Negative stage design

[David Lyga]

It would be interesting to see what feedback this warrants. I am talking about 35mm format here:

Is the enlarged image quality best served by 1) allowing a glass plate to touch the top of the negative and thus keep it flatter (at the real expense of introducing some possible 'in focus' dust) or 2) is it better to be able to use a traditional negative carrier in which nothing touches either the top or bottom of said negative (thus allowing a slight curvature to result on the top of the negative)?

The Leitz Valoy and the Durst M301 utilize the first design and most other enlargers (especially Japanese) utilize the second design. Personally, I cannot find any comfort using the first as the introduction of that other surface to keep immaculate greatly bothers me. The slight curvature that might result from not allowing any glass to touch the upper portion of the negative can be greatly mitigated, even eliminated, by stopping the enlarging lens down. But is there any real validity to the first approach that I am not seeing? I recently turned down an enlarger (Durst M 301) because of this. - David Lyga.

 

[hpulley]

I have an old Durst M-300. It has a glass negative carrier but I rarely find dust problems with that, instead it is dust on my negatives I need to work on. I simply blow off all surfaces before I begin. It's the only style I've ever used so perhaps I don't know what I'm missing. I am looking at an M-605 soon which I think is the same design.

 

[Mick Fagan]

If you wish for optimal quality, then two sheets of glass is a virtual requirement, regardless of format.

That said I don’t use glass too much these days, but in another life working in a pro lab, glass was the go.

If you wished to enlarge 135 to 20x24” then you had to use glass. Enlarging 135 to 24x30” or larger you need an optimally aligned enlarger, otherwise you will find very noticeable out of focus fall-off in all corners and along the long edges of the negative frame.

You can get away with using removable magic tape on either side of a 135 film to stretch it slightly. I use this technique, on every negative I enlarge without glass.

Mick.

 

[Nicholas Lindan]

For ultimate image quality with an APO lens you need to use the lens close to wide open and thus need a glass carrier as there is close to no depth of field. Another consideration is negative popping and unpopping which are greatly mitigated by glass carriers.

The arrangement with the bottom of the condenser providing a 1/2 glass carrier is a good compromise between dust problems and flatness. If you keep the negatives clean the glass stays clean. Glass carriers that leave the enalrger are prone to picking up dust when put on the table to load negatives. Additionally a full glass carrier has four dust collecting surfaces while the condenser-as-carrier design only has one.

 

[Mark Crabtree]

... The slight curvature that might result from not allowing any glass to touch the upper portion of the negative can be greatly mitigated, even eliminated, by stopping the enlarging lens down. ...

Your comment above is true, but is also the problem. If you stop down enough to get the depth of focus to cover the negative curvature, then you are reducing the crispness of the image by diffraction.

I was enlarging 35mm to 11x14" a couple nights ago and noticed the edges and corners of my print had very slightly mushy grain. I was worried that my enlarger had gone out of alignment, but simply putting the negative into a glass carrier made the grain crisp to the corners at my printing aperture of f 5.6. With the glassless carrier I was preheating my negative to pop it before the actual exposure, so it was stable, just not flat.

Glassless carriers are a convenience when they give you sharpness adequate to you needs, and they often do.

 

[nworth]

The Leitz and Durst enlargers you mention are particularly notable for their sharpness. Flatness does count. But 35 mm negatives are small, and most of the glassless carriers do a good job of keeping all but the most badly curled negatives flat. A few designs allow a badly curled negative to push the flaps of the carrier open, thus defeating its purpose. With either design, you have to be careful about the potential of the carrier scratching the film as well. Glass carriers require regular cleaning, but dust is really not much of a problem with them.

 

[David Lyga]

Mike Fagan, your reply offers the answer to my dilemma: using magic tape on each long side (sprocket sides) to force (by pulling) the negative to stay quite flat. Theoretically, this will STILL not be as flat as 'the glass alternative' but the exceptional advantage of not having anything touching that negative, despite naysayers out there, gives at least one of us a greater sense of security. Thank you. Pragmatism in darkroom matters is too scarce a commodity. Routinely going 'by the book' can sometimes prevent this from happening. And I think that the magic tape would also aid with potential popping (which I never experience with heat absorbing glass). - David Lyga

 

[Bob Carnie]

what mick says

If you wish for optimal quality, then two sheets of glass is a virtual requirement, regardless of format.

That said I don’t use glass too much these days, but in another life working in a pro lab, glass was the go.

If you wished to enlarge 135 to 20x24” then you had to use glass. Enlarging 135 to 24x30” or larger you need an optimally aligned enlarger, otherwise you will find very noticeable out of focus fall-off in all corners and along the long edges of the negative frame.

You can get away with using removable magic tape on either side of a 135 film to stretch it slightly. I use this technique, on every negative I enlarge without glass.

Mick.

 

[RalphLambrecht]

For ultimate image quality with an APO lens you need to use the lens close to wide open and thus need a glass carrier as there is close to no depth of field. Another consideration is negative popping and unpopping which are greatly mitigated by glass carriers. ...

That's my recommendation too!
There might be another 'sweet spot' with non-APO lenses, rather than wide-open, but ultimate focus accuracy is only achieved with glass carriers.

 

[jmcd]

I have a Valoy II and it is a great enlarger, and can often be found for relatively little. I have no problems created by the glass pressing on the neg, and noticed from the beginning how sharp the projected negative is. I have the standard, not the the frosted condenser, and have never had any problem with Newton's rings, or dust projected into the image. I take reasonable care and do not worry about anything being immaculate, and I don't think my standards are that low!

I use my aligned Beseler 45-VXL to make contact sheets and for printing larger negatives. It does a good job with 35, but between the two the Valoy II is really a pleasure to use.

 

[RalphLambrecht]

If you wish for optimal quality, then two sheets of glass is a virtual requirement, regardless of format. ...

Less so with small formats, but yes.
I'll deal with the dust. It's much easier to deal with than popping negatives!