Repairs

Minolta SR-2 vs SR-1 comparison

Ever wondered what the real internal differences are between Minolta‘s first SLRs? First pic is of an SR-2 stripped of the ‘leather’, top and bottom plates off and my high-tech protection for the mirror box internals. The front plate with the mount and self-timer has not yet been removed.

SR-1 partially dismantled, but with the front mount section already off and the self-timer no longer fitted. Notice the difference between the castings and the ‘SRC’ in relief on the front next the mount: on the SR-2 there is not any such marking.

Here I’ll give a short look inside to still your curiosity (and mine!). So the SR-2 was the first in late 1958 and is put next to an SR-1 from around 1961, the ‘c’-version; the last one before the change was made to the aperture automatic. Two quite different mechanicals altogether, despite looking very similar, especially the bottom end, where the aperture and shutter actuation takes place.

Optically, the early and later models are relatively easy to tell apart if you know what to look for.. all the 1959 models have a much smaller eyepiece on the back, which is not so easy to spot at a glance. Easier to notice is the shutter-speed knob on the really early ones (the SR-1, too) that needed to be lifted to change the shutter-speed. On the top the scale is not quite evenly distributed, the 250, 500 and 1000 look evenly spaced, but they do have a little white line engraved to show the actual position needed to dial in those three speeds. From the front, the early dial is more conical in shape, wider at the bottom and smaller in diameter on the top than the later model (there is about a 2mm gap to the winder-lever). The later one, as you can see, is more straight from the side, and is as a result larger on top and has evenly spaced engravings up to 500, without the extra lines. The earliest SR-1 shutter-speed dial was similar in shape and size to the SE-2, missing the top speed, of course. There follows a series of photos showing some of the the external and the internal differences. Later I will show the internals of the first SR-1 model, but the differences between these two models are more obvious 🙂 The picture below shows the SRC on the casting rather more plainly.

There are, of course, lots of detail differences, that are too many to mention here, but worth mentioning and visible in this shot, is the mirror-fixing with screws, rather than the riveted-on mirror in the SR-2 🙂 There are also subtle differences between the self-timers, not only the front casting which they are mounted to: The one on the bottom or the right in this picture is off the SR-2 and fits behind the oblong brass plate. It also has an extra large flat screw (taken off on this picture below, but visible later once mounted) on the front side and the teeth on the spring-gear (the largest one) look like they have been ground or worn down… look closely at the pictures and you will see what I mean! The difference in the gear is plain to see.

SR-2 with the sellotape and here the differences in the gear-teeth are more obvious on this one. Note also that the backing plates are not the same, though the mechanisms are largely interchangeable:

Here the SR-2 self-timer is fitted and the large screw which is no longer on the later models at the front is rather obvious. The screw behind it on later ones is also significantly thicker (see pictures above).


Below shows the shutter-release mechanism in the base which is distributed half-half between topside and bottom. Most jamming can/must be sorted down here, the shutter speeds are controlled on topside. The lead-wires are for the flash synch and every camera seems to have them differently routed, depending on the wishes of the assembler! Here the difference in the size and shape of the tripod-mount is also visible, along with the completely different mechanical layout… few interchangeable parts here!

A look at the base plates shows that both are also different, as the mechanism on the SR-1 needs a cut-out at front (behind the lens-mount) to accommodate it – in preparation for the following model. At this stage, they both still have the long-travel aperture lever. the hole for the tripod-thread is also larger on the baseplate of the later body.

Well, that wraps it up for today. I will sort out the orientation of the pictures when I get home… I wrote this on my phone and it won’t let me do everything I want to!

