Sony 100mm f/2.8 macro

[Braeside]

That is most odd, I confess I don't understand why that should be.

I have not seen either of those tests, but wonder if they were both done at 1:1 or not, because the effective aperture reduces by 2 stops there, possibly accounting for the discrepancy between the two test results for the diffraction effects.

 

[edwardkaraa]

That is most odd, I confess I don't understand why that should be.

I have not seen either of those tests, but wonder if they were both done at 1:1 or not, because the effective aperture reduces by 2 stops there, possibly accounting for the discrepancy between the two test results for the diffraction effects.

The usual distance to resolution charts is between 1 to 2 meters depending on the lens FL.

By the way, the aperture does not change with magnification. The aperture as a mathematical value remains the same. It is the light that diminishes with the increased distance to the sensor (light fall off). That's at least how I understand it, but of course I could be wrong.

 

[Braeside]

Edward, I have being trying to get a definitive answer on that myself. Eventually I convinced myself that the "effective aperture" would determine the diffraction, from an article and web calculator I found today. This particular one specifically allows DOF at different Reproduction Ratios and with different sensor sizes etc.

http://www.rags-int-inc.com/PhotoTechStuff/DoF_Calculator/DoF_Calculator.html

I put some figures in for the A900 at 1:1 and diffraction should just start to be noticeable at f/5.6, and on the 22MP ZD larger 48x36mm sensor it should be f/8

The notes are at: http://www.rags-int-inc.com/PhotoTechStuff/DoF_Calculator/DoF_Users_Guide.html

In it he states " The effective aperture (EF) is shown based on the current real aperture size and the distance between the image and focal planes. At close up subject distances this becomes a factor in exposure settings and diffraction."

It was that that led me to believe that the effects of diffraction depended on the effective aperture rather than the numeric aperture.

 

[Braeside]

I also found this illuminating article on diffraction at macro:

http://www.zen20934.zen.co.uk/photography/dof/dof.htm#Diffraction

Basically confirming that the diffraction effects become significant about two f-stops earlier for every doubling in magnification. So at 1:1 diffraction would be significant at 2 stops earlier than at infinity.

Examples shown are for 35mm at 1:1 Diffraction limit is approx f16 versus f32 for infinity.

 

[edwardkaraa]

I also found this illuminating article on diffraction at macro:

http://www.zen20934.zen.co.uk/photography/dof/dof.htm#Diffraction

Basically confirming that the diffraction effects become significant about two f-stops earlier for every doubling in magnification. So at 1:1 diffraction would be significant at 2 stops earlier than at infinity.

Examples shown are for 35mm at 1:1 Diffraction limit is approx f16 versus f32 for infinity.

Very interesting David. So the blur effect gets stronger as the aperture opening goes further away from the sensor. Very interesting.

 

[fotografz]

Was cruising Lloyd Chambers' site this AM ( www.diglloyd.com ) and came across some info that may enlighten us about the performance of "Legacy Macros" in the world of high meg., full frame digital sensors.

According to Lloyd, Even with the 21 meg Canon 1DsMKIII, the much acclaimed Costal Optics 60/4 APO macro peaks at f/5.6 due to diffraction ... and that a theoretical 36 meg camera would drop that limit a stop or so to f/4. So somewhere in there is our 24 meg FF Sony ... and the Sony 100/2.8 Macro is hardly a comparable lens to the $4,000. Costal Optics APO. This implies that pixel size and resulting resolution has an impact on diffraction ( I admit to not understanding the science of this, but have found Lloyd's observations to be pretty reliable.) So you add up all the things working against it, and the old school rebadged Sony seems to come up short when hung off the front of an A900.

In other parts of the site, it appears the Nikon PC Macro gets decent marks, and Lloyd apparently is even using one adapted to a Canon 1DsMKIII. I wonder how good existing Nikon to Minolta/Alpha adapters are?

http://cgi.ebay.com/Nikon-F-to-Mino...pter-Nice_W0QQitemZ180296207960QQcmdZViewItem

If it would work, than investing in a 85/2.8 Nikon PC-E Macro might be a worthwhile investment since the tilt function would mitigate the need to stop down so much thus introducing diffraction.

http://www.bhphotovideo.com/c/product/570522-USA/Nikon_2175_PC_E_Micro_Nikkor_85mm.html

Not to mention that would allow use of the Ziess ZF optics on the Sony ... and lenses like my Nikon 200/2 :thumbs:

What is not clear is whether this adapter has an optic in it, and whether it covers FF ... I suspect it does since it says it's a Minolta/Alpha ... but it could be referencing crop frame digital.

Your thoughts?

 

[Braeside]

The effects of diffraction will be seen earlier with smaller pixels, the diffraction is the same angle, just that the smaller pixels can show the effect quicker.

I still doubt that there anything much wrong with the Sony 100mmm Macro, as it clearly is diffraction limited at a fairly large aperture, a sign of a good lens not a bad one.

Agree T&S is needed for better DOF.

