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Thalmees
8-Nov-2006, 20:35
Hi all,
I was trying to photocopy part of newspaper @ more than 1:1 magnification(but lesser than 2:1), using Rodenstock APO Ronar 300mm f/9.0 on DBM mount, as part of an exercise.
From my experience in MF macro photography, vibration & DOF are plying the major role in destroying a lot of photos. In LF macro photography, and @ that scale(around 1.5:1), I have found it very difficult(if not impossible) to get a usable, sharp film.
I put the newspaper flat on desktop, tilted the huge camera around 45 degrees, adjusted the bellow extension till 1.5:1magnification achieved, focused on the farthest point(shortest below draw), adjusted the tilt/swing dial to zero, then focused on the nearest point(longest below draw). At this point I started to feel trapped in a corner.
(1) The focusing to the nearest point(longest below draw), is not achievable with the fine focus knob(it stopped @ the middle of the area photographed). That mean, the amount of needed tilt, could not be calculated with tilt/swing dial, completely. Even at that position, the dial was pointing toward 31 degrees of forward tilt. When I apply it to the front standard, I was not able to see the image on the GG. But, When I apply it to the film standard, every thing was OK but with massive distortion. The Image Circle of my lens @ infinity(according to camera review) is about 264mm(it should be bigger @ 1.5:1magnification), & Angle Of View of 48 degrees.
I know that 31 degrees of forward tilt is not usual in the real life. But I would like to solve this problem as best as I can. I also realized that, the lens axis may shifted beyond the GG area(with front tilt) so that I could not see the image any more.
How could I proceed to get a sharp photo of the same subject?
(2) I'm using behind lens shutter. And from reading in the archive of this forum, I noted that I've to take care of vibration may created by the shutter. For that, and on the same situation mentioned above(@ 1.5:1magnification & even shorter below draw), I tried to see how much vibration could be created by the shutter. I placed a long slice of light weight paper on the film standard(to observe its peripheries during exposure), and released the shutter @ deferent shutter speed. I noticed that there is vibration @ all shutter speeds(ranging from just noticeable to very clear)according to the mechanism used in releasing the shutter(all with cable release).
Can that vibrations(if kept minimal) ruin the photo? Is it transferable to the film?
From my short experience in landscape photography, I did not feel any problem(on film) in this regard. Could it be a new problem?

Some people who have engaged(long enough) in real life experience, may find this exercise of an odd looking. Appreciating any help in clarification of this situation.
Thanks.

Ole Tjugen
9-Nov-2006, 00:34
Forget about image circle when applying big front tilts: Your lens has an angle of view of 48 degrees, meaning it gives an image out to 24 degrees either side of the lens axis. Applying a tilt of 21 degrees would put the edge of the image circle smack in the middle of your film plane, at 31 degrees your whole film is out in the darkness.

You must either use front fall to get the "cone of view" back in the film area, or rear rise to put the film back in the image area.

Sometimes there's no other solution than to reduce the angle between film plane and subject.

Paul Moshay
9-Nov-2006, 00:53
I don't understand the reason for tilting the camera to photograph a newspaper, why wouldn't you tape the paper to a wall, square the camera to it, and make the exposure. In order to defeat distortion the film must be square to the subject, so in your case, the back and lens must be tilted down 45 degrees, what is gained by tilting the camera in the first place. Is it just an experiment to mangle your brain, or is there something I don't get. Paul

Thalmees
9-Nov-2006, 01:19
Forget about image circle when applying big front tilts: Your lens has an angle of view of 48 degrees, meaning it gives an image out to 24 degrees either side of the lens axis. Applying a tilt of 21 degrees would put the edge of the image circle smack in the middle of your film plane, at 31 degrees your whole film is out in the darkness.
You must either use front fall to get the "cone of view" back in the film area, or rear rise to put the film back in the image area.
Sometimes there's no other solution than to reduce the angle between film plane and subject.
Thanks Ole,
I did not think in rise & fall movements. But I'm sure it'll help.
The situation is suggesting more than 31 degrees, but the fine focusing knob, stopped @ mid point of area photographed(NOT the nearest point). In these extreme situation, how can I proceed to calculate the magnitude of tilt?
You are absolutely correct:
Sometimes there's no other solution than to reduce the angle between film plane and subject.
Thanks soooooo much Ole Tjugen.
Best regards.

