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Rokkor RF 250mm F5,6
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PostPosted: Wed Apr 08, 2020 11:27 pm    Post subject: Rokkor RF 250mm F5,6 Reply with quote

I guess this one is quite uncommon and I red a number of dicussions on the merits of this lens with quite diverging opinions.

Make your own.



PostPosted: Fri Apr 10, 2020 8:02 am    Post subject: Reply with quote

Like 1 small Like 1 small nice!


PostPosted: Fri Apr 10, 2020 10:58 am    Post subject: Reply with quote

Is this the best mirror lens ever made?


PostPosted: Fri Apr 10, 2020 1:57 pm    Post subject: Reply with quote

blotafton wrote:
Is this the best mirror lens ever made?


Not sure. But today the most expensive one. Wink


PostPosted: Fri Apr 10, 2020 4:08 pm    Post subject: Reply with quote

blotafton wrote:
Is this the best mirror lens ever made?


Hardly Twisted Evil . It is expensive now because it is quite rare (not unlike the Tamron SP 350 mm f/5,6). In fact, at the time it was sold, most prospective buyers of mirror lenses favored longer focal lengths and the RF 250 mm f/5,6 was a commercial failure and quickly abandonned while the RF 500 mm f/8 even got a successor with AF. The price of the 250 mm f/5,6 thus mainly reflects rarity and collector's value, the IQ being very good but not outstandingly so.


PostPosted: Fri Apr 10, 2020 4:11 pm    Post subject: Reply with quote

The spooks have the best mirror lenses ever made. Think, Hubble size mirror aimed down at your roof.


PostPosted: Fri Apr 10, 2020 5:01 pm    Post subject: Reply with quote

Alsatian2017 wrote:

Hardly Twisted Evil . It is expensive now because it is quite rare . . .


Thank you for the summation. I certainly understand collector mania, but the prices I see for this lens are amazing!

https://www.ebay.com/sch/i.html?_from=R40&_nkw=minolta+rf+250+5.6&_sacat=625&LH_Sold=1&rt=nc


PostPosted: Fri Apr 10, 2020 5:04 pm    Post subject: Reply with quote

Antoine wrote:
Like 1 small Like 1 small nice!


Antoine you have a quite nice set of Minolta lenses. I have some of them and I remain curious about the ones I do not have, for example the 20mm 2,8 and the 45mm 2,0.

How the 20 compares to common same era wide angles such as Tokina RMC 17 that we both own? The 45 intrigues me. I am found of the focal lenght since I have good memories of 28mm on APSC but I find difficult to justify the 5mm difference with common fifties and the tests I read here and there claiming it is inferior to any 50, at least on full frame.

Any opinion would be highly appreciated.


PostPosted: Fri Apr 10, 2020 5:57 pm    Post subject: Reply with quote

I bought the 20 mm early on and have to admit I loved it (30 mm on aps) for its compactness and built quality and associated it often with a focal reducer (eq 21.4mm) as 30 is not very wide. Of course, a 17 mm (eq 25.5 mm) is a much wider angle and can be used extensively without the focus reducer.
The 45 mm was offered to me, it is very compact and is nicer with full frame or with the focal reducer on aps.

I now use much more my A7Rii than the A6000 which I only take to travel which is forbidden these days.... The rf 250 (eq375mm on aps) offers a great compactness and great images when one controls out of focus rings. Contrast does not seem such a big issue these days with post treatment (sure purists will disagree...)


PostPosted: Fri Apr 10, 2020 9:48 pm    Post subject: Reply with quote

Antoine wrote:
I bought the 20 mm early on and have to admit I loved it (30 mm on aps) for its compactness and built quality and associated it often with a focal reducer (eq 21.4mm) as 30 is not very wide. Of course, a 17 mm (eq 25.5 mm) is a much wider angle and can be used extensively without the focus reducer.
The 45 mm was offered to me, it is very compact and is nicer with full frame or with the focal reducer on aps.

I now use much more my A7Rii than the A6000 which I only take to travel which is forbidden these days.... The rf 250 (eq375mm on aps) offers a great compactness and great images when one controls out of focus rings. Contrast does not seem such a big issue these days with post treatment (sure purists will disagree...)


This is about the 250mm mirror lens - guys, behave please - or make up a separate thread...


PostPosted: Sat Apr 11, 2020 8:27 am    Post subject: Reply with quote

Sorry my fault I guess.


PostPosted: Sat Apr 11, 2020 5:38 pm    Post subject: Reply with quote

Alsatian2017 wrote:
blotafton wrote:
Is this the best mirror lens ever made?


Hardly Twisted Evil . It is expensive now because it is quite rare (not unlike the Tamron SP 350 mm f/5,6). In fact, at the time it was sold, most prospective buyers of mirror lenses favored longer focal lengths and the RF 250 mm f/5,6 was a commercial failure and quickly abandonned while the RF 500 mm f/8 even got a successor with AF. The price of the 250 mm f/5,6 thus mainly reflects rarity and collector's value, the IQ being very good but not outstandingly so.


Maybe it's the short focal length that hides the flaws of the mirror design. I'm impressed by the various samples I've seen from the 250mm. If there is no obvious bokeh in the shot it's not easy to identify it thanks to the good sharpness and contrast.


PostPosted: Sun Apr 12, 2020 11:41 am    Post subject: Reply with quote

blotafton wrote:
Alsatian2017 wrote:
blotafton wrote:
Is this the best mirror lens ever made?


Hardly Twisted Evil . It is expensive now because it is quite rare (not unlike the Tamron SP 350 mm f/5,6). In fact, at the time it was sold, most prospective buyers of mirror lenses favored longer focal lengths and the RF 250 mm f/5,6 was a commercial failure and quickly abandonned while the RF 500 mm f/8 even got a successor with AF. The price of the 250 mm f/5,6 thus mainly reflects rarity and collector's value, the IQ being very good but not outstandingly so.


Maybe it's the short focal length that hides the flaws of the mirror design. I'm impressed by the various samples I've seen from the 250mm. If there is no obvious bokeh in the shot it's not easy to identify it thanks to the good sharpness and contrast.


Here are a two 100% crops from the 43 MP FullFrame Sony A7RII. The first crop is from the center:


The second crop is fro the extreme orner:


No CA corrections were applied.
I'd say that CA correction is pretty well done; detail resolution decreases a bit, but it's still acceptable, even on 43 MP FF. Vignetting is quite pronounced; it may be disturbing (e. g. landscapes) or enhancing the image (e. g. portraits), depending on the subject. Of course on the common 24 MP FF cameras the image quality looks even better!

S


PostPosted: Sun Apr 12, 2020 12:15 pm    Post subject: Reply with quote

Your crop images concur with my impressions although I do not have a 43M pix full frame. I might test it on a 24M pix APSC that is even more demanding.

My feeling is that it is not optimized for short distance and your photo and mine are close to minimum focus distance.

More info to come.


PostPosted: Sun Apr 12, 2020 1:20 pm    Post subject: Reply with quote

lumens pixel wrote:

...

My feeling is that it is not optimized for short distance and your photo and mine are close to minimum focus distance.


That may well be true - however at the moment we have too much "air movements" (sorry, i don't know the correct English term) so i can't really test at infinity ...

S