Yashica T5/ T4 Super has trouble focusing, especially at infinity

bottlegardener · Jun 30, 2018

Hi,
Just wondering if anyone encountered this issue?
I've seen lots of people online complain of T5s or T4s stuck on infinity but this is a headscratcher. I wonder if this could be something simple like an obscruction on the screw in the focus mechanism. I noticed that craigcamera.com sells a copy of the service manual and I plan to buy it but I just wanted to ask here first in case this hints at an irreplaceable broken part or something.

removed account4 · Jul 2, 2018

bottlegardener said:
Hi,
Just wondering if anyone encountered this issue?
I've seen lots of people online complain of T5s or T4s stuck on infinity but this is a headscratcher. I wonder if this could be something simple like an obscruction on the screw in the focus mechanism. I noticed that craigcamera.com sells a copy of the service manual and I plan to buy it but I just wanted to ask here first in case this hints at an irreplaceable broken part or something.

hi
we have a T4 that has a jammed zone focus mechanism. i was told by 3 repair people it is unfixable.
seems the zone focus mechanism is the achiles heal of that camera.

choiliefan · Jul 2, 2018

There's a guy on youtube who sprayed wd40 into the mechanism and voila, it's all fixed. YMMV.

bottlegardener · Jul 5, 2018

Thanks for the responses folks. I think I'll try the service manual. If nothing else, it should be a learning experience. Maybe wd40 or something similar could work but I don't feel confident spraying until I see an exploded view diagram. Also, isn't graphite mixed in lighter fluid a safer lubricant? (I'm still vary much learning the very basics of camera repair but that's what I read somewhere).

shutterfinger · Jul 5, 2018

WD40 is a water displacement. It has become a trade name for the company. It dries out in a month or two and leaves a sticky residue that builds up with repeated use, same for 3in1 oil. Not good products for cameras.
Lighter fluid's main ingredient is Naphtha. Naphtha will damage plastics and rubber. Not a good product for use in cameras that are not 100% metal and glass.

bottlegardener · Jul 6, 2018

Thanks, I didn't realize naphtha . I'll order the service manual and report back if it recommends a specific lubricant.

bvy · Jul 6, 2018

These cameras are great when they work, useless when they stop. Mark Hama used to repair them but stopped, claiming parts have become too scarce.

shutterfinger · Jul 6, 2018

Not being familiar with that camera I cannot recommend any lubricants and definitely would not spray anything into it unless it was dead and no loss if the spraying did not revive it.
For cleaning 90% Isopropyl Alcohol and or CRC QD Electronic Contact Cleaner https://www.homedepot.com/p/CRC-11-oz-QD-Electronic-Cleaner-05103/205021975
For lubrication TriFlow https://www.amazon.com/Tri-Flow-Squ...e=UTF8&qid=1530912633&sr=8-3&keywords=triflow , Finish Line Premium Grease with teflon https://www.amazon.com/Finish-Line-...&qid=1530912695&sr=8-5&keywords=teflon+grease and Dupont Dry film Teflon https://www.amazon.com/DuPont-Non-S...qid=1530912695&sr=8-11&keywords=teflon+grease
Are safe for use in cameras as a general rule.

bottlegardener · Jul 12, 2018

Thanks for those links to recommended solvents and lubricants!

I bought the service manual. As it turns out, there is a service procedure for adjusting the infinity focus position that doesn't even appear to require disassembly. At first glance It looks like you can write the the changes to the eeprom though a mode where the focus position is adjustable in 0.027mm increments.
The bad news for me is that a collimator with a readable scale is necessary to calculate the focus compensation.

bottlegardener · Jul 27, 2018

Hi again, a local camera tech declined to take on this job and seeing as I have little to lose, I think I'll try to tackle this calibration myself. I'll try using a variation on this method http://elekm.net/zeiss-ikon/repair/collimate/
One question: the T4 Super requires its door closed for the lens infinity calibration. Has anyone here ever found a trick for lighting a compact cameras's film gate with the door closed? Is there maybe a bright-but-tiny LED flashlight model that could fit in the place of the 35mm cassette and sufficiently light up the film plane?

bernard_L · Jul 27, 2018

bottlegardener said:
Is there maybe a bright-but-tiny LED flashlight model that could fit in the place of the 35mm cassette and sufficiently light up the film plane?

