Praktica FX2 and Pentacon electric lens

[seany65]

Wasn't sure if I should post this in my other fx2 thread, but as it's nothing to do with prism viewfinders I thought it best to make a separate thread.

I've got a Praktica FX 2 and a Pentacon Electric 50mm f1.8 lens (to give me the option of getting a plc3 later), and while the lens seems to work properly, the infinity focus point seems to be very close.

I compared the rangefinder image of my Agfa Super Silette, who's focus scale is in meters, and goes "... 2, 3, 5, 10, inf." to the viewfinder image given by the Pentacon, who's focus scale also goes "... 2, 3, 5, 10, inf."

The Agfa shows the focus index mark to a metal fence beyond my garden and on my side of a car park is on the "0" of " 10", but the focus index mark of the FX2 says it is at "infinity".

The Agfa shows the houses that are just past the other side of the car park to be at not quite "infinity".

The only film I've put through the Agfa seems to be in reasonable focus, that is, if it's out a bit it could be my fault.

So I'd like to know if a 1970's Pentacon lens can be put on a 1950's Praktica camera without problems?

Any help would be much appreciated.

 

[xayraa33]

The 1970s Pentacon lens is M42 mount so it should fit the FX2 , just place the lens diaphragm switch to manual and it should work with no auto stop down aperture feature on the FX2.

Screw the lens on slowly to mount it in case it snags on something at first, like can happen on some late Fujica M42 cameras using non Fujinon M42 lenses.

If I had a Praktica FX2 body, I would mount my Helios 44-2 lens on it, totally manual stop down aperture and a great Zeiss Biotar copy to boot with wonderful swirly bokeh, very Petzval like in the image it produces.

 

[johnf04]

I've just tried a Mayer Optik Oreston electric lens on a Praktica FX3 - it focuses to infinity.

 

[tunalegs]

It really doesn't matter what the distance markings on the lens say - all that matters is what you see on the ground glass. If it is in focus on the ground glass, it will be in focus on the film (supposing nobody has messed with the mirror adjustment). The distance markings on the lens are basically decorative, since with an SLR focusing is done optically (rather than with a mechanical linkage of some sort).

 

[seany65]

Thanks for the replies.

@xayraa33: The FX2 can operate the auto aperture as it has the same sort of 'aperture pin pressing plate' that appears on the later cameras, and the aperture does stop down automatically when I fire the shutter. It just doesn't open up automatically after the shutter has closed, as the plate is still pressing on the pin because of my finger. Which took me a few seconds to realise.😱

@johnf04: How far away is is the nearest object that is in focus when the scale says "Infinity"?

@tunalegs: I understand that, but it seems really odd the me that the nearest object to me that is in focus when the lens is at "Infinty" should barely be beyond my garden, when on a lens with the same distance markings on a different camera (Super Silette) would have the nearest object in focus (when the lens is at "Infinity") beyond the other side of the car park.

 

[johnf04]

Seany - the most distant object I can see from my house - a line of trees on a hill about 2km away - is slightly out of focus with the Mayer lens set to infinity, so infinity is beyond that line of trees. How the trees would look on a negative, I don't know. This is all with the lens at f1.8. Smaller apertures will, of course, give more depth of field....according to the scale on the lens, with the lens set with the hyperfocal mark for f4 on infinity, everything from under 10M to infinity is in focus.

 

[xayraa33]

Thanks for the replies.

@xayraa33: The FX2 can operate the auto aperture as it has the same sort of 'aperture pin pressing plate' that appears on the later cameras, and the aperture does stop down automatically when I fire the shutter. It just doesn't open up automatically after the shutter has closed, as the plate is still pressing on the pin because of my finger. Which took me a few seconds to realise.😱

@johnf04: How far away is is the nearest object that is in focus when the scale says "Infinity"?

@tunalegs: I understand that, but it seems really odd the me that the nearest object to me that is in focus when the lens is at "Infinty" should barely be beyond my garden, when on a lens with the same distance markings on a different camera (Super Silette) would have the nearest object in focus (when the lens is at "Infinity") beyond the other side of the car park.

That is good to know.

I never owned a Praktica camera older than the L series (intro circa 1969 or 1970) and the one model before that used the cloth shutter ( I believe it was called the "Nova") seemed like poorly made junk, not much better than a Zenit SLR, in fact it seemed more fragile then a Zenit.

I am still a big fan of the L series Prakticas, my first decent camera was a Praktica LTL with a 50mm Tessar lens and it never let me down.

 

[johnf04]

That is good to know.

I never owned a Praktica camera older than the L series (intro circa 1969 or 1970) and the one model before that used the cloth shutter ( I believe it was called the "Nova") seemed like poorly made junk, not much better than a Zenit SLR, in fact it seemed more fragile then a Zenit.

I am still a big fan of the L series Prakiticas, my first decent camera was a Praktica LTL with a 50mm Tessar lens and it never let me down.

The original Prakticas looked similar to the Nova, but they are reputedly better engineered. I have an FX, an FX3, and a IV, and all 3 work fine, after some care and attention.

