Cheap Fresnel and questions

[timbo10ca]

I am trying to find a cheap alternative for a fresnel, and I came across a website called 3Dlens.com- Does anybody have any experience with this company? They have one made out of "optical acrylic" (sounds durable...!) and is 2mm thick. I would have to cut it down to size, but I don't think it would be too difficult- I just have to make sure the center circle remains in the center, right? I only recently discovered that fresnels have different focal length, and a "normal" is advised if not shooting alot of wide lenses. I have a 5x7 and this one's focal length is 200mm. It sounds like a perfect match for my 210mm normal lens- would it be ok for longer and wider lenses as well? I know Office Depot etc carry these cheap page magnifiers, and I tried that route, but they're pretty poor quality. The one I found was all scratched up too. The fresnel at this website is around USD$25 shipped, so it's probably worth a try, but should I practice cutting and mounting on one of the $5 Office Depot cheapies first?

Thanks,
Tim

[Rob Vinnedge]

It sounds cheap enough to try, but check in with Tracy Storer at www.mammothcamera.com. He has more fresnel info and resources than any of us.

[timbo10ca]

It sounds cheap enough to try, but check in with Tracy Storer at www.mammothcamera.com. He has more fresnel info and resources than any of us.

Thanks- I dropped him an email.

[Gordon Moat]

I did my own cheap alternative using a page magnifier from Barnes & Noble bookstore. They sell these in a size that is almost 4x5, and they work quite well. After I got a Satin Snow ground glass replacement, then I stopped using the fresnel.

Ciao!

Gordon Moat Photography (http://www.gordonmoat.com)

[Jim Noel]

I bought some 8.5x11" full page magnifiers at a hardware store several years ago for about $5 each. I carry one in the 8x10 film bag and hold it against the ground glass when I need the extra brightness. They work very well. I have never attempted to measure the focal length.

[Robbie Shymanski]

This is exactly what I used to amend the GG on my Calumet C-1. I cut it down to fit the glass on my 5x7 reducing back. Attached it with some Scotch tape on the edges. Works like a champ!

[timbo10ca]

I got this lens from 3DLens.com- quite good quality, actually. Now I just have to cut it down. The biggest problem seems to be making the outline to cut, with the optic center of the fresnel in the center of the template.

Tim

[timbo10ca]

Just an update:

I cut the lens down and was able to fit it pretty well with the GG clips and some spacers. I have nothing to compare it to, but it definitely brightens up my image nicely.

Tim

[mccormickstudio]

I recently saw an 8x10 fresnel made from the fresnel of an overhead projector found at a thrift store. It was incredibly bright and obviously inexpensive, but not useful for critical focusing.

[Alan Davenport]

I'd certainly practice with the O.D. cheapie first; if you cherry-pick through the offerings in the store you might get one that's perfectly usable and not need to get a more expensive replacement. Cheap fresnels are all likely to suffer from the same problem, mainly a wider pitch between grooves, making it perhaps more difficult to focus accurately.

I'll add (with my asbestos britches near to hand) -- the belief that it is necessary to match the focal length of the fresnel to that of the camera lens, is erroneous. The only thing that will change with differing focal lengths, will be the distance behind the groundglass that the viewed image is most uniformly bright.

[JimL]

I'll add one thing that I haven't seen mentioned anywhere - you can stack fresnel lenses, which adds their individual refractive effects. This is good for wide angle lenses and can give you a remarkably even illumination with ultra-wide lenses, even in low-light conditions.... just experiment to find with what works for you. The downside is that the corners get messed up and there can be a bit of an interference pattern between the 2 sets of grooves. I had one setup which was a Beattie intenscreen, which has its own built-in fresnel, and then I would add another fresnel on top when using wide angle lenses.

Jim