G2 Focus Distance Measurement

N

new2rf

Guest
I just bought an used G2 body. I found out the distance it indicated on the display is CONSISTENTLY over the actual distance. I have not run a roll film through it. Is that possible that the number on the display is wrong, but the actual picture is focused????

Very upset. Bought from eBay, not sure how to deal with this.

I tried different lenses on to focus something 3.1 M away, but al ways came back as 3.3 M!!!!!!

Is there any way to re-calibrate the camera?
 
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It made need a CLA. You can send to Kyocera for a fairly reasonble service. Just like every other rangfinder:)

Congrats on the buy. Also, if you shot at range, it should not really hinder you much, if at all. Test it with film would be my suggestion.
 
I was planning on using this for my 90mm lens for close portrait....

for distance about 1 to 2 M, the reading came bach about 4 cm off. that's a lot.

I am waiting for the film test results

How do i send it to Kyocera? What's CLA?

is it going to be more than $100 to service this kind of problem?

I probably should not buy from eBay any more....

:(



NoTx said:
It made need a CLA. You can send to Kyocera for a fairly reasonble service. Just like every other rangfinder:)

Congrats on the buy. Also, if you shot at range, it should not really hinder you much, if at all. Test it with film would be my suggestion.
Click to expand...
 
new2rf said:
I was planning on using this for my 90mm lens for close portrait....

for distance about 1 to 2 M, the reading came bach about 4 cm off. that's a lot.

I am waiting for the film test results

How do i send it to Kyocera? What's CLA?

is it going to be more than $100 to service this kind of problem?

I probably should not buy from eBay any more....

:(
Click to expand...

Mine is correct to 1 cm. Did you measure from the film plane? It is indicated on top of the camera with a symbol looking like this -o-

CLA is Clean Lube Adjust and I don't think you'll get one short of $200, never needed one on my Contaxes but on a Rollei 35TE and Rollei in Braunschweig/Germany charges 125 Euro.

Another thing is the focusing point itself. I found mine to be at the top of the indicated frame and not in the middle.

But I`m more of a fair weather snapshooter and so use apertures smaller than F5.6 most of the time.
 
I bought a beautiful black G2 from a friendly neighborhood dealer. The camera was "almost unused," and indeed appeared that way.
It didn't take me long to find out why. Most pictures were soft, and it was because just about everything was out of focus. The distance scale on the top of the camera was off by 4-6cm, AND the camera was clearly mis-focusing the 90mm from 15-20M (the crossover point on that camera- where the 90mm wide open needs accurate focusing)

I sent it back to Kyocera, and it cost me $155 plus shipping. The turn-around time was about 10 days. The camera is perfectly focusing now. All functions are as expected.

And I promised myself (PROMISED!) that any camera purchases *used* will take into account the cost of a CLA, whether or not the camera "needs" it. Every single one of my cameras that I've purchased for the past year or so has needed focusing work in one form or another. Every one. The Prominents needed collimating. The Leicas needed adjustment. The G2? You already heard about that one. Heck, I just purchased a Canon 10D from a store, used, and a 28mm f/1.8 lens, and guess what? That's right- it didn't focus correctly wide open (though the shop exchanged the lens and now all is well).

The CLA/adjustment is simply a cost of doing business. Always.

To send it back to Kyocera, visit www.kyocera.com and follow the links for "Customer Service." Heck, give 'em a call, they are friendly folks.
 
My film test came back. It seems to me that the focusing is ok. I didn't do any scientific or systematic test.

Is that possible that the measurements in the LCD is off, but the actual focusing is alright????
 
I've used the ContaxG system for several years and learned that the autofocus mechanism connects directly to the lens while the indicated distance measurement is a crude byproduct. So it's very probable that the lens is focusing correctly and just the indicated distance is hosed up.

I've also learned that keeping the viewfinder windows clean is critical to ability to focus. A smudgy fingerprint on the window really impacts the ability to focus.

Lastly, when the ContaxG does focus, it's almost spot on. Any problems usually occur when eithe G1 or G2 can't focus at all, indicated in the viewfinder by two dots, one at infinity and one at min focus distance. One dot means it's focused correctly. Just learn to use the focus lock for objects not in the center of the frame.

Bob Michaels
 
The final arbiter in quality is YOU. So, don;t worry about what the display says, trust your photos. The G series can give you some of the most exciting and equsite photos ... but it will take some practice, don't be supprised. Just be patient. I love my G1, and want a G2.

Congrats.
 
Bob Michaels said:
I've used the ContaxG system for several years and learned that the autofocus mechanism connects directly to the lens while the indicated distance measurement is a crude byproduct. So it's very probable that the lens is focusing correctly and just the indicated distance is hosed up.

I've also learned that keeping the viewfinder windows clean is critical to ability to focus. A smudgy fingerprint on the window really impacts the ability to focus.

Bob Michaels
Click to expand...

Intereting...

How did you know distance measurement is a by product? What's your experience on that?
 
New member alert! Welcome to Bob Michaels, joining in with a helpful knowledgeable comment too! :D
 
Bob Michaels said:
I've used the ContaxG system for several years and learned that the autofocus mechanism connects directly to the lens while the indicated distance measurement is a crude byproduct. So it's very probable that the lens is focusing correctly and just the indicated distance is hosed up.

Bob Michaels
Click to expand...