 

[xayraa33]

The original Prakticas looked similar to the Nova, but they are reputedly better engineered. I have an FX, an FX3, and a IV, and all 3 work fine, after some care and attention.

The Praktica Nova I examined many years ago seemed very flimsily made and not very reliable looking.

The L series Prakticas, with their vertical running metal bladed shutters have always been very reliable cameras for inexpensive SLRs.

I had more problems with big name brand top shelf Japanese made SLRs, despite their costly price, hi reputation and hype.

 

[seany65]

Seany - the most distant object I can see from my house - a line of trees on a hill about 2km away - is slightly out of focus with the Mayer lens set to infinity, so infinity is beyond that line of trees. How the trees would look on a negative, I don't know. This is all with the lens at f1.8. Smaller apertures will, of course, give more depth of field....according to the scale on the lens, with the lens set with the hyperfocal mark for f4 on infinity, everything from under 10M to infinity is in focus.

On the one hand:

Thanks for the info.

On the other:

That is rather puzzling. You're 'Infinity' with a Praktica FX3 and Mayer Optik Oreston Electric 50mm f1.8 is over 2km away, but my 'Infinity' with a Praktica FX2 and multicoated Pentacon (I'm led to believe it's a renamed Mayer Optik Oreston) 50mm f1.8 is less than 60 feet away!


The bit in my last post regarding the aperture not opening up automatically because my finger was still pressing on the shutter button:

I was wrong! Since then I've had another play with the fx2 and the aperture sometimes opens quite quickly and sometimes slowly even when my finger isn't on the shutter button. I took the lens off and pressed the stop-down pin with the lens at f11 and there were no problems with it opening up instantly. So it looks like the camera's pin-pushing plate isn't moving back quickly.

 

[tunalegs]

If there is an issue, it is likely with the lens, not the camera. In any event, comparing two completely different lenses is apples and oranges. If they're not the same focal length and speed.

In practical terms "infinity" for a 1.8/50 lens would be about 150-155 feet (depth of field carries the distance to "infinity"). But on ground glass, everything from about 76 feet would appear in focus when the lens is focused on something 150 feet away.

Again, the markings on the lens barrel are nominal, not actual. I have found more often, old lenses focus beyond infinity (glass too close to focal plane) due to wear on the mount or other mechanical issues. All that matters though is what you see on the ground glass. But not quite infinity can be an issue too.

 

[Nokton48]

My first 35mm camera was an FX3. I was in my teens.

 

[seany65]

@tunalegs: I paced out the distance from my house to the bit of the car park that is in focus when my pentacon 50mm f1.8 is at 'infinity'. It's less than 40 feet away. So if I've understood you tunalegs, mine really is focusing well short of infinity, as I suspected. It also seems johnf04's mayer oreston 50mm f1.8 lens is focusing beyond infinity.

@Nokton: Did you like it? Did you own it for long?

 

[retinax]

Both your lenses or bodies are out. Are you sure it's not the body? Is the minimum focusing distance something close to what's noted on the lens? I don't know that lens, but in my experience, the minimum is usually fairly accurate on the scale. An infinity for a fast lens definitelydoesnt start at 40 ft.
Does the Praktika FX2 have rubber padding on the stop upon which the mirror rests? If so, that's a suspect for getting the focus out of spec, see my thread in the repair forum.

 

[johnf04]

I rely on the image on the focusing screen of an SLR camera to confirm focus - I never use the focus scale on the lens.

 

[tunalegs]

Both your lenses or bodies are out. Are you sure it's not the body? Is the minimum focusing distance something close to what's noted on the lens? I don't know that lens, but in my experience, the minimum is usually fairly accurate on the scale. An infinity for a fast lens definitelydoesnt start at 40 ft.
Does the Praktika FX2 have rubber padding on the stop upon which the mirror rests? If so, that's a suspect for getting the focus out of spec, see my thread in the repair forum.

I don't have my FX to check, but it if it is like most old Prakticas, the mirror rests on a screw when in the down position, and this is used to adjust the ground glass focus. But this is rarely a problem area unless an unwitting tinkerer has messed with it.

 

[seany65]

@retinax: I've just set the lens to "1.1 feet" and held the camera so my pc screen is in focus and measured it with a measuring tape and it seems to be about right.

I've looked in the mirror box with the mirror up but I can't really see anything that the mirror rests on, but I don' really know what I'm looking for.

Edit: I've slowly wound on without the lens and I think I can see a small flat bit on the left (as I look) which points upwards when the mirror is up. This is on a slotted metal bit that has a short, small pin thing sticking into the gap from the body side of the slot. This pin seems to be part of the shutter assembly as when the shutter is pressed it moves forward making the slotted bit move and the stop-down pin pressure plate move. I can't see any foam or any way to adjust the height of the mirror when down. Of course there could be a blindingly obvious adjuster thing, but I don't know what I'm looking at.

Is there any significance in the fact there is a slight gap between the back of the body of the lens and the front of the body that the lens screws into?

Thanks to everyone for the help so far.