Praise for the Spotmatic

p.giannakis said:
How are the pre-spotmatics activating the lens aperture? Are they using the same level at the bottom of the mount? Maybe this part is struggling with pushing the lens pin in?
Click to expand...
Yes, there’s a hinged lever plate similar to the Spotmatics.

In my experience this is the weak point of the design, and I’ve had several SV’s hang on the same way mentioned above.

Keep in mind that there are compatibility issues with some S-series bodies and some Takumars. Bodies with a green ‘R’ on the rewind lever should *not* be used with certain versions of the 50/f1.4 (8 element version) and 55/f1.8.
 
Yes, correct, a plate that pushes on the lens pin. I'm wondering whether the pin isn't striking that plate correctly.
 
nickthetasmaniac said:
Yes, there’s a hinged lever plate similar to the Spotmatics.

In my experience this is the weak point of the design, and I’ve had several SV’s hang on the same way mentioned above.

Keep in mind that there are compatibility issues with some S-series bodies and some Takumars. Bodies with a green ‘R’ on the rewind lever should *not* be used with certain versions of the 50/f1.4 (8 element version) and 55/f1.8.
Click to expand...
I will take a look, but I think all my cameras have the orange R.
 
KoNickon said:
… the camera works fine -- when the lens is off the camera. When it's mounted, though, the mirror often stays up at the end of the shutter cycle. The advance is not jammed; the mirror just doesn't return. …
Click to expand...
It seems to be an interaction between the lens’ stop down pin and the aperture actuation plate in the camera. I wonder if it’s a particular lens or the camera where the problem is.

Does this happen with other lenses?

When the mirror stays up, does the lens aperture remain stopped down?

Regardless, see if the problem occurs with the lens wide open.
 
Yes, it happens with other lenses. That thought had occurred to me but it doesn't appear to be one bad lens.

Aperture remains stopped down. I'll try it with the aperture at the widest setting
 
KoNickon said:
But staying on this topic (sort of) -- I have several of the pre-Spotmatic Pentaxes (e.g. SV) and the mirror sticks up on these with regularity. I've judiciously oiled in the places described in several online videos and the camera works fine -- when the lens is off the camera. When it's mounted, though, the mirror often stays up at the end of the shutter cycle. The advance is not jammed; the mirror just doesn't return. I can't figure out why -- I'm wondering whether the rear pin on the lens somehow hangs up on the "pusher plate" (my term) at the bottom of the lens opening. I know these cameras probably just need a full overhaul, but I'm wondering if there are specific causes an amateur like me can address.
Click to expand...
How sticky is the foam in the top of the mirror?
have you replaced that?
 
There's like, no foam at the top of the mirror. The pre-Spotmatics have a metal baffle at the top of the lens throat and the mirror swings up just behind it. I don't think there ever was foam there. But in any event there is none now.
 
My first thought is that it might be a lubrication issue; my second thought is that the effect is the opposite of what I’d expect, given the way the lens aperture pin operates - noting that when the pin is pressed in, it stops the lens down and, when no pressure is on the pin, spring tension of the aperture mechanism opens the aperture and the pin moves outwards.

Mechanically, the whole process is: when the shutter release is pressed, the mirror is first driven upwards under spring tension and the plate moves forward to push the aperture pin inwards. The mirror reaching the top of its travel causes the first curtain to be released. At some time interval, based on the shutter speed, the second curtain is released and, as it travels, a shaft also revolves which has a “pin” affixed to it. When the second curtain completes its travel, the pin on this shaft pushes aside a lever which is holding the mirror up. The mirror then begins to drop to its normal down position. At sometime during this latter process of the mirror being released, the aperture plate should be released as well.

With lack of lubrication and no lens mounted, I could understand how this plate might fail to return to its rearward position and also hang the mirror.

What confuses me is that, if there is some lack of lubrication with this plate, the presence of a lens with the aperture pin pushing back on the plate should actually make it more likely for the plate to move back and more likely for the mirror to come down.
 
Pál_K said:
My first thought is that it might be a lubrication issue; my second thought is that the effect is the opposite of what I’d expect, given the way the lens aperture pin operates - noting that when the pin is pressed in, it stops the lens down and, when no pressure is on the pin, spring tension of the aperture mechanism opens the aperture and the pin moves outwards.

Mechanically, the whole process is: when the shutter release is pressed, the mirror is first driven upwards under spring tension and the plate moves forward to push the aperture pin inwards. The mirror reaching the top of its travel causes the first curtain to be released. At some time interval, based on the shutter speed, the second curtain is released and, as it travels, a shaft also revolves which has a “pin” affixed to it. When the second curtain completes its travel, the pin on this shaft pushes aside a lever which is holding the mirror up. The mirror then begins to drop to its normal down position. At sometime during this latter process of the mirror being released, the aperture plate should be released as well.

With lack of lubrication and no lens mounted, I could understand how this plate might fail to return to its rearward position and also hang the mirror.

What confuses me is that, if there is some lack of lubrication with this plate, the presence of a lens with the aperture pin pushing back on the plate should actually make it more likely for the plate to move back and more likely for the mirror to come down.
Click to expand...
Rather than dropping to its rest position, the mirror is driven back by spring pressure. There are a number of levers and pivots involved in the working of the mirror and stop down plate. To fix the problem, the mirror box should be removed from the camera, the old lubricants and dirt washed off, and new lubricants applied.
 
Vickko said:
Yep, it was the first SLR that I "fell in love" with. Then came the Nikon F/F2. Good solid cameras.

And little things, like the curve of the advance lever. It is like the curve of the Spitfire wing.
Click to expand...
The Spitfire aircraft (especially the Mk XVI) are the most curvaceous aircraft ever built!!
 
In 1979 I was considering buying my first SLR, I had been previously shooting 126 format through a Kodak x177 and 110 format through a Halina, (my memory lets me down, again, regarding the model), anyway, I decided on Pentax and bought a MV , followed quickly by an MX. Why Pentax, well a neighbour around the corner, (block), was a very keen Pentax man, he owned three bodies, all spotmatics and a huge selection of Takamaur glass, not to mention catalogues, info sheets etc. I spent many a happy hour ploughing through all the Pentax kit, great glass and great build quality.
 
The Spotmatic was a great camera, i owned 2 of them at one time. However, I always thought that the Takumars, Super Takumars and SMC Takumars in M42 were the stars. I sold both Spotmatics, regret selling the various lenses about 15 years ago.
 
dexdog said:
The Spotmatic was a great camera, i owned 2 of them at one time. However, I always thought that the Takumars, Super Takumars and SMC Takumars in M42 were the stars. I sold both Spotmatics, regret selling the various lenses about 15 years ago.
Click to expand...

I'm with you, dexdog. I have a couple of Spotmatics (a II and an F) and a sprinkling of Super Takumars and Super Multi-Coated Takumars. I, too, am far more enamored of the lenses than I am of the cameras.

- Murray
 
You must log in or register to reply here.
Back
Top Bottom