Wednesday 22 May 2013

Legacy lens adapters

In the course of collecting these old camera, I have also collected a number of old lenses, some of which are very good.

My Olympus OM10 camera has a Zuiko 50mm, f1.8 lens which six elements in five groups and a Vivitar zoom lens (75-205mm) which has a very good reputation.  I also have another Vivitar zoom lens (20-200mm) which doesn't have quite the same reputation as the other Vivitar but performs very well nonetheless.

My Zenit E came with the famous Helios-44 which is a superb copy of the Carl Zeiss Biotar (six elements in four groups) and my Praktica LT3 came with a Meyer Optiks Domiplan which is a triplet - so not in the Zuiko or Helios-44 league but a good performer when stopped down.

When thinking about a 50mm prime lens for my Canon DSLR, it occurred to me that I already had several good  50mm prime lenses and was there any point in buying another?

With this thought in mind, I looked into buying an adapter so I could use one of my old prime lenses (it would seem that these  have morphed into legacy lenses while i wasn't looking).

First, I looked into buying an adapter for my Olympus OM lenses.   There are a number of these available and they are quite cheap.  These range from simple metal rings with an OM female bayonet on one side and an EF male bayonet on the other - these cost £2 to £3 each - to more complex adapters with electrical contacts and a chip.  this is then one I bought and it cost me £12.99 including postage.

The adapter ring is very well made out of brass which has been chrome plated.  The EF bayonet fits smoothly into the Canon digital camera and, similarly, the Olympus lenses fit smoothly into the female side of the adapter.

When the lens, adapter and camera are all fitted together, the result is snug and secure.  There is no significant play, even with the heavy and long Vivitar zoom.    The electrical contacts make contact and the camera recognises the adapter.

The point of the contacts and chip is so that the focal length and aperture of the lens can be stored in the Exif data of the resulting digital file.  th achieve this it is necessary to programme the chip on the adapter.  t5rhis is actually quite easy - but not simple as it involves quite a few steps. Once the adapter is programmed for a particular lens, it is necessary to manually set the aperture on the lens and then separately set the aperture on the camera - this aperture is then stored in the Exif data.

If accurate Exif data is important to you, this process will be worthwhile (and will be necessary to repeat for each lens you use with the adapter) but I routinely ignore Exif data so I do not bother with the process.  If, like me, you want to be simple, you just focus the lens, set the aperture (you need the camera to be in Av mode) and let the camera select the shutter speed.

The adapter works well so long as you remember the lens is entirely manual - you need to focus and set the aperture for each shot.  Given that I use fully manual cameras a lot of the time, this should be second nature, but as soon as I pick up my digital DSLR I forget to worry about focus and exposure.

My next adapter is for M42 lenses (also known as Pentax fit, although developed by Zeiss Ikon in Dresden in the 1940s).

I had two M42 lenses when I bought this adapter - the Helios-44 Biotar copy and the Meyer-Optik Domiplan.  Both screwed nicely into the adapter but there is a problem with the Domiplan lens in that it is an automatic lens - there is a pin on the lens that must be depressed by the camera just before the shutter is released in order to close the diaphragm. The adapter leaves this pin alone so the Domiplan can only be used wide open.  

Actually, while trying to get this lens to work with the adapter, I noticed that the lens has a significant fungal growth on one of the inner glass surfaces.  This lens is now in the dustbin!

The Helios-44 lens worked well.  This adapter is a simple aluminium disc with no contacts or chip sop there is no need to set anything up.  The same working method as with the OM adapter is required - focus with the lens diaphragm wide open, stop down the lens to the required aperture and let the camera sort out the shutter speed.  As there are no contacts, no lens details are stored in the Exif data.

Both adapters are easy to use and work well.  Not being interested in the Exif data, I would have been better off buying a cheaper and simpler OM adapter, but the one I did buy was certainly cheap enough.

Theoretically, as the camera is metering the light through the lens it should give the right exposure regardless of the lens used.  It has been suggested to me that TTL meters do not cope well at low light levels so will give poor exposure at small apertures.  I have not found that.  Initially, using the OM adapter with the Zuiko 50mm lens, the camera consistently overexposed at all apertures with the highlights clipping in all photographs.  The cause of this is that I was not setting the aperture on the camera as well as on the lens so the metering system assumed - incorrectly - that the lens would shut down when I pressed the shutter release.

Repeating my OM test exposures with the camera set to f1.8, the exposures were fine with the histograms coming up well to the left with no clipping.  This setting of the aperture on the camera as well as on the lens is only a problem with chipped adapters - or you can do as I now will and keep the camera set to its smallest aperture.

When using the Helios-44 with its simple adapter, the exposure histograms were well to the left and without any clipping so giving usable photographs.  This is regardless of the aperture set on the lens.  With this adapter, it is not possible to set an aperture on the camera as the absence of contacts makes the camera default to f00

Test pictures:  first, the same scene at different apertures (after these, a focal plane test).