Thalmees
9-Nov-2006, 01:28
I don't understand the reason for tilting the camera to photograph a newspaper, why wouldn't you tape the paper to a wall, square the camera to it, and make the exposure. In order to defeat distortion the film must be square to the subject, so in your case, the back and lens must be tilted down 45 degrees, what is gained by tilting the camera in the first place. Is it just an experiment to mangle your brain, or is there something I don't get. Paul
Hi Paul,
Not exactly. This is an exercise of extreme situation that I most probably encounter, in the real work. Of course, I'm mangling my brain:)(& some repliers here;)/sorry for that) now, to save my time, effort & money wallet, later.
Thanks a lot.
Best wishes.

Brian K
9-Nov-2006, 05:21
When you state that you are using a DB mounted lens I assume that you are using the Sinar Auto Aperture shutter. Unless you use strobe this is not a good shutter to work with in macro situations. It is a large shutter with large shutter blades. There is a significant amount of mass moving when you fire that shutter and working in macro will magnify that movement in the image. You are best off either using strobe or using a long exposure, like 4-8 seconds and using what we used to call an Arm Strong Shutter. That is cover/block the lens with a blackcard, but don't actually touch the lens or camera, set the shutter to "B", open the shutter with your card blocking the lens, wait for the camera to relax (stop vibrating) and then do your 4-8 seconds exposure, cover the lens with your black card and close the shutter.

As for the tilts, you need to understand Scheimpflug. If the camera is at 45 degrees, the subject is flat on a table at 90 degrees, then the front tilt should be at the point where the axis of the film (45 degrees) intersects the angle of the subject (90 degrees) if you extend those axis out. Basically if the lens is tilted to be halfway between the angle of the film and the angle of the subject, the subject will then be entirely in the plane of focus. It's easy when you are dealing with a flat object, if you now add a vertical object to that flat object, it becomes far more complex.

Struan Gray
9-Nov-2006, 07:17
Another point: how were you holding the rail. My experience with long extensions (albeit with long lenses, not macro shooting) is that a single rail clamp is not really stable enough once you get beyond 18" of rail. Sinar's double rail clamp plate, or a second tripod may well help.

You are also well into the regime where the tripod crown can flex where the legs attach (and most centre columns will flex too). For example, my Gitzo 13xx tripod works fine with the centre column with a 250 mm lens on 6x6, but the torques are so much larger with 4x5 that anything longer than 450 mm is too wobbly, so I swap out the centre column on my Gitzo for a flat plate when using 4x5. A second tripod or a studio stand will help even more.

Finally, APO-Ronars are not wide coverage designs. Worse, they typically get mushy very quickly once the circle of good definition is exceeded, and the mush does not improve much as you stop down. This may be softening your results even more than vibration.

Thalmees
9-Nov-2006, 22:16
When you state that you are using a DB mounted lens I assume that you are using the Sinar Auto Aperture shutter. Unless you use strobe this is not a good shutter to work with in macro situations. It is a large shutter with large shutter blades. There is a significant amount of mass moving when you fire that shutter and working in macro will magnify that movement in the image. You are best off either using strobe or using a long exposure, like 4-8 seconds and using what we used to call an Arm Strong Shutter. That is cover/block the lens with a blackcard, but don't actually touch the lens or camera, set the shutter to "B", open the shutter with your card blocking the lens, wait for the camera to relax (stop vibrating) and then do your 4-8 seconds exposure, cover the lens with your black card and close the shutter.
As for the tilts, you need to understand Scheimpflug. If the camera is at 45 degrees, the subject is flat on a table at 90 degrees, then the front tilt should be at the point where the axis of the film (45 degrees) intersects the angle of the subject (90 degrees) if you extend those axis out. Basically if the lens is tilted to be halfway between the angle of the film and the angle of the subject, the subject will then be entirely in the plane of focus. It's easy when you are dealing with a flat object, if you now add a vertical object to that flat object, it becomes far more complex.
Brian, agree with you.
Appreciate your help.
Your post, stimulated me to try to resolve the problem of vibration @ least partially(see below please). Thanks.
Best regards.

