Mods: DIY Focusing Screen for DX Cameras

Hello, everybody! We are supposed to have the usual lens teardown today but I am too lazy and tired today to prepare the pictures and commentaries so I will just write a short entry this time around. I am also very busy in our studio because my cute assistant is currently working off-site for a couple of months. She should be back by the end of this month.

Introduction:

When I still had the D7200, I was always straining my eyes at the tiny DX viewfinder every time I used a manual focus lens with it. I focus using the focusing scale so I generally get a nice and focused picture when I am using the lens stopped-down. Shooting the lens at it’s biggest aperture is another story and I had to find a better solution for this.

12241211_10153244985416911_7368475265942359102_n.jpgThe first solution that I thought about was using focusing screens! You can buy one for any camera or ask a shop to trim one for you but I am cheap so I simply opted to DIY the screen myself to save some money. I ended up saving enough money that if ever I failed at this, I would have enough money to attempt 3 more times!

I got a new K-type screen for the Nikon FM3A. The screen will not fit the D7200 because it is 2x as big and the picture above illustrates this point. The D7200’s screen came off rather easily after I unlatched the braces. There are a couple of guides on the web that will teach you how to do this so I am not going to show it here.

IMPORTANT: Use a clean cotton glove when handling the screens and avoid touching the matte surface of the screen. As soon as you removed the screen from it’s case, cover the matte side of the screen with 3M Magic Tape. The Magic Tape will not leave any adhesive marks and if it did, you can easily wipe it off. You can also write on it’s surface if you need to and I always find this very handy. You may want to practice on an old junk screen.

Before you start doing anything to the K-type screen, you must first measure how much you should trim from it in order to make it fit the D7200. Get a calliper and measure as carefully as you can, divide the difference by 2 and you get how much you should trim away from both edges. Do this again for the sides of the screen. I used a strip of 3M Magic Tape to mark where I should trim, this tape will also protects the screen from scratches.

As soon as you got your measurements ready, superimpose the D7200’s screen on top of the new screen and see if you got a nice fit. You have to centre it as close as possible since you want to have the new screen’s prism to be in line with the central AF point. This is not possible most of the time but you should try your best to get it right. Many people report of the central AF point not lining up with the centre of the screen even if they used branded screens or cheap knock-off screens from mainland china.

Now that you got the matte side of the screen completely covered and the shiny part of the screen partially covered (unwanted parts exposed), you are now ready to trim away at the extra material! These screens are made of acrylic it seems, you may be tempted to use your plastic scriber on it and snap the excess material away but I will tell you now to stop it and think of another way. While scribing will leave a nice and clean cut, you also run the risk of ruining your screen when it cracks outside the line. This is a huge possibility and I do not want you to waste money attempting this.

What I recommend doing is to grind away at the material with a Dremel on a stand. Simply grind away enough material until you are just 1mm away from where you wanted the line to be and then use a fine file to get finish it off. A fine sandpaper is also nice for finishing the rough edges. Slowly work on one edge at a time until you get all 4 edges trimmed. Place the screen on top of the original screen and see if you got a good fit. A small precision saw is also a good idea.

Peel away the Magic Tape and remove any residues by pressing a fresh tape on the residue and pull away the tape at an angle. If this did not work then you are screwed! You will need to use a gentle solvent to wipe away the junk and this will risk ruining the matte prism or the shiny side of the screen. I also cleaned my screen with dish washing liquid and warm water just in case and carefully dry it with canned air.

Once you are satisfied with your handiwork, place the new screen into the mirror box and you should end up with something like what I have below. Be sure that the screen is facing in the correct direction!

FullSizeRender

I got it right where I wanted it but it is less than a millimetre off – not bad at all. This really helped a lot for rough focus acquisition, specially if you have bad eyesight where focusing in the dark becomes really challenging.

UPDATE:

Frank Fremerey & Bjørn Rørslett said:

“www.focusingscreen.com is the correct URL for the Taiwanese company”

Thank you for correcting this, no wonder I am getting a dead link! They are currently the last reputable company doing this. Sadly, the Canadian company Katzeye went belly-up…

Conclusion:

While this mod is helpful for general photography, I found that the prism gets in the way when I needed to use the camera for macro photography so I got the old screen back after a few weeks of using the D7200 in this manner. The focusing screen is now stored safely and is slowly gathering dust because I have not used it for around a year now.

I would like to add that using lenses that is slower then f/4 will make your screen dark. It is a problem for manual focus cameras and it is still a problem for DSLR’s. I would also like to add that having the focusing screen on a DSLR or any recent film Nikons will not affect the auto-focus performance of the camera. All DSLR’s use a semitransparent pellicle mirror to meter and autofocus. The AF/metering module is tucked neatly under the mirror so it will never have any effect whatsoever because this module and the prism/focusing screen are both self-contained. Having mentioned this, you may notice at times that the camera may lock on an object in focus but it looks like the object is not focused properly when viewed from the split prism and the previous issue of the 2 modules having very little to do with each other is the cause. That is why using Live View to calibrate your focusing is the most accurate way to determine focus tolerances.

I hope that you enjoyed and learned something from this post. I just wanted to show you that you can save money by doing something yourself provided you have the proper tools for the job and some know-how. There are focusing screens coming from mainland china and you can try and order them just for the heck of it. They are reported to be of poor make and dark. If you want to pay for quality then you should look for Katzeye. The company is now dead but they will still sell any left-over stocks available. Another good company is focusingscreen.comthis Taiwanese company will cut and trim original screens from the big makers to fit any DSLR or film camera so the quality of the screens themselves are great. It will take them a couple of days to source and process your screens,though. I recommend that you buy from them and skip the cheap “Made in China(PRoC)” brands so that they will not end up like Katzeye. They were the best in the industry and their good Opti-Brite fresnel screens were fantastic by many people’s accounts.

The previous blog post drained me of energy as it took plenty of effort to write. I hope that resting a bit will help me regain my strength, I am probably burnt-out from the busy life  at work and home. Please take plenty of rest yourself. Regards, Ric.

Help Support this Blog:

Maintaining this blog requires money to operate. If you think that this site has helped you or you want to show your support by helping with the upkeep of this site, you can simple make a small donation to my paypal.com account (richardHaw888@gmail.com). Money is not my prime motivation for this blog and I believe that I have enough to run this but you can help me make this site (and the companion facebook page) grow.

Helping support this site will ensure that this will be kept going as long as I have the time and energy for this. I would appreciate it if you just leave out your name or details like your country and other information so that the donations will totally be anonymous it is at all possible. This is a labor of love and I intend to keep it that way for as long as I can. Ric.

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3 Comments (+add yours?)

  1. Bjørn Rørslett
    Aug 14, 2016 @ 10:42:20

    Nice walk-through, Richard.

    A minor nit pick: the company you refer to is found at http:///www.focusingscreen.com , do note the singular form. I purchased a K3 screen for my Df from them. The price was OK, they had a fairly quick turn-around and the screen was perfect.

    Reply

  2. Trackback: Mod: Nikon Df Split Prism | Richard Haw's Classic Nikkor Maintenance Site

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