Poor macro lense sharpness--why?

[mdijb]

I am using a Sony 100 macro f2.8 Alpha A mount lens on a Sony A7r with a Sony adapter.  I am shooting closeups of flowers, doing focus stacking with 6-8 Images.  I am also using a Sony 5 inch LCD monitor to help focusing.  The images look sharp on the monitor and focus peaking verifies this on each frame in the sequence.  However, after stacking in Photoshop, the images are not sharp—see attached sample and look at 100 % .

When I use my Sigma 50mm Merrill—the  stacking result is razor sharp.  This may  not be a fair comparison, but I do expect much sharper results using the Sony Macro.

Could focus shift explain the above result??    Any other explanation?  I do not understand how the image appears sharp on the camera LCD and viewfinder, as well as the Large monitor but the result is so unsharp, even with stacking.

I did discuss the problem with B+H and they suggested I exchange the  lens and that is in the works.

MDIJB

[Jim Kasson]

I am using a Sony 100 macro f2.8 Alpha A mount lens on a Sony A7r with a Sony adapter.  I am shooting closeups of flowers, doing focus stacking with 6-8 Images.  I am also using a Sony 5 inch LCD monitor to help focusing.  The images look sharp on the monitor and focus peaking verifies this on each frame in the sequence.  However, after stacking in Photoshop, the images are not sharp—see attached sample and look at 100 % .

When I use my Sigma 50mm Merrill—the  stacking result is razor sharp.  This may  not be a fair comparison, but I do expect much sharper results using the Sony Macro.

Shutter shock?

http://blog.kasson.com/?p=5402

I use 2 second exposures with the Otus 55mm when working close on this series, and I get good results. I am doing focus stacking, too.

Here's the test series that made me settle on 2 seconds.

http://blog.kasson.com/?p=5296

Jim

[Fine_Art]

That is one of my main A mount lenses. If you are using live view it cant be focus tuning. I would guess shutter as well. Try long shutter as Jim says or very fast shutter.

[mdijb]

I was using speeds of 1/4 to 1/2 Second.  That should be long enough to avoid the shutter vibration issue.

MDIJB

[Fine_Art]

I was using speeds of 1/4 to 1/2 Second.  That should be long enough to avoid the shutter vibration issue.

MDIJB

I have no testing to back up my theory: Avoid 1/10 to 1/2 second. It's not just the shutter, it is the time for the vibration to dissipate.

[mdijb]

I have used the same lens on a Sony A6000 with the same result but to a lesser degree--no vibration issue with this camera or shutter.

[Fine_Art]

Maybe it's a bum copy.

I'll post a raw with mine, so you can see if it is a sample issue.

[Fine_Art]

http://www.megafileupload.com/en/file/547748/-DSC6532-zip.html

The zip has a macro type raw and a 100% jpg converted in Raw Therapee.

I typically use the Sony/Minolta Macros are regular lenses. The OOF is quite nice.

[mdijb]

thanks for the upload.  In your image the center at lease is pretty sharp.. Your shot was at f5.6.  My shots were at f11 and after reviewing the focus stack and some single shots in the stack again, nothing is real shape at all--anywhere!!

The replacement lens is on the way.  I will try again using longer shutter speeds and see what happens.

[degrub]

Any chance the camera was refocusing when the shutter tripped ?

Is there enough edge contrast for the stacking software to get the pixel registration correct ?

Tripod / mount vibration issue ?

Just a couple ideas from what i have been bitten by before.

Frank

[elf]

What aperture are you using? When focus stacking you should normally chose the sharpest aperture for a lens and let the software handle the DOF.

[Fine_Art]

What aperture are you using? When focus stacking you should normally chose the sharpest aperture for a lens and let the software handle the DOF.

He said F11 which contributes. I would focus stack that lens at f5.6 which is why I shot the raw that way. I read Jim's blog link to shutter data with that camera this evening. That is probably the #1 issue.

[Bart_van_der_Wolf]

I am using a Sony 100 macro f2.8 Alpha A mount lens on a Sony A7r with a Sony adapter.  I am shooting closeups of flowers, doing focus stacking with 6-8 Images.  I am also using a Sony 5 inch LCD monitor to help focusing.  The images look sharp on the monitor and focus peaking verifies this on each frame in the sequence.  However, after stacking in Photoshop, the images are not sharp—see attached sample and look at 100 % .

Hi,

In addition to the potential shuttershock issue on the A7r, and possible lens quality issues, there are also things to consider in shooting technique and post-processing.