 

[douglasf13]

The Nikon adapter does have a glass element in it to achieve infinity focus.

 

[fotografz]

The Nikon adapter does have a glass element in it to achieve infinity focus.

Maybe I could just take a hammer to it ... for Macro who needs infinity ...:ROTFL:

 

[Braeside]

Maybe I could just take a hammer to it ... for Macro who needs infinity ...:ROTFL:

Great idea :ROTFL:

 

[douglasf13]

Maybe I could just take a hammer to it ... for Macro who needs infinity ...:ROTFL:

I was thinking the same thing It seems like someone would be able to come up with a way to mount Nikkors without an element, but I've seen zilch about it.

 

[edwardkaraa]

I did a few comparisons between the Sony macro and the ZA 135 with extension tubes. It was impossible to get exactly the same frame due to the different focal length and the high magnification so it's difficult to make definitive conclusions. I believe that the ZA 135 with tubes is sharper by a noticeable margin but seems to produce more CA than the macro. Not bad for a non-macro lens. However the lens is quite big and heavy and the extension tubes are quite flimsy and the whole set up doesn't balance well, so for the time being the Sony remains the more practical option. However judging by the above, I have every reason to believe that an eventual Zeiss Makro will produce much better results.

 

[gtmerideth]

I have a ZK 100/2 macro planar which I respect as a fine piece of glass.
Even though the adapters with glass degrade the IQ, I wanted to know how much so I purchased the Russian Pentax to MA and was pretty disappointed.

Some day I will find a way to use that 100/2 on the Sony.
g

 

[fotografz]

Anyone ever try the AF Tamron 180/3.5 LD IF Macro?

http://www.bhphotovideo.com/bnh/controller/home?O=cart_accessories&A=details&Q=&sku=284405&is=REG

 

[surfotog]

I just got the Tamron180/3.5 macro as a stop gap until Sony/Zeiss grace us with a longer pro caliber macro. Can't comment yet on IQ, but the feel of the manual focus is horrible. You can actually hear, and feel the focus ring grind. I don't know if this is normal for this lens, or if I got a dud, but it's going back to B&H. I'm disappointed as this lens is supposed to be pretty good optically.

 

[edwardkaraa]

I just got the Tamron180/3.5 macro as a stop gap until Sony/Zeiss grace us with a longer pro caliber macro. Can't comment yet on IQ, but the feel of the manual focus is horrible. You can actually hear, and feel the focus ring grind. I don't know if this is normal for this lens, or if I got a dud, but it's going back to B&H. I'm disappointed as this lens is supposed to be pretty good optically.

Too bad because the specifications sound impressive. If it focuses via screwdriver, then the grinding sound is normal (I guess).

 

[surfotog]

I have the older Minolta 20/2.8, and manual focus with that is much nicer, no grinding, quiet. The Tamron also had a bit of slop which made really critical focus very difficult.

 

[gsking]

Its odd how one becomes inclined to mince one's words. I am as prone to do so as anyone.

Actually my personal view is that the Sony 100mm macro is - given the pedigree - a rubbish lens. Its poorly made and optically dubious. Independent manufacturers like Sigma and Tamron make better lenses for less money. Sony or Zeiss need to do better. My apologies for being less than 100% candid before

Quentin

Given what pedigree??? You mean it should be better since it's a Minolta lens???

Edward, I agree the Sony appears to have more in common with the Minolta lens contrasts than the Zeiss that is for sure. It also has 'bokeh' CA when wide open.

Very strange, the Minolta 100mm/2.8 macro (old version) that is supposed to be the same as the new Sony version, is absolutely superb.

Yes, it is...it's identical to the Minolta 100mm D, which ironically was rated IIRC as one of the top lenses of all time.

Now, I sense a bit of QC shift in Sony's fabrication process, because it seems they may have cut some corners to make things cheaper. This could contribute to the higher incidence of "sloppy" lenses on the street.

Or, you guys could just be unfairly treating the lens based on their use of newfangled plastics.

Hi Jono,

My understanding has evolved, shall we say. It does a workmanlike job, but I can't think of any area where its not just a little short of other macro lenses I have used, including Sigma and Tamron macros on the Kodak 14nx. The lens hood is flimsy. General build quality is low end. If it cost less I'd not mind, but I now think I should have purchased a Tamron 90mm macro instead.
Quentin

Aha, so I was right. Negatives on build quality and hood stiffness infect the optical rating? Come on, guys.

Greg

 

[fotografz]

I cannot agree with this. My 120mm Mamiya macro on a 22mp Mamiya ZD is good at around F.20 so there is no excuse for softness with the Sony macro at similar f-stops. The fact is the Sony macro is a hobbyist consumer grade lens, not up to professional use and it shows.

The photosites on the ZD back are huge compared to the Sony's ... that's why it works better.

 

[edwardkaraa]

Greg,

The lens is fine in terms of resolution and sharpness. But I guess we Zeiss users have come to expect certain characteristics that are lacking in the 100 macro, not only build quality but also micro-contrast and colors.