Adjusting focus on a rolleiflex (Automat), the correct way.
First time post here at APUG, have been a lurker for a while. Rollei owner and user, have a 500C/M; quite a few Contaflice, a few Voigtlaenders, M42 stuff and more. Anyway I have managed to get a few Rolleis working a bit better than they were when I bought them. But enough about me.
Originally Posted by Helinophoto
You were lucky with the adjustments you made. I have not tackled an earlier Automat yet, however every other later Rolleiflex or Rolleicord I've looked at, such as the 2.8C and Ds, the Cord V, Va, Vb, and the Tele, does have an adjustment for the focus of the taking lens. I cannot envisage the Automats being any different. The adjustment is located inside the centre of the focus knob, and consists of a locking screw and collar. Loosening this permits the position of the infinity stop of the focus knob to be adjusted, relative to the position of the lens board. Depending on the model you may need to remove the film speed/type reminder dial first and the machined ring that retains this from the edge or the inside diameter of the focus knob. A lens spanner or rubber tools may be needed (depending on Rollei model).
Whenever a Rollei has focussing problems, the first place that you should always start is with a check of the taking lens focus. Everything else hinges on that. It is absolutely pointless setting the viewing lens of a Rollei to good viewfinder focus, unless it also tracks with the taking lens. The taking lens captures the image. This must be set correctly in the first instance. Having done this, the viewing lens may then be dialled in to agree with the taking. If you set the viewing lens well and are able to get a good focus at infinity, for instance—that's great—however, if the taking lens diverges from this, the pin sharp focus you can see through the finder will not be recorded on film.
Broadly there are four states the two lenses of a Rollei may have in relation to each other.
- Viewing lens shows good infinity focus; taking lens is off
- Taking lens shows good infinity focus; viewing lens is off
- Taking lens infinity focus is off; viewing lens is also off
- Taking lens shows good infinity focus; viewing lens is also good.
Obviously, only the last condition is desirable. The point is that unless both lenses are checked you cannot know if the other agrees. The viewing lens must be dialled in to the taking lens, and not vice-versa. Hence, you really must start with the taking lens adjustment, and if this is not correct, the viewing lens is by default almost certain to subsequently need re-setting, anyway.
I generally use a ground glass I made myself over the film rails with a magnifying loupe on a distant tree. I live in an rural area so this is a plus for me here. In general there is some tolerance for small errors in adjustment at infinity, or near infinity. If you have access to an auto-collimator, so much the better, alternatively many will be aware of the procedure used to check focus by employing an SLR and telephoto lens to check infinity. I'll assume you're using a ground glass or similar on the film rails, though.
The procedure is to set the focus image on the ground glass with the lens open on bulb. A locking cable release makes this a little easier. If this is in fact achieved with the the focus knob set on its infinity stop, congratulations; the taking lens is probably good (more below). If the lens will focus past true infinity, you need to loosen the locking screw previously mentioned, and set the knob to the infinity stop (without moving the lens board, of course). Having set the actual focus of the lens to the infinity setting of the knob, shorter distances should then fall into place.
If, with the focus knob at the infinity stop, the lens is still short of true infinity, things are a little more involved. You will need to loosen the lock screw, turn the knob slightly towards a shorter focus setting on the scale; lock the screw again temporarily, and then adjust the lens back in towards the film rails until infinity falls into place. You can then loosen the locking screw, reset the knob to the infinity stop and re-fasten the locking screw. If you are really unlucky, the trim plate around the edge of the focus plate won't have enough clearance to the front of the camera body to get the lens board in far enough to reach infinity. This potentially, opens up a whole new can of worms to deal with, as it might, for instance, mean the lens board parallelism to the film plane is also off and must be re-set (much disassembly for an Automat model, and generally done with dial or depth gauge, blocks, and surface plate, to 0.05mm across the diagonal corners of the board). Let's be optimistic, and assume that, if you strike this issue, the parallelism is good, and that the trim simply needs some shims under its four securing screws to lift it up a fraction. I've re-set the parallelism successfully, but it's fiddly, and time consuming, without custom tools to speed things up...
Having got the taking lens looking good on the ground glass at a distant target, for me, the acid test is to: set the camera up on a tripod or other support; at minimum focus distance, or close to this, set the taking lens, until the image on ground glass is critically sharp; and check that the distance measurement on the focus scale of the camera agrees exactly with an accurate tape measure. If infinity has been well set, they should tie in perfectly. If not, you likely haven't quite nailed the distance check. Go and check it again: you'll probably find it's just a little off. The catch is that a small deviation at infinity, can make for a substantial error at close range. Get both ends of the range sweet, and any distance in between should fall in fine.
You've now got the taking lens set beautifully at infinity and at close range. So you can be confident that—even without looking through the viewfinder—should you set the camera focus to a distant mountain, for example, the film image will be tack sharp. Having verified this, now you can proceed to dial in the focus of the viewing lens. By rotating the viewing lens in its thread—after first loosening the set screw that fastens it, which has been explained in post 1 of this thread—you can now set the focus through the viewfinder until the finder image is sharp. I use a small loupe that just fits inside the hood of a Rollei to give me greater magnification, for slightly better accuracy. Providing you haven't moved the focus knob of the camera during this process, both the viewing and the taking lenses should now be in agreement. If it's good, nip up the set screw that retains the viewing lens.
Again, to verify your adjustments are good, set the camera up on a close focus target, take your time getting the focus spot on, and compare against the taking lens with the shutter on bulb etc. Both lenses should now show a nice sharp image on their respective ground glasses. If so, you've nailed it. Otherwise, re-check viewing lens on infinity again as described previously. To cross-check your adjustments, set the camera focal plane to a distance marked on the focussing scale (Eg four feet, or the metric equivelant, depending on the camera) using an accurate tape measure, with the film plane parallel to the focus target. (I use a small magnetic calendar on the front of my refrigerator that features crisp white font on a black background). With the distance from the camera to the target carefully adjusted (and remember, of course, that with all these adjustments you are measuring to the film rails, not the front of the lens) set the focus knob to this exactly distance. Both lenses should show tack sharp images of the target on the ground glass, at the actual distance the knob is set to.
Last edited by Brett Rogers; 02-27-2013 at 07:02 AM. Click to view previous post history.
Reason: typos, bloody typos...