Toyo 45A/ 45AII GG/Fresnel - need help please

[Nikkornos_Toyo]

Hello

I need some help on the ground glass on the Toyo 45A. My 45A was bought in Japan with two backs: a black universal back and an older rotating back (milky white).

Both backs have a ground glass/Fresnel combination in the following order -->

Smooth side of the GG facing the lens
Coarse side of the GG mated with the smooth side of the Fresnel
Rough side of the Fresnel facing the photographer

Is this the correct orientation?? (I read from forum the Fresnel is right behind the lens.??)

On the black universal back, the Ground glass comes with the 69/67 marking, and sits directly onto the groove of the back. The GG/Fresnel assembly is held onto the back by two spring plate, each held by 3 screws.

On the milky white rotating back, the Ground glass does not have the 69/67 marking. It sits on two paper/plastic gaskets before sitting onto the groove of the back. Again, the GG/Fresnel assembly is held onto the back by two spring plate, each held by 3 screws.

I wish to replace the GG as they are somewhat stained. Do I need to get a GG that is of the same thickness? What if I do not want to use the Fresnel?

So far I have not seen much focusing issue, as I shoot at F22 or smaller most of the time.

If someone can help me clear this up, I will be very grateful. Thanks! :)

[IanG]

There's various combinations and the correct one depends on how the manufacture designed the back for the correct placement of the actual ground side of the focus screen.

The data I have from Beattie Intensescreen is that the Toyo's needs their fresnel screen combo fitted with the fresnel side towards the lens the screen side is towards the eye, this is also how my Wista is set up.

If the glass & fresnel are the same thickness then it works either way around but you don't really want the ridges of the fresnel facing you unless covered by anothr protective glass as they srcatch very easily.

If the glass goes in first un-ground side towards the lens then thickness would be important. However that's most like the wrong way a Toyo state (on their website (http://www.toyoview.com/Products/45AX/45AX.html)) that their super bright fresnels fit in front of the ground glass and that they are precision fit.

Ian

[Nikkornos_Toyo]

Thanks Ian for the reply.

Considering only the Ground glass, having the matt side facing the lens should be the correct way.

I bought the Toyo 45A and the rovolving back from different shops in Japan. And they were made in different period. It is strange that both sets have the Fresnel rough side facing the photographer.

[IanG]

Well Toyo took over the Graflex tooling for the Super Graphic and those Graflex cameras that came from the factory with a fresnel have it fitted under the glass screen between screen & lens.

However if the camera came with a plain screen and you want to add a fresnel then you have to place it on the outside, but the groundside of the screen remains facing the lens. That's how the fresnel on my Cambo works. Somee manufacturer put it under some on top.

The early Toyo literaturedoesn't mention a fresnel screen for the 45A so there's a good chance these were fiited later. However at some point they added a fesnel as standard to later versions of the 45A hence there can be some confusion.

Ian

[Nikkornos_Toyo]

Hi Ian,

I did a simple test using the Fujifilm PA45 and FP100 45.

A test shot with the 'original' configuration shot using a 180mm f5.6 wide open towards a test chart show that the focusing isn't really spot on.

I disassembled the back carefully, and cleaned the ground glass and Fresnel using IPA. The Fresnel rearranged to the front, smooth side facing the lens board. The rough side touches the matt side of the ground glass. The smooth side of the glass faces me the photographer. The assembly sits nicely into the slot.

This configuration has a more flushed and uniform arrangement of the top and bottom metal holders, as well as the two side pressing plates.

I did a test shot again with the same lens wide open and the same subject. This time, the photo shows that the focus agrees with what is shown on the ground glass!

Thanks very much for the tip that the Fresnel is in front.

I am excited to shoot again to see if there is significant improvement using the 'correct' F,GG arrangement! :)

** Looks like the previous gusy who fitted the F and GG did it by guessing and did not test the result. Its strange that two guys can make the same mistake.

[Shawn Dougherty]

My 45AII came with the Fresnel factory installed and I can't remember what side of the Fresnel goes which way. However, I would think that as far as ground glass goes rough side facing photographer is always incorrect...?

[IanG]

When fitted internally the smooth side of the fresnel should ideally be against the ground side of the glass. The idea is that each ring of the fresnel is acting more like a prism to to bend the light so that it hits the screen closer to perpedicular.

Ian

[Nikkornos_Toyo]

Thanks for the great advise again! :)

Now I have it flipped and it does help.

[Nikkornos_Toyo]

Info mac group, the official Toyo support site has responded. They sent me the documentation for Toyo screen which many of you have seen before. The document explains the installation of the ground glass and Fresnel:

Remove the six screws (1) holding the retainer (2) and the ground glass
(4). Take the Fresnel screen (5) and center it against the ground glass (4)
(etched side against the ground glass, smooth side with the raised lettering
towards the lens board).

Use the two holders (3) to clip the ground glass to the Fresnel screen (keep
the Fresnel screen centered).

Place the two spacers (7) on the focusing frame (6), where the retainers
were removed (2) being sure to line up the screw holes.

Place the Fresnel (5) screen into the opening of the focusing frame (6) so
that the ground glass (4) rests on the spacers (7).
(Note: If the Fresnel screen (5) rests on the frame (6) or the spacers
(7), the ground glass (4) will crack when the retainers (2) are
installed.)

Put the retainers (2) back in the position from where they were removed. If
installed correctly, you will be able to read “Toyo View” through the ground
glass (4).

Some reported the Toyo 45A II has focusing issues. I have since replaced the focusing screen altogether, and put in the 'Yanke' screen from China. It appears to give slightly better results after checking the negative.

I have two backs, a rotating back from an old Toyo and the Toyo graflock back. The graflock back appear to have better precision. I use the 6X9 film holder with the rotating back. If shooting only 4X5, I would use the Toyo universal (aka Graflock).

Thanks for all the great help.