Early Minolta Auto Rokkor-QE 1:3.5 f=100mm comparison

How interesting it is to get two lenses like this next to one another to compare, made only a few years apart. The two in question are probably the most underestimated in Minolta’s lineup for very many years and still perform very well even against modern lenses at 43MP… These are just as sharp, if not better, certainly in the edge resolution than the 2.5 and the 100mm 2.0 that is in high demand (only because it is rare, not for its performance).  I might  go into that in more detail later, around when I release a test of the 24mm VFC 2.8, how to use it to do what it does, what VFC is actually useful for and some ideas about lens-testing methods in general, including inherent non-flat focus field (curvature) in lenses in general – which is always taken as given.

So, to start off with, looking at the fronts, I have two 100mm, 3.5 lenses from Minolta, built only a few years apart. The early one, an ARI, ser 1201946. Looking at many lenses, I might conclude that this is a lens of series code 12, number 01946 produced? There are many theories about the Minolta serial numbers and any of them could be right or wrong in the absence of any proof 🙂 Made somewhere in 1959-60. Whatever, the front engraving is as expected. The second one, an ARII with the serial 1213805  is missing the expected ‘Lens made in Japan’ engraving on the front, so is one of the earlier ones of this series produced.

If you look closely, you will also see that the front lens is more deeply recessed into the front on the later model.

Now turning to the back, we can see more differences: ARI-typical closed ring and screwed-on aperture link, ARII-typical linkage poking out of a slot in the back and, of course the stop-down lever now necessary after the automatic diaphragm was introduced on the SR-1 (4th model) and the second run of the SR-3, meaning that after the exposure, the aperture opened immediately. Yes, the knurled ring is missing on the stop-down lever, but will be added when I get one in 🙂

Also note the relative position of the rear lens elements, both focussed at infinity in this picture.

Here shown at an angle to emphasise the differences between the two, the ARI sits considerably deeper, which makes me wonder about them being the same formula for lenses and groupings…

Now both are focussed as close as can be done, 1.2m and 4ft, ARI Stil much deeper.

Interesting how both are so different internally, obvious from the back. Look how the shrouding goes right in to cover the full depth of the travel of the rear element here on the ARII…

… Whereby here the thread of the focus ring is exposed when wound to close-focus!

Now take a look at the difference in size between them: First the length is obvious. The added length of the later one (here on the left) seems to have mostly been added on to the front of the focus-ring :). Just also take note of the difference in the thickness of the focus-ring (which is why there is a bigger step in the front of the barrel of the earlier lens).

Here the nice even engravings are obvious (except for the ‘4’ on the ARI, missing on the later one altogether) as are the absence of engraved dots indicating half-stop clicks. Nice unblemished ‘Minolta green’ on the ft. engravings!

Same again at infinity, same difference in length (3mm)

Now the other side and here the white ‘Lens made in Japan’ on the ARII  and the simple ‘Japan’ in black on the early lens.

The big change for the ARII was not only the rear actuation of the aperture but in the iris itself, which had to be lighter and better balanced to react quickly to shut down and reopen adequately for the new shutter action on the now modernised cameras. Take a look down the barrel and the differences are obvious in the different shape of the iris itself. Still 8 blades, but very differently arranged, ‘back to front’, so to speak.

At f8 both look pretty much the same, though the earlier one is just a tad ’rounder’, but not enough to make any difference to the bokeh.

One surprise yet, is that the earlier, shorter by 3mm and narrower by 2mm in diameter lens, is heavier (402g against 382g) than the later one! Remember the difference in the thickness of the focussing-ring-casting?

The extra overall diameter of the later lens does have one potentially slightly annoying drawback… The DK57KD lenshood designed for it no longer fits on the lens backwards as it did on the early lens, so extra storage has to be found for it. Not really anything in the least important, but nonetheless worth mentioning.

Next up? Not sure yet, as I go into hospital on Tuesday to operate on my right shoulder again 🙁 I also have to make sure that the car is back on its wheels by then…

Minolta AES Viewfinder repair

A Minolta AES viewfinder, rather desirable if not so dented! If it were only the dent, that would not be so bad, but usually other things have also suffered as a result of the bash that caused the dent in the first place. Let’s have a closer look ‘under the bonnet’…

OK, this kind of space is all you need, so there is no excuse for not having a go yourself! Yes, I could have cleaned up before the photo, but it just goes to show the general arrangement. There are tools and materials for all sorts of tinkering and yes, while I’m actually working, there is more space around the working area as such.

