What are the bellows for on an enlarger?

[ted_smith]

The pics in the zip file attached is my enlarger.

Can anyone explain what the black bellow is for, because my prints are generally always in focus when the bellows are contracted, not expanded. Does the picture degrade or improve the further the lens moves away from the negative? Is there a "good practice" element to follow?

http://www.tedsmithphotography.com/temp/enlarger.zip

Also, note the negative carrier. This one is rubbish and partially broke - where can I get a replacement and what sort should I get?

 

[anon12345]

The bellows keeps the light from escaping into the darkroom.

 

[voretaq7]

The bellows keeps the light from escaping into the darkroom.

Mine don't - that's what the patch tape is for!

 

[MattKing]

Hi Ted:

The enlarger you have pictured is a Durst Enlarger with an Ilford Multigrade 400HS head mounted on it. That Ilford head can be used for negatives that range between sub-miniature (smaller than 35mm) negatives through 6cm x 7cm negatives.

Can you tell us what model of Durst enlarger it is? That will help us suggest a repacement negative holder for you.

Assuming that the enlarger is designed to be used with a range of negatives (e.g. sub-miniature though 6cm x 6cm) then you will find that if you use it with larger negatives and the associated longer enlarging lenses, you will need to use it with an expanded bellows.

Here is a pic of the turret on my enlarger, showing the three different lenses I have mounted on it, and the bellows' extended a typical amount for one of the longer lenses:



Hope this helps

Edit: as Michael says above, the bellows will also extend or contract as you change magnification. You just won't notice it as much when you are printing from 35mm negatives.

 

[Worker 11811]

Theoretically, you don't need to have bellows on your enlarger. However, if you don't have them, light will spill out all over the room and potentially destroy any photosensitve materials it falls on. You might have a small problem with contrast or intensity of light that falls on the target (photo paper) due to loss of light but that's a topic for another discussion, all together.

I took the bellows off my enlarger when I was doing the alignment procedure because it allowed better access to the negative stage and the lens board adjustments without trying to reach in and tweak them with a screwdriver. I could just slide the spirit level in and do the adjustment.

But for the above mentioned light leakage, the enlarger operated normally.

When you focus the enlarger, you will move the lens board up and down to bring the focal plane of the lens into alignment with the film plane. When these two planes (or zones) are perfectly aligned, plumb, level and square to each other, your image will be in focus on the baseboard/easel. If the image is not focus, you must turn the focus knob which will rack the lens board up or down until focus is achieved.

The distance between the film plane and the lens focal plane will vary in direct proportion to the focal length of the lens. (i.e. The longer the focal length, the farther apart the lens and the film will be.) The bellows expand or contract to fill the space between the lens and the film plane.

Basically, the bellows are just along for the ride.

As Matt says, if your lens focal length is too long for your bellows to reach, you will either have to get a longer bellows or a shorter focal length lens... Assuming that a lens of the given focal length will correctly project the image from your film without vignetting or distortion.

 

[Steve Smith]

The bellows keeps the light from escaping into the darkroom.

No. They stop the dark from getting in.


Steve.

 

[ic-racer]

And there is no reason you can't also put a bellows between the lens and paper (so you can use it in the daylight).http://www.bhphotovideo.com/c/product/171728-REG/Daylab_100625_120_Head_ONLY_Requires.html

 

[ted_smith]

Thanks for the info guys - that makes sense!

 

[2F/2F]

What are any photographic bellows for? To allow various movements - mostly changes in extension - whilst remaining light tight.