Pentax 6x7 Focus questions..eyes are getting old and its been a while! (2024)


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03-24-2017, 09:06 AM #1

foyle

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Pentax 6x7 Focus questions..eyes are getting old and its been a while!

Hello all
Im new to this forum but not to the world of medium format. I've worked with Rolleiflex and Mamiya medium formats in the past but seem to be having problems with focusing with my old Pentax 6x7 MLU (TTL prism) camera. Its been a while since ive used the Pentax 6x7, it has the original micro prism (would love a split screen) focus screen installed on it. After shooting a roll of film with my 105mm f2.4 and 55mm f4 lenses ive come to the conclusion that its either my ageing eyesight or the camera needs calibrating after so many years?! Someone did mention it could be a "mechanical bdoy focus" issue?!

I've read a couple of other posts with regard to Pentax 67 focusing issues on this site but thought it might be an idea to post up a photo or two to see if any expert eyes out there could confirm anything by looking at some test images I took? The photo of my son was taken with the 105mm and the one of my daughter was taken with the 55mm lens, both wide open. On both images I focussed on the eyes to get them sharp yet they somehow the zones appears soft?!

Any help or advice would be gratefully received very much as I'm a newbie on this site. Many thanks in advance

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03-24-2017, 10:08 AM - 1 Like #2

MysteryOnion

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Ruling out the screen calibration as the error...
One method...try to check the focusing screen with a small focus aid and and look at a target out at infinity? I use a small focusing loupe sitting on the screen, it has a base that is only an inch or 24mm wide so I can move it around. On a tripod, I check the four corners against the middle and move the alignment around to see the same target as all points. It helps to first do a check as all points and then come back with a wiggle of the focus ring at all points. This will help you see if it seems to be different. Also, try setting the focus at the best corner setting and come back to the center to see if it matches. Properly calibrated, you should see not differing settings.

Precaution against other errors...extra step. Check at the film plane first. If someone had repaired it and took the mount apart loosing or mixing up the shims, the lens mount could be the issue and not the screen. If possible, do the five point check with a focusing screen at the film plane first before altering the screen above.

You'll need to get under the trim frame by way of two screws and the two alignment posts to access the three screws that adjust the height and get all 5 points to match up.

If you are not comfortable in doing it yourself, then check with a repair technician to get it done.

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Last edited by MysteryOnion; 03-24-2017 at 10:29 AM.

03-24-2017, 10:16 AM - 1 Like #3

gofour3

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Shooting wide open with a 6x7 is tricky due to the shallow DOF. I would stop down a bit so you have more DOF, but still have a nice bokeh. Also a tripod is a must for this type of shooting and I would also recommend the 6x7 magnifier for critical focusing. Also faster shutter speeds (1/125 and above) are recommended, less chance of camera vibrations and your model moving.

Phil.

03-24-2017, 11:04 PM - 1 Like #4

cobbu2

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Another potential cause (and I had this happen with a 35mm SLR) is that the mirror isn't resting in its proper place when focusing, either up too high or down too low. In my case, someone had attempted a repair to the mirror and used thick putty as an adhesive to the mirror carrier causing the mirror to be resting slightly higher that it should have been. It manifested itself with nearly every image being out of focus; you could see it through the viewfinder with the lens at the infinity stop or when the lens focusing ring was set to a known distance, the image was slightly out of focus in the viewfinder. I removed (very carefully) the mirror from its platform and re-glued it with epoxy. That solved the problem.

Other that that, when hand-holding a 6x7, for me it's with a 55mm or shorter lens and 400 speed (or higher) film to ensure faster shutter speeds (as Phil mentioned).

03-24-2017, 11:35 PM - 1 Like #5

Silent Street

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Neither the 55mm nor the 105mm are the best performers when shooting at the widest aperture (f4).
The 105mm could be used at f8, with increased separation required of the subject from the background (for blur).
Focus on the eyes and eyes alone (never on the nose or the cheeks). What you have though is a pair of incredibly expressive portraits: those big, BIG eyes!!

Consider a dioptric correction lens that suits your visual deficit; the one installed on the eyepiece is not suitable for everybody and can indeed give rise to squinting and potential focusing errors. Unscrew the knurled ring and locate the glass. Take it to your optometrist so he can make up a correction lens best suited for you without glasses. They are otherwise very hard to come across on the market.

If you have the patience of a Hindu cow and the ambidexterity of a jeweller, the suggestion to tackle the foucusing screen aligment might be your key to thrills. If not, leave it to a repair technician (as he mentions).

