MF Macro examples

[synn]

You can download c1p7 demo and use it in db mode to do tethered shooting. It should work with your back.

I'd say do a tethered shoot to eliminate focusing errors and then check the files to see if the lens has a sharpness issue.

[Justinr]

Just for comparison here's one taken on the Nikon D3, 24-85mm at 85mm.

I would say there is more definition in this shot but it is difficult to be sure without doing a Macro back to back comparison on the cameras. Could it not be the lens but the firmware that's causing the problems in the Mamiya ZD back? I might follow Synn's advice and see if a different RAW converter gives any improvement.

Edit. I found the Mamiya Capture Software and as I feared it doesn't seem to get on with Windows 7, it installs but won't open images.

[EricWHiss]

I'm pretty sure at f/16 with your back, you'll still get usably sharp images and you'll need it since the DOF will be very thin otherwise.
In the comparison you posted of the pentax and lichen, it seems that neither subject is entirely within the DOF as both have areas of sharpness and softness. I'd say your DOF is only a few mm deep only.  This isn't enough to catch everything.


Have you tried backing away from your subject yet?  A farther camera to subject distance will increase the focus DOF (depth of field).   In the example's I posted, the one with the rollei 150mm the DOF isn't sufficient to cover the thickness of the medallion, but in the mamiya 120 samples you can see several inches of DOF - therefore backing away is one way to get your subject to be all included in DOF.    It means you have to crop down your file significantly, however you may end up with a more usable image.  

[Justinr]

I'm pretty sure at f/16 with your back, you'll still get usably sharp images and you'll need it since the DOF will be very thin otherwise.
In the comparison you posted of the pentax and lichen, it seems that neither subject is entirely within the DOF as both have areas of sharpness and softness. I'd say your DOF is only a few mm deep only.  This isn't enough to catch everything.


Have you tried backing away from your subject yet?  A farther camera to subject distance will increase the focus DOF (depth of field).   In the example's I posted, the one with the rollei 150mm the DOF isn't sufficient to cover the thickness of the medallion, but in the mamiya 120 samples you can see several inches of DOF - therefore backing away is one way to get your subject to be all included in DOF.    It means you have to crop down your file significantly, however you may end up with a more usable image.  

I think that I am getting somewhere now.

This was taken with the Mamiya 120mm lens at f16 and and about an inch further away. The big difference is though that it is a stack of 12 shots using Combine XP. I'm still not 100% happy but it's looking a lot better.

[ErikKaffehr]

Hi,

Is the crop you show actual pixels? What distance are you shooting at (distance from sensor plane to subject)?



Some ideas to improve your image:

- Have you tried different sharpening methods?
- You could repeat the experiment with f/8, even if I feel you should have good results at f/16

Best regards
Erik

I think that I am getting somewhere now.

This was taken with the Mamiya 120mm lens at f16 and and about an inch further away. The big difference is though that it is a stack of 12 shots using Combine XP. I'm still not 100% happy but it's looking a lot better.

[synn]

Extension tubes will also help to get closer to the subject without facing the issues you're facing now with close focusing.

[EricWHiss]

If you are willing to focus stack, then it's better to use a little bigger aperture - perhaps f/11 would be a good compromise between number of frames and sharpness for your setup.

Definitely you've made some improvements, but still I wonder if this is as sharp as you can get it? 

[Bart_van_der_Wolf]

If you are willing to focus stack, then it's better to use a little bigger aperture - perhaps f/11 would be a good compromise between number of frames and sharpness for your setup.

Stacking is indeed a compromise between optimal quality with the lens used, and number of frames. One should first establish the best aperture that's possible for the magnification factor one requires. Since close-up focusing not only increases the magnification factor of our subject matter, it also magnifies the diffraction and defocus blur per pixel. That will lead to an optimal aperture that may be a bit wider than expected. Depending on the specific lens involved, an initial guess at 2 stops narrowed than wide open is often not too far off the mark.

That will lead to a DOF, based on a COC for the intended use of the image, and that will dictate the number of frames for stacking. 

Definitely you've made some improvements, but still I wonder if this is as sharp as you can get it?

I share your doubts.

Cheers,
Bart

[Justinr]

So what we are saying is that if using focus stacking then we might as well rely on the software to provide DoF whilst trying to provide the sharpest material for it to work with? It sounds a sensible approach and I'll try it again with a much a wider aperture. Many thanks for the suggestions so far BTW.

[Bart_van_der_Wolf]

So what we are saying is that if using focus stacking then we might as well rely on the software to provide DoF whilst trying to provide the sharpest material for it to work with?

Absolutely, assuming there are no other lens issues and the increased number of required frames is no objection.

As a tool to provide guidance with stacking, such as the number of frames needed to achieve a given output quality goal, you can use my free output quality planning tool, discussed here.

Cheers,
Bart

[EricWHiss]

Total aside, but I've been doing a LOT of lens testing lately and while some MF lenses like the Rollei Schneider ones reach their peak sharpness at or near wide open, many others such as older Zeiss MF are still developing sharpness stopped further and further down even as they become affected by diffraction.  Like Bart suggests, knowing the behavior of your lens will help you decide what aperture to use.  If you shoot at f/8  you'll need more frames for stacking.

