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Olympus lens diagram misprint- unknown 50mm?
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PostPosted: Wed Mar 30, 2022 10:13 am    Post subject: Olympus lens diagram misprint- unknown 50mm? Reply with quote
Click to go to larger version of all of these:


Very quick freehand photo:





This is an odd one I encountered looking at my literature- clearly the wrong diagram printed for a 28mm SLR lens.

But I can't seem to find an Olympus SLR lens- around 50mm- that actually matches it.

Dating the brochure - from the lenses listed -such as the 28-48mm f4 introduced in 1983- the one with the error is clearly the latest of the bunch. Just because it doesn't say "MC" doesn't mean it's early- probably not novel by then.

This may make identification even trickier, because the only similar lens is the original OM F.Zuiko Auto-S 50mm F/1.8 from 1972 (old) not the later version:

Earlier:



Later:



Not only is the airspace in the front section is much larger in my diagram, but the cemented surface in the rear section is plano/slightly convex towards the image plane whereas in the OM F.Zuiko Auto-S 50mm F/1.8 it's clearly concave. The front element is also abit larger than all the other elements in my diagram, not as much in the OM F.Zuiko Auto-S 50mm F/1.8.

So- any idea?[/img]


PostPosted: Wed Mar 30, 2022 10:43 am    Post subject: Reply with quote
There were six versions of the 50mm 1.8 The first three had a 6/5 design, the last three a 6/4 design.

http://allphotolenses.com/lenses/item/c_41.html#prettyPhoto


PostPosted: Wed Mar 30, 2022 10:51 am    Post subject: Reply with quote
Looks like this 50mm f1.8
http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/zuiko/htmls/50mm1a.htm


PostPosted: Wed Mar 30, 2022 10:51 am    Post subject: Reply with quote
D1N0 wrote:
There were six versions of the 50mm 1.8 The first three had a 6/5 design, the last three a 6/4 design.

http://allphotolenses.com/lenses/item/c_41.html#prettyPhoto


Yeah- and I'm suggesting neither of these resemble the one in the diagram:

Quote:
Not only is the airspace in the front section is much larger in my diagram, but the cemented surface in the rear section is plano/slightly convex towards the image plane whereas in the OM F.Zuiko Auto-S 50mm F/1.8 it's clearly concave. The front element is also abit larger than all the other elements in my diagram, not as much in the OM F.Zuiko Auto-S 50mm F/1.8.


PostPosted: Wed Mar 30, 2022 10:58 am    Post subject: Reply with quote
Slalom wrote:
Looks like this 50mm f1.8
http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/zuiko/htmls/50mm1a.htm


Seems to be the earlier 50mm f1.8 from 1972 I was talking about, which I don't actually find to be identical.

I know diagrams can be drawn differently- line thickness might change an airspace- but I really do see a different lens here. The line thickness would not change it- the airspace really is less in my unknown lens. The diagram in the booklet is resolute enough to show it, too.

As I said the rear section doublet has a very differently shaped cemented surface.



PostPosted: Wed Mar 30, 2022 11:24 am    Post subject: Reply with quote
Maybe it looks more like the later AF version



PostPosted: Wed Mar 30, 2022 11:34 am    Post subject: Reply with quote
D1N0 wrote:
Maybe it looks more like the later AF version



This is getting even weirder- the front is closer to matching, but I still think my airspace is a tad smaller. More importantly the rear section looks different. The last element is much thicker in this AF model, and the elements in the cemented rear component are the same diameter whereas in mine they are different:




Knowing your diagram is someone's trace uploaded to Wikipedia, I thought it was a tracing error, but it appears not to be.

Is mine some sort of beta version?


PostPosted: Wed Mar 30, 2022 11:44 am    Post subject: Reply with quote
The differences in the rear group are probably partly due to lens barrel differences in the AF version. Maybe Olympus recalculated the 6/5 design but ultimately chose a 6/4 design and left the new 6/5 on the shelf until the AF version, likely recalculating again.


PostPosted: Wed Mar 30, 2022 2:45 pm    Post subject: Reply with quote
I think if these were taken from lenses sawn through the middle, this deep analysis would be worthwhile, but as they may be pseude blueprints, we may conclude it is close enough to 50mm f1.8 we have found.
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