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Eric Woodbury
13-Sep-2010, 13:32
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
13-Sep-2010, 13:48
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 donīt 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 itīs 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 negativeīs 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
13-Sep-2010, 13:53
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
13-Sep-2010, 14:19
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 :)

http://img.photobucket.com/albums/v670/ic-racer/DSCF4801.jpg

Eric Woodbury
13-Sep-2010, 14:23
Ic-racer, that's what I'm talking about, but I don't think that enlarger would fit in my darkroom.

lenser
13-Sep-2010, 14:58
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
13-Sep-2010, 15:16
It is a Beseler 45MXT. Some Omega accessories cross over. At least the idea would. Thanks.

lenser
13-Sep-2010, 18:28
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
14-Sep-2010, 03:08
It follows the same principle as correcting perspective with view cameras and itīs 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
14-Sep-2010, 10:59
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.

http://img.photobucket.com/albums/v670/ic-racer/M600perspective.jpg

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.

AJ Edmondson
14-Sep-2010, 11:47
The Omega Negative Stage with the appropriate carrier is about as simple and quick as you can get and they do show up on the auction site (infrequently). There was also an adjustable "prop" of some sort for inclining the enlarging easel but I haven't seen one in years and it is easy enough to use a small block of wood.

Eric Woodbury
14-Sep-2010, 12:46
Thanks everyone.

I have never seen or even heard of this Omega negative stage corrector, but I can image what it is. It sounds nice in that the alignment of the negative stage of the enlarger is not changed. My Beseler can be lens or neg stage tilted, but resetting is a pain. The zeros aren't that good.

A PC lens is not made for my MF camera, the Mamiya 7, and it wouldn't fix all the negs that I have. I don't have to be able to do this, and won't do it very often, but I'd like this tool in my toolbox.

Since I have two enlargers in the DR, I can modify one without disturbing the workflow on the other.

Thanks again.

ic-racer
15-Sep-2010, 12:13
Ok, so the Omega device should work for what you want to do, but in that case (ie with the Omega lens non-swingable) you have to fiddle with BOTH the negative and paper to get both focus and perspective the way you want them with some trial and error.
Whereas with an enlarger that has a swinging lens, you can set the perspective you want with EITHER negative tilt and/or paper tilt, then just swing the lens to get it all in focus.

If you do go with the Omega device, post some pictures, as I am not familiar with that.

Robert Opheim
22-May-2011, 11:11
I have an omega perspective control device for 4x5 and was able to simple fabricate a negative holder into fitting for 2 1/4x 3 1/4 format.

Merg Ross
22-May-2011, 11:43
I have an omega perspective control device for 4x5 and was able to simple fabricate a negative holder into fitting for 2 1/4x 3 1/4 format.

Robert,

I will soon be taking delivery on an Omega perspective attachment with 4x5 carrier. I will need to modify it to accomodate 6x7 negatives. I was curious to know what material you used to modify the carrier.

Thank you.

Robert Opheim
22-May-2011, 12:02
I bought an extra D2 negative carrier for the enlarger - in my case it was a 6x9 carrier. The carrier for the perspective control device is round not rectangular. I went to a friends house who had a band saw and grinder. Using the 4x5 carried as a template I cut and ground the aluminum negative carrier to circular (about 6 5/16" across). it fits into the perspective control device and works perfectly. I use it more than the 4x5 one as my medium format cameras have no perspective control.

You will need a pivoting grain focuser. There is some back and forth required between the easel pivot and the negative carrier pivot. I am usually trying to get verticals vertical and get rid of converging verticals etc. so I can use a triangle to check that those are all equal. Of course not every image should be done that way..
Good luck with your perspective control.

I did see an image of Ice-racer's enlarger - boy I wish I had that set-up!!

Merg Ross
22-May-2011, 12:20
I bought an extra D2 negative carrier for the enlarger - in my case it was a 6x9 carrier. The carrier for the perspective control device is round not rectangular. I went to a friends house who had a band saw and grinder. Using the 4x5 carried as a template I cut and ground the aluminum negative carrier to circular (about 6 5/16" across). it fits into the perspective control device and works perfectly. I use it more than the 4x5 one as my medium format cameras have no perspective control.

You will need a pivoting grain focuser. There is some back and forth required between the easel pivot and the negative carrier pivot. I am usually trying to get verticals vertical and get rid of converging verticals etc. so I can use a triangle to check that those are all equal. Of course not every image should be done that way..
Good luck with your perspective control.

I did see an image of Ice-racer's enlarger - boy I wish I had that set-up!!