But I am still wondering if you can't get a 'workable' image backed off a fair bit, not just a few inches but a few feet back.  Your lichen sample may only fill but a fraction of the frame, but you may get the whole of it within DOF then in a single frame.   I'm not sure what your intended use is, but perhaps if you end up with a3000 pixel wide crop with a sharp image it would be sufficient for your use?

[Phil Indeblanc]

I would take the UV glass off the lens, if anything to at least rule it out.

[Justinr]

Slight change of photographic subject just to try and get a handle on what's going on.

It's a dull afternoon so I went for f6.3 at 1/60th, ISO 200. Much above 200 and the ZD gets quite noisy and even at iso 50 noise can still be a problem which is why I'm not too keen on taking from a distance and then cropping right in, I fear it will exaggerate it. This shot is composed of 11 images.

There is something of a blur around the area of the clutch fluid reservoir which is more a software issue as one of the slices has that in focus.

[EricWHiss]

What do you get of the bike with just one image instead of a stack?  And with the 80mm?    I'm still wondering about your 120 lens….

[siebel]

 Keep also in mind that if you use extension, it makes the real aperture smaller. So f/16 at 1:1 is usually f/32.

Lest we create more confusion (Circles of? ) here, this needs some clarification. For purposes of discussing diffraction, f/16 is f/16, regardless of focus distance or magnification. At 1:1 magnification, the amount of light coming through a given lens opening, say f/16, is spread over 4 times the area it would be covering compared to infinity focus. Thus, any given spot on your sensor is receiving 1/4 the illumination intensity, hence the 2stop loss. The key word here is intensity (remember, e=i x t). This has nothing whatsoever to do with how much diffraction you have at that aperture. So, when your lens is set to f/16 and your image magnification is 1:1, your illumination intensity or exposure is the equivalent of f/32(2-stops loss) but your diffraction remains what it would be at f/16.

[Doug Peterson]

Lest we create more confusion (Circles of? ) here, this needs some clarification. For purposes of discussing diffraction, f/16 is f/16, regardless of focus distance or magnification. At 1:1 magnification, the amount of light coming through a given lens opening, say f/16, is spread over 4 times the area it would be covering compared to infinity focus. Thus, any given spot on your sensor is receiving 1/4 the illumination intensity, hence the 2stop loss. The key word here is intensity (remember, e=i x t). This has nothing whatsoever to do with how much diffraction you have at that aperture. So, when your lens is set to f/16 and your image magnification is 1:1, your illumination intensity or exposure is the equivalent of f/32(2-stops loss) but your diffraction remains what it would be at f/16.

That's not correct.

Diffraction is based on effective aperture, not marked aperture (unless your camera system makes adjustments to account for bellows-loss for the displayed aperture).

This effect becomes quite obvious when dealing with very high magnification imaging. At 18:1 magnification diffraction on an 80mp back is meaningful starting at a lens marking of f/2.8 .

Think of it from the perspective of the sensor: Here is the same sized physical opening, as seen with more and less extension:


You can read more about this in my article on Extreme Macro Photography.

[siebel]

That's not correct.

Diffraction is based on effective aperture, not marked aperture (unless your camera system makes adjustments to account for bellows-loss for the displayed aperture).

This effect becomes quite obvious when dealing with very high magnification imaging. At 18:1 magnification diffraction on an 80mp back is meaningful starting at a lens marking of f/2.8 .

Think of it from the perspective of the sensor: Here is the same sized physical opening, as seen with more and less extension:


You can read more about this in my article on Extreme Macro Photography.

You are right. I stand corrected. Thanks for jumping in!

[Justinr]

Eric

I have attached the middle slice of the stack taken with the 120mm. I didn't have too much time yesterday to do much more than this image.


Doug

I've just addressed myself to your link and two things occurred to me.

1. Lighting. I note that you shoot in the dark to avoid shutter 'shake' but do you feel that extraneous ambient light or slight over exposure will reduce the clarity of the image? I slightly underexposed the bike shots to test this (although it's in no way a true comparison) for the brighter areas of the lichen shots appeared the least sharp.

2. You use a motion table to move the subject through the plane of focus, is this to avoid having to touch or disturb the camera or do you feel that there is some optical advantage over moving the plane of focus through the subject as I do by adjusting the lens?

[Bart_van_der_Wolf]

2. You use a motion table to move the subject through the plane of focus, is this to avoid having to touch or disturb the camera [...]

That will potentially help, but,

[...]or do you feel that there is some optical advantage over moving the plane of focus through the subject as I do by adjusting the lens?

Optimal for stacking would be to leave the entrance pupil of the lens stationary with respect to the subject, and move the sensor plane for different focus planes. That will produce unchanged perspective between slices.

Second best depends on the ability to keep the entrance pupil as stationary as possible, probably by focusing the lens (if its focus throw allows such accurate and predictable setting). For really close-up work one can use a moving camera+lens bar, or use such a bar to move the subject (but try to have the lighting move along to avoid changing light directons).

Cheers,
Bart

[EricWHiss]

Eric
I have attached the middle slice of the stack taken with the 120mm. I didn't have too much time yesterday to do much more than this image.

This looks more like the front of the stack than the middle to me. What on the bike do you consider to be your target?