Zeiss Super Ikonta IV focus problem

Yes, it does. But, every once in a while, it jams up, somehow, causing me to either have to double expose a frame or skip one all together.

Winding before shooting and making sure that the knob goes all the way to the stop seems to prevent that from happening as often.

steven_e007 said:

I don't think it is due to the age of the model - I think they stuck on a focussing ring to suit the country in which the cameras were sold.

Most of my folding cameras are 'UK' models, so they are always in feet. A few I've bought on eBay from elsewhere in Europe are in metres. I have two Agfa Isolettes, about the same vintage. Virtually identical, except the German model is in metres and the UK version is in feet.

Click to expand...

It's interesting to learn this. So mine must be a Euro model. I have loved this camera since I first opened the box. It just so sophisticated and primitive, klunky and smooth, all at the same time. My first non-35mm, it opened up a whole new avenue of folding GAS desires.

Return on that old thread :

I extracted from the high resolution scan that was provided two details :

One letter of the message that the camera was focused on (at 10-15 feet, for me - continental european - easier : 3-4m)

The sea horizon line (at random near the middle) of the picture (at infinity, indeed)

The discussion was about : while the picture was taken at D = 22 (with a 75mm lens), shouldn't the horizon line be sharper ?

The well known hyperfocal formula for a confusion circle c is :

h = f²/Dc

So, when focusing at distance h, the blurring of details at infinity should be :

c = f²/Dh

and taking f=75mm , D=22 and h = 3.5m you get a confusion circle of (approximately) 0.1mm

I put a white blob of this diameter in the middle of the horizon line, and you can notice that the blurring is of similar magnitude.

So to my opinion, the camera has absolutely no focusing problem, it's only an issue of DOF.

Paul

Worker 11811 said:

I read that ... if you close or open the bellows too fast, you create a vacuum that pulls the film out of the focal plane.

Click to expand...

Old wives' tale I'm afraid. Unless you have a large hole in the pressure plate venting to the outside atmosphere so that air can get in to push on the film ... a feature of old Hasselblad backs, but Hassy's don't have bellows.

There isn't any air between the film and the pressure plate to expand outwards - heck, if there were the film would have to be bowed out all ready. And as the bellows is opened all the air in the camera all looses pressure at the same time: so the air pressure around the pressure plate (and in back of the plate if it has a hole for a red-window) is the same as the air pressure in front of the film so even if air were claimed to rush in behind the film at the last minute it won't.

The film in some cameras is backwound around the rollers - again Hasselblad comes to mind - and the film can have a bowed out crease if it is wound on just before a shot. The second shot can have a crease if the camera had been left alone for a while even if the film was kept wound on. Most (all?) folders have a straight film path so this isn't a problem.

My practice from 50 years of shooting with folders and other cameras without double-exposure-prevention is to wind the film right after talking a shot, then the camera is always ready to take a picture and there is never any question of 'did I wind the film????'. I may open and close the bellows several times in anticipation without taking a picture. A double exposure is a very sure way to ruin a photo.

You can check infinity focus by aiming at an infinity target, setting the lens at infinity and checking focus at the film plane. A bit of Scotch frosted sticky tape stretched across the rollers makes a good temporary 'ground glass'. The lens should be at infinity, the image in focus and the rangefinder in co-incidence if all is copacetic.

I don't believe either to the risc of "pulling the film out of the focal plane" when opening a folder. But I DO spool the film AFTER opening the folder and JUST BEFORE shooting, for another reason, that I justified experimentally :

When I did not proceed this way (doing like you the spooling just after shooting), I often found white spots on my negs (yielding black spots on the positive enlargments), and I desespered to determine what caused that, until I noticed that when I took two views without closing the camera in between, the second was free of these spots : thus I deduced that inside the chamber, dust is likely to be moved on the film either when the folder is closed or when it is opened (or at anytime between shooting). And when this happens before shooting, this dust would be "silouhetted" on the picture. But when you spool new film JUST before shooting, it should not happen.

Thus, I tried this new sequence of operation systematically, and it worked. Besides, when you use folders that don't have safeguards against multiple exposure, it's a good thing to adopt a systematic sequence of operation, to be sure that you spooled the film between shoots ; and if the sequence tells you to spool the film "just before" shooting, it's easier to remember ?

Maybe you never experienced such spots because your folders are very clean (dust free) inside, but I can tell this sequence of operation cured a lot of problems I had with mine.

Bye Paul

You can check infinity focus by aiming at an infinity target, setting the lens at infinity and checking focus at the film plane. A bit of Scotch frosted sticky tape stretched across the rollers makes a good temporary 'ground glass'.

Click to expand...

I do not agree that this way is working (in case of medium or small format cameras) ; when I have to check the focusing, I do it systematically by test shoots with real film (an old wife practice, I guess).

For two reasons :

1/ usually, accurate focusing means at least 0.03mm detail resolution on the neg (maybe even smaller on small format). So, are you sure that you can see this - naked eyed - on a makeshift groundglass ?

2/ when you test for focus accuracy, you should do it lens full open ; let's say, for a MF camera it means f/stop 3.5 . To reach focusing details of less than 0.03mm, you are at this f/stop not allowed a focus plane misplacement error of more than 0.1mm : are you sure that your "bit of Scotch frosted sticky tape stretched across the rollers" is positionned at the same place as a film with an accuracy better than 0.1mm ?

Bye Paul

I would first check to see if infinity focus is correct. Then check the calibration of the rangefinder. The images in the rangefinder should align when the lens is at infinity and when the camera is pointed to a distant object. Some people use the moon, but I could never determine if this was correct. I usually took it to work and focused on a building across town.

I think that the sweet spot for the Tessar design generally has been from f/8 to f/11, possibly f/16 for a medium format camera.