Thanks. You have given me an idea. I will do some cutting and grinding!

tgtaylor
22-May-2011, 15:39
Another way for the Beseler enlarger - perhaps simpler and less costly - would be to use Delta Bes-Align Adjustable Lens Board:
http://www.bhphotovideo.com/c/product/15669-REG/Delta_13310_Bes_Align_4x4_Adjustable_Lens.html

If you need movements greater than that allowed using the provided foam, simply replace it with a thicker foam and longer adjustment screws.

This idea can be easily applied to other brands of enlargers.

Thomas

Paul Fitzgerald
22-May-2011, 18:37
"If you need movements greater than that allowed using the provided foam, simply replace it with a thicker foam and longer adjustment screws."

Careful with that idea, you could damage the lens against the inner board if you go too far.

Most Beseler enlargers have more lens tilt than most lens have coverage, should not be a problem.

Jim Jones
22-May-2011, 21:02
I used strips of mat board to tilt the negative carrier in an Omega B22, and whatever was handy to tilt the easel. A piece of black cloth and a clothespin blocked the resulting light leak. My DeJur 4x5 has built-in lens board and negative carrier tilt. It might be cheaper to find one of those than to do extensive modification on whatever enlarger one has.

Randy Moe
20-Dec-2015, 14:05
Old thread.

I want to do the opposite, which should be the same process. I think.

I want to take a 'normal' perspective sharp in all places neg and heavily distort proportion, yet retain sharpness of focus.

Retaining sharp focus is my conceptual breakdown, until I try enlarger distortion later today. I can tilt my CB7 neg stage alot, then fiddle with easel.

Can I heavily distort AND maintain focus? I will probably be beyond DOF limits.

Perhaps do some distort in camera, using wide DOF and then again distort with wide DOF in enlarger?

No points for digital solutions. I know how to that...

Thanks

Michael R
20-Dec-2015, 17:20
Yes this can be done. If you have a tilting lens stage, you'd first tilt the easel to get the distortion you want, and then tilt the lens to correct the plane of sharp focus. If you have a fixed lens stage and a tilting negative stage, you'd combine negative stage and easel tilt.

IanG
20-Dec-2015, 17:26
Yes this can be done. If you have a tilting lens stage, you'd first tilt the easel to get the distortion you want, and then tilt the lens to correct the plane of sharp focus. If you have a fixed lens stage and a tilting negative stage, you'd combine negative stage and easel tilt.

You can go one step further, with some enlargers you can tilt the enlarger head as well as the lens stage and DOF doesn't come into it at all. If only the lens stage tilts then as Michael says tilt the easel as well.

Ian

Randy Moe
20-Dec-2015, 17:44
Good advice guys, and I just checked, a CB7 does have neg +- 7.5 degrees neg stage tilt. Never used it.

Just an odd project, I dreamed up.

Thanks Michael and Ian.

143833

Michael R
20-Dec-2015, 19:22
In the picture it looks to me like you have both negative stage and lens stage tilt, in which case as Ian points out, you have more options. Think of the enlarger as a view camera. The negative is your subject (which conveniently happens to be a two dimensional plane). The lens stage is your camera's front standard, and the easel is your camera back.

Randy Moe
20-Dec-2015, 19:28
In the picture it looks to me like you have both negative stage and lens stage tilt, in which case as Ian points out, you have more options. Think of the enlarger as a view camera. The negative is your subject (which conveniently happens to be a two dimensional plane). The lens stage is your camera's front standard, and the easel is your camera back.

Yes, that's why I posted that picture. It's becoming clear in my head how to do what I want.

Thanks again!

Luis-F-S
21-Dec-2015, 11:27
You'll get really good at re-aligning the enlarger! L

Bob Salomon
21-Dec-2015, 13:53
You might like to read this, even though it addresses digital.

http://www.rodenstock-photo.com/Archiv/Perspective%20Control.pdf

Jim Jones
21-Dec-2015, 17:34
When expecting to correct the perspective in any shot, either optically or digitally, also take a shot in correct perspective for comparison to the corrected image. With digital correction, the aspect ratio in the corrective image can easily be corrected as described at great length in the above cited article.

Randy Moe
21-Dec-2015, 18:33
Thanks Bob, for the Rodenstock research and documentation brochure. Rather dense reading, and obvious to me when I have done digital perspective control. I wish I could use their modern glass with the latest capture methods, but I am happy to use 'old' Rodenstock in my film experiments. Conceptually identical methodology, as warping spreads data too thin regardless of media.

Jim, yes i must remember to capture 'straight' as well as 'bent' however achieved.

I may never catch up, but the journey is fun.