Your camera may already have a fresnel so you need to look into that before buying one; double-dipping won’t help you here. For years, I used the fresnel out of an old Crown Graphic on my Toyo camera and it worked great. I’ve also used a $40 Fresnel that you can get on eBay it’s also a good option, with much smaller and less visible rings than the old one I was using. A lot of 4×5 cameras use a standard sized fresnel lenses, but not all so you might need to buy one specific to your camera. Depending on the design of your camera, you may need to install the fresnel on the lens side or the user side of the ground glass. Either way is fine and won’t mess up your focus so long as you do not move the ground glass at all. The last part of that sentence is important.
Don’t go down the rabbit hole chasing the brightest ground glass on earth unless you have deep pockets. A lot of people think my ground glass is some magically bright screen, but on social media you’re only seeing the scenes where it composed brightly. So very often – especially when using wide lenses – the view is so dim that I can hardly see it, let alone photograph the ground glass view. Same goes with buying the brightest lenses with the biggest apertures; you’ll end up with a lot of heavy glass in your bag and a view that’s hardly any brighter, so you’re better off spending your time practicing some of these tips to compose in the dark.
Check focus with a loupe
Holding a loupe up to the ground glass really brings that small patch of the screen into brilliant detail when compared to the rest. After I have my rough focus set and a best guess at any tilt I might need applied, I pull out the loupe. Sunrise light happens quickly so try not to spend too much time here. Check your focus on a distant subject and a nearby subject and readjust your tilt or swing as needed. Movements in general can (and will) fill a whole blog post so I won’t go too deeply into them here.
Chances are in the dim of twilight that you’ll still be able to focus on your distant objects, such as mountains or a building. The contrast between the sky and objects will always allow you to focus on that fine line unless you’re working in the pure dark of a moonless night (when using a view camera becomes rather impossible anyway). If you’re having trouble focusing on your foreground then you can try using a very bright flashlight. The flashlight on your phone won’t do the trick here. I’ve used my hiking headlamp a handful of times, and some people have found some clamp-on lights to be useful on their tripods. Even in all the times I’ve shot in very dark twilight, It’s only been a few times that I’ve ever needed to illuminate the foreground to nail the focus. There’s almost always an object that will stand out enough from the rest of the foreground, such as the outline of water where it meets shore of a pond or a white rock in a field of grass.