Consider supplementary viewing aids to enhance focusing accuracy: the central-spot magnifier and the right-angle viewing finder are exceptionally useful in conditions where you feel compromised in your ability to focus accurately. True though either attachment is a bit of a fiddle to attach to the camera and should never be left on it as it can lead to serious damage to the prism and/or camera through being knocked, additional to the blighters poking you in the eye!!

Mounting the P6x7 / P67 on a tripod for portraiture, and making use of mirror lock-up before firing is most definitely the way to go. Neither of these big cameras are ideal for spontaneous, hand-held photography unless you are happy using very high speed film and a fast lens (e.g. f2.8 or better). Tripod-mounted portraiture will provide enhanced focusing ability. There appears to be vibration-induced blur on the boy's shoulders (?).

03-25-2017, 01:21 AM #6

foyle

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Wow! cheers for the very helpful comments its very much appreciated. You have all mentioned possible fixes and causes with regard to the issues im having. With regard to the shutter speeds and the two test rolls (one of 105mm lens and other with 55mm f4 lens) I made notes of the what i was using (f stops/speeds) and in most cases the speeds with the wider apertures were over 1/125 sec in most cases with the full open apertures it was at 1/1000 sec and a tripod (in the case of the portraits of my daughter).

One thing I didnt try was use the MLU function, so will try to shoot a roll solely using the mirror lock up and see what that brings in results. Someone did suggest download a target from the internet and shoot a test roll, although what is the procedure? Pin onto flat wall and focus on target using all apertures?

If failing I will send the camera to a technician for a service, I've already been in contact with Asahi Photo, Harrow Technical and Bill Wright, they all seem very knowledgeable, any particular recommendations with any of them? I'd much prefer to send to a technician that has the capability of being able to measure the body focus etc...Once again many thanks for a massive response in help,and great to see such passion, enthusiasm and knowledge still shared in the film camera world!

03-25-2017, 12:46 PM #7

desertscape

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (41)Originally posted by foyle

speeds with the wider apertures were over 1/125 sec in most cases with the full open apertures it was at 1/1000 sec and a tripod (in the case of the portraits of my daughter).

One thing I didnt try was use the MLU function, so will try to shoot a roll solely using the mirror lock up and see what that brings in results.

At those shutter speeds, using the MLU will not be a benefit.

03-25-2017, 03:36 PM #8

Silent Street

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (49)Originally posted by foyle

One thing I didnt try was use the MLU function, so will try to shoot a roll solely using the mirror lock up and see what that brings in results. Someone did suggest download a target from the internet and shoot a test roll, although what is the procedure? Pin onto flat wall and focus on target using all apertures?

Remember that mirror lock-up and shutter firing is a two-step process, not a one-press of the shutter button, and is at its most useful when using Bulb or any of the lower-speed settings on the shutter dial. It also separates that annoying "thwack!" of the mirror and shutter firing at the same time. Much of my own work uses Bulb with extended exposures up to 45 seconds to a minute, and MLU is routinely first set, followed "when I'm ready", by the shutter being tripped. MLU is battery-dependant for operation and indeed, should the camera be stowed away in the pack and the MLU nib is by misadventure pushed up, then you go and remove the camera and find you have a dead battery! So... 1) place a piece of tape over the MLU nib when storing in the pack; 2) always carry a spare battery ... or two!

03-27-2017, 05:00 AM - 1 Like #9

MysteryOnion

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If you are looking to send it off because the focus is still not quite right, consider asking for them to check:
If the body and mount calibration is the cause...if any shims are missing.
Correct calibration of the focusing screen...for errors.
Also, ask about the condition of the lone pad for the mirror and if the mirror was twisted off angle.
These are my things to look at if you've ruled no luck with tripod shooting, 125th speed and greater or pressure plate issues?

03-27-2017, 04:14 PM #10

Silent Street

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (63)Originally posted by MysteryOnion

If you are looking to send it off because the focus is still not quite right, consider asking for them to check:
If the body and mount calibration is the cause...if any shims are missing.
Correct calibration of the focusing screen...for errors.
Also, ask about the condition of the lone pad for the mirror and if the mirror was twisted off angle.
These are my things to look at if you've ruled no luck with tripod shooting, 125th speed and greater or pressure plate issues?

