Changing your camera's focusing screen: Some personal experience

[vandergus]

Well I've seen some people inquire about this issue on this forum but haven't seen anyone with personal experience comment. I have just recently acquired some personal experience so I thought I'd share.

Some background. If you haven't read any threads on this, the basic idea is to replace the focusing screen in a DSLR (which is designed for an autofocusing system) with a focusing screen that makes manual focusing easier. Currently, I have to judge the focus based on what my eye can perceive in the viewfinder or from the focus indicator located down in the bottom left corner of the screen. I plan on picking up some cheap (in price only) old manual focus lenses in the future so I would like my manual focusing to be as efficient as possible. Traditional focusing screens with split prisms are much better suited to this.

There are several places where you can get focusing screens including Katzeye, Hoada, Virtual Village and ebay. They run from $100 to $20 on ebay. While $20 sounded dangerously cheap, I had the name of a particular seller who had provided someone else with a satisfactory product, so I went cheap. The other brands will offer more options for the screen layout and provide more accesories to make installation easier. The ebay option will also take about 3 weeks to ship because it's coming from China.

Once you've recieved your screen you get to install it yourself or pay a shop ~$60 to do it for you. Since the whole point of this venture for me was to be as cheap as possible, I did it myself. Honestly, it wasn't that bad. I thought I would have to take apart the plastic housing and lose little screws in the cracks of my floors but it was much simpler. Here's a youtube video that runs through the motions.

http://www.youtube.com/watch?v=3IjSPL584zg

The hard part is keeping it all clean. I was wearing latex gloves, had pec cloth handy, and was swabing everything insight and still ended up with a messy viewfinder when I was done (mostly dust specs). Note that this doesn't effect the actual image, it's just really annoying. I'm planning on going back for a good cleaning once I find a cleaner environment.

The other tricky part is getting your manual focus calibrated. My replacement screen was 1-2 THOUSANDTHS of an inch thinner, which made it notably back focus (the camera focused behind the intended spot). If you're really far off, you'll have to add shims to move the screen closer to the mirror. Luckily , I was close enough that I could make the necessary adjustments with the calibration screw in the mirror box. If this is all starting to get confusing, have a look at this link. It helped me understand all of the focusing systems in my camera. It's really very interesting regardless of whether you're doing this installation or not.

http://leongoodman.tripod.com/d70focuspart3.html

One thing you may be wondering is how does all of this messing around inside my camera affect with the auto-focusing system. Well, as far as I understand, not at all. The auto-focusing sensors are located in a separate part of the camera and are not affected by the new focusing screen or he adjustment of the calibration screw (if you turned the right screw).

After all that, I have to say that the screen is wonderful. Focusing is miles better with the split prism/microprisms. Best $20 I ever spent on my camera. I can't wait to pick up some old fast primes to try out now.

[inkista]

Just in case, if you have a Canon 40D/5D/1D/1Ds, it's a bit simpler than all that, since the Canon higher-end bodies are made to have replaceable focus screens (I'd assume the higher-end Nikons do, too). Replacing the focus screen on a 40D takes about 30 seconds. If only the entry-level bodies made it so easy....

The three major caveats I've heard about the split-focus screens is that 1) AF confirm signals may no longer be visible, 2) for lenses with max. apertures smaller than f/2.8 you can get viewfinder blackout (particularly dark with f/5.6 superteles), and 3) spot metering will not be accurate if you use the center AF spot.

[Cuchulainn]

Thanks to both of you for sharing your experiences with this. I use a number of manual focus lenses and have considered changing the focus screens to make focusing easier with those lenses. I am going to have to dive in and buy one and give it a shot. Appreciate the info!

[wulf]

I'm tempted! Most of my lenses require manual focusing anyway so a split-prism screen would be a big advantage. I'd be interested in a link to the ebay shop you used (on the understanding that it doesn't represent a guarantee from either you or DPS... just a place people might like to look if they are willing to perform a similar upgrade).

Wulf

[vandergus]

I'd be interested in a link to the ebay shop you used (on the understanding that it doesn't represent a guarantee from either you or DPS... just a place people might like to look if they are willing to perform a similar upgrade).

I went through a seller called jinfinance.

Inkista: Those are all valid concerns. Here are my experiences with them.

1. AF brackets still illuminate to confirm focus. Yay.

2. I put my 18-200mm on and zoomed out to 200mm so I was looking through f5.6. I went into my dim bedroom to see how bad the viewfinder would get. The microprism collar blacked when my camera was metering f5.6, 1/30, ISO 800. I couldn't get the split prism to blackout but it was getting noticeably dimmer. I would say, in general, the viewfinder is a little dimmer than the original. I think the more expensive screen from KatzEye and the like would perform better.

3. I set my camera to spot metering, then switched between the different focusing brackets, but metering the same spot with each one. The center spot seemed to meter 1/3 to 2/3 stops lower than the side spots.