Thalmees
9-Nov-2006, 22:26
Another point: how were you holding the rail. My experience with long extensions (albeit with long lenses, not macro shooting) is that a single rail clamp is not really stable enough once you get beyond 18" of rail. Sinar's double rail clamp plate, or a second tripod may well help.

You are also well into the regime where the tripod crown can flex where the legs attach (and most centre columns will flex too). For example, my Gitzo 13xx tripod works fine with the centre column with a 250 mm lens on 6x6, but the torques are so much larger with 4x5 that anything longer than 450 mm is too wobbly, so I swap out the centre column on my Gitzo for a flat plate when using 4x5. A second tripod or a studio stand will help even more.

Finally, APO-Ronars are not wide coverage designs. Worse, they typically get mushy very quickly once the circle of good definition is exceeded, and the mush does not improve much as you stop down. This may be softening your results even more than vibration.
Hi Struan,
I used three rail extensions(two long & one short) on a single rail clamp, over Sinar pan/tilt head. The distance between the film standard & lens standard, is 72cm(~28"). The tripod is heavy duty.
you are absolutely correct.
appreciate your input. Thanks.
Best regards.

Thalmees
9-Nov-2006, 22:55
The issue of Sinar Auto Aperture shutter & vibrations, is of great debate(reviewing the history of the forum). For my self( and for any body who will agree with me, or any potential user of that shutter), I found a simple way(this is what I think) to reduce vibrations, even at an extreme situation(bellows draw of 72cm). Simply put, the Sinar Auto Aperture shutter, need to be fit with new resilient rubber strips(DON'T REMOVE IT), or just put your own fresh rubber pieces. The discussion(URLs & details) below, is directed mainly toward potential & new users of Sinar Auto Aperture shutter.
If you find me wrong, please correct me.
Appreciating any discussion.

________________________________________________________________________
.
After reading the responses here(very informative), I really found my self trapped more in the same corner. Could the shutter causing problem that I could not see? May be!
For that, I searched in the forum, but unfortunately the situation is turning to be more complicated.
One of the threads I read, was this: http://www.largeformatphotography.info/forum/showthread.php?t=4915&highlight=Sinar+Copal+shutter+Vibration (Posts# 3,11,14 & 15). The debate there(like other threads), was confirming to me that buying a Sinar Auto Aperture shutter for outdoor photography, is a pure mistake. But, I couldn't notice any problem of vibration with my shutter for almost one year.
Through that thread, I knew there are two rubber strips, almost filling the two vertical grooves of the front face of the shutter. See please, the (convex and resilient) rubber strips on the vertical dimensions of the squared front face of the shutter: http://www.sinarcameras.com/file_uploads/preview/86_0_autoapertureshutter_kl.jpg
There function, could be absorbing the vibration created by shutter movement. Some of the posters there, advising to remove them, to be able to put the shutter on the front standard easily with its clip(which hold the shutter in place) is closed down.
My shutter has also rubber strips, and I can put the shutter on the front standard after two trials, only(most of the time).
No need to remove the rubber strips. I remember the first time I took out the shutter. It was very hard. Later, this process became easier. I noticed the rubber strips surfaces turned to be concave and looks not resilient any more. This is the effect of pressure against front standard for long time.
There is another groove(but empty of rubber) in the rear face of the front standard. It is similar to this: http://i15.ebayimg.com/05/i/07/70/14/7c_1_b.JPG
After this brain storming, I thought: Why I do not try to add few rubber pieces(for more absorption of vibration) in that groove & see if the clip(which hold the shutter in place) will close down?
I ended by adding 12 small pieces of rubber, distributed along the four sides of the groove. Even, the shutter can be fit easily & securely on the front standard.
The rubber I used, are of small dimensions(1.5X3mm each), just fit into the groove of the rear face of the front standard. Actually, they are rubber letters used in personal stamps. See the letters plate, beneath the tweezer: http://www.media-land.net/images/artikel_big/0/043800A1.GIF
To see if the rubber pieces have done any thing to reduce the vibration, I performed the same primitive test(slice of paper test:)) I mention it in my first post. The result, was great. The vibrations was reduced dramatically.
I think, any body using this type of shutter(or similar), should consider the following points at least(plus factors of un sharpness out side the shutter issue):
(1) Loose knobs(chick all knobs of the camera before exposure & tighten them again).
(2) Cable release(any excessive movement of the cable release, can be transmitted via its knob to the camera).
(3) Mechanism of releasing shutter(advance/push the cable release slowly, with no interruption, till maximum & hold it there till the shutter close again. Then release it).
(4) Rubber strips(change the rubber strips when become old and not resilient).
(5) Shutter itself(still un avoidable amount of vibration. Can be reduced by considering the above mentioned points).
I appreciate any correction or discussion.
Thanks.

