Should I buy a Pentax Spotmatic or the Pentax K1000?

flavio81 · Mar 24, 2017

Steve Smith said:
No. The resting position is the centre position. Correct exposure is shown when equal current flows through both sides of the bridge and zero current flows through the meter. Therefore, it is not voltage sensitive.

Steve.

No, no, and no.

Sorry for being blunt, but this misconception gets often repeated through forums.

The resting position on the Spotmatic is not the centre position. It is a position that is on the minus (-) zone. Take a look at any spotmatic*, or at the spotmatic service manual (it is online on the net) if you don't believe me.

So, to get the meter needle to the centre, a precise current flow is needed. This makes the meter voltage sensitive.

* If YOUR spotmatic has the resting position in the exact center, then you can be sure a technician has moved the meter position.

flavio81 · Mar 24, 2017

Steve Smith said:
No. The resting position is the centre position. Correct exposure is shown when equal current flows through both sides of the bridge and zero current flows through the meter. Therefore, it is not voltage sensitive.

To illustrate my point:

Straight from the Pentax Spotmatic service manual:

faberryman · Mar 24, 2017

Notice that the instructions say that the needle of the ammeter (a meter which measures current and not voltage) must rest at the center of the notch when 3 microamps current (not a specified voltage) is applied. The off position is just where the meter falls (gravity) when no current is applied.

flavio81 · Mar 24, 2017

faberryman said:
Notice that the instructions say that the needle of the ammeter (a meter which measures current and not voltage) must rest at the center of the notch when 3 microamps current (not a specified voltage) is applied. The off position is just where the meter falls (gravity) when no current is applied.

Exactly, that's my point.
This point i'm making was already discussed on other Pentax forums and other places.

Steve Smith · Mar 27, 2017

flavio81 said:
The resting position on the Spotmatic is not the centre position. It is a position that is on the minus (-) zone. Take a look at any spotmatic*, or at the spotmatic service manual (it is online on the net) if you don't believe me.

This is correct - but it's so close as to make no discernable difference with cells differing by only 0.15 volts.

Steve.

BMbikerider · Mar 27, 2017

This seems to be ruffling a few feathers, but as it happens I have just exposed half a 35mm Fuji Superia colour film in a Minolta SRT101b, rewound the film and reloaded it into a Minolta XE1 then would the film on past the half way mark. Whilst the cameras are of a different make the principals are the same. The SRT used to need a 1.35v mercury cell and the XE1 a normal 1.5v silver oxide. I processed the film at home and then made a proof sheet of the 24 exposures. There was no discernable difference in the density of the seperate frames. I now feel that the difference in voltage making a noticable change in exposures has been largely exagerated and people are worrying unnessessarily.

Even the test position for the SRT101b's meter needle put it in precisely the correct place. I have yet to do the same test on Nikon camera bodies but I don't have an appropriate body to use. perhaps the same result would come about by checking an Olympus OM1n and and Om2n they use the same batteries as my Minoltas

John_Nikon_F · Mar 27, 2017

The Spotmatic F is the only body that doesn't care about voltage. The Spotmatic (original, SP500, and SP1000), and the Spot II/IIa all require recalibration or fudging of the ASA to provide correct exposure with newer batteries. I've owned a few of them. One was converted to 1.5 volts, the others weren't. The ones that weren't, I had to adjust the ASA about 2/3 stops slower, just like I do with my Nikon F bodies that are metered. With respect to batteries that fit, if I remember correctly, a 386 will fit, but the cap won't screw down all the way. So, the camera will sit slightly higher on the side with the battery chamber when you place it on a table.

Also, like the K1000, the power switch on the Spotmatic F is the lens cap.

With respect to the Minolta SRT-101, has it ever been serviced? If it has, the meter may have been recalibrated. Most mercury battery bodies that have been serviced in the past 20 years have been converted to use alkaline 625's or silver PX76's, etc.

Hatchetman · Mar 27, 2017

Slide film 1.5V battery, no problem. never had a problem ever.

Helios 1984 · Mar 27, 2017

Hatchetman said:
Slide film 1.5V battery, no problem. never had a problem ever.

Beautifull shot of the Kinkakuji

John_Nikon_F · Mar 28, 2017

Slide film usually seems to like being underexposed slightly (well, except for original Velvia), so an uncalibrated Spottie, early Nikkormat, etc, should shoot slide film fine with the meter set to the box speed. Anyway, nice shot.

