Changing the Alpha 900 focusing screen
This is not a step by step, since the instructions for this operation are very clear and the procedure is simple and nearly foolproof. It is simply a reassurance for those worried about changing their screen, with some tips.
First of all, clear a suitable table – I used a table in my studio, and lit it with a flash unit, good light is essential. Next, I made sure I had an unused cleaning cloth and a blower bulb handy; then I blew all dust off the camera, noting that the rear screen (which has an adhesive plastic protector on my A900) tended to attract dust with static.
Then the package containing the screen and instructions was opened. It includes a pink warning slip advising you how to open the container, but this is badly devised. It is meant to ensure you don’t open the clamshell holder upside down and spill the contents, but the diagram is not clear in any way (it should show the direction of the latch to indicate which side is up, and does not).
The latch is attached to the top half of the plastic case, which should be opened with the Alpha logo on top. Most people will do this anyway. The instructions are pictorial, with a written commentary in each language. There are some ambiguities and imprecise descriptions, but generally they are clear and easily understood.
One opened, the screen pack resembles vintage Minolta screen changing kits, with a spring loaded tweezer tool and the screen supported so as to be easily accessed. Only open the pack when you are ready, to avoid dust landing on the face of the screen. Work with the pack to the right hand side of the camera if you are right handed, and place the camera so that access to the right side of the screen is easy (don’t rotate it the other way).
This view shows about the angle you need to work at, if you are right handed. Left handed users may prefer to place the screen box to the left of the camera, but the angle of the camera still need to be as shown. The process is simple – you remove the white tweezers, and using the nib on the end, gently press into a slot clearly visible just below the electrical contact array in the lens throat. When you do so, the frame holding the screen will open with no help other than gravity, and will rest parallel to the reflex mirror with the screen itself apparently 1-2mm above it. Note this, it is important.
The tweezers are then used to grab the two lugs (visible in the opened box) at the right hand end inside the camera. This is surprisingly easy and it is hard to mis-locate the tool. The screen can now be lifted out without any effect on the holding frame, it is ‘free’ at this stage. A slot is provided in the case for placing the removed screen, before lifting up the replacement.
As you can see, having let the screen go, I have rested the tweezers on the case, ready to pick up the new screen. When you do so, the replacement is already perfectly oriented relative to the camera (the correct side is up). You introduce the new screen into the camera remembering that the old screen was not pushed down into the frame, but rested freely on it. Just dropping the screen into the corner created by the frame and focus screen bezel it sufficient to locate it correctly. No pressure or adjustment should be needed. If necessary, lift the camera body and gently tap to make the screen seat itself, before using the nib of the tool to close the frame. Again, there is only a very slight controlled spring pressure. There should be no sense of resistance. The frame clicks home securely and positively with hardly any effort.
All you need to do now is lift the old screen from its holding slot, and place it where the new one was, replace the tool, and seal the box. But Sony made a minor error in specifying the shape and weight of the box. Here is what actually happened the instant I lifted the tweezers off the edge of the box:
The box was no longer balanced, it tipped backwards and propelled the screen from its safe vertical holder on to my (clean) table top! So, before you even remove the new screen, place a coin or some other small weight on the front edge of the case to avoid this happening.
When I checked the viewfinder, the grid screen was installed straight, but two dust specks were present. I opened the frame with the tool, again, allowing the screen to fall away from the prism, and blasted a couple of quick jets from my blower bulb, then closed it. This removed the two specks. I then did a routine air-blast sensor clean before replacing the lens (I have never needed to clean my A900 by any other means).
Finally the tweezers were replaced in the case, and everything put back in the original packaging.
For the Type L grid screen I fitted (FDA-FL1AM) no exposure program adjustment appears to be needed compared to Type G, the standard screen, but the Alpha 900 still includes a menu entry to program the camera for this screen. This should be done, as the Type L may have slightly varying effects on exposure according to the aperture and focal length of the lens fitted. Just because L and G settings give exactly the same result with most lenses does not mean the L setting is redundant.
The Alpha 900 screen replacement is a very different processor from manual replacement of screens for Alpha 100, KM DSLRs, and so on. There are no shims, and there’s no loose second layer AF-point display screen. The A900 focus screen is not pressed against the condensor lens, and the (factory adjustable) 100% framing mask is not moved during the screen change process.
It’s a pity the Alpha 700 was not provided with the same system, and the Menu options for reprogramming the exposure slope. As it is, the 700 must go back to Sony for a screen change and recalibration. Those obtaining a Type L for 700 by ordering spare parts will be able to change it, but there may be some change of exposure calibration.
The Type L screen for the A900 is a very delicately engraved, understated grid screen. If you compare it with Nikon’s electronically created grids it is almost invisible and does not interfere with viewing in the same way. The markings are so fine you can forget they are there if you want, and so sharp that seeing them is no problem when you need to. Fitting this screen does not mean living with a superimposed grid that wrecks your view of portraits; once fitted, you will not feel any need to revert to the original screen. It is less obvious visually than the grid screens for the Minolta AF or X-series SLRs.
The cost, compared to factory changes, is very reasonable and the procedure for changing is completely safe as long as you have reasonable eyesight and dexterity.