Struan Gray
10-Nov-2006, 01:16
Brian K. and I have traded experiences with vibration and the Sinar Copal shutter at APUG (where Brian is known as earlyriser):

http://www.apug.org/forums/showthread.php?t=23057

You pays your money and takes your choice. The simplest way to tell if the shutter is creating unacceptable blur in your particular setup is to take the same photograph in ambient light and with flash. The flash will freeze any motion, so differences in sharpness between the two shots will tell you if you have a vibration problem or not.

I can't comment on the rubber strips from experience, but they do look like they are there to provide a combination of light trapping, resistance to the clamping slides and, perhaps, some damping of movement. I wouldn't remove them, but most flexible materials degrade with time, and if they are hardened you won't be able to clamp the board properly.

Armin Seeholzer
10-Nov-2006, 03:36
You need 2 rail clamps the long rail and the flat basis rail and everthing works just fine!
If there is vibration its after the shutter is closed anyway!!
Good luck, Armin

Struan Gray
10-Nov-2006, 03:52
Incidentally, compare this:

http://www.bhphotovideo.com/bnh/controller/home?O=101&A=details&Q=&sku=47859&is=REG&addedTroughType=categoryNavigation

to this:

http://www.bhphotovideo.com/bnh/controller/home?O=10831&A=details&Q=&sku=86373&is=REG&addedTroughType=categoryNavigation

I know which I would buy :-)

Ted Harris
10-Nov-2006, 06:03
Finally, since we are talking in a theoretical as well as real sense, I would never atempt critical macro work with a monorail mounted on any tripod as opposed to a heavy studio stand. Something like this http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=217061&is=REG&addedTroughType=search ... and while talking about price this is another example of an item that is often availabel on the used market for tenths of pennies on the dollar as long as you can haul it away. The heavy duty Cambo stand that I have been using in my studio for the past four years sells new for over 4K and I got it for under 200 .... just had to get it to my place. The difference in how well it anchors a heavy monorail is definitely noticable.

David A. Goldfarb
10-Nov-2006, 06:21
For macro with LF and continuous light, sometimes it makes sense just not to use a shutter. Exposures tend to be long (on the order of minutes often), so you can just use a black card or the hat trick.

If you're using strobes, a press shutter is convenient for multiple pops, but you can also just dim the studio lights and fire the flash repeatedly. Flash will be so much brighter than ambient that the exposure between flashes will be irrelevant.

Here's a 10X macro I posted on APUG a while back, with a photo of the setup. If you're not an APUG subscriber, you may not be able to see the main photo, but I think you should be able to see the setup shot in the comments--

http://www.apug.org/gallery/showphoto.php?photo=7389&cat=500&ppuser=60

Studio stands are nice, but I managed this one with a Tiltall. Instead of a shutter I just pulled the envelope (Polaroid) and put it back in at the end, which is fine for a 16 min. exposure.

