jerry_bodine

<p>Since no one here has offered to help, I sent a query to Ilford a couple of days ago, asking if they could send me 4-6 sheets of this 8x10 film (either fresh or expired) from their scraps that they had no further use for. I explained my intended use for non-image forming masks. I offered to pay any postage involved. I received their reply this morning: They are sending me, free of postage, a box of <strong>fresh FP4+</strong> containing an estimated <strong>15</strong> sheets. How's that for customer service? I've said it before and I'll say it again: <strong>ILFORD ROCKS!</strong></p>

<p>Regarding the 8x10 enlarger, some folks have used a view camera as an enlarger. Searching the large format forum will turn up experience for this (if at some future time you decide to give it a whirl and spend the time and money). Also some have converted 4x5 enlargers to 8x10; LFF searches are useful here too. That forum is free and provides a veritable library of info to study up on the subject (http://www.largeformatphotography.info/). Scroll down to near bottom of the page and find the link to the forum.</p>

<p>I'm making a glass negative carrier for my 5x7 Omega enlarger. To position either a 4x5 or 5x7 negative centered on the lens axis, my plan is to insert an 8x10 sheet of film as a mask with appropriate cutout for the intended negative size. The cutout would be located exactly over the lens axis. Since I only use the subject films, I want the masks to have the same thickness as either of these films, so that the top AN glass rests on both negative and mask. My plan is to use expired film for the masks to expose and develop to maximum density and hope to approach opaque as much as possible. So, <strong>I'm hoping someone has four 8x10 sheets of the subject films that they do not intend to use and would be amenable to send them to me (I'd be happy to pay shipping via PayPal or check)</strong>. My fresh film is in the freezer but don't want to open until I'm ready to use. Please let me know if anyone can help.</p>

<p>Thanks, Jim. That's what I need to know. The 1mm difference isn't going to matter for my little project.</p>

<p>I'm making a glass negative carrier for my 5x7 Omega enlarger, and I want to install a system for locating a negative precisely in the carrier so that the center of the negative is at the lens axis. To do this I need to know the <strong>actual</strong> length & width of Ilford's 5x7 sheet film (in case it might be slightly different for other brands). Anyone know these dimensions or could measure a developed negative?</p>

<p>I have two older model aluminum Gitzos from the late 60s/early 70s for my Sinar monorails from 4x5 to 8x10. One has non-winged locks, the other has the wings. The only problem I've had is with deterioration of the rubber grippers on the leg locks of the non-winged type, and these were fixed by removing the dried-up rubber and replacing with wraps of friction tape from the local hardware store; the repairs have held up for many years. I'm very careful about applying too much tightening force.</p>

<p>Rather than my recollection of his workshop comments, here is a verbatim quote from his text on p.74 of his book 'Camera and Lens' (1st Revised Edition, 1970), on the topic of CdS meters:</p> <p><strong>Both zero adjustment and battery check should be observed frequently. "Conditioning" of the meter for accurate readings is described in the "Guide to Good Exposure" by James O. Milmoe, APSA (which is the best instruction book for any exposure meter I have ever seen). "Conditioning" for low-level illumination readings is very important with all meters operating with CdS cells. The meter must be exposed to moderately strong luminance areas prior to measuring low-level areas, and several seconds may be required before the meter needle stops "drifting" when directed to subjects of low luminance value. This does not imply any meter defect; it is typical of instruments of this type.</strong></p> <p>I do not recall him mentioning (at the workshop or in any of his books) anything about lengthy recovery time from exposure to bright light, which sounds to me like something akin to the eye's response to looking at a flash where the bright spot persists for a time - a condition I've heard referred to as "persistence of vision."</p>

<p>BTW, Q.G., since that particular part of the workshop was centered on a discussion of light meters, I suspect AA was simply trying to convey to the group that those relationships of aperture/ISO/shutter speed are ONLY valid when measuring luminance of objects in candles per square foot. Some meters, such as the Weston series, were calibrated in those units at that time. Nowadays, most meters are in EV system, which is why he described in his later text how to convert an EV meter's dial to the candles/sq.ft. values. It's not complicated to do that.<br> <br /> During that discussion he also pointed out that cds meters, also common at that time, suffered from drift of low light level readings, but said drift could be eliminated by pointing the meter at a bright light for 20s or so and then taking the reading of a shadow value, thus "pre-conditioning" the meter.</p>

<p>Q.G., if I gave the impression that I was recommending that procedure, I'm sorry. I agree it's overly complex. I was just relating the method to illustrate the complexity and the reaction of the workshop participants as I saw it. I probably went overboard in presenting the details of the method.</p>

<p>Lenny's explanation of the Zone System is good and simple. I was reminded of my first AA workshop in 1966; on the first day, Ansel introduced himself to the group and began to explain the <em>exposure formula</em> (which he explains in greater detail in "The Negative" book). Most of the eyes in the group began to glaze over quickly, but he said that with a little mental practice it becomes easy (i.e., easy for the nerd of nerds). Use of a spot meter is a huge help with the system. Many of today's spot meters are calibrated in EV units, but he describes in the book how to re-calibrate such meters so they are more useful with the <em>exposure formula</em> method (which allows for very quick exposure settings without having to read the dial on the meter.<br /> The method follows:<br /> The meter must read in candles per sq. ft. (c/ft²) or converted EV.<br /> The square root (rounded off) of the film’s box speed = key stop (aperture)<br /> e.g., ASA/ISO 125 = f/11<br /> The shutter speed, used in combination with the key stop, that produces Zone V in the metered area = the reciprocal of the c/ft²reading.<br /> e.g., 60 c/ft²reading means a shutter speed of 1/60s at f/11 would give Zone V, and if you wanted that area to give you Zone III then you’d use 1/250s at f/11 (or an equivalent combination).<br /> Important: In this example, if your film speed tests for .10 above film base + fog (fb+f) indicate, for example, a film speed one stop more exposure than box speed, you MUST apply that correction after determining the exposure of 1/250s at f/11 (or equivalent). Also any filter factor MUST be applied at the same time as the speed correction.<br /> AA used this method for the “Moonrise” exposure, as he didn’t have much time in the quickly fading light and could not find his meter. But he somehow remembered that the c/ft² luminance of the full moon at that zenith was 200 c/ft², allowing him to place the moon on a preferred zone and pray for adequate shadow detail. It missed in the shadows, but he was able to apply some toning locally in the shadows at the bottom of the negative to boost the local contrast somewhat and save it.</p>

<p>And, btw, my results with this lens do not show a need for a center filter.</p>

<p>I bought this same lens new around 1970 and chose a Sinar-badged version. The Sinar catalog published at that time (which I still have in my files) listed all the Super Angulon focal lengths for which they recommended a center filter, and the 165mm lens was not on that list.</p>