I have thought about this quite a bit.
Over time I have said this before: If the camera is in fact the late-1960s era Pentax 6x7, then I would strongly recommend a complete assessment of the camera, not just focusing, but shutter, winding mechanism, seals, mirror condition, solenoid "grip", shutter speed accuracy, the meter coupling chain ... a lot of things. Realistically, it is a very old camera that today gives people a lot of trouble with reliability and incidental faults / failures, and true, these big workhorses have seen very heavy professional use early on in their life. It could well be so that more than one problem is manifesting other than the question of focus, so a thorough professional check — possibly even a complete CLA (by Eric?) would be the next step. The one concern with that is a complete overhaul can cost well over the nett value of the camera itself, and parts being replaced come off like-aged cameras, resulting in a circle of redundancy and unreliability. My own recommendation is that people steer clear of the old Pentax 6x7 bodies and seek out the newer (1989 onward) Pentax 67 bodies in very good-excellent to mint condition.

03-28-2017, 01:19 AM #11

foyle

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (67)Originally posted by MysteryOnion

If you are looking to send it off because the focus is still not quite right, consider asking for them to check:
If the body and mount calibration is the cause...if any shims are missing.
Correct calibration of the focusing screen...for errors.
Also, ask about the condition of the lone pad for the mirror and if the mirror was twisted off angle.
These are my things to look at if you've ruled no luck with tripod shooting, 125th speed and greater or pressure plate issues?

Thanks will make a note of those points and mention them when sending off for a service.

03-28-2017, 01:30 AM #12

foyle

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (71)Originally posted by Silent Street

I have thought about this quite a bit.
Over time I have said this before: If the camera is in fact the late-1960s era Pentax 6x7, then I would strongly recommend a complete assessment of the camera, not just focusing, but shutter, winding mechanism, seals, mirror condition, solenoid "grip", shutter speed accuracy, the meter coupling chain ... a lot of things. Realistically, it is a very old camera that today gives people a lot of trouble with reliability and incidental faults / failures, and true, these big workhorses have seen very heavy professional use early on in their life. It could well be so that more than one problem is manifesting other than the question of focus, so a thorough professional check — possibly even a complete CLA (by Eric?) would be the next step. The one concern with that is a complete overhaul can cost well over the nett value of the camera itself, and parts being replaced come off like-aged cameras, resulting in a circle of redundancy and unreliability. My own recommendation is that people steer clear of the old Pentax 6x7 bodies and seek out the newer (1989 onward) Pentax 67 bodies in very good-excellent to mint condition.

Thanks for the advice and insight it's much appreciate. I have a Pentax 6x7 MLU body but only it's had one owner before me and was in mint- condition when i bought it i.e. didn't see heavy professional use, no knocks etc... The seals definitely need replacing but don’t leak light yet and the shutter speeds all seem to work fine (shot test roll and made note of exposures which all seem to be correctly exposed when the films were developed.) Other than that I reckon it needs a technician to give a service and check all the electronic parts are all in good condition i.e.capacitors etc.. I guess like any old camera it needs to be used in order to keep it ticking over rather like an engine. I heard wonders about Eric at CLA but I'm based in the UK so it wouldn’t be cost effective to send to Eric. Any recommendations on UK technician? Preferably one that has a calibrating lens or machine?!

03-28-2017, 04:34 AM #13

MysteryOnion

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I've always heard Harrow as being the place to go. Someone here in the group mentioned that they have many pentax tools too. Not sure about the parts, but if they check the usual things like film tension and the anti-reverse springs, they'll have the usual dial gauges and a proper collminator to inspects if the body is to spec.

03-28-2017, 05:50 AM - 1 Like #14

foyle

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Pentax 6x7 Focus questions..eyes are getting old and its been a while! (81)Originally posted by MysteryOnion

I've always heard Harrow as being the place to go. Someone here in the group mentioned that they have many pentax tools too. Not sure about the parts, but if they check the usual things like film tension and the anti-reverse springs, they'll have the usual dial gauges and a proper collminator to inspects if the body is to spec.

cheers for the reply again. Yes ive had a chat with Robin at Harrow seems very knowledgeable but unfortunately does not have anything to measure the body focus. Also had a chat with Pramath at Asahi Photo and he has a Pentax calibrating lens so he can check the body focus is ok (mirror alignment etc...) . Anyone on here used or can recommend Asahi Photo in Brentford, Middlesex for Pentax 6x7 repairs?!

03-28-2017, 09:19 AM - 1 Like #15

MysteryOnion

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I'm shocked... no surface check comparator?
Well, it looks as if it is Brentford or bust.
I'll make a note of that about Harrow...thanks.

Way...way back when I sent my first 6x7 camera to Eric, it felt like a new camera when it came back and still works perfectly.
The 6x7 bodies I've now worked on I've tried to get that feel of all oiled or greased up and clean like that first body.
Good luck with it...Well, I hope you are ready to send it off. It is a good feeling to get a near perfect camera back.

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