Struan Gray
10-Nov-2006, 06:38
Finally, since we are talking in a theoretical as well as real sense.....

http://www.techmfg.com/portals/stacis.html

Thalmees
10-Nov-2006, 14:48
I would like to thank each poster here. Through your contributions here, the thread became a valuable reference for those whom may complain of vibrations as well as potential & new users of this type of shutters.
No argument of any degree, that the best tools to be implemented, to reduce vibrations of any kind(including vibrations created by Sinar Auto Aperture & similar shutters), are those mentioned above.
But, an advanced amateur, like me(who does not find a customer ringing him/her every now & then, asking him/her about the photo he/she signed its contract few hours ago) is thinking in a deferent way(some times & in other times in contrasty way) compared with a professional photographers.
If I add any thing, it would be this illustrated photo of my primitive test. The metallic ruler is so elastic, that with only a touch, it may take few minutes to calm down in resting position.
http://show.imagehosting.us/show/1737544/0/nouser_1737/T1_-1_1737544.jpg (http://www.imagehosting.us/index.php?action=show&ident=1737544)

http://www.thefreeimagehosting.com/Uploads/Images/5537452662500Vibration%20TEST.jpg
http://www.imagehosting.us/index.php?action=show&ident=1737544
The original photo was taken during similar(bellows, bellows draw & tripod head)exercise in Sinar Workshop II, several years ago.
Thanks, best regards.

Ted Harris
10-Nov-2006, 19:56
Struan, Looks like it will do the job. Imagine I will have to sell my house to buy one <smile>.

Dan Fromm
10-Nov-2006, 21:45
Folks, the original poster described a situation -- an exercise, he wrote -- that seems pretty contrived. The exercise seems to have been designed to teach the student what not to do.

As a matter of practice, does anyone who regularly shoots near or above 1:1 routinely subject himself to such difficulties?

I can't imagine setting up to shoot a flat subject with the film plane not parallel to the subject or using such a long lens to shoot at 1:1 or not using electronic flash to stop motion (of the subject relative to the camera/lens assembly and within the camera/lens assembly). Ted, you and I often disagree about how to do things, but in case you don't know it, I greatly respect your skill and experience. What am I missing here?

Cheers,

Dan

Thalmees
11-Nov-2006, 08:09
thanks dan.
What I'm doing dan, is a matter of extending my visibility, to reach best performance in the real work. That contrived:( exercise is nearly similar to one of the real exercises presented in the Sinar LF Workshop II. This Workshop is directed, mainly, toward professionals, and offered worldwide.
The problem of photographing flat subject, turned to be minimal compared to vibration. I'll be delighted, if you comment on the later one.
Thanks again.

Folks, the original poster described a situation -- an exercise, he wrote -- that seems pretty contrived. The exercise seems to have been designed to teach the student what not to do.

As a matter of practice, does anyone who regularly shoots near or above 1:1 routinely subject himself to such difficulties?

I can't imagine setting up to shoot a flat subject with the film plane not parallel to the subject or using such a long lens to shoot at 1:1 or not using electronic flash to stop motion (of the subject relative to the camera/lens assembly and within the camera/lens assembly). Ted, you and I often disagree about how to do things, but in case you don't know it, I greatly respect your skill and experience. What am I missing here?

Cheers,

Dan

Dan Fromm
11-Nov-2006, 09:04
Thalmees, as I said, I use flash as much as possible when working at high magnifications. Doing this isn't always feasible and getting the desired lighting effect isn't always easy, especially when working in the field, but it does eliminate most problems of steadiness. The one situation where flash doesn't completely solve steadiness problems for me is shooting 35 mm hand held at magnifications above roughly 1:2. There wind and my own lack of steadiness sometimes cause the plane of best focus not to be where I thought it was when I pushed the button.

If you're not comfortable using flash close up, work. When I was a beginner I was averse to flash. I hadn't learned enough to know how to use it and I thought it was too complicated. As usual, I was mistaken.

I should add that unfortunately flash is very hard to use in the field with fast films. Ambient can be too bright to overpower at the desired aperture and highest shutter speed available. My best solution to that problem, and I don't like it at all, is a couple of stops of ND filter on the lens.

Cheers,

Dan

Thalmees
11-Nov-2006, 21:27
Thalmees, as I said, I use flash as much as possible when working at high magnifications. Doing this isn't always feasible and getting the desired lighting effect isn't always easy, especially when working in the field, but it does eliminate most problems of steadiness. The one situation where flash doesn't completely solve steadiness problems for me is shooting 35 mm hand held at magnifications above roughly 1:2. There wind and my own lack of steadiness sometimes cause the plane of best focus not to be where I thought it was when I pushed the button.