When I use my Sigma 50mm Merrill—the  stacking result is razor sharp.  This may  not be a fair comparison, but I do expect much sharper results using the Sony Macro.

The DP3 Merrill will produce something like 6mm depth of field at f/11 per focus tile. The exact DOF range will depend on the exact magnification factor. I assumed a magnification that allows to fill the frame with a subject width of 150mm.
If we use the same aperture and subject magnification to fill the frame of the A7R with 150mm subject width with your 100mm lens, your focus tiles will have something like 7mm depth of field. So with 6-8 tiles, you'll be able to cover something like around 1.5 to 2.2 inches of DOF.

When you use larger focus step increments, you will need to reduce your output dimensions to cover up for the lower resolution transition zones between focus planes of the tiles. Shooting smaller subjects, closer up, will reduce the DOF significantly.

You would probably get better quality when you use a wider aperture, the optimum for the lens whatever that happens to be. It would require to take more focus increments to cover the same total DOF.

Could focus shift explain the above result??    Any other explanation?  I do not understand how the image appears sharp on the camera LCD and viewfinder, as well as the Large monitor but the result is so unsharp, even with stacking.

Shuttershock and lens quality remain the most likely causes. However, it may also be partly caused by something going wrong with the Stacking post-processing procedure. Unfortunately Photoshop does not offer much control. So you would have to check/compare the sharpness of the individual planes to eliminate the Stacking software influence.

I did discuss the problem with B+H and they suggested I exchange the  lens and that is in the works.

Maybe that will give a better result, assuming the lens is indeed the culprit.

Cheers,
Bart

[mdijb]

Thanks for your thoughtfull and detail reply.

I will receive the new lens tomorrow and will begin trying your suggestions.

I did look a the Kasson articles and now think I may be seeing shutter vibration.

MDIJB

[Ajoy Roy]

Have you checked individual images for sharpness? Try a shot at F11 and F16. If they are sharp, then it may be a problem with stacking software. If not, then it is either the lense or the shutter.
. Shoot at F11 to f16 with a flash at high speed. That should eliminate the shutter vibration.
. I have shot with the D3300 at minimum distance and got quite sharp images.

Here is a shot with the kit 18-55 lense, at 29mm, F16, 1/400sec

[mdijb]

After receiving the lens today I did testing.  I used the chart and testing method supplied by Digilloyd.

I found NO focus shift Occurring with this lens.  Stopping down to f11 resulted in sharp images with good DOF.

However, i did see image degradation caused by shutter vibration.  Exposures of 1-2 seconds or more second were clean--less than that were less than sharp but the degree was mild.  I can verify the results reported by the Kasson articles.

That leaves shooting at F 5.6  instead of f11, and focus stacking--that will be next.

[ErikKaffehr]

Hi,

Yuck…, sorry to hear you have problems with vibration. No big surprise, but many users have not seen it. Depends on a lot of parameters.

You could crank up ISO or use electronic flash if practical.

Best regards

After receiving the lens today I did testing.  I used the chart and testing method supplied by Digilloyd.

I found NO focus shift Occurring with this lens.  Stopping down to f11 resulted in sharp images with good DOF.

However, i did see image degradation caused by shutter vibration.  Exposures of 1-2 seconds or more second were clean--less than that were less than sharp but the degree was mild.  I can verify the results reported by the Kasson articles.

That leaves shooting at F 5.6  instead of f11, and focus stacking--that will be next.

[Bart_van_der_Wolf]

Yuck…, sorry to hear you have problems with vibration. No big surprise, but many users have not seen it. Depends on a lot of parameters.

Indeed, but higher subject magnification, such as with long foca lengths and close-up or photomacrography will 'magnify' the effect.

Cheers,
Bart

[mdijb]

I  photographed some new flowers today with the new Macro lens.  I shot at f5.6, instead of f11and used a ND filter to get exposures of 2 seconds or more, and did focus stacking.

The results have been much more pleasing.  Much sharper and acceptable.

Still not quite as sharp and images taken with the DP Merrills  but much improved.

Out of the three variables that I changed, I believe the shutter vibration, and shooting at the f stop that gives best quality made the difference.

I have not done extensive, detailed testing but the improvement leaves me satisfied--Attention to more detail was the key on these macro images.

The 3D quality and sharpness of the Images taken with DP Merrils are remarkable, but with the changes I made with the A7r now give me results that approach, but not quite reach the results from the Sigma camera--With additional post processing of the A7r images, very acceptable results can be achieved.

MDIJB

MDIJB