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biedron
11-Jun-2011, 22:05
Does anyone know whether the Ground Glass / Fresnel "sandwich" on the Toyo 45AX uses the same spacers shown in the attached installation instructions for the 45C,D,E... models?

I ask because back in March I bought a used 45AX (from the auction site), that someone had replaced the GG and Fresnel combo with a plain third-party GG. The original Toyo GG and Fresnel lens were also included with the camera. However, neither the spacers nor the clips shown in the attached pdf were included. But I don't know if those items are part of the 45AX installation or just the 45C,D... installation. Right after I got the camera, I emailed Toyo explaining I just purchased a used 45AX and asked about the installation order of the GG and Fresnel (I had searched enough here and elsewhere to know the order was important, but I found conflicting info on the proper order). The attached pdf for these other models is what they sent me - not one for the 45AX. Anyway, I wanted the brightest screen possible so I put the original GG/Fresnel back in the order shown in the pdf, without spacers. At the time I didn't think anymore about the spacers.

I am now concerned whether spacers are needed because I have finally shot my first images with the camera with Fuji FP100-C45 instant film, and none of them seem very sharp. I also shot some with Velvia 100, but I haven't gotten those processed yet. A recent thread over in Darkroom: Film, Processing and Printing questioned whether images shot with FP100 are inherently "soft", but the consensus seems to be that is not the case (i.e. FP100 should not be soft). I am pretty sure my focus on the GG was good (but I am a newbie at LF, so...). But if the spacers should be there and they are not, then obviously the plane of the GG is not where it is supposed to be relative to the film plane.

Thanks for any insight.

Bob

Steve Barber
12-Jun-2011, 02:50
Ah, you have opened Pandora’s Box with this one. Trying to come up with a simple way to resolve the issue, whether your ground glass is correctly registered, I came across a test target posted on the web that would be a big help. First, there is an overview at this link:

http://www.ragarecords.com/photo/focustest.html

Looking at that will give a quick idea of what is involved. At the bottom is a link to a printable test target:

http://www.ragarecords.com/photo/images/focustesttarget.tif

Ordinarily, I would not rely on instant film for testing focus. However, since you have no sheet film developed and you have some instant film available, you can at least see if the focus on the film is the same as what you see on the ground glass when you focus the camera. In other words, whether the ground glass is correctly registered and, if not, in what direction it is off.

Just to see how this would work, I printed out a target and set a camera up—one that I know gives good results—looking down on the target. I used a 210mm lens looking down on the target at an angle of about 30 degrees so that I had an image like what is shown on the overview.

Looking at the test target, on the side with the marking “CM”, there are some very fine lines that you can focus on. To focus on the middle, where it is marked, took about 30cm of bellows with the 210mm lens about 60cm from the middle of the target. The idea is to get the center of the range of lines that are most in focus as near to the mark as possible. When you have, making sure that the camera is not moved, take an image with your instant film. Then, compare the instant film image with what is on the ground glass and see if the location of the center of the range of lines that are in the sharpest focus is the same as what you have on the ground glass. If not, then the ground glass is not correctly positioned. If the center of the range of lines in sharpest focus is at the mark, then ground glass registration is not the problem. Note: the lines may not be as sharp as you would like, but that is because of some other problem. Also, if the focus on the ground glass has changed after removing the film holder; then, you moved the camera when manipulating the film holder and the instant image is not valid for comparison.

If you find that ground glass registration is not a problem using the instant film, then you can quit worrying about it. However, if it appears that there is a problem with the registration, I strongly recommend that you look at your developed sheet film before deciding whether there actually is a problem or not. If the developed sheet film indicates that there is a problem, then do your testing using sheet film with the test target and sort it out that way, first.

Brian C. Miller
12-Jun-2011, 12:40
On my Toyo 45AX, it's shiny side out on both, "Toyo View" in the lower-right corner.

I didn't disassemble mine, so I don't know if there is a spacer there, and I didn't see a spacer on the diagram. Since Mamiya is the parent company, there must be a repair center in the CONUS, so you don't have to send it back to Japan. It shouldn't cost a lot to have them do the installation.

When I bought my Navy surplus Graflex Super Graphic, the GG had been replaced with plain GG. My photos were out of focus by just a hair, and I had a hard time figuring out the problem. I bought a replacement GG-fresnel combo from Brightscreen (http://www.brightscreenstore.com/store/), and I found that I still had to shim it a little bit to get it into proper position. Now I can count bicycle spokes at two blocks with the 135mm Optar! Is it perfect? I don't know, but it's good enough for me!

biedron
12-Jun-2011, 13:58
Steve and Brian,

Thanks to both for the replies. Brian, my GG and Fresnel are oriented as you describe - shiny side out for both. "Toyo View" is in the lower right corner and right-reading when looking at the GG.

I tried Steve's suggestion of using the focus target. I also made a set of shims, with 0.02" thickness, based on info obtained from a web search (supposedly the Fresnel displaces focus by about 1/3 its thickness - mine is 0.06"). So the shims move the ground glass 0.02" aft (away from the lens) compared to no shims. I did 4 focus chart tests with FP100 - 2 without shims and 2 with. The no shim images seemed to be consistently in better agreement with the ground glass focus. With the shims, the resulting focus point on the print was further away from the camera than where I focused on the ground glass. I think that observation is optically consistent with moving the focus point on the GG aft using the shims.

So from this focus test I would conclude the shims are not needed, at least on my camera.

Although the focus chart provided in the the links Steve furnished indicate pretty clearly the focus range, the images on the FP100 prints still don't seem very sharp to me. Steve, you seemed to indicate that the FP100 prints might not be as sharp as I would like (you got that right), but that was due to some other problem. So the other problem might be...?

Guess I'll see what my trannies look like when I get them processed.

Bob

Brian C. Miller
12-Jun-2011, 22:49
Bob, there is an article on the New 55 Project (http://new55project.blogspot.com/) site about recovering the negative from a Fujiroid. You need to do it while it's fresh, and remove the backing with bleach. I used normal liquid bleach for mine. This is the actual place where the image is focused. The paper print is always going to be "soft" because of the chemical reaction required to create it.

Steve Barber
13-Jun-2011, 03:23
The paper print is always going to be "soft" because of the chemical reaction required to create it.

What he said.

I was simply alluding to the lack of sharpness that has always bothered me with instant prints; first with Polaroid and, after Polaroid was discontinued, the same softness I get when I try the Fuji version.

Brian’s explanation would account for that.

biedron
18-Jun-2011, 22:56
Transparencies (my first!) looked fine, so it looks like there is no issue with the installation. Sent them off to Praus Productions and add them back inside a week. So I guess it was just the inherent lack of sharpness of the instant print itself as both Brian and Steve suggested. Thanks again for the responses.

Bob

Steve Barber
19-Jun-2011, 00:56
Bob,

Interesting, thank you for the follow-up.

Steve

beemermark
21-Jun-2011, 09:43
Talk about timely articles. Being a world class procrastinator I took my 45ax screen apart a year or so ago to replace the Fresnel (I had scratched it badly) and finally got around to trying to put it all back together last night. I have the same pdf from Toyo and I couldn't find the spacers in the pictures. I was assuming I lost them but now I wonder if they ever existing.