Circular Aperture

[Wes Gibbon]

I believe that 'RS' indicates KM lenses with circular aperture. I asked a seller on Ebay if his lens was the circular aperture version, and he asked back: 'how can you tell'? Apart from counting the iris blades, how do you tell. I have only seen photographs of such lenses, but I cannot see 'RS' or anything else on the boxes or the lens itself to indicate this feature.

Apart from bokeh, does the circular aperture confer any other advantages, and are there any lenses which were improved when the circular aperture version was released. Was this feature carried forward to Sony lenses?

Could be a big subject, but any information would be a help. Have there been any threads in the past that covered this topic? (Sorry if missed them!).

[PhotoTraveler]

RS is restyled, and while it often means circular aperture, it's not an absolute. The 1.7/50 RS for instance does not have circular aperture.

You also won't see RS on the box.

You need to look up the lens in Dyxum lens database and see which it is, that will tell you what it has for aperture. You can tell RS lenses as they don't look like originals, they have a cleaner newer looks, with rubber focus ring, not the gear looking focus ring. Of course if a lens never had an Original design, then it will look RS without being an RS lens.

[harveyzone]

I believe that 'RS' indicates KM lenses with circular aperture. I asked a seller on Ebay if his lens was the circular aperture version, and he asked back: 'how can you tell'? Apart from counting the iris blades, how do you tell. I have only seen photographs of such lenses, but I cannot see 'RS' or anything else on the boxes or the lens itself to indicate this feature.

RS means re-styled. i.e. they have the newer 'softer' look with rubber focus ring etc. It is nothing specifically to do with circlar blades (some lenses were changed in the re-modelling, but that is model specific and is not a given just because it says RS, many are identical except for looks).

[01af]

I believe that 'RS' indicates KM lenses with circular aperture.

Your assumption is wrong.

Many 're-styled' Minolta lenses have circular apertures indeed---but not all. And not all lenses with circular apertures are 're-styled.'

Apart from counting the iris blades ...

The number of aperture blades won't tell you whether the aperture's shape is polygonal or circular.

... how do you tell?

Simply take a look.

Apart from bokeh, does the circular aperture confer any other advantages ...?

No. And the shape of the aperture hardly affects bokeh; it just affects the shape of the out-of-focus highlights which is only a subsidiary aspect of bokeh.

Was this feature carried forward to Sony lenses?

With most lenses, yes, but not all.

Could be a big subject ...

It's not.

-- Olaf

[KevinBarrett]

All apertures are circular when fully open, however, "circular apertures" stay more circular longer. When stopped down from full, they immediately become polygons of some kind; pentagons, hexagons, heptagons, octagons, nonagons, decagons, and so on...except they are harder to notice because all of their sides are curved sections of a larger circle. There is no way for the aperture to stay circular through its entire range, but by using curved blades, and more of them, you can keep the appearance of a circular aperture a few stops farther into the range.

"RS" has mostly been explained above. Some of Minolta's lenses didn't have "circular apertures" before the restyle, and this aspect could easily be changed without having to re-engineer any other part of the lens.

[Dr. Harout]

All apertures are circular when fully open, however, "circular apertures" stay more circular longer. When stopped down from full, they immediately become polygons of some kind; pentagons, hexagons, heptagons, octagons, nonagons, decagons, and so on...except they are harder to notice because all of their sides are curved sections of a larger circle. There is no way for the aperture to stay circular through its entire range, but by using curved blades, and more of them, you can keep the appearance of a circular aperture a few stops farther into the range.

"RS" has mostly been explained above. Some of Minolta's lenses didn't have "circular apertures" before the restyle, and this aspect could easily be changed without having to re-engineer any other part of the lens.

You can even encounter star shaped apertures like this:

[KevinBarrett]

You can even encounter star shaped apertures like this

LOL

[Wes Gibbon]

Thank you for all your comments. I now feel I have been initiated into some of the secrets...

One of my main concerns was that if a lens was redesigned (of at least 'tweaked') when the RS version came out, that might make a difference when buying a lens on Ebay (or other second hand source). I suppose that if the seller can't really say which version it is, perhaps he is not the best person to buy from. On the other hand, it does seem unsatisfactory if the only way to tell which version a lens is is to compare it with a photo on Dyxum. Of course, you can't blame Sony, and it's a bit late to criticise Minolta.

Clearly you guys know your RS from your originals, but for a newcomer to Minolta AF/Sony (for 35mm I used Minolta MD until fairly recently) it's not at all obvious, but thank you to you all for such a speedy and helpful reponse. I also appreciate the photo of a Star of David aperture ring! I wonder if out of focus sparkle on water would rival the doughnut rings you can get from a mirror lens?

All the best,

[Vidgamer]

....
One of my main concerns was that if a lens was redesigned (of at least 'tweaked') when the RS version came out, that might make a difference when buying a lens on Ebay (or other second hand source). I suppose that if the seller can't really say which version it is, perhaps he is not the best person to buy from. On the other hand, it does seem unsatisfactory if the only way to tell which version a lens is is to compare it with a photo on Dyxum. Of course, you can't blame Sony, and it's a bit late to criticise Minolta.

Well, I think the older Minolta lenses have a certain look to them, and the rubber grip has very fine ridges. Most of the RS lenses have widely space ridges on the rubber, and a bit of a more rounded look, and a more space-age-y font.

Clearly you guys know your RS from your originals, but for a newcomer to Minolta AF/Sony (for 35mm I used Minolta MD until fairly recently) it's not at all obvious, but thank you to you all for such a speedy and helpful reponse. I also appreciate the photo of a Star of David aperture ring! I wonder if out of focus sparkle on water would rival the doughnut rings you can get from a mirror lens?

I bet that would be interesting... although, I wonder if you could simulate that to some extent in software?

Some people don't like the donut look, but David mentioned in another thread (about a month ago?) that people have gone out of their way to go for that look. At least it's something different. Sometimes I like some non-round highlights -- I think it gives it some character. It's not as if it ruins photos.

[Dr. Harout]

The star shaped aperture is on the soviet made Industar-61L/Z-MC, only in between 5.6 and 8, after that it becomes a hexagon.