my poor mathematical preponderance, but can we safely say "focus is less critical" with such lenses and why? Is the focus line longer or is it appearing in focus closer from say 15 feet to infinity?
    In my application I believe 90mm lens is equivalent to say 35mm on 24x36? I find this usually very nice as a general purpose focal length and as I shoot mostly landscapes, ideal.

    One final damning factor is my deteriorating eyesight. I initially made some pencil marks for infinity from inside looking out. However, outside in better light, I moved this back an additional 5-6mm. I am just barely touching the rails. I've shot two frames, but waiting for the sun to show to make two more, and then develop.

    Might have to postpone this... running out of time ..


    20210925_120327.jpg

    Pencil marks right at the hinge


    20210925_120401.jpg

    Frontal view
     
  2. Wide angle focussing is not less critical. It is said to be, because depth of field is larger, compared to longer focal lengths. But unsharp is unsharp.

    Short focal length focussing is more difficult, because of that depth of field, and because of the smaller increase and decrease of extension that is needed for a focus shift.
    Both less so with a 90 mm lens on 4x5 than with a 28 mm on 35 mm format.
     
  3. I've never considered a press camera as the ideal wide angle LF machine. An LF with a bag bellows is the better setup. LF is often set up with a longer than normal lens so full advantage can be taken of movements. 210 mm is a common one. After cataract surgery, my eyesight is better than ever, but only at the distances my glasses are set up for. Even with a strong lower bifocal, I find it necessary to use a magnifier to get critical focus. I had a Calumet when I was a teenager and had no trouble focusing it at all. Must be climate change or something.
     
    Julio Fernandez likes this.
  4. Chuck, how are you focusing?

    I ask because I shoot 2x3 Graphics. 2x3's normal focal length is 100 mm +/-. I have no trouble focusing on the ground glass with a normal lens wide open, using a 3.6x Toyo loupe. 90mm isn't that much shorter than 101 or even 105 mm.

    In fact, I have no trouble focusing a 60/14 Berthiot Perigraphe wide open on my 2x3 Century Graphic. To put 60 mm in perspective, this is a long "normal" focal length for 35 mm still.

    You may want to get and use a loupe, also to clean the ground glass. If you clean the GG, be careful when refitting it to the camera. Shiny side towards photographer, matte/ground side towards lens.

    To find the infinity position, mount your camera on a tripod, pull the front standard out, roll the rails as far back as they will go and lock them in place, aim a a target at least a mile away and slide the standard back and forth while checking focus on the GG. Use a loupe, naked eye won't do.

    Marking the infinity position on the rails isn't a bad idea. However, I use a variety of lenses on my little Graphics, haven't taken the trouble to find the infinity position for any of them. I just put the standard in more or less the right place and focus on the GG. If I've put the standard in the wrong place for the shot I want to take, I move it appropriately. I always focus on the GG.

    This procedure -- not using proper bed stops to ensure that the standard is square to the rails -- introduces the risk of slight unintended swing. I mitigate the risk by using a sort of moveable stop. My first was made by the late Fred Lustig, who called it a Chinaman. Seriously. My second was made by SKGrimes. You can see them and read more about them at http://www.galerie-photo.com/telechargement/dan-fromm-6x9-lenses-v2-2011-03-29.pdf
     
  5. For many years I shot with lots of different 4x5 Graflex cameras.
    Loved the Marine Combat Graflex, Used it on a tripod with 4x5 Plus-X or Tri-X film packs, focused on the ground screen almost always. One of the exceptions was a hand-held shot of looters at a site we were "mitigating".
    39SL4-looters.jpg
    Probably my most widely printed image - used by the Smithsonian in pamphlets.
    More conventional 4x5s used with film packs and, my favorite, Polaroid Type 52.
    If they still made that film, I'd still be shooting 4x5.

    Almost always on all of them, used a tripod or copy stand and the ground glass.
     
    Mike Gammill and James Bryant like this.
  6. Conrad, this really depends on the press camera and on the monorail. The shortest lens that will cover 2x3 (6x9 in metric) is the 35/4.5 Apo Grandagon. Mine focuses to infinity with mm to spare on my 2x3 Crown Graphics and Century Graphic. Using it on my 2x3 Cambo SC-1 isn't really possible, even with Cambo's own bag bellows. I can use it on a funny sort of hybrid Cambo (SC-1 front standard, my own bag bellows, SC-2 bag bellows) with some gymnastics.

    FWIW, the 2x3 Crown/Century's minimum extension is 34.9 mm. The 4x 5 Crown's is 41.3 mm. Crowns are quite friendly to short lenses. Speed Graphics, not so much. Graphics lack movements but they're more useful than they appear.
     