So, having taken the top off (easily enough done on this) it can be seen that the dent wasn’t all that was wrong: the mirror and lens which allow the numbers on the aperture-ring to show in the finder are gone! The thin red outline shows the aperture-link in the ‘normal’ position without a lens in place – more of that in a minute.

Here a clearer view from the top and at the back, the long mirror for the shutter-speed display is also missing, but thankfully had dropped inside and could be reduced in its proper place 🙂

Here even more obvious, the REASON for what it missing and how it lines up with the lens ring. All I needed was to find a mirror and lens in my goodies-box and the case was solved. If I’m honest, a piece of 1mm thick polished Stainless would replace any missing mirror if you don’t have an original handy (the mirroring on these is on the FRONT surface, not on the back like a household mirror). For the lens, any one cut out of another Minolta SLR will do, even if you do have to trim it to size, it will do the same job since the distances of all finders from the lens-ring are very similar.

Below is a very different problem which afflicts almost every Minolta AES and AE viewfinder (not the others, since they don’t have metering). When the finder is removed, before replacing it the aperture ring follower has to be ‘cocked’, so that it snaps into the right place, should a lens be on the camera (in use that would be the norm). However, these cameras are a few years old now and have gone through the hands of many people, some salespersons, some of them photographers, some of them collectors and some of them without any knowledge of the workings of such things, from any of the above. This design was intended to save the camera being damaged by replacing the viewfinder with force and perhaps bending the linkages in the process. If you try to replace it ‘just like that’, you will notice that it doesn’t sit quite right at the front. Unfortunately, the uninitiated will just press harder until it clicks in place – the result of which can be seen below! The arrow on the right shows the follower correctly cocked on the right hand side and in the middle the release lever to reset it.

See the flat on the release lever? That comes from pushing the viewfinder down at the front until it clicks into place, as this lever, when the follower is not cocked, protrudes a bit as a reminder… of cocked properly, it retracts out of the way, of course.

So, who cares if it has a flat on it? Well, the user, actually, because having read the handbook and having cocked the lever properly, when the viewfinder goes back on, the follower doesn’t return to it’s proper place again and the metering is all haywire as a result!

The cure is to build up the front of the camera-frame, where the lever ‘lands’ with a strip of tape or whatever you have handy that it just thick enough to ‘trip’ the lever and something that does not permanently fix to the camera or damage it. Here I took a strip of cardboard and some insulating tape to fix it. It’s cheap and easy, works fine and doesn’t do any damage. Win-win! Don’t worry about light-leaks up here, the well is deep enough to shield any light that might come in – don’t forget, the eyepiece lets a lot more light into the prism.

Just a reminder of how the top looked like before. Suffice to say, I did a bit of persuasion with an appropriate piece of wood and repaired the dent without needing any touching up of the paint, which sticks like shit to an army blanket (ask anyone who has ever been a soldier).

You can’t see it here, but once the mirrors etc. have been replaced, the next step is re-assembly, which is pretty straightforward. Working from right to left in reverse order of disassembly.

 

 

 

 

Finally assembled with ISO 160 showing here and ready to go! All adjustments and cross-checks of the mechanics and metering were also done while the lid was off, of course.

The repair to the top is acceptable, I think.

