Hello, Thanks a lot for all the replies I got from my "How to get huge grain" query. I will definitely experiment a lot. But problems don't stop. Now I have another one. I noticed that when I set focus on the baseboard (with a focus magnifier) at the center of the picture the lower side is clearly out of focus.Because in the final print I can identify the grain structure everywhere except in the lower part. To solve this problem (partially) I have to tilt up the upper part of the easel by appr 5 degrees. But when I have a look at the setup (with easel tilted up) from the side everything looks so weird.The easel is definitely not paralel to the film plane then.

What's going wrong?

I have read a lot about enlarger alignment, i.e. that it should be tested.On the other hand, there is almost nothing written about how to rectify any enlarger misalignment.

Any suggestions or ideas???

(BTW, I have a Durst Graduate enlarger with a Rodenstock Rodagon lens. I had the Rogonar previously but bought the Rodagon since the corners were soft with the Rogonar. It really drives me crazy. I'm using the best prime lenses and a good enlarger lens. However I still have soft parts in my picture. Should I have bought a better enlarger?Durst M670 for example)

Kind Regards, omar

-- Omar Ozenir (omar.ozenir@turkcell.com.tr), December 30, 1999

Answers

Before anyone can make any suggestions, we need to know what focal length your lens is and what format of film you are using.

-- (edbuffaloe@unblinkingeye.com), December 30, 1999.

I'm not familiar with the Durst Graduate, but if it is a condenser enlarger you might want to adjust the various condensor lenses inside to make sure you are getting an even spread of illumination. In your later post you say you are using 35mm film and a 50mm lens, which is the normal focal length. Are you stopping the lens down? If everything is properly aligned, and the Rodenstock lens is stopped down (it will be sharpest in its mid-range), you should have perfect focus from corner to corner. Is the lens in good condition, clean and free of haze?

-- (edbuffaloe@unblinkingeye.com), December 31, 1999.

Illumination aside, two conditions need to be fulfilled. First, the negative, lens board, and base board must all be parallel. Second, the axis of the lens should pass through the center of the negative.

If you can get a commercial alignment tool like the little laser device, that's probably best. For a quick check, use a bubble level. Using cardboard shims, level the baseboard. Next, check the negative carrier resting surface. Easiest way is to find a piece of glass or mirror about 2" wide and 6" to 10" long. Put it where the carrier goes, then put the level on top of the glass. Check the lens in a similar way by holding the glass up to the filter ring of the lens. There are other methods, some of which are better than this, but this is easy and you probably already have a small level.

I haven't given any suggestions as to how to correct the alignment, as all enlargers differ. Look at how it's screwed together and apply some thought to the problem. Often the negative stage and lens are fixed to each other, and all you can do is move the head as a unit in relation to the base board. There may be adjustment screws. Or not. It may be possible to shim the column. Also, don't rule out something being bent, broken, or mis-manufacturered.

It's more difficult to check the lens and negative axis. I use a machined plastic plug that fits in the hole where the lens goes. This is raised up to the negative carrier, and the position of some concentric rings is noted (I can see the carrier by raising the condensers- not all enlargers will do this) A carefully made paper tube might also work. You'd like the lens to be within about 1/8" of center if possible. You'd also like the rest of the optical system to be on center, but there's little you can adjust there. Good Luck & Happy Y2K!

-- Conrad Hoffman (choffman@rpa.net), December 31, 1999.

Omar, as you see from the responses, there are a number of things that can cause uneven focus. Most common is misalignment between the lens board and film holder. However, film bending is also a possiblity that occurs often with condenser enlargers. Lens softness is the third most common. The thing you need is a good reference negative. It is possible to buy film or glass ruled gratings which will project a sharp and square set of lines on the paper/holder. They cost lots. You can make your own for a lot less. Get a few sheets of drafting paper, ruled for millimeter (ten to the centimeter) and make a high contrast image on film. When copying, be very sure that the film plane and the paper are exactly parallel. This is critical. Using fine grain transparency film, you can make positives (dark lines on bright field) or use b&w film for negatives. Both is best. When enlarged, you will see the sharp lines on the easel, and if they go out of focus it will be obvious. To make it even better, use clear balsam cement to mount the slide or negative on a thin piece of glass, such as a glass slide mount cover (anti- Newton ring is best). This will prevent any bending of the negative. Balsam cement is usually available at most optical supply houses, especially those who provide materials for microscopes. This cement is used to mound covers on slides. Also, do not use the cheap quarter inch ruled paper you can buy at school supply stores. The lines are not as sharp as on drafting paper, and you won't be able to get as sharp an image. With this in the enlarger, you will be able to see the real sharpness and linearity of your system, and the effects of any changes you make. I hope this helps solve your problem. Good luck.

-- Richard Newman (rnewman@snip.net), January 03, 2000.

Here's a suggested method from Kachel for testing alignment. Use a small format film like 35mm (to reduce film bend issues). Thoroughly fog it and develop it. With a sharp knife, make a clean X mark in the middle and the four corners. Raise the enlarger as much as you can. Focus the center X and make prints of all of them. See if any are out. If all of the corners are out, your lens may not be absolutely flat field (solution - stop down). If they are selectively out, you probably have an alignment problem (possible cheap solution - shims). Hope this helps. DJ

-- N Dhananjay (ndhanu@umich.edu), January 04, 2000.