BMbikerider · Mar 28, 2017

John_Nikon_F said:
With respect to the Minolta SRT-101, has it ever been serviced? If it has, the meter may have been recalibrated. Most mercury battery bodies that have been serviced in the past 20 years have been converted to use alkaline 625's or silver PX76's, etc.

As far as I am aware it has not been serviced ever. I knew the original owner and he never had anything serviced - Car, central heating, nothing! He considered the time to have it looked at was when it packed up!

flavio81 · Mar 28, 2017

John_Nikon_F said:
The Spotmatic F is the only body that doesn't care about voltage. The Spotmatic (original, SP500, and SP1000), and the Spot II/IIa all require recalibration or fudging of the ASA to provide correct exposure with newer batteries. I've owned a few of them. One was converted to 1.5 volts, the others weren't. The ones that weren't, I had to adjust the ASA about 2/3 stops slower, just like I do with my Nikon F bodies that are metered.

Thanks John, that was my point.

oreston · Mar 28, 2017

flavio81 said:
* If YOUR spotmatic has the resting position in the exact center, then you can be sure a technician has moved the meter position.

Not necessarily. On the very earliest 1964-65 Spotmatics (Asahi product #231 as opposed to the revised #23102 and all later Spotmatic versions) the resting position is in fact in the centre of the detent. I imagine they changed it because it was just stupidity to have the needle's "correct exposure" position the same as it's "off" position.

flavio81 · Mar 28, 2017

oreston said:
Not necessarily. On the very earliest 1964-65 Spotmatics (Asahi product #231 as opposed to the revised #23102 and all later Spotmatic versions) the resting position is in fact in the centre of the detent. I imagine they changed it because it was just stupidity to have the needle's "correct exposure" position the same as it's "off" position.

Wow... Thanks for this information, mr. Oreston 50/1.8!

I guess one learns something new every day.

Hatchetman · Mar 28, 2017

So I compared my Spotmatic to my EOS 3. Both with new batteries, but the Spotmatic had the 1.5V. The Spotmatic was about 1/4 stop BELOW the EOS 3. I have no idea what this means but that's what it was. LOL.

flavio81 · Mar 28, 2017

Hatchetman said:
So I compared my Spotmatic to my EOS 3. Both with new batteries, but the Spotmatic had the 1.5V. The Spotmatic was about 1/4 stop BELOW the EOS 3. I have no idea what this means but that's what it was. LOL.

Did you set the EOS 3 to centerweighted metering and pointed to an evenly-lit wall, lit by DAYLIGHT (not tungsten light or warm fluorescent/LED light)?

I use my EOS 5 to calibrate my other cameras the same way. The spotmatic has an average meter (thus the need to set the EOS to centerweighed and aim to a wall); and it is a CdS meter so it is color-sensitive (unlike the EOS meter.)

This gives you the best reference for recalibrating the meter. (Recalibrating the spotmatic meter is easy, just remove the film type indicator (under the rewind knob) and you will find a hole where you can fit a screwdriver to adjust a potentiometer).

Hatchetman · Mar 28, 2017

I wasn't exactly sure what to use so I used evaluative metering but it was at a brick wall in low sunlight - it was the only thing either camera could see - bricks.

flavio81 · Mar 30, 2017

Hatchetman said:
I wasn't exactly sure what to use so I used evaluative metering but it was at a brick wall in low sunlight - it was the only thing either camera could see - bricks.

Don't use evaluative as a reference point. It is unpredictable.

Pioneer · Mar 31, 2017

Hatchetman said:
So I compared my Spotmatic to my EOS 3. Both with new batteries, but the Spotmatic had the 1.5V. The Spotmatic was about 1/4 stop BELOW the EOS 3. I have no idea what this means but that's what it was. LOL.

It means that everything is working as the designer intended and is well within tolerance.

BTW - I can't identify 1/4 stop under on my Spotmatic.

Hatchetman · Mar 31, 2017

Pioneer said:
BTW - I can't identify 1/4 stop under on my Spotmatic.

I moved up the ASA dial 1/3 stop but that was too much!

Should I buy a Pentax Spotmatic or the Pentax K1000?

Privacy & Transparency

Privacy & Transparency