  7. I have a 2x3 Crown and a 4x5. Can't remember what lens, but probably the 127mm on the 2x3. I'm trying to remember the configuration for wide angle and what model does it- bed pointed down and lens raised so you don't photograph the bed? No, I haven't had them out in a while! My monorail, though it could focus a wide (I don't have one), would collide with itself or need a recessed board. IMO, most of the reason for large format is the use of movements, so I stay with longer lenses.
     
  8. On Pacemaker Graphics dropped bed will do it. I can't say anything about older Graphics, no recent experience and I'm too lazy/uninterested to take the book off the shelf ... Front rise -- 19 mm on 2x3 Pacemakers -- works with all focal lengths.

    As for monorails, my hybrid Cambo will allow useful movements with my 47 SA and longer lenses. Can't say anything about a normally configured SC-1 or SC-2, haven't had to try them 'cos I have the hybrid.
     
  9. @dan "Chuck, how are you focusing? " ......aim a a target at least a mile away and slide the standard back and forth while checking focus on the GG. ....Marking the infinity position on the rails isn't a bad idea.....
    I guess using a magnifying glass is a Loupe.. :) I find myself leaning in to check focus and I'm too close, but when I lean back I am unsure of what I' seeing is sharp. I didn'T use this yet and 6.8 isn't very bright :)

    I have not spent that much time with it. I just thought the procedure I did inside was basically the same as I did outside but the "infinity" mark was now 5-6mm more recessed...and I was running out of rail .


    The others mentioning the 4x5 Speed Graphic is not perhaps the best too... I think I get that. The appeal of of the similar ratio of a 35mm in 135 was interesting. I have seen only too clearly some excellent work done with true view cameras and WA lenses. An expression I once read referring to Speed Graphics as LF on a beer budget is fitting to my approach. I believe I once asked you Dan Fromm what WA you would recommend that was inexpensive for our favorite 2x3 Baby Speed and Century Graphic respectively. I also have a XL with a 3.5 Tessar....it's in really rough shape the focus is very stiff and the Compur needs to be overhauled. I believe the GG for the Century works on the XL ie it fits the Graflok back. I digress.
    So sharp is sharp but depth of field may cover a lot ..especially when using WA lenses. The Speed with its deep cavity is not ideal as the WA lens may run out of rail.. so shorter than 90mm is not going to work on a Speed Graphic, but the 90mm might very well be Ok on the thinner body Crown. No knowing, but asking has anyone used a wider angle than 90mm successfully on a 4x5 Crown... I assume the "Graflex" with the FP shutter like the Speed requires too much space?
     
  10. Clean your ground glass. If I can focus a 60/14 Perigraphe you should be able to focus a 90/6.8.
    Which "Speed Graphic" do you have? Pacemaker and Anniversary types both have linked inner and outer bed rails, which make focusing lenses that make infinity with the standard on the inner bed rails easy. The Pacemaker's minimum extension is 66.7 mm, the Anny's is 65.1, if you want to use a lens shorter than 90 mm, check flange-focal distances before shopping.

    Re the beer budget, these days f/8 Super Angulon types down to 65 mm aren't quite beer, still wine -- not champagne -- is more like it, but if you want to go that way look into Fuji SW lenses.
     
  11. I have a slightly later (coated) Wollensak-branded version of the 90mm W.A., and it is not at all sharp wide open (f/6.8). It begins to clear up at f/11, and it's reasonably sharp in the center at f/16. If you can get enough light to try focusing when stopped down a bit, it should show whether or not that is the problem. I'll also suggest measuring the distance from the film plane to the aperture with the bellows collapsed, just to verify that it's no longer than 90mm.
     
  12. Roy, what you're seeing is pretty normal for 4 elements in 4 groups double Gauss type wide angle lenses. The general recommendation for them is to use full aperture for focusing and to stop down to get good image quality. This doesn't quite go for Wide Field Ektars because they were designed for less coverage -- 80 degrees -- instead of the usual 100 degrees for most others of this type.
     
  13. The thing that isn't typical, though, at least as far as my copy of the 90mm W.A., is that it is so soft wide open that I can't identify the focus point with any assurance. It's good enough for framing, but not for focusing. But if it's stopped down just a little, it becomes sharp enough to focus. So, what I am suggesting is that if stopping down is all it takes to cure the problem, that would actually seem normal to me for this lens. (If it still doesn't focus, there is likely to be an actual problem.)

    It looks like I misjudged the age of Chuck's lens. I couldn't make out the first three characters of the serial number, so I was going by the lack of the symbol that Wollensak put on their lenses to show they were coated. Apparently, the Optar versions did not have that symbol, regardless of coating status. Based on the labeling on the shutter, I'd say his lens might be 10 or more years newer than mine.
     

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