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Minolta 24mm f2.8 on sony a7 series
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PostPosted: Tue Jun 19, 2018 12:42 pm    Post subject: Reply with quote

So now I am little confused...

I feel like I have to buy both MD-III for video work and AF version for stills. I didnt' know that thses two share the same optical design.
Do I have to assume that these two have the same image quality and color rendition ?

If yes, then maybe I should get firstly the AF lens version (which is half the price by the way) and live with its focus ring size until I find a more elegant solution to use it for video work such as a follow focus ring or something...


PostPosted: Tue Jun 19, 2018 12:47 pm    Post subject: Reply with quote

Yes these manual focus are metal and glass while the AF are probably plastic. May explain the price difference...


PostPosted: Tue Jun 19, 2018 2:10 pm    Post subject: Reply with quote

Nouh wrote:
So now I am little confused...

I feel like I have to buy both MD-III for video work and AF version for stills. I didnt' know that thses two share the same optical design.
Do I have to assume that these two have the same image quality and color rendition ?

If yes, then maybe I should get firstly the AF lens version (which is half the price by the way) and live with its focus ring size until I find a more elegant solution to use it for video work such as a follow focus ring or something...


No reason for confusion. Wink

As already stated before, both lenses perform quite similar. At least on APS-C I've shown that already here: http://forum.mflenses.com/24mm-lens-comparison-minolta-pentax-tokina-t76783.html

The MD variant is simply better to adapt to other cameras as well as the AF version doesn't make much sense on other bodies than Minolta and Sony A-mount ones for proper aperture control. On the A7 series I would therefore recommend to use the LA-EA4 adapter for that reason. That may explain the price difference. My special adapter used for the shown comparison (Minolta AF to Leica M) only allows to open or to close the aperture without knowing the actual aperture.


PostPosted: Tue Jun 19, 2018 9:07 pm    Post subject: Reply with quote

[quote="tb_a"]
visualopsins wrote:
tb_a wrote:
...

Sorry to say that, Stephan. But you are definitely living in "Cockaigne" (Schlaraffenland) when it comes to used camera gear

...

...
Nevertheless, I think Stephan got it right as in our German-speaking world "Schlaraffenland" is rather harmless and means that everything is available very easily for everybody. Something like paradise. If you take into account that the average income in Switzerland is more than double compared to Austria and the used camera gear is half the price then it's in comparison simply Schlaraffenland or Paradise for lens collectors at least compared to my country and most other countries in Europe.
That's a simple observation and not nasty at all.


Don't worry, i got it right Wink

The MD-III and the Minolta AF 2.8/24mm have not the same optical construction; the AF lens is a completely new computation, and it share the basic construction with the AF 2.8/20mm. Both these lenses have a rear focusing system.

The MD-III focusing is in fact a bit stiff - especially compared to the earlier MC-X 2.8/24mm. Maybe increased precision (=less lubricant), probably also because their focusing is "alu-alu", not "alu-brass" as with the MC 2.8/24mm.

Stephan


PostPosted: Tue Jun 19, 2018 9:32 pm    Post subject: Reply with quote

stevemark wrote:
The MD-III and the Minolta AF 2.8/24mm have not the same optical construction; the AF lens is a completely new computation, and it share the basic construction with the AF 2.8/20mm. Both these lenses have a rear focusing system


Interesting. The construction drawings of both 24mm MD-III and AF lenses look very similar (8 lenses in 8 groups) whereas the 20mm lens is a 10/9 construction. Anyway, IMHO their performance is quite comparable...


PostPosted: Wed Jun 20, 2018 9:11 am    Post subject: Reply with quote

tb_a wrote:
stevemark wrote:
The MD-III and the Minolta AF 2.8/24mm have not the same optical construction; the AF lens is a completely new computation, and it shares the basic construction with the AF 2.8/20mm. Both these lenses have a rear focusing system


Interesting. The construction drawings of both 24mm MD-III and AF lenses look very similar (8 lenses in 8 groups) whereas the 20mm lens is a 10/9 construction. Anyway, IMHO their performance is quite comparable...


I'll check the technical details later (glass used, calculated performance and the like). The MD-III focuses by moving the entire lens (albeit with floating element); both the AF 2.8/24 and 2.8/20 use only the rear part for focusing. The front part does not move at all!

Stephan


PostPosted: Wed Jun 20, 2018 9:27 am    Post subject: Reply with quote

stevemark wrote:

I'll check the technical details later (glass used, calculated performance and the like). The MD-III focuses by moving the entire lens (albeit with floating element); both the AF 2.8/24 and 2.8/20 use only the rear part for focusing. The front part does not move at all!


Just to confirm, the size of the 24mm AF version lens doesn't change when focusing, right ? because my current Minolta AF 50mm f1.7 does.

Generally this feature is appreciated for video work with a gimbal.