Next up for discussion? The comparison of two very early 100mm F3.5 lenses an AR1 and an AR2 (by the way, one of Minoltas best-kept secrets, an inexplicably underrated razor-sharp lens). Construction, mount, iris, size and weight are different… Though they look very similar, until you have them up close 🙂

 

P-39 Airacobra Restoration

For those interested in Aviation, warbirds and the modelling of the aforementioned, here are a few pictures I took while working on the Airacobra in Australia at the ‘Classic Jets’ Museum at Parafield Airport in South Australia. Actually the busiest airport in the whole of Australia, mainly due to it’s being the home of a number of flying schools, including one used for flight training of quite a few large airlines, Parafield is also home to a number of classic ‘fly-ins’ and the Museum, of course, where almost all the work is done by volunteers. I worked on a few aircraft, but this is the one I spent most time working on.

Here a couple of views inside the workshop hangar.

Gives a general idea of things. The RAAF Airacobra in question in the background. Here are a few pics of the instruments and cockpit as it goes together:

And here a closer view of few of some of the individual instruments:

 

Lots of engine-details for the modelling enthusiast. These pictures are big, just click on them for larger, click again for super-size! Not much chance to see one of these up close, though used for many aircraft. Carburettor at the top and induction charger below it, the (shiny!) induction manifold on the top of the engine between the ‘V’. The pic on the top left shows it in the initial stages of build. As we progress it gets ‘smarter’ 🙂

  

The pictures below are of the other, running, engine in the public hangar which was originally out of a P40, which is why it has the reduction gear on the front, unlike the P39, which had it installed just behing the propeller and spinner, of course, fed by the propshaft which ran between the pilot;s legs… Makes quite a racket in the hangar and we converted it to run on Gas, as when on Avgas, the open carburettor spat flames to the roof on a cold start… 🙂

Here a few official pictures of the engine from Allinson themselves:

   

 

Here some detail pictures of the armament and ammo-boxes being built for up front. Ours didn’t have guns in the wings. Two machine-guns synchronised through the prop and a cannon shooting through the centre of the spinner. Convenient that the reduction gearbox, mounted on the front-most bulkhead had a hollow spindle! Drive from the prop-shaft enters at the bottom of the reduction-gear casting and the actual drive to the prop is a larger gear above it, allowing plenty of space for the ‘shooter’.

The rearmost, larger but narrower, munitions-boxes are for the machine-guns, the wider curved rails are for the larger (and fewer) cannon-shells:

Here how it is set up in the ‘plane still in primer:

 

Not in primer anymore and fitted up in TG*R !

And finally finished and mounted : (this one in Victoria, another A/C, another museum) The red box is a battery! More weight up front, critical for the distribution of weight and balance necessary to fly the aircraft. The mid-engine made it more maneuverable, but more sensitive to weight distribution. Cannon-shells fitted, MC Ammo-boxes not yet.

Here a few pics of some work I did on a pair of rearmost wing-fillets. We had one original on loan to copy and I had to make up left and right copies, hence the reversible template. The finished items were made slightly large all round for final ‘fitting’:

 

Here the aircraft ready and finished for the Parafield Airport Vintage Fly-In in 2009

Renault Megane/Scenic RX4 gearbox swap 1

Let’s start at the very beginning: This is a Right-hand-Drive, 2001 Renault Megane Scenic RX4 2litre (permanent 4WD), bought in England, now registered in Germany and being used (when it runs again!) in Ukraine. No, this is not a new model that is hovering in the air, I have already taken the wheels off! That is a starting point for removing the gearbox, which involves taking the whole of the front sub-frame with the lower wishbones and the steering-box (rack and pinion) attached. The engine has to remain inside, as undisturbed as possible and the steering has to be locked in the dead-ahead position, also because of the airbag sensors. The steering-wheel gets locked first:

The picture above shows all you have to do – then loosen the wheel-nuts and the large wheel-bearing/drive-shaft nut on each wheel (Both R/H thread) with the brakes on for obvious reasons. Then the car can be jacked up and put on blocks and the wheels can be taken off.

From under the bonnet, the first thing that is useful at this stage is the removal of the battery and battery-box, so that you can get at the gearbox and its mount from the topside:

A nice open space with the gearbox-mount showing (bottom centre to the right). Then it’s back to our right, to work on the left-hand-side under the wheel-arch, as there is a fair amount to be done before we are finished.