Another question:

I thought, the distance was detect by the triangle for view finders, which told the lens how much it should turn.
The inaccurate display of the distance in the LCD is an indication that somehow the distance triangulation is wrong...

How could that result in lens focusing correctly?

Whereas in SLR, the lens keeps turning until the image is sharply focused on to the prism (which had the exact distance as the lens is to the film plane). In this case, the focusing mechanism does NOT tell the lens how much to turn, instead, just keep turning until the sensor detect the image is sharp in the prism.

RF calculate the distance first, then tells the lens how much it should turn.

That's why I am so concerned by the inaccurate number it displays.
 
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Focus Repeatability

Focus Repeatability

I have been getting familar with focussing a G1 (new to me), focusing with a 45 Planar on a book shelf across the room. The books spines are all flat relative to each other, and I am being careful to keep my head in the same position. I am focusing on the same spot, multiple times, locking the focus and then looking at the distance in the top LCD (the numeric output, not the scale in the viewfinder).

The readings go like this:

4_1, 4_1, 3_8, 4_0, 4_1, 4_1, 4_0, 3_9...

What's going on? I might expect a bounce in 10cm if I was close to the border between measurements, but 30cm? Is this "normal", and should I be concerned?
 
Re: Focus Repeatability

Re: Focus Repeatability

Issy said:


What's going on? I might expect a bounce in 10cm if I was close to the border between measurements, but 30cm? Is this "normal", and should I be concerned?
Click to expand...

First of all, put the camera on a realy sturdy tripod.
Record the readings and take pictures, then compare those.

Often focus is fine, but the subject moves. Like here:

Mike moved!
 
Well, if the books are moving, I am in serious trouble.... :)

I thought I was being _very_ careful not to move, but I will try it ( tripod and cable release) and post a reply. I really can't believe that I was moving my head 20-30cm forward and back, but let's rule it out.
 
Re: Focus Repeatability

Re: Focus Repeatability

The readings go like this:

4_1, 4_1, 3_8, 4_0, 4_1, 4_1, 4_0, 3_9...

What's going on? I might expect a bounce in 10cm if I was close to the border between measurements, but 30cm? Is this "normal", and should I be concerned?
Click to expand...

The readings on the LCD are rounded to some extent -- how much depends on the subject distance and the lens in use.

I recall corresponding with someone who did a very careful test, involving moving the camera back and forth by small distances on a focusing rail, and found that the camera does focus in much smaller increments than the distance readouts display.

So, remember that the display is only approximate. If your photos are in focus, you've got nothing to worry about.


Also, re your test method: note that the spines of books standing vertically on a shelf actually are a rather difficult target for an AF system that senses only vertical lines (as is the case on a G.) It's sort of similar to the notorious case of trying to focus on the bars of a cage at the zoo with a split-image rangefinder: It's easy enough to line up the images of bars, but you can't always be sure that you've lined up the CORRECT bar.

You can distinguish books by eye by looking at the titles, colors, etc., but the CCD focus detector in a G may not have enough resolution to tell them apart that way. So, it's quite possible you'll get slightly different focus readings on different trials, as the AF system lines up different sets of verticals.

If you want to make a good target for testing, use a single bold vertical line on a contrasting background. I used to use a strip of black electrical tape run down a white wall. This way there's no risk of confusing the AF, and you can determine exactly how it behaves.
 
Issy said:
Well, if the books are moving, I am in serious trouble.... :)

I thought I was being _very_ careful not to move, but I will try it ( tripod and cable release) and post a reply. I really can't believe that I was moving my head 20-30cm forward and back, but let's rule it out.
Click to expand...

Possibly you turned your head and the camera so it focused on a different book.
 
Eating Crow

Eating Crow

I finally had a chance to do what jlw suggested... I put a strip of black electrical tape on the wall vertically, and set up the G1 on a tripod, and put the tape line directly through the focus brackets.

Pressed the shutter multiple times, and got the same (exact) reading each time.

(can you pass the salt for my crow, please? Thanks.)


So, knowing that the focus system is optimize for a single vertical line, what do the more experienced users use for "focus points"?

Examples:

1) Tight portrait --- the edge of the iris? the edge of an eyelid?

2) I have a shot of a Xmas tree that is clearly out of focus. Should I have used the right or left edge of a light glass bulb against the darker tree?

Others?
 
I sit at the dining room table and focus across the table, into the kitchen onto...the kitchen faucet and sprayer.

This is exectly 15 feet, and allows me to match up vertical AND horizontal images.

-Paul
 
But I mean, for the subjects that you want to take pictures of, what points on them do you usually use for focus points... obviously, I have learned that multiple vertical lines are a bad thing (the spines of the books in the first excercise).... does it have to be a line (a line through a white field), or will it get an edge (the vertical interface between light and dark)?
 
Depends on the subject, there is allways soemthing to focus on but I'm not one of the no depth of field supporters.

To get a picture with only the tip of the third eyelash from the right in focus I'd shoot a puppet with a Linhof Mastertechnika.
The Contax G2 is very good for general purpose shooting, it is my favorite travel companion and I'll cary it with me whenever possible.


Here is a snapshot from a co-worker ca. 3am at this years 6-Tage Rennen in Bremen where we selected and edited pictures for the website and a daily newsletter.
Taken with a Contax G2. Planar 45, TLA200 on Tri-X with most light from three notebook screens and some dimmed lights on the ceiling
 
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