Last edited by Nouh on Wed Jun 20, 2018 9:48 am; edited 1 time in total


PostPosted: Wed Jun 20, 2018 9:46 am    Post subject: Reply with quote

Just to show my ignorance. I have both manual MDII and MDIII. While I understand the MDII has a floating element (meaning the front turns with focusing while the back moves backward and forward when focusing but does NOT turn, is it the correct definition of floating element?), The MDIII seems to be one block going forward and backward without turning when focusing. Is it still floating element? I clearly am not clear on the definition...


PostPosted: Wed Jun 20, 2018 10:52 am    Post subject: Reply with quote

In order to make a long story short I just compared both MD-III and AF lenses on my A7R2 and can confirm now that they are performing nearly identical. The AF version seems to be the slightly better one as the vignetting on the MD-III is more pronounced fully open at F2.8 (easily correctable in Lightroom, lens profile exists). However, stopped down a little bit those lenses are definitely indistinguishable. Even the bokeh on short distance is identical. Both lenses perform really excellent and deliver razor sharp pictures already fully open from edge to edge on 42MP/FF. The AF version in combination with the LA-EA4 adapter is more joy to use as AF and electronic communication with the lens is fully supported (full EXIF information incl. operating aperture available).
Conclusion: My MD-III lens goes back into my repository. Wink


PostPosted: Wed Jun 20, 2018 11:06 am    Post subject: Reply with quote

Nouh wrote:
Just to confirm, the size of the 24mm AF version lens doesn't change when focusing, right ?


That's right.


PostPosted: Wed Jun 20, 2018 12:36 pm    Post subject: Reply with quote

tb_a wrote:
In order to make a long story short I just compared both MD-III and AF lenses on my A7R2 and can confirm now that they are performing nearly identical. The AF version seems to be the slightly better one as the vignetting on the MD-III is more pronounced fully open at F2.8 (easily correctable in Lightroom, lens profile exists). However, stopped down a little bit those lenses are definitely indistinguishable. Even the bokeh on short distance is identical. Both lenses perform really excellent and deliver razor sharp pictures already fully open from edge to edge on 42MP/FF. The AF version in combination with the LA-EA4 adapter is more joy to use as AF and electronic communication with the lens is fully supported (full EXIF information incl. operating aperture available).
Conclusion: My MD-III lens goes back into my repository. Wink

Thanks sir for your time, I appreciated that! I already have LA-EA4 adapter when I switched from my A-mount camera.
I'll just assume that theses lenses perform similarly on the less demanding 12mpx a7sii censor.


PostPosted: Wed Jun 20, 2018 4:12 pm    Post subject: Reply with quote

Antoine wrote:
Just to show my ignorance. I have both manual MDII and MDIII. While I understand the MDII has a floating element (meaning the front turns with focusing while the back moves backward and forward when focusing but does NOT turn, is it the correct definition of floating element?), The MDIII seems to be one block going forward and backward without turning when focusing. Is it still floating element? I clearly am not clear on the definition...


"flating element" (or "floating focusing", as Minolta called it) does not necessarily mean a rotating front element. Early "floating focusing" lenses (e. g. Minolta MC 2.8/24mm) often do have a rotating front element, since this facilitates the mechanical construction of the barrel. Later (since a rotating floating element is not ideal for polarizing filters!) often a non-rotating front element was used.

Stephan


PostPosted: Wed Jun 20, 2018 8:29 pm    Post subject: Reply with quote

Thanks Steve


PostPosted: Thu Jun 21, 2018 7:56 am    Post subject: Reply with quote

I have checked some information about different Minolta 24mm prototypes in the 1980-1985 time range.

From a simple side-by-side comparition it is obvious that the MD-III 2.8/24mm and the AF 2.8/24mm do not share the same optical construction; the front element of the AF lens is much bigger, and focusing is different (rear focusing, as said before).

Both lenses are [8/8] formulas, and both are made from very similar glasses. Since the AF version relies on focusing by moving the rear six lenses only (the two front lenses are stationary), the correction of the two groups (moving vs. non-moving) has to be done in a different way, compared to the MD-III version (where all groups are moving).

It may be interesting to know that Minolta had several 2.8/24mm prototypes with a quite complicated independent movement of three or even four groups before developing the rather simply rear focusing solution of the AF 2.8/24mm and 2.8/20mm lenses.

Stephan


PostPosted: Tue Sep 04, 2018 9:09 pm    Post subject: Reply with quote

Hi all,

So, I bought the Minolta 24mm AF version to use on the a7sii and I am pleased with results so far. I just have to be careful when manual focusing to avoid having a part of my fingers in the shot.

Also, I would like to share with you a footage (preview) that I shot using mostly this lens during a trip.

Do you think that the footage still has a vintage look even after the color grading ? what about the overall footage quality / details ? thanks.

https://youtu.be/p6mB4ycQ-Ok