Contax FX1-screen

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Guest

I got a FX-1 yesterday for my N1 but found that hard to install it. It's hard to position the central focus point to the middle of the split image circle on the focus screen. The position of screen holder is not fixed... can shift a little bit to the right / left... Whenever I place the FX-1 to the right place, it shifts right when I press the shutter a few times...

Seems I have to take my N1 body back to the distributor here... I just bought my N1 for 9 days!!!!!!!!!!!!!!!!!!!!!!!!!
 
G

Guest

Hell! I to have just ordered a FX-1 for my N1, heres hoping the same thing doesn't apply. I think I will get my dealer to fix it,then the ball is in his court fi the allignment isn't correct. I will post again as soon as it has been fitted, and I have had the chance to use it. By the way is there anyone else out there that is having the same problem, please let us know.
 
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Guest

I bought an FX-1 about a week ago and found that the autofocus doesn't exactly correspond to the split screen. The split screen almost always show the focus target to be a little further. I've tried reinstalling the FX-1 but the same problem persist. Does anyone have the same problem or know whether it is a problem with the autofocus calibration or the split screen?
 
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Guest

Tay
Did you Program the auto function for the screen? Dirk mentions not to forget this in his posting of tne "N1/NX in german press". I do not own the N1 but am considering buying and am troubled by your experience.
 
G

Guest

Hi Kevin, the program function is only for the metering. I had my N1 calibrated twice and on both times while the focus matched the split screen the focus was out. The original calibration seemed much better but the focusing didn't match the split screen. My local distributor has just changed my whole set but using the same FX-1 as before I find that again the focus does not march the split screen. Does anyone know whether the problem could be with the screen and not the calibration?
 
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Guest

Tay,

there are only three possibilities. Either the focussing screen is not properly adjusted in the body, or the Af is not properly adjusted, or both at the same time.

For all 3 cases, Contax can fix this. But is is not normal that you see a different focus point between FX-1 and AF. If it stays like after getting it back from Contax, then they did their job not properly. IT HAS TO MATCH!

Dirk
 
G

Guest

Thanks Dirk. Is it possible that it is just the screen that is defective. My local agent thinks that it is not likely but it only seems logical given that a match on the split screen on two of the calibrations still produced out of focus pictures.
 
G

Guest

I have tried the FX-1 screen and noticed that the centre focus marks are not dead in the centre fo the split image circle, being slightly to the right as you look through the viewfinder. I have noticed that soemtimes the AF and the split image agree, sometimes the AF and image don't agree and I then correct manually a very, very small amount (so minute a movement that I wonder if it makes any difference at all to the image that is produced, and maybe only moved the split image), and sometimes I correct and when I press the focus button again it doesn't move focus and the focus confirmation lights up with no refocussing.

I suspect that the calibration is so sensitive that a hairsbreadth difference in the AF and split image would not be noticeable on the film. Every image I have taken with the N1 using the original screen was in focus, so I would suggest that anyone with this problem that is not getting out of focus pictures might want to put the old screen back in, and then the misalignment of the split image will not be annoying them. I think the AF is correct, and the split image is not in most cases.

Simon
 
G

Guest

I just read this article which contains some interesting thoughts on autofocus, and could explain why I sometimes have AF and FX-1 agreeing and sometimes not.

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Simon
 
G

Guest

Hi! Sorry it has taken me so long to reply to my previous posting ( September 15th ). However I did have the FX1 fitted to my N1, and the resultant effect is exactly the same as Simon's. Initially I was really worried about the focusing of the N1, with all the various remarks that had been posted,even to the extent that I almost went back to Canon. That thought has now left me, as the focusing as Simon says is more or less spot on,and even if I do notice a slight difference it is very minute. In fact,even when I use the A/F I nearly always adjust the with the focusing ring on the lense, which gives me a greater satisfaction that everything is OK, so much so that I have no intention of putting the original screen back in, another thing is, that being retired I have plenty of time to play about. I hope these few comments gives you the N1 users a little more confidence.
 
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Guest

Ken

I believe we are seeing the anomaly created by having a hybrid camera - both AF and MF in one body. If it was a pure manual focus camera we would all be using the ground glass and split image and be very happy users. If it was pure AF then we would let the camera focus and, as long as the images were in focus, we would again be happy users.

Where we have the issue is that we have an AF camera whose focus we can check with the split image, and I believe we are seeing the difference between the AFaccuracy and the split image accuracy. I have to say that the adjustment need to get the split image to align after and AF operation is so minute that I doubt the focal plane has moved anywhere near enough to fall outside of the depth of field, and probably by not more than a fraction of a millimetre.

