This is a list of frequently asked questions and my answers. Note that I am not a native English speaker, so be patient with my language... Table of contents: 1. Other large format places 2. How to build a homebrew large format camera 3. What bellows and about the film holder interface 4. Rear frame design considerations 5. Using surveying tripods in photography 6. How to modify a surveying tripod 7. Using the Depth-Of-Field scale of professional cameras 8. Exposure metering for large format photography 9. About tray developping of sheet film 10. Where can I find more info about large format photography? 11. Can I get instructions, booklets, drawings about your design? ============================ 1. Other large format places http://robotics.eecs.berkeley.edu/~qtluong/photography/lf/index.html http://www.slip.net/~bbarrett/Photography.html http://www.scotborders.co.uk/PHOTON/photon.html http://www.cascade.net/~jbender http://www.eecs.wsu.edu/geoff/bender-faq http://home.online.no/~gjon/ http://www.cyberbeach.net/~dbardell/ The next is about pinhole photography, closely related to large format: http://everest.hunter.cuny.edu/~rwheeler/pinhole.html (here I found most other links) ============================================== 2. How to build a homebrew large format camera In message Helen Stavridou writes: > I just read your article about a large format camera you built yourself > for arond 120$. I am a photographer located in Montreal, Canada and was > wondering if you could send me some informations about how to build such > a camera...or where I can find more info... > > Thanks a lot for your help > > Denis Hello Denis, I do not have a detailed article about how to build a large format camera, to write such a paper is a project for the evening of my life... Basically, the monorail construction is made from standard aluminium profile material as it is available in those do-it-yourself shops for house/garden/furniture etc. (what is the correct term?). The slides could be made from massive blocks of alu, or any other material which is sturdy enough and easy to work on. I chose "Pertinax" which is a very hard kind of plastic used in former times for making printed circuit boards. The front part of the camera, which holds the lens, and the back, which holds the ground glass and/or the film cassette, is made from wood, e.g. batten and plywood. The hardest part was the bellows. I made this, after a long evaluation of alternatives, from a special kind of cotton, twill. After cutting out and ironing I painted it with a black rubber paint-color (which was meant for painting tyres of cars...). This resulted in desaster, because the heavy color sucked the bellows down like a wet T-shirt, I almost started to cry, but after some hours struggling I got it back into form, and the second and third painting sessions were just OK. Finally I had a bellows costing almost nothing except my nerves. This was 1979 (!), and it still works OK, but it is now a bit too stiff. But it is still usable. Once I have more time I will write a real article about this including some technical drawings of the slides, which in the end are the crucial parts, but not so hard to do. Good luck, rm P.S. Don't forget to make some snapshots when building your own, and send some to me... =================================================== 3.1 What bellows and about the film holder interface Stephen Sarinana-Lampson writes: > Greetings-- > > I am currently designing an 8x10 wood field camera for use in producing > fine art photographs (primarily portraiture). Any correspondence from > others who have undertaken this endeavor who be greatly enjoyed. > > Of particular interest is parts availability (bellows, etc.) and solving > several technical considerations (film holder interface, etc). > I did a monorail design. The wooden flatbed one as shown on my page is an old (antique) camera. For my monorail view camera I used aluminium profiles from a do-it-yourself shop. The front and back were made from wood and painted black. The ground glass is from another camera. The bellows I did myself, because professional bellows are easy to get but really expensive (400...800$ I think). =================================================== 3.2 More about the bellows Bradley M. Small writes: >Rudolf -- > >I have looked at his site. (D.Bardell http://www.cyberbeach.net/~dbardell/) > I think the explaination he has there is pretty >good. However, is that how you did it or did you do it differently or buy >one? What knid of materials did you use? > >-- Bradley > My way of Bellows construction: I cut to pieces from a kind of cotton twill, the outline is on my drawing on my website. I ironed them using a flat-iron. The folds were 2.5 cm when I remember right. This was a long and boring work, took some hours because it was so *large*. When finished I glued together the two parts, see the drawing. I used a all-purpose elastic glue (UHU kontakt 2000). Then I planned to paint it using a rubber-based paint, which was used in former days by car-addicts for making the car wheels deeper black... When I started to paint my already good looking bellows, it just collapsed together, one mess of wet stinking color and formless cotton - I could have started to cry loud. All in vane? It was a hot day and under the roof (in the attika) it was 40-50 degree Celsius. I