Correcting Perspective w/ Enlarger

[Eric Woodbury]

I don't do this very often. Whenever possible, I correct in the camera, but for medium format, this isn't usually possible. I have corrected perspective under the enlarger a few times, but there are two things I don't like about this:

1) It seems very haphazard. It is difficult to set up and get everything perfect.

2) Getting my enlarger back to parallel is a pain.

I have two enlargers and I've been thinking of modifying one to make this easier. Maybe I could chop up a view camera and make the front end of the enlarger easier to adjust.

So, how often do you use this technique, how do you do it, and what are your secrets?

[A49]

So, how often do you use this technique, how do you do it, and what are your secrets?

I did it only once a long time ago. So I can offer only theory which you might already know. The best kind of correcting perspective while enlarging is when you can incline both: the paper (holder) and the board with the enlarger lens. The thought lines (if you look from in front of the enlarger) of the paper holder (sorry, I don´t know the right term for this in English), the lens board and the negative holder (sorry again) should meet in one point. It follows the same principle as correcting perspective with view cameras and it´s called Scheimpflug principle. Here is something about it, although too theoretical

http://en.wikipedia.org/wiki/Scheimpflug_principle

...maybe a good starting point nevertheless. The good thing about Scheimpflug is that you get both: perspective correction and overall sharpness at every point of your negative´s projected image at the paper board even with open aperture of the enlarging lens.


Hope this helps and sorry if bored you with something you already did know.

Best regards,
Andreas

[BetterSense]

Whenever I did it, I just tilted the easel, and stopped the enlarger lens way down so I had some centimeters of DOF. I don't think my enlargers allow the lensboard or the negative carrier to be tilted.

[ic-racer]

Sometimes the amount you need to move is more than expected. This arrangement is for just a little upward camera tilt with an 8x10 camera and a 'just covers' 210mm lens.

It is nice to have an enlarger with 3 moving planes and solid detents on the 'zero' positions for when you are done.

Basically it is done just like using a view camera. The negative and baseboard are adjusted to get the correct keystone distortion to correct the image and then the lens is swung to get it all in focus. Moving either the baseboard or negative stage produces the same effect. If you can tilt both, then the baseboard isn't so tilted that the easel slides off to the floor

[Eric Woodbury]

Ic-racer, that's what I'm talking about, but I don't think that enlarger would fit in my darkroom.

[lenser]

Eric, We don't know what kind of enlargers you are using, but if one happens to be a D series Omega, they made a perspective control tilt mechanism and 4x5 negative carrier combined into one unit. The tilt was variable and the"box" had a wheel to rotate the neg in place while working with the correction planes.

I doubt there would be a problem in fabricating a medium format carrier or just mask off the opening as there is lots of room inside the box.

I still see them on ebay once in awhile.

Could be that it might be adaptable to another type of enlarger as well.

If you need further tilt against the plane of this adapter, just prop one end of the easel on books of varying thicknesses.

[Eric Woodbury]

It is a Beseler 45MXT. Some Omega accessories cross over. At least the idea would. Thanks.

[lenser]

Eric,

I wasn't able to find an illustration, but I did find parts numbers and info beyond what I had known about formats.

The "Distortion Correction Attachment" is catalog #429-080 and it has negative carriers for 35mm up to 4x5.

35mm #423-902
6x6 #423-903
6x9 #423-904
4x5 #423-905

I'm betting it would work in your Beseler.

My Omega D2-V has a gap of 1.25 inches at most and this slides right in with a bit of room to spare. Your enlarger has tilting stages that mine does not, so you may not even need this, but it is a handy gadget.

Also, in his volume 2 book "Darkroom Techniques", Andreas Feininger has several pages and diagrams on procedures of perspective/distortion controls in print making (page 117). Probably out of print, so if you want, I'll email the data to you.

Tim

[A49]

It follows the same principle as correcting perspective with view cameras and it´s called Scheimpflug principle.

I was kind of absent-minded yesterday in the late evening. Naturally you use Scheimpflug with the camera to tilt the sharpness plane and perspective correction is done by shifting the lens board.

Andreas

[ic-racer]

Ic-racer, that's what I'm talking about, but I don't think that enlarger would fit in my darkroom.

Even the little Durst M600 does it. Getting another enlarger that does what you want might be easier than modifications these days.



Just some observations:
Square format images will become 'portrait' orientation
Rectangular format images will become square
Just a little rise with a wide angle lens on the camera can do more than a lot of tilt under then enlarger.

I wound up getting a Angulon 210mm for my 8x10 camera because correcting 'in camera' is much easier.

You might want to look into a PC lens for you MF camera. I don't have the PC lens for my Rollei 6x6 but I have a Horseman VHR to use instead.