Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

f/1.2 side by side comparison
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Sun Mar 31, 2013 12:38 pm    Post subject: Re: Lens tests! Reply with quote
OPAL wrote:
The majority of photo lenses are developed to achieve the best optical results at the "infinity" distance.


This has been discussed on this forum before, and there seems to be no consensus that this is the case, and others say that many lenses are optimized for portrait distances etc.

In any case, even if the lenses were optimized for infinity focus, those using them at portrait distances would care more about the performance at portrait distances than at infinity, even if infinity were better. And testing at true infinity is problematic since lens infinity focus calibration may be off.

(But, yes, I agree that testing at or near the close focusing limit of the lens is not perfect, either, so the double-spread of New York Times could be a good compromise. =)


PostPosted: Sun Mar 31, 2013 12:47 pm    Post subject: Reply with quote
dejmir wrote:
Finally, I managed to adapt the Porst 50mm f/1.2 in Fujica mount to EOS. It will not hit the mirror on my 6D at 30m. I may still shave off some more material to reach the infinity focus – not that I really need that at f/1.2 :D


This lens is believed to be very similar to the X-Fujinon 50mm f/1.2, and it is possible to convert that lens with infinity focus without removing any material… As as simple starting point, look for two screws on the outside of the lens, near the meters and feet text on the distance scale. Open up the lens and you should find the focusing range limiter underneath those screws. Remove the limiter (open the screws) and see if you get infinity focus then (focusing ring will turn past infinity position)… If yes, improvise a limiter that lets you reach infinity but does not let the lens fall off its threads at the close focusing end.

(You can also try to deliberately take the lens off the focusing helicoid threads and put it back in a different position; this will alter infinity position; maybe you get lucky and one of them works directly. There should also be a more fine-grained adjusting mechanism for calibrating the position, but I don't know where it is on this lens… possibly screws under the name ring? Let us know if you find it.)


PostPosted: Sun Mar 31, 2013 8:58 pm    Post subject: Reply with quote
I did use a QBM to EOS adapter which is quite thin. I think it has only 0.46 mm where it touches the lens. Consequently the lens focused past infinity and I inserted a separate thin brass ring between the adapter and lens. Now, this ring is too thick - I reckon for a fraction of a millimetre – to reach the infinity focus. Anyhow, the max focus at 30m doesn't really bother me.

As I already mentioned, between the lines, I don’t use these lenses to take landscape pics. For this I prefer Flektogons. However, I use the f/1.2s as portrait lenses on both full frame and cropped sensor cameras.

As suggested by nick_cool, and when I find time, I’ll make a comparison of bokehs that these lenses render at f/1.2. Anyhow, I guess you would all agree with me if I say that the bokeh is a matter of personal taste. For example, I particularly like the swirly bokeh of Primoplans and Biotars, which some just hate. My Porst 55mm also throws really crazy bokeh that I find attractive in BW. Personally, I find creamy bokehs, in some way, dull. But hey, isn’t this forum about old MF lenses Smile


PostPosted: Sun Mar 31, 2013 9:18 pm    Post subject: Re: Lens tests! Reply with quote
Arkku wrote:
OPAL wrote:
The majority of photo lenses are developed to achieve the best optical results at the "infinity" distance.


This has been discussed on this forum before, and there seems to be no consensus that this is the case, and others say that many lenses are optimized for portrait distances etc.

In any case, even if the lenses were optimized for infinity focus, those using them at portrait distances would care more about the performance at portrait distances than at infinity, even if infinity were better. And testing at true infinity is problematic since lens infinity focus calibration may be off.

(But, yes, I agree that testing at or near the close focusing limit of the lens is not perfect, either, so the double-spread of New York Times could be a good compromise. =)


btw, the test chart I used is A3 format and the working distance was around 80cm - I know it is far from being perfect.


PostPosted: Mon Apr 21, 2014 6:53 pm    Post subject: Bokeh close to a portrait distance Reply with quote


Here is a bokeh comparison I made a while ago, but failed uploading promptly. Anyhow, someone might find it useful.

All snaps are taken using this scene:


PostPosted: Mon Apr 21, 2014 8:21 pm    Post subject: Reply with quote
Some late comments on the testing procedure:

1) The ISO 12233 chart is outdated for today's sensors. For example, the converging lines in the center allow measuring resolution only up to 2000 LWPH. Even compact cameras exceed that value. I built a simplified test chart by scaling down the converging lines so to be able to measure resolution up to 4000 LWPH.

2) The chart must be framed appropriately for the resolution markings have a meaning. For a FF or APS-C camera, this means the test chart must be framed so the 3:2 lines coincide with the vertical edges of the field.

3) The letter to A3 size is a bit too small for a serious test.
Post new topic   Reply to topic
Home   Manual Focus Lenses
Goto page Previous  1, 2
Page 2 of 2