made an improvised support construction from some spare alu parts to dry the bellows hanging at least such as to keep the basic shape (without the creases)... For about two hours I stayed there to always correct the shape here and there... I was almost naked, over and over blotted with that stinking rubber paint... Finally it got hard, then I reformed the shape of the foldings. This was easier than I had feared: The cotton seemed to remember the ironing session somehow... Next day I switched on my 100W lamp and illuminated the bellows from short distance. I put in my head into the bellows and expected to see just darkness with maybe two or three holes... What I saw was a fascinating view into an alien galaxis. Black sky and millions of stars. It was great. - But it was not a camera bellows. I repeated painting three times, finally I decided to stop and to start using it as is. And it works just fine. Now this was 1979. In the meantime the rubber paint became rather hard, which makes focusing and movement a bit cumbersome. Luckily the alu construction is so sturdy that this inconvenience does not lead to real problems. Before using the camera I "train" it by expanding and contracting it some times, then afterwards it works acceptable. All in all I am satisfied with my camera still, but I do not recommend to do it exactly this way, there must be better ways. Have fun, rm =================================== 4. Rear frame design considerations Stephen Sarinana-Lampson writes: > Rudolf-- > > Thank you for your reply... My biggest concern right now is the design of > the rear frame which holds the inserted film holder. Is there a specific > design required such that the ground glass is on the same focus plane as the > loaded film. My thoughts were to find an old, antique camera and measure > the various rear components.... > Stephen, of course the most important feature of the back frame is that it has exactly the same focal distance for the ground glass as for the film. But this is easy to achieve. Just buy the film holder cassettes first (you don't want to do those by yourself, do you?). Then design the back frame in such a way that - it allows easy switching from portrait to landscape view - it is light-proof with film holder inserted - it has changeable mount for the bellows - it has a convenient way of holding/lifting the ground glass in place (either the ground glass or the film holder is in place, but it is quite inconvenient to remove the ground glass entirely when inserting the film holder, so there should be a lifting mechanism allowing to slip the film holder in front of the lifted g. glass. - after all the frame should not be too large (outside), because the whole camera would get larger too otherwise. The *ONLY* precision requirement of large scale camera: The distance from the front frame of the film holder to the sheet film (!) has to be exactly the same as the distance from the front frame of the ground glass to the diffusing side of the ground glass. Exactly means +/- 0.5mm here. This is the only critical distance of the whole camera! Compare this to the problems of constructing a 35mm SLR camera, where each and any distance inside the body has to be exact to 1/100 to 1/1000 mm!!! Linhof, Sinar, Horseman, Toyo et al. make much yahoo about their high precision super-expensive cameras, which seems quite ridiculous in the light of the above argument... ========================================= 5. Using surveying tripods in photography Richard Wheeler writes: > Your use of surveying tripods fascinates me. I have a Burke and James 8x10 > which is way to big to fit on the tripod I have, but I can't really afford a > high-end wooden tripod, or any high-end tripod, for that matter. Where > should > I look for a surveying tripod, what kind of company would sell this item. > Also, how did you fabricate the head for your tripod? > In Europe you would shop for surveying articles in special shops, which usually have such thing as well as those instruments needed by wanderers (compass, altimeters, ...), thermometers, barometers, and often hearing aids (funny but true). Dunno about your country. There are tripods with sperical mounts, and others with flat mounts. The latter are by far easier to adapt to photo equipment, I think. The head was made from two very sturdy plastic parts, about 5 x 7 x 10 cm each. I joined them using a long screw (M8, but M10 or more would be better). Below and above I mounted a plate of a rather hard material which accomodates the tripod or camera, resp. The lower connection was done such that it is easy to rotate it ("panorama" tilt). =================================== 6. How to modify a surveying tripod In message <9507150048.AA20465@perutz.salk.edu> Matthew Bowen Harrington writes: > > > I saw that you modified a surveyor's tripod for photography. > What a good idea! I just went to a surveying equipment > store here in San Diego and picked up a catalog from the > manufacturer Sokkia. > > How did you modify your surveyor's tripod? > > > Matt > > matt@sbl.salk.edu > I chose a tripod with a flat (plane) top surface. Most have a spherical top, which is much harder to adapt. The top had already a round hole, of about 1 1/2 inches diameter. I built a tripod head very primitively, but robust and sturdy, which has a long thread at its bottom, which I simply