The cassette chamber is not ideal for a light source to illuminate the film plane. Better would be the (bottom of) space between lens and film plane. That would be OK for a MF camera. Even a 35mm camera, with non-retracting lens. For the T4 I would suggest battery in film cassette location, wiring, and LED bulb behind lens, facing film gate. You need to observe the right polarity, and to insert a proper resistor to control the current. I will elaborate with details in case you are actually going that route.

bottlegardener said:
The bad news for me is that a collimator with a readable scale is necessary to calculate the focus compensation.

Not sure how this would work, as the T4 lens seems to move to actual focus position just for the exposure. Anyway, you don't have a collimator. Assuming the only problem is a general shift in the focus scale, I propose the following;

Make a 1-exposure test of a focus target as in these examples:
http://regex.info/blog/photo-tech/focus-chart
https://www.amazon.com/Focus-Pyramid-AutoFocus-Calibration-Adjustment/dp/B007QUG3XA
http://www.dphotojournal.com/focus-test-chart.pdf
http://www.vinland.com/FocusTarget.html
I would suggest to aim for a nominal distance of 1m.
Develop, and do the simple calculations with distances, in m, cm, mm whatever, but all in the same unit
d0 (1m) distance to the nominal target, the one that the AF locks to
d the distance that appears sharp on the developed film
r = 1/(1/d0 - 1/d) how much the infinity position must be racked forward.
f = 35mm = 3.5cm = 0.035m focal distance of the lens.
r = (d-d0) x f^2 / d^2
This is approximate but should get you pretty close.

Making a partial exposure of a roll of film with a P&S may be non-trivial. You can open the back in the dark and cut the film at the cassette lip, but the camera may or may not let you pull the exposed film out. Or, just do a premature rewind; then use an extractor; and make an educated guess how much beyond the leader you need to develop to obtain your test exposure.

bottlegardener · Jul 27, 2018

Thanks so much for the tips and links Bernard! That's a lot to chew on.
The debug mode for the T5/T4 Super has a setting where the lens is at infinity and shutter remains open (the service manual warns that it drains batteries quickly and they recommend keeping the shutter open less than 3 minutes).

bernard_L · Jul 27, 2018

bottlegardener said:
The debug mode for the T5/T4 Super has a setting where the lens is at infinity and shutter remains open (the service manual warns that it drains batteries quickly and they recommend keeping the shutter open less than 3 minutes).

Then you don't need the focus target.Good for you.

bottlegardener said:
I'll try using a variation on this method http://elekm.net/zeiss-ikon/repair/collimate/

I would advise to keep as close as possible to actual operating conditions, and therefore use an actual piece of (clear) film in the film gate. Just remove the edge with the perforations where the sprocket wheel is, or the camera will try to "load" the film as soon as you close the back door. If you disable the film advance as I suggest the camera will probably just complain with a flashing "E".
Prepare a variety of targets on the emulsion side of the piece of film: black line with super-thin marker, linear scratch, etc. Hard to tell in advance which one will work best. In my experience, it's best to have an SLR with a split-prism in the center. You may have to position your eye carefully to have both halves of the prism working properly (not blacked out). Experiment with various focal lengths of the lens on the SLR: longer is more sensitive, but more susceptible to vignetting by the pupil of the camera under test, creating blackout of one or both halves of the split prism.
Good luck.

bernard_L · Jul 27, 2018

A word of caution concerning the advice of Mike Elek:
"A telephoto lens for the SLR – at least 85mm"
That my be true when collimating a 50mm Sonnar open ar f:2, but not when collimating the 35mm f:3.5 lens of the T4. See my previous post.

Eric Rose · Jul 27, 2018

I had a couple of the T cameras and both jammed focus. I was so frustrated I took the last one apart and was shocked to find all the gears were cheap plastic. No wonder they wore out and jammed. That's why I am amazed people still pay top dollar for essentially a crappy camera. Great optics but crappy insides.

Yashica T5/ T4 Super has trouble focusing, especially at infinity

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