Lens recommendations

Will this lens work with an Omega C-700 black and white enlarger?

Generally 50mm for 35mm film, 70mm to 85mm for 120 film and 135mm to 150mm for 4"x5".

The specs are here:

That lens has a standard Leica thread so all you need is a standard lensboard -- so it will work with your enlarger. Will it work with your film? That depends on what film format you are using, as has been mentioned.

xkaes said:

That lens has a standard Leica thread so all you need is a standard lensboard -- so it will work with your enlarger. Will it work with your film? That depends on what film format you are using, as has been mentioned.

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What exactly is a lensboard?

Like many sheet film cameras some enlargers have a lens board that can be changed out depending on the lens being used. Some are pretty simple, my Opmus has a a lens board that is recessed on one side when using a 50mm lens, the other side for a 75 or 80s, for convince I have two boards one for a 50mm the other a 76mm My Omega D3 has a number of lens boards for lens ranging from 40mm, even 28mm for 110 film, to 163mm for 4X5. With the early Omega Ds, the longer lens are matched to a lens cone. Other like the Bessler 45 and LP 4X5 which uses a double bellows lens boards are used for ease of changing lens. The C700 does use lens boards, the lens screws in directly in the bottom of the unit. The C700 will take a 105.

Here is a link the the manual.

bdoss2006 said:

What exactly is a lensboard?

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a lens board adapts your lens to your enlarger

bdoss2006 said:

What exactly is a lensboard?

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Your C700 doesn't use one - it has a fixed, 39mm screw in thread.
Which means that you are a little bit more limited in lens choice than with other enlargers, which accept replaceable lensboards or lens mounts.
The 39mm thread is about as close to a standard size as you will find, so it isn't a big problem for you. That particular lens should fit perfectly.
The 105mm lens will cover a 6x9 film frame, so if your enlarger illuminated 6x9, it would be well suited to that format.
If you were to obtain an oversized, non-standard 6x9 negative carrier for your enlarger, that lens would cover as much of the image from 6x9 frames as the limited illumination of your enlarger can provide.
The longer the lens, the smaller the image on the baseboard. For that reason, the 105mm lens may limit your maximum print size on the baseboard a bit compared to a 90mm or 80mm lens (some of those were designed for 6x7 too).
To deal with print size limits, some enlargers have extra long columns or make it easy to rotate the column and print on to the floor.
FWIW, I use a 105mm lens when I want to make small prints from medium format negatives - 6x4.5, 6x6 and 6x7 - but want the convenience of a larger print to lens distance. But I have enlargers where it is very quick and easy to swap lenses - marginally quicker and easier anyways than having to screw one lens out and screw another in.