screw tight for fixing, or loosen to make a panorama tilt. I further added three chains leading from each end of the legs to a ring in the middle, where the chains may be attached using snap hooks. This helps tremendously when using the tripod inhouse or on rocks, to get the legs fixed in any position. ========================================================= 7. Using the Depth-Of-Field scale of professional cameras Marian Ward writes: > Hi! > Do you have any tips on the use of the depth of field scale, and the tilt > angle indicator of my Sinar F1? I seem to have trouble with obtaining a > sharp infinity setting using the D of F scale in particular. My lens is an > Apo-Symar 150mm. Any help would be appreciated. > > Thank you in advance. > > Marian, I never worked with a Sinar myself, but from what I know of books and journals it should work about like this: You focus an object in the middle of your D of F range. Then you can defocus in both directions with the rear slide as far as the f-stop marking on the D of F scale allows You watch the ground glass and see the range of objects which will get sharp with this f-stop (e.g. 16, 22, 32, ...). For infinity motives (which of course are the exception for large formats) you would focus on the infinite object and preadjust the scale for the "farest" f-stop marking of your choice, (e.g. 22, ...) then turn back the rear slide to the neutral setting. Then yoou will get the largest D of F including infinity for this f-stop (22) possible. ================================================= 8. Exposure metering for large format photography In message <950808143559_133417011@aol.com> writes: > I shoot a lot of 4x5/8x10 in the studio, no problem firuring out exposures > there, have a card I use in the frame and a ruler, and polaroid of course. > > I want to get out in the field more and need some a quick and dirty way to > figure bellows factor-- Any thoughts. > > Peter Hollander > Photographer > Peteyhol@aol.com Because of my inferior knowledge of English I have some problems understanding your question. What is the bellows factor? I use a Gossen meter to measure the basic exposure value. Then I add the corrections (on the calculating wheel on the meter) to get the final exposure. These factors include - some general correction depending on subject - filter factor, if a filter is used (nearly always the case) - focal extension (bellows factor???) for not-infinity focusing (nearly always the case in 8x10 format, because anything is a close-up in that format!) I obtain the factor by measuring the distance d from the lens to the ground glass and using the formula factor= (d/f)^2 where f is the focal length of the lens and ^2 means "squared" finally: - Schwarzschild, when exposure-time is more than half a second (to be exact, the time value where Schwarzschild comes in depends on the film used - refer to your film data sheet) =============================================== 9. About tray developping of sheet film Excerpt from the newsgroup rec.photo.equipment.large-format: tom@peggysue.as.utexas.edu (Tom Benedict) wrote: > As someone pointed out, Ansel Adams has an excellent section in "The > Negative" on tray developing. One pertinent point I left out the > first time was how to agitate. Adams did tray agitation by lifting > the sheet out and replacing it in the solution. I too find the procedure of Ansel Adams good and practical, but I cannot do it as *fast* as he, however hard I try. This is especially true for larger formats. To pull out the lowest of a stack of sheets and put it back on top of the stack, may be done in 2-4 secs for 4x5', but for 8x10' this lasts about 10 secs (when I do it...) So if the stack consists of 5 sheet, one whole rotation is almost a minute. => No way to get *two* rotations in one minute done. Because I found that the resting between agitation is important (for UNIFORM**2 negs) I develop stacks of at most 4 sheets, doing one rotation per minute as fast as I can, and leaving the stack resting the rest of that minute. rm ================================================== 10. Where can I find more info about large format photography? See question 1, and additionally: There is the newsgroup "rec.photo.equipment.large-format", and there are some links on my page html://www.cast.uni-linz.ac.at/st/staff/rm/foto/ where you can find more links to follow. The best source of large format topics is IMHO the Ansel Adams series of books: The Camera, The Negative, The Positive. =================================================== 11. Can I get instructions, booklets, drawings about your design? I have no booklet with detailed instructions on how to build a large format camera. There is this FAQ, which gives some hints, probably enough for an engaged do-it-yourselfer. What I have are fairly detailed drawings. These are available in various file formats on my web page. Which format should you download? - For on-screen viewing I recommand using the GIF files. - For printing the PostScript versions should be optimal (color printer preferred, greyscale necessary). - As a starting point for your own development you would use one of the editable vector graphic versions, CGM or CDR, or - if you are on a Macintosh with Canvas, you could use the original Canvas drawings, best for all purposes. ===================================================