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I came across a lens with a built-in hood expansion and contraction mechanism that I was thinking about, so I obtained it, maintained it, and took a test shot.The lens I purchased for double digits had a defect on one side of the cam roller, and there was a problem. I got the same thing at a bargain price, Sigma Zoom-θIII 28~84mm/f3.5~4.5.
I can't find any good reports or reviews on the website. I assembled it with the Minolta MD mount as a matter of fact, but the case of the zooming module is glued fixed with a screw thread, and it took me some hard time to disassemble it. After that, there were failures such as reversing the front and rear of the lens alignment, and it took a long time, but it was ready to use.In the live action, if even a little oblique light hits, the poor backlight characteristics are exposed.
Covering the inside of the hood with a brushed non-reflective cloth and try again with some hope to over it come.
It has characteristics that reflect the romance of the Showa era, and it can be enjoyed depending on how it is used.

Teledyne Hanau Pneumatic oil flask press machine for dental laboratory use was repaired last night, that has been in out of order for few weeks because of oil leak, only center bolt thread was utilized for temporal convenience losing original physical performance. This kind of machinery is easily changed into void if oil pressure was lost. The performance of a small nitrile rubber oil ring must be destroyed after some interval of use, as long as 20 years!

Replacing 2 pieces of tiny O shape rubber lings could solved the problem, but full overhaul was required in order to check any crogged material, to know it's oil garally and also to know bubble removing plug. As the last step of this kind of oil pressure circuitry, removing bubble is indispensable even if it is small amount, also as the same as brake oil caliper control in a car.

It is often the case that an original performance is lost just because of rubber sealing in an expensive factory machinery, same is said on our vehicles. We should continue our factory machineries once obtained until all the performance in every portion are lost.

Warm Sunlight in early Summer brings blooming energy on every flowers as usual. All the Botanical Gardens would be crowded from now without doubt. I have a planning to visit Suminoe Public Park next week but on a weekday. The better weather condition with a bit cloudy is desirable?

Lenses for the SLR135 that can also be applied for large formats are obtained at extremely low prices. According to the time pass, old second-handed item are scattered in the Web market. If you give up on the easy-to-use functions such as autofocus and auto-iris, and if you have the know-how to disassemble and to clean mould. Every time I try to repair a new object, it gives me some fantastic and exited moment. Because I can feel and understand the concept of the industrial designing engineer at that time. Whenever I disassemble lens module, I make it a rule to apply so to speak "Lens Edge Coating" as needed. Not only removing mould dirt but preventing unnecessary irregular internal reflections leading to increasing picture contrast. Trifle modification like this would be great if it is piled.

Precise toy repairs are a good way to kill time for geriatric.

Lightweight hand holding 300mm lens was obtained the other day, from Yahoo auction as usual at some reasonable price, 500 yen. The latest Minolta MD 300mm/f4.5 with only 700gr was the reason to obtain, the external condition was great like new but with mould invasion on every surface inside leading to inevitable full disassembling maintenance. Probably, this is why the seller set the cheapest price.

Front and rear elements were easy to access on ordinary Minolta production, but the focusing system was different from those in MC, not all group extension but internal middle group complicated movement, so the lens length does not change while focusing.

2 lenses were so constructed to move independently supported by cam and cam follower design, ordinary common sense shows 3 ponts support to keep the surface flat, but this one was done with only 2 point support, this extraordinary designing was achieved by precision machining technology just like floating piston and cylinder relationship in a combustion motor----2 positions support means piston pin.

For example, former model MC 300mm/f4.5 HF with all group extension system weighs 1,100gr. It's seldom to go out with me because of it's innate gravity though it has good performance.

Anyway, as MD 300mm/f4.5 telephoto lens with 700gr is available even of 50 M pixel format, so it will last me so long.