LF Newb Needs a little help with Fresnel Question

[Shadowtracker]

Hi all,

I'm new to LF and picked up an Omega 45F for dirt cheap. I know I have to replace the bellows and I'm working on getting that together. I have a couple lenses on the way.

My eyes are such that I will probably need a Fresnel lens on the ground glass but I don't know how to tell if it goes on the outside of the ground glass or on the Film Holder side of the ground glass. The ground glass framework is recessed toward the Film Holders. I am supposing that the Fresnel goes on the outside of this in the recessed area. I don't understand how a Fresnel will attach to it though.

I have the owners manual, downloaded from the internet but it doesn't say anything about a Fresnel lens.

Thanks for your help.

Apug is a great place!

 

[Tom Nutter]

On some cameras, the Fresnel snaps on, on others, like my Toyo, it is attached under the ground glass. It's hard to tell....try it first without the Fresnel, which actually hinders focusing in my opinion, though it does make it easier to see the entire ground-glass image. My toyo 4X5, with a Fresnel, is much harder ( For me) to focus accurately.than my ancient agfa-ansco 8X10, without the fresnel, though on the 8X10, it virtually impossible to see the entireGG image at once.

 

[JBrunner]

IME Fresnels make things brighter, but fuzzier. Also, the bright spot tends to travel around as you move your head. I'd try a good lupe instead. FWIW my good eye is focused at exactly sixteen inches. How's that for nearsighted. By bad eye is far sighted. No cataracts though. If you have cataracts or something the Fresnel will be useful. On my camera (Tachihara) the Fresnel simply was in the indent for the glass facing the holder. It was plastic, one piece, no glass. I replaced it with a Satin Snow, finest GG I have ever had at any price. Sadly, I think Dave is OOB.

 

[Martin Aislabie]

Here is my $0.02 - which may or may not help

I put my Fresnel between me and the Ground Glass (as I operate the Camera from the rear) - smooth side to the GG and ridged side facing me.

I then have a piece of plain smooth glass to go behind it (towards me) on which I place the Lupe to focus.

I have an Ebony so none of this might be relevant but the only thing I needed to do was ease back the "fingers" holding the GG/Fresnel/Plain Glass into the wooden frame on the rear face of the camera.

Fresnels seem to be a love/hate thing - personally, I like mine but other people don't get on with them

I have a Wide Angle Fresnel which improves the brightness of the viewed image significantly when a shortish lens is being used at around infinity.

I can tolerate the Fresnel when I use a longish lens and/or focus a normal lens close to 1:1 - here you get dark and bright spots in the viewed image and I overcome this by weaving my head from side to side and up and down - goodness knows what I look like to the casual observer when I am doing this - but who cares.

IMO it would be better to start without a Fresnel and see how you get on with the lenses you have chosen. Then when you have had a bit of practice in different shooting conditions, buy and fit one if you find you do need a Fresnel.

A decent Darkcloth of some description is essential what ever solution you end up with.

Hope this was of some help

Good luck

Martin

 

[RalphLambrecht]

...I don't know how to tell if it goes on the outside of the ground glass or on the Film Holder side of the ground glass...

It can be done either way (see attachment), but it is important that the plane of focus on the ground glass exactly matches the film plane. In other words, adding a fresnel to an existing system is easy, just put it behind the ground glass (fig.5a), but if you want to put it in front of it (fig.5b), then the camera back has to be machined to make room for the fresnel thickness.

The setup in 5b has the benefit of fresnel and ground glass having a combined plane of focus. The setup in 5a is simpler, and it works, but it can cause double images and a bit of focusing confusion.

 

[Shadowtracker]

Thank you all, this has been very helpful. I will try without one initially but probably end up getting one at some point, just to see if it makes a difference for me. I wasn't sure if one was needed or not though I did know they brightened things up. The attachment explained a lot to me as well. I think my Omega is designed to have it on the back side of the gg; there are a couple slots there and I'm betting that if I use one, I want it to fit into those.