At this stage it is worth mentioning that there will be a load of screws and nuts that will have to be taken off. Where it is sensible or convenient, put the screws or nuts back where they belong after taking off the bits that they attach. That way, you won’t lose anything or mix them up. For those bits, and there will be many, for which that is not possible, a large piece of card or a cardboard box is very useful to store the screws and ANNOTATE where they belong. Here I have just begun:

It will, of course, fill up as time goes on… The beauty of the box is that it does not take up so much space, that the screws can be stuck through it and grouped on different sides and, most importantly, that we all have at least one lying around somewhere just begging to be used in this way!

I’ll be updating this on a regular basis as I progress. Due to a shoulder injury, I have to take my time and try not to overdo things, so I am taking it slowly, so as not to do any more damage than I have already done! If you like this sort of thing – and I hope that it could even be useful to see how it is done – come back later and see how it all comes together!

Vintage 135mm f2.8 with sticky Aperture Blades

This is one of the rarest lenses that I have had the pleasure to work on: a 1958 Minolta Auto Tele Rokkor with yellow LV engravings, apparently less than 2,000 ever made, to coincide with the release of the new SR2, Minolta’s first SLR in a long line, with loads of new features. I digress. The lens is a 7-lens construction and actually very good even by today’s standards. Not as clinically sharp as the much later 5- and 4-lensers, but still very nice.

This one is outside very pretty, the problem with it is that the iris had oil on it, making it rather sluggish. Not SO much of a problem, but definitely needed looking at to use it regularly.

Actually quite easy to dismantle (I never had one of these in my hands yet!) and the solution to the problem, largely due to the iris assembly being in the centre of the lens, was also simple enough.

There are a few things that can be done incorrectly regarding the order of dismantling – guess how I know – so it would be wise to stick to the order given as follows:

1: Undo the three black screws round the aperture ring. The one at this spot is the longest and belongs back here on reassembly. Inside the ring there are tiny balls that detent into the slots on the barrel (as can be seen on the picture) to give those snappy click-stops and to smooth the turning of the ring. Don’t lose them! A spot of grease will hold them on place for reassembly.

2) Remove the three silver screws around the barrel, which then can be easily pulled off the front.

3) The front lens element needs to be taken off next to access the blades. Do this CAREFULLY and with the PROPER TOOL, otherwise you risk scratching or damaging the ring, or MUCH WORSE, the lens, which if it is in good nick, will be almost impossible to replace in a hurry. If you have undone the grub screws by accident due to impatience or curiosity, you will now reap the reward by having a pile of separate (thankfully only six) aperture blades rattling around the inside! Oh Joy! Never mind. The construction is so simple and needs no explaining here, apart from to mention that a steady hand and a pair of nice pointy tweezers do come in handy 🙂

At this stage, you should be able to see the blades and what condition they are in. If they are only oily, then no further dismantling is necessary and they can simply be washed with a paintbrush dipped in some Methylated spirits or lighter fuel. While doing so, you can wiggle the stop-down lever thingy, to make the blades move open and closed, so they get a good rinsing. Be careful not to use too much meths and splash the rear lens from the inside. If you did, then you need to disassemble a bit more from the back (see further down) and wipe the lens properly using a moist lint-free cloth.

READ THIS FIRST BEFORE GOING ANY FURTHER: If you haven’t already done so, turn the whole assembly so that you are looking down the front at the blades. NOW, AFTER you have marked the position of the outside ring in the barrel, you can at last undo the grub screws and take out the inner ring holding the blades in. When you undo the grub screws, the outside ring could rotate, so mark it BEFORE you undo even one screw. The position of the outside of the ring is critical to the iris opening and therefore the exposure, so please don’t forget this. Dead centre in this picture, you can see the little silver ball that detents the aperture ring – lose it at your peril!