If you're not comfortable using flash close up, work. When I was a beginner I was averse to flash. I hadn't learned enough to know how to use it and I thought it was too complicated. As usual, I was mistaken.

I should add that unfortunately flash is very hard to use in the field with fast films. Ambient can be too bright to overpower at the desired aperture and highest shutter speed available. My best solution to that problem, and I don't like it at all, is a couple of stops of ND filter on the lens.

Cheers,

Dan
Hi Dan,
Agree with most of what you have mention. Thanks for the help.
At full daylight(around EV15), with ISO/ASA100 film, and selecting f/no64(one f/stop wider than the narrowest f/stop in my Ronar), and considering correction for bellows extension of around 1:1 magnification(+ 2 f/stops), we should end by a lot of pairs of choices(among them, f/64 @ 1/2sec, & f/45 @ 1/4sec). Both, are the same exposure(even, both will give the same exposure result for the ambient light). But, the former can control(decrease) the flash exposure(effect) @ the same ambient light exposure (compared to the later). While the later, can give more flash effect(exposure) @ the same ambient light exposure (compared to the former). In the two choices above, there will be no deference in ambient light exposure, but there are two f/stops deference in flash exposure.
As far as I know, the ND filters will control(decrease) both lights @ the same time(ambient and flash).
As for flash units, the macro photography in the field with LF, does not require all that studio flashes to be accomplished. An EV of 13, @ f/64 or f/45, need only flash of GN45 or so @ 0.6meter(this is equivalent to f/75 without correction), to add fill-in light of -2.7 f/stops(bellows extension & flash diffuser, are considered). Of course, if you add another flash unit &/or used a reflector properly, the fill-in flash may increased to -1.5 to -2 f/stops compared to the ambient light. All of these differences, are well, within film limits, although using fill flash in the field is not that easy.
All photographic applications, are a matter of problem solving related to reality(i.e: not contrived). The difference here, is the way you solve that problem.
Macro photography, should not be always of 1:1 magnification. At a lower magnification, I believe most of the problems of DOF & fill in light(due to shorter bellow draw), as well as vibrations, are all reduced accordingly.
Again, vibrations(which was not concerning me too much, in landscape photography), turned to be like a night mare. Results on film, should till wither this problem can be resolved by care & simple remedies, or not.
appreciating you input Dan.
Best wishes.

Dan Fromm
12-Nov-2006, 04:20
Thalmees, I've done the arithmetic. Many times. Its bad luck to shoot at an effective aperture smaller than f/45, which limits us to around 4x enlargements. At 1:1, marked f/22 = effective f/45.

I try to shoot my rocks and flowers at magnifications from 1:10 to 2:1 at an effective aperture of around f/22 - f/32. Smaller doesn't pay. One of the paradoxes of photomacrography is that stopping down can reduce depth of field.

By sunny 16, f/22 @ 1/125 is about 1 stop under with ISO 100 film. Too much exposure from ambient in this, the worst case. Shooting at 1/400 helps a little. Do the arithmetic, you'll see that even at 1/400 shooting near wide open is out.

In the field, the problem with shooting flowers -- not rocks -- isn't so much vibration as subject movement. Wind, usually. Bad problem regardless of magnfication, and another reason to use flash.

Cheers,

Dan

Thalmees
13-Nov-2006, 17:09
Thalmees, I've done the arithmetic. Many times. Its bad luck to shoot at an effective aperture smaller than f/45, which limits us to around 4x enlargements. At 1:1, marked f/22 = effective f/45.

I try to shoot my rocks and flowers at magnifications from 1:10 to 2:1 at an effective aperture of around f/22 - f/32. Smaller doesn't pay. One of the paradoxes of photomacrography is that stopping down can reduce depth of field.

By sunny 16, f/22 @ 1/125 is about 1 stop under with ISO 100 film. Too much exposure from ambient in this, the worst case. Shooting at 1/400 helps a little. Do the arithmetic, you'll see that even at 1/400 shooting near wide open is out.