I use manual focussing all the time for macro work of course, as even a fraction of a millimetre at f/22 on a macro shot can render the image out of focus.

Simon
 
G

Guest

I am so furious right now that I probably should not comment but I fell like I have to vent somewhere. I just tested my N1 autofocus and FX-1 slit image by putting the camera on a tripod and focusing on different points. Since I work a lot with cinema lenses, I measured the distance to my focus points with a tape measure and compared the results to the lens markings. The result was that the autofocus seemed to match my measurements more exactly than the split image focus obtained with the FX-1. I have just taken a couple of rolls of slides during a trip in Germany and I am very worried because I trusted the split image.

For my next test, I reinstalled the original focusing screen, and by manually determining critical focus by eye on this screen, the autofocus seems to be dead on.

So here is my WARNING: It seems that we should quickly discard of the FX-1 because it seems to be highly inaccurate for critical focus situations. I will definitely do so myself since I take a lot pictures with shallow depth of field taking advantage of the 1.4 T-stop of the 50mm.

The FX-1 has definitely made me very insecure about the reliability of the N1, which I think is a shame with a camera of this price.
I have always loved the quality and accuracy Carl Zeiss products and I am starting to think that their partnership with Kyocera might not have been the best decision.

Please if any of you has an OFFICIAL answer about the accuracy of the FX-1 versus the autofocus, please let me know because I really feel like selling my whole package and switching to LEICA.
 
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Guest

I have just ordered the FX-1 for my N1, but I will not install it based on many comments on this site, the camera was sent back once for recalibration, and I have thought about going the same route as you.
good luck

Rick
 
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Guest

Berndt, I can't comment on the accuracy of the N1 and the FX-1, but I can assure you the 50mm 1.4 lens is an F stop not a "T" stop. Zeiss do not quote the actual T stop of their lenses(I'm not aware of any manufacturer who currently delcares the T stop). It probably doesn't matter too much in these days of built in exposure meters anyway.
Colin
 
G

Guest

Hi Collin, I haven't even thought about the fact that still camera lenses do not give T-stops. Obviously on the 50mm it is the same since it is a prime lens. On the 70-300mm with all the glass however, I am sure that there is a difference. It really doesn't matter since it is usually no more than a third stop difference at the most anyway, which is nothing that can't be compensated for in post anyway. It is only habit that makes me refer to T-stops since I am usually concerned with exposure more than with depth of field.
It made me think though that maybe the zooms let in less light on the long end and Zeiss therefore quotes the 24-85mm as a 3.5-4.5 and the 70-300mm as a 4-5.6 respectively.
 
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Guest

> Bernd I would do a more thorough test if i were you. Like running some film through with the fastest lens you have wide open and compare Autofocus against MF. I am not sure from where you made your mesurements but I believe that you would have to measure distance from film plane to subject. It seems to me that this would be hard to do easily and to the tight tolarances that you described (the small possible difference between AF and Mf) You may find that the AF is off slightly. This may only matter/be noticable wide open. Also Variable Zoom lenses do lose light on the far end as the focal length is increased. This is somehow akin to Bellows Extension--If you Have ever worked with large format cameras you are very familiar with this concept.

Hope this suggestion heps Kevin
 
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Guest

Kevin I will definitely run some sharp slide film through the camera and focus on a lens test chart and I will let everybody know about the results. However, I am not complaining about a significant difference between MF and AF at all. On the contrary, the AF seems to be dead on when compared to MF with the original ground glass. But the forum, I am commenting on is concerned with the FX-1 split screen, and believe me that is considerably off. To give you an ex&le, I measured to an object that was 10 feet away from the film plane. I let AF focus on it and the lens read 10 feet exactly. With the FX-1 split image, I focused and the lens read almost 20 feet. Trust me, Zeiss would never put such numbers on their lenses if they were that far off from the actual object distance.

My second question is, now that we have established that zoom lenses are slower on the long end due to bellows extension and there are now T-stop markings on the lens, is what is marked on the lens as f8 still an f8 or do I have to compensate and open up a touch when I'm on the long end of my zoom?

This question of course is more theoretical because the difference is probably not that significant.
 
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Guest

Bernd
I have a question,which is off, is the split screen correct and the focus off, or is the focus ok and the split screen off,I just ordered a FX-1 but I am holding off installing it,or I may send it in and let Contax do it, I am having a tough time manual focusing with the original screen in some situations, I am really giving this a chance ,do to the fact we will take a beating on the resale ,and the optics are just so superb

Rick
 
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