OM adapter with a Zuiko 50mm, f1.8 lens.

 
aperture f16
aperture f5.6

aperture f1.8
M42 adapter with Helios-44 58mm, f2 lens.

aperture f16

aperture f56.
aperture f2

Focal plane test:  in order to focus on infinity, it is necessary that the focal node of the lens is the right distance from the film/sensor.  For a 50mm lens, this distance is 50mm (in some designs, the node might be in front of the physical lens).  This distance is split in two.  The first part is the film/sensor to mount distance (obviously, this never changes) and the second part is the mount to node distance.  This second part is susceptible to being changed by the adapter.  If the mount is too thin, the lens will still focus on infinity but its near focus point will be further away than intended.  If the mount is too thick, the lens will focus on nearer objects ok but will not be able to focus on infinity.  It is this last that I want to check.  I am not too bothered if I cannot focus on an object two feet away but I am very bothered about not being able to focus on infinity.  To be clear, I had better define 'infinity' - for this purpose, it is anything over 50metres away.

First the OM adapter.  The first picture is a standard scene in Lincoln.  The second picture is an enlarged crop from the centre to critically check the focus.



detail from the centre

Now the M42 adapter.


detail from the centre
You can see by comparing the two details that the Zuiko is performing better at a distance.  I think I can safely say that this lens adapter is correctly placing the lens in the mount.  The detail from the Helios-44 photograph is a lot less clear - but I cannot say if it is down to the adapter or the lens performance.  It is certainly good enough to use.


Tuesday 14 May 2013

Voigtlander Vito I




Voigtlander Vito
I have used as a title for this article 'Vito I' but the camera is actually the Vito - Voigtlander were not aware of the forthcoming Vito range at this point.  I already have an article on the Vito II here and much in that article applies here as well.  The two cameras are very similar as you might expect.  The lens serial number says the lens was made in 1945 which is also the probable date of manufacture - one of the first cameras to be made in war-ravished Germany.

lens: Skopar
focal length: 50mm
apertures: 3.5 to 16
focus range: 1 metre to infinity
lens fitting: fixed
shutter: Prontor II
speeds:  1/5 to 1/200
flash: synchronised for bulbs
film size:  35mm

The camera is a folder and nicely compact when closed.  It measures 120mm by 70mm by 40mm closed and 120mm by 70mm by 80mm when open.  Closed, it nicely fits in a trouser or jacket pocket.  The only distinguishing mark on the closed camera is an ornate 'V' on the lens door and a fairly indistinct 'Voigtlander' is embossed on the leatherette on the back together with the model name 'Vito'.  There is also the country of origin embossed on the back which is 'Germany'.  As Germany is the English name for the country this indicates that it is an official import.  Strangely, for an official import, the focussing scale is in metres rather than feet, suggesting that Voigtlander were not fully geared up for export in 1945.
Vito top view

The top plate is very uncluttered.  There is a knurled ring at either end.  The right-hand ring is the film advance and the left-hand ring the rewind.  In the centre of the top plate is a very small, reverse Galilean viewfinder.  The eyepiece is only 5mm by 2.5mm.  The image seen is roughly 0.5 times life size.  This is very small compared to more modern viewfinders but it is more than adequate.  There is also a frame counter which counts up from one.  There is no accessory shoe (flash shoe) although one was available as an extra and fitted over the viewfinder.

On the rear of the top plate is a lever.  In the normal position (down) the film advance will only advance one frame.  When raised, the film can be advanced as far as you want and can be rewound.  The toothed wheel which is exposed by raising the this lever can be used to set the frame number to one.

The underside of the camera contains three items.  Close to the centre is a 3/8 Whitworth tripod boss.  A 1/4 Whitworth insert would have been available for the more usual tripod size.  There is also a button to release the lens door.  This is spring loaded and partially opens the door.  This door never sprung open under its own steam and from new they needed the user to fully open the door once it was released.

The third item on the base is two 'feet'.  These are little more than pins.  A third foot is on the lens door giving three feet altogether which allow the camera to sit stably on a flat surface.  This is primarily intended to allow group portraits using the self-timer.

When the door is opened, the lens comes forward on its bellows and locks in place.  The shutter release is on the top edge of the door together with a threaded socket for a standard cable release.
Vito - lens door open

The lens is a Skopar f3.5, 50mm lens.  This is the original version of the famous Color-Skopar and is not calculated for colour film.  However, it is intended for panchromatic film so should perform well with colour film.  See the test pictures below for details.  This lens focusses from one metre to infinity and has Voigtlander's usual two Happy Snapper settings - a circle for the hyperfocal distance at f5.6 (approximately five metres to infinity at f5.6 or 2.5 metres to infinity at f16) and a triangle which gives a focus range of 2.5 metres to five metres at f5.6 (ideal for groups).  This lens has no blue/purple tinge and so cannot have been coated as was normal post-WWII and so will be liable to flare.

