DIY fresnel

[IanG]

Who sells the £2.35 fresnel in the UK ?

Ian

[BennehBoy]

This is the one I picked up, but there are plenty of other sellers

[IanG]

Thanks, I looked for them on my last visit back to the UK with no luck, the Staples version has been mentioned on this site a few times, but they weren't a stock item in the UK Staples stores. At that price they are worth a try

I've ordered 3, try on the spare 10x8 when I've made a new screen for it and a couple of 9x12's

Ian

[jbenedict]

I'm a little bit confused about where the fresnel goes- none of my cameras have had them.

These go on the front side of the ground glass (where the image is formed) with the flat side of the fresnel against the ground glass?

Jeff "I have questions" Benedict

[BennehBoy]

well they _can_ go on the front side, but it's easier to just place them against the rear side, my p2 has little clips to accomodate one.

[bobwysiwyg]

OK, now this novice is confused. If you put it in front (lens side) of the GG, aren't you moving the GG back from the film plane, wouldn't there be a focus difference? I'm assuming, quite falsely perhaps, that even with the fresnel screen, you are still focusing the image on the GG.

[Robert Hughes]

Hello bobwysiwyg (hope I spelx'd that right). Adding a fresnel lens adds a bit of complication to your focus point calculations if you place it between the lens and your GG; where is the lens supposed to focus, on the fresnel or the GG? Does addition of the fresnel throw off the actual focus point from the film plane? Which was do the fresnel elements go?

If you place the fresnel between the glass and you, these issues disappear. But the additional space taken by the fresnel may interfere with your ability to close any protective doors or glass coverings.

[IanG]

The Fresnels we are talking about are very thin, so no problems with closing the back of a Crown/Speed Graphic, although you may well need to trim a bit it's not perfect

Some backs are designed for the fresnel to be the film side, this does alter the focus plane if you put a different one or remove it.

Ian

[bobwysiwyg]

Phew, OK, the novice feels better. I use one and it is mounted between me and the GG.