When I first read the topic heading I thought that you were really stupid. Then read the post and thought about it, and concluded that you're absolutely correct. My bad. Thank you (with apologies)!
Wilhelm (Sarasota)
I generally agree with what you are saying, but with lenses like the 240 and 350 I am rarely at the edges of the image circle but see uniform image degradation with front tilt. I often have to work really fast for fleeting light so the pre-correction thing is not likely a route I will take, I try to work with as little movements or iterations of such as possible.
So far, using mostly rear tilt is allowing me to nail it super fast and sharp, I'll stick with a combo of that and a little front tilt.
I like the discussion though, I went out not long ago to get my annual Earth Day photos and really enjoyed using the 4x5, experience always pays off and the eye can really get to work when the tech stuff is a lot more soundly & confidently versed...
Dan, with the lenses you are referencing I can't believe you are could be running out of coverage on 4x5. The only explanation I can think of why you are seeng a difference between front and rear tilt is that you might be tilting more than is needed with the front and not realizing it. I'm not questioning your competence, but a tiny bit of tilt goes a long way, especially in landscape situations. That being said, if it looks good on the ground glass that's all that matters-front or rear tilt, use what works best for and your eyes
With front tilt or swing the correction requires less physical movement than the rear (assuming the front board is about 1/2 as small as the rear) so it is quite easy to under or over-correct with front swing. Assuming you make the adjustment correctly I don't see that it would make any difference in terms of absolute sharpness over the entire field, and never observed this in my own work, with the obvious caveat that you can lose the sweet spot of the lens much quicker with front swings than rear swings.
On the other hand, if I have enough coverage my preference is to place the rear standard level and at right angle to the subject and adjust whenever possible with front rise and fall, or front shift and tilt. Course, if you need dramatic correction for perspective you will eventually run out of movements on the front and have to use the back as well.
With a view camera there are often several adjustments that give an equivalent result.
A classic book on the use of the view camera is View Camera Technique by Leslie Stroebel.
Sandy
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Some good investigating K25. When I was new with 4x5 many years ago, I ran a series of tests on an arrangement of my kid's LEGO blocks with front tilts versus rear tilts. I had been reading Fred Picker's articles on view camera movements and decided to find out for myself. The test was all on Polaroid Type 52 instant B&W prints (RIP). An excellent learning exercise as it turned out. As Joel said, the rear movements emphasize the foreground objects, and it was confirmed on the Polaroids. Being Polaroids, relative sharpness couldn't be compared. As a result I use front or rear or both when the circumstance calls for it. Rear tilts and swings are easier on 8x10, and especially on 11x14, because of the long bellows extensions.
I'm glad people are adding as much as they are, when it comes to movements, a little bit does seem to go a long way but there is such nuance in all of it, easy to get carried away. For what it is worth, I only use 4x5, lenses are 65, 90, 120 macro, 135, 180, 200, 240 and 350, all top quality modern plasmats, most with lots of coverage.
Kodachrome25,
You are checking focus at top and bottom when you use tilts and on both sides when using swings aren't you? I know it's a stupid and obvious question, but I can't think of anything else that could be causing your problem.
Theoretically, the camera itself is a "black box" as far as lens and film are concerned. The only thing that matters is the orientation of lens to film plane, regardless of how that is achieved. I could easily make exactly the same set-up with front tilt or back tilt; same with swings.
As Sandy mentions, the amount of front tilt/swing you need will be physically smaller if the lens standard is much smaller than the back, but, if you are checking focus and doing your iterations, you would be correcting for that by seeing that you have overcompensated.
Since tilting or swinging either the back or the lens standard moves the plane of sharp focus around. Normally, one has an idea of what one wants in (or out) of focus before applying movements and just enough movement is applied to do the job. I always have focus points top and bottom when I tilt and on each side when I swing to check. I'm assuming you are doing the same, and adjusting focus while applying the movements. The techniques are slightly different for base and axis movements, but the result is the same. Again, the camera is just a black box...
With the lenses you mention, there should not only be adequate coverage for lots of movements, but edge sharpness should be acceptable as well out to the point of vignetting. So, I can really only assume that your problem is due to lack of sharp focus, either from not checking after the movements have been applied, or from not being aware of, and not checking focus for the displaced plane of sharp focus top/bottom or left/right after applying the movement.
Let us know how you do solving this glitch. However, keep in mind that it should not matter if you use front or back movements.
Best,
As several P's correctly said, there is no optical reason on Earth why front movements should introduce worsening of optical quality of the image as opposed to back movements. Of course, provided the image circle itself holds decent image quality inside its limits.
Doremus, yep, doing all that you mentioned and agree. Hoffner, while I agree and thought the same my self, the simple notion that the change in the angle of the projected image coming in with a front tilt/swing VS no change with rear tilt aslo makes sense to me from a standpoint of a lens's given "Sweet spot".
Like I said, all my lenses are top notch at the moment so I can use some less expensive film and play around with it some more when time permits. All in all thanks for weighing in, at least it is a hurdle I am learning to work my way around in and if the images are coming out as improved by employing some modifications in the way I work, well at least for now when I simply have to get the shot right, it's good to know I will.
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