The shutter is a Prontor II (which is the same as a Klio on a Zeiss Ikon camera) which is a pre-war design and was soon to be updated to the Prontor S.  This Prontor II has a PC connector and so must be synchronised for flash - I would suspect for fast flash bulbs (F: sync) but there is no indication of this on the shutter housing (my Vito II has a Pronto shutter and this is specifically marked F:).  Shutter speeds are 1/5, 1/10, 1/25, 1/50, 1/100 and 1/200 which is more than adequate.  The bezel of the shutter housing bears the shutter name - Prontor II - Gauthier's maker logo and Voigtlander's script name.
Vito - lens and shutter

There is a self-timer lever which we are always told not to use on old cameras to prevent damage to the shutter.  It barely works on this camera, taking 16 seconds to actuate the shutter and then needing a little help from my finger over the last two or three seconds.

This shutter needs cocking before use - the cocking lever moves from left to right and up to cock the shutter.

Apertures available are f3.5 to f16.  As there are no click-stops, you can set an intermediate value if you want to.  The only other item of note on the shutter assembly is a stellate lever.  I am not entirely sure what this is for but I suspect it was to do with the hinged yellow filter that the early Vitos were fitted with.  The shutter bezel has three screws in it that are also part of the filter assembly.  When production had used up the store of pre-war parts, the bezel no longer had these three screws.

Inside is where this camera gets interesting.  The design dates from 1939 and the camera was intended to use unperforated 35mm film.  As the film was unperforated, there are no sprockets in the camera.  Instead, the camera judges the film framing with a feeler roller as in an up-market 120 camera. I have been led to believe  by the Interweb that this camera was designed to use Kodak's 828 film which is unperforated 35 mm film with backing paper like 120 film. As the film came on a spool with backing paper (again, as with 120 film) there are springs fitted to the film chambers to keep the film tight on the spools. Actually, looking at the camera, there is no reason why the camera should not have used unperforated 35 mm film in a reloadable cassette - Leica and Zeiss Ikon made such cassettes for their 35 mm cameras. I have never seen a 1939 Vito - this would tells us immediately whether the camera used 828 film or a loadable cassette as 828 film would require a red window on the back of the camera to allow the user to see at least the first frame number. There is no red window on my 1945 Vito - was there one on the 1939 version? When production restarted in 1945, Voigtlander decided to modify the camera for modern perforated 35mm film (135 format).  The only real change is that the film gate (the rectangular opening that lets the light hit the film in the correct place) is reduced to 24mm by 36mm (originally it had been 30mm by 40mm).

The film take up chamber will take the standard spool from a 35mm cassette as a take-up spool or an empty cassette can be fitted which means that when the film is finished you can open the back and cut the film with the exposed part already in a cassette.

These pictures were taken with this camera on Agfa Vista plus 200 ISO colour negative film (details here): (the black wedge would seem to be a scanning artifact.  The frames all overlap about 1-2 mm and this overlap is also wedge shaped)

Cowslip close-up (from one metre away)

Lincoln Broadgate

Lincoln High Street

Lincoln Pottergate

Wednesday 1 May 2013

Bencini Comet 44

Comet 44, front view

This is a later development of the Comet line.  I also have a Comet S which is a half-frame camera.  This Comet is a full-frame camera.  It is a well designed and well made cheap camera.  In that respect it compares well with the Japanese Meisupii and Halina ranges which are not that well made. This is a 127 camera which takes square pictures 4 x 4 cm (hence the '44' in the name?).

The main body is made from cast aluminium alloy with an anodised finish.  Internally, there are some aluminium plates as well.  The back, which is also aluminium, comes away entirely to load the film.

The lens is marked as Bencini Acromatic 5.5 cm, f8.  The lens is actually a simple single meniscus lens.  In this camera, the lens is loose because someone has attempted to dismantle the camera.  Unfortunately, it is not possible to tighten the lens without a special tool which I do not have.

The shutter is a simple shutter with two speeds - 1/100 and 1/50 - and includes flash synchronisation.  The flash sync. mechanism is rather crude and is unlikely to work with electronic flash.

On the top plate on the left is the spool release to allow the insertion of a new roll of film - this is pulled up while putting the film in or taking the used spool out.  It is spring loaded to keep the film securely in place.
Comet 44, top view

Next to the spool release is an accessory shoe with a large chrome spring.  Next to this is the shutter release.  This is nicely placed for the index finger.  The last item on the top plate is a knurled chrome knob to advance the film.  This also pulls up to allow the insertion of an empty spool and removal of the finished film.

In the centre of the top is a bright yellow viewfinder.  That is, it looks yellow until you use it but looking through it, it is purple.  As is usual with roll film cameras, there is a red window on the back to allow you to see the frame numbers when you are winding the film on.