Saunders/LPL 4500 II - Troubleshooting Light Projection Issue

[xvelids]

Hi fellow LF Community!

I've been trying to troubleshoot my Saunders/LPL 4500-II set up - it may be a simple solution, but I've been unfortunately stumped for the last couple of days! Had no issue printing 35mm or 6x7 on my set-up, but once I decided to print my 4x5 negatives I ran into a problem on the enlarger where the light projection is uneven and smaller than the print size. I am unsure if this is a blockage issue related to the negative stage plate or something else. I've included some pictures and measurements below of my set up for context.

To further technically clarify my set-up - this is a Saunders LPL 4500-II. Lens = APO 150mm Rodagon N. I am using a LPL 4x5 anti-newton glass carrier, the negative stage plate is the masking attachment version (for reference - http://store.khbphotografix.com/Mask...Enlargers.html), not the standard negative stage plate (for reference - http://store.khbphotografix.com/Nega...Enlargers.html).

The images I included show the negative, my enlarger set-up, the lens w/lens board, contact sheet/print, print with the light loss where the chin and the top of the head is obscured, the easel (set for a 8x10 print) and another easel shot, but with the negative carrier rotated on the negative stage plate. With the shape of the blockage, I think the problem is with the negative stage plate as you can see in the photograph. From the negative stage plate-to-the-lens board measures ~ 8 5/16 in; Lens Board-to-Lens measures ~ 1 7/8 in and the Lens-to-Paper measures ~20 inches.

This post has the first initial images and my subsequent one will have the rest! Thank you for reading and hope to hear from the community. I hope it's an easy fix and perhaps one that I simply overlooked! Let me know, thanks!

[xvelids]

The rest of the images illustrating the print and the easel.

[Oren Grad]

I use a 4500II with masking stage and glass carrier and have no problem printing 4x5 negatives with a 135mm EL-Nikkor.

With apologies if these questions seem stupid or obvious:

* Are the blades in the masking stage all the way open?
* Does your head have the standard 4x5 diffusion box, or is there any chance that you have one of the smaller-format diffusion boxes installed?

[agregov]

Pop the top off and check your mixing chamber. They come in three different models: 4x5, medium format and 35mm. You might have the medium format mixing chamber. If so, you’ll need to purchase a 4x5 mixing chamber. You can buy them new or often used.

[Oren Grad]

To avoid any confusion for the OP: "diffusion box" = "mixing chamber". We're saying the same thing.

[xvelids]

Hi! Thanks for the replies. I really appreciate it.

1. I doubled checked the negative stage plate - the masking attachment is wide open.
2. I pulled out the diffusion box and it looks like to my eye that this may be the medium format diffusion box.

Attaching an image of my diffusion box/mixing chamber for your review. I also found a picture of the three diffusion boxes together for reference. Do you guys think this is the medium format diffusion box? Also, my diffusion box is quite yellow (I guess from age)...would that affect print quality in the foreseeable future?

[Michael R]

The more yellow it is, the less contrast you will get on variable contrast papers.

Hi! Thanks for the replies. I really appreciate it.

1. I doubled checked the negative stage plate - the masking attachment is wide open.
2. I pulled out the diffusion box and it looks like to my eye that this may be the medium format diffusion box.

Attaching an image of my diffusion box/mixing chamber for your review. I also found a picture of the three diffusion boxes together for reference. Do you guys think this is the medium format diffusion box? Also, my diffusion box is quite yellow (I guess from age)...would that affect print quality in the foreseeable future?

[PRJ]

Looks like the medium format box to me. I'd take the diffusion plate off and see what is going on inside. That looks bad. You just need to remove the two screws on the side to take the plate off IIRC. You are going to need a 4x5 box though if you want to print 4x5. On the upside, once you buy the 4x5 box you can use it for medium format as well. Most people do that (I do) since it is hard to find the medium format box.

[ic-racer]

If you need to make a new diffusion plate, a PhotoTrio member is experimenting with diffusion material for a project right now. Maybe some useful information there about available diffusion material.

https://www.photrio.com/forum/thread.../#post-2449581

[Sal Santamaura]

If you need to make a new diffusion plate, a PhotoTrio member is experimenting with diffusion material for a project right now. Maybe some useful information there about available diffusion material.

https://www.photrio.com/forum/thread.../#post-2449581

Note that the plastic plate on a 4500 II 4x5 diffusion box is denser in its center than at its edges. In other words, it's a "center filter" designed to even illumination on the negative. Using a uniform material to replace it will result in a center "hot spot."