Now you can remove the parts carefully with preferably copper tweezers (make your own!) and clean and inspect properly, prior to reassembly – with cotton gloves on, please: fingerprints on the blades are so unprofessional!

OK, so yours, like mine were not only oily, but one was a bit bent? I can only assume that someone else with good intentions tried to fix it years ago and oiled them for good measure, but was not very light handed with reassembly. It’s always only ONE blade that gets bent, the last one, since it has to be tucked under rest that are already in place – a bit like Escher’s endless staircase! You know how to do it, if you have ever closed a cardboard box by overlapping the ears on the lid: Same principle, if a bit smaller. It will be obvious when you get that far. Not much is needed to make the blades ‘sluggish’ due to the added friction and no amount of oil helps (it in fact makes it worse, as we now know).

This is what they look like when reassembled through the replaced front lens. Reassembly is simply the reverse of the dismantling job, not forgetting to place the long screw where it belongs. In this picture, you can just see the nick on the top screw slot on the lens-ring, where I slipped despite having the correct tool – the lens was VERY tight. I suspect that it was secured with Loctite or similar.

Here a bit closer, in focus and nice and clean!

So, just because we are curious and maybe because we spilled meths on the rear element, or to get at the mechanism and to be able to not only disassemble but also adjust, the rear end has to be taken off. There is actually no reason to NEED to disassemble further, as everything for the aperture blades can be accessed from the front, but since we got this far, here goes:

4) Remove the rear mount (4 screws)

5) Unscrew the tube and rectangular hole (!) around the rear lens and put them out of  harm’s way.

6) Now you can safely unwind the focus-ring and PLEASE note and mark the spot where it comes off the thread to realign it when reassembling. Time consuming if you forget and have to find the right spot by trial and error – there are lots of possible ways to start the thread (8, actually). Once off and with the simple barrel at the front removed (3 screws), this is what it looks like:

The red arrow shows where the end of the spring belongs when the rear end is reassembled – tucked INSIDE the front tube/barrel when replaced!

In the above picture, the stop-down-knob is around the back, hidden by the rear lens element in this shot, but this shows the arrangement of the spring on the lever which actually causes the iris to open and close. Its function will be obvious when you actually have it in your hand and actuate the stop-down. It also shows the rear element which can simply be unscrewed to clean.

Reassembly:

7) Put the blades back together carefully (especially the last one), arranging firstly the blades the only way that they fit – yes, there is only one way! – and then placing the front ring over them and aligning the pins on the blades in the slots/holes provided.

8) Line up the outer ring with the mark you made OR look for the bright-spots/ dents in the aluminium where the grub-screws originally were. You might have to turn the ring once or twice, since there are three possible positions 🙂 Replace the grub-screws and make sure that they pinch not too tight, but hold everything in place.

9) Now you can test the freedom of the blades by twiddling the stop-down-knob.

10) If all is OK, replace the front end complete with aperture-ring and lens as a reversal of the disassembly. If not, try again!

11) Fix the screw-thread for the focus in place and the front tube/barrel, not forgetting to tuck the little spring inside by the stop-down-thingy before securing the 3 screws.

12) Position the outer focus barrel to screw onto the inner thread in the right place to enable to focus full length without fouling the stop-down-lever (you marked the position, remember?). If not, it’s trial and error time, looking at the bottom of the thread-travel for the stop-down-button to sit where the swept cutout is in the front edge of the barrel.

13) Once you have managed that, replace the rest of the parts around the rear lens and the mount and you are done! (Oh, and you’re a HERO, too! Have a beer/coffee/tea/wine/lemonade/schnapps!)

Actually a lot simpler than it was to describe, so have a go. You can pick up a similar one of these lenses for not much more than a tenner (if you find one with the yellow numbers engraved, BUY IT, KEEP IT!) to practice on, so don’t be afraid. What I haven’t shown in pictures here is self explanatory when you are doing it ‘live’, so don’t be intimidated.

Have fun!