In the field, the problem with shooting flowers -- not rocks -- isn't so much vibration as subject movement. Wind, usually. Bad problem regardless of magnfication, and another reason to use flash.

Cheers,

Dan
Dan,
Really I'm grateful for this enlightenment.
Diffraction, still working here, also. And, I believe that further narrowing(after a limit) of aperture, can degrade image sharpness.
Thanks again & again.
Best regards.

David A. Goldfarb
13-Nov-2006, 18:28
I think the reason that this would be an exercise in a Sinar workshop is this is one of those things that you might never do in practice, but with a Sinar it would be really easy. I've done this sort of thing just to figure out how to use the assymetric tilts on the 8x10 P and the tilt calculator on the 4x5" F (usually with the camera aimed 45-degrees at a piano keyboard, or to figure out the swing mechanism 45-degrees at a bookshelf along the wall).

Thalmees
13-Nov-2006, 20:47
I think the reason that this would be an exercise in a Sinar workshop is this is one of those things that you might never do in practice, but with a Sinar it would be really easy. I've done this sort of thing just to figure out how to use the assymetric tilts on the 8x10 P and the tilt calculator on the 4x5" F (usually with the camera aimed 45-degrees at a piano keyboard, or to figure out the swing mechanism 45-degrees at a bookshelf along the wall).
Hi David,
You are returning me back to the problem of calculating the angle of tilt @ around 1:1 magnification. Thanks in advance for help.
Let me start with the Sinar exercise. Its an exercise of photographing a (three dimensional)red motor @ around 1:1 magnification. See please the photo below:
http://show.imagehosting.us/show/1744317/0/nouser_1744/T0_-1_1744317.jpg
http://www.imagehosting.us/index.php?action=show&ident=1744317
Sinar exercise is very related to the practice, I believe.
Then, my exercise is two dimensional(NOT three) and one of the craziest things(I know:)), is to treat a flat subject(@ high magnification) with large tilt only(once you can do that without tilt). But my exercise(which I'll never do it, as it is, in the practice) guided me toward a practice related problem. That problem is: How to calculate tilt angle(on tilt knob) when the rear focusing knob is not any more focusing?(i.e: after doing every thing properly, the rear focusing knob stopped when the sharp focus reached the middle of the area intended to be photographed. Even, the tilt dial was pointing to 31 degrees of forward tilt).
In another way, is it possible to photograph a flat subject @ high magnification(1:1), without film plane being parallel to the subject, using principle of Scheimpflug, and getting all area sharp?
Its may be the image circle of that lens which limits the needed tilt to be performed. I'll try with other lens to see.
Thanks in advance David.

David A. Goldfarb
14-Nov-2006, 06:04
If you run out of tilt on the calculator with the F, then tilt partway on the front standard, zero the rear standard and start again.

On the P what I would do for a large tilt would be to use, say 15-20 degrees of base tilt on the front standard, measure the remaining tilt in the normal way with the asymmetric tilt on the rear standard, and then usually transfer that reading to the asymmetric tilt on the front standard and zero the rear standard (presuming the lens will cover that sort of large front tilt).

If you run out of image circle, use rear tilt, or split the tilt between the front and rear.

Thalmees
16-Nov-2006, 18:21
If you run out of tilt on the calculator with the F, then tilt partway on the front standard, zero the rear standard and start again.

On the P what I would do for a large tilt would be to use, say 15-20 degrees of base tilt on the front standard, measure the remaining tilt in the normal way with the asymmetric tilt on the rear standard, and then usually transfer that reading to the asymmetric tilt on the front standard and zero the rear standard (presuming the lens will cover that sort of large front tilt).

If you run out of image circle, use rear tilt, or split the tilt between the front and rear.
Hi David,
Really I'm grateful for this help.
May be the most specific answer I got(dealing with tilt).
I only succeeded with the widest image circle I have(210mm/5.6, IC = 305mm @ infinity). The IC of the lens(although big), could not help to apply all the needed tilt on the front standard alone.
Less than half of the needed tilt was applied on the front standard & even greater backward tilt was applied on the rear standard.
Thanks again, appreciate it.
Best regards.