Macro Images appear Soft

[Dr_Jimmy]

Hi there,

I am relatively new to Macro Photography and after much experimentation I still do not appear to be getting the results I require.

And I am wondering where it is I am going wrong, I have a couple of Images listed on this site under the Photo Critique Section, to try and analyze where it is I am going wrong, some people at Cannock Photographic Society believe it might be down to either a faulty lens, but I personally believe it might be down to poor technique my end.

I have found that shooting at a Higher ISO, is one factor which ruined some images for me, but I had some slight wind movement I tried to counteract with a higher ISO, perhaps next time off camera flash might help.

So I have taken a series of pictures of a "Crib Board and Matches" to try and analyze the results to see where the issues lie



And this appears correct, so I am at a loss.... But I did notice that at F32 the Front to Back Sharpness was not quite correct, or not as sharp as I had anticipated, the DOF seems to be only about an Inch or Less... Is this correct?

If so why are my results not as sharp as I would like them to be...

My equipment is:

Nikon D70s
Sigma 105mm Macro Lens
Manfrotto 190CLB Tripod with 390RC2 Head
Macro Focusing Rail
Remote Shutter Release

Any Assistance on this would be much appreciated

[WestLothian]

Hi

Yes they do look soft and even the closest matches look to be out of focus.
Are you focusing manually or using the camera autofocus?

In macro it is often worth using manual focus and taking a "bracket" of shots passing the focus from the near to the far side of the object and slightly beyond. This is particularly important for spectacle wearers. It is quite natural to focus your eyes at less than infinity through the viewfinder and that can leave your sensor still with a bit of ground to cover in order to be really sharply focussed.

[WestLothian]

Also on the DoF question it depends on how far you are from the subject.
For 31cm (12") in front of the lens the subject would be at 41.5cm from the sensor, giving 1.49cm (19/32") depth of field for your camera.

(This is a handy calculator:- Online Depth of Field Calculator)

Camera, film format, or circle of confusion = Nikon D70

Focal length (mm) = 105

Selected f-stop = f/32

Subject distance = 41.5 cm


Depth of field
Near limit 40.8 cm
Far limit 42.3 cm
Total 1.49 cm

In front of subject 0.73 cm (49%)
Behind subject 0.76 cm (51%)

Hyperfocal distance 1733.2 cm
Circle of confusion 0.02 mm

[Andy Warne]

Hi,
The Sigma 105mm is a bit soft and images need processing to sharpen them up a little.
Stopping the aperture down increases the sharpness only up to a point (around f16 generally, depends on the lens), beyond which it actually makes it softer due to diffraction.
And unfortunately depth of field is measured in millimetres when it comes to macro!

What shutter speed were you using when taking these shots?

[Dr_Jimmy]

Hi there,

Focusing was done Manually hence the use of the Macro Focusing Rail, The Camera was set to Aperture Priority for ease in the Experimentation stage of things.

The Subject was focused at 1:1 Ratio and the lens was 5.7" roughly 145mm from the subject.

I have not done any bracketing of the shots at this stage, I have just gone up the scale from F2.8 to F32 to try and understand my lens.





If you look at the Images above they are all wrong, even the Strawberry Flower looks wrong, it's just not sharp, it's out of focus in places.

Could this be an issue with the Lens or with Me and my technique.

What other experiments can we try?

Any suggestions any one might have I am prepared to try as I need to know if the lens needs to go back before it's out of Guarantee.

I have had it around 6 months now and I am still struggling to get a decent image from it.


Also if the Lens is OK what Post Processing do you recommend, to combat the Front to Back Sharpness issues I appear to be having.

[DaiTheDragon]

The images don't have any exif data so I don't know what shutter speed you were using. The butterfly and flower shots are not sharp anywhere in the photo so I would say it's down to human error with focusing. For the majority of my macro shots I use about f16 and 250sec.
Try this as an experiment. Place a sheet of newspaper on a table at abot 45% angle. Draw a rectangle around a small paragraph with a pen. Place camera on tripod and try settings of f11 to f22 and shutter speed of 200sec.
One thing you may want to check is your viewfinder diopter adjustment. Whe I go out for a walk I find a sign with high contrast and let the camera auto focus, I then look through my viewfinder to see if diopter adjusment has accidently changed.

Dai

[WestLothian]

1. Do you normally wear glasses?
2. Have you set the viewfinder diopter focus to give you relaxed viewing at infinity?
3. Do you try to think of looking to infinity while you focus not looking closer at the subject?

From the strawberry flower picture the new bud at the bottom left is much sharper so your camera and the lens is performing well. I think that you are setting the focus to close due to your own eyesight either not looking into the viewfinder at infinity or due to a out-of-adjustment diopter on the viewfinder.

A simple adjustment of the viewfinder will sort it all out I'm sure.

[Dr_Jimmy]

Ok That's given me something to think about, had the camera just over Twelve Months and only ever adjusted the diopter focus once, might be whats causing me so much trouble.

I do not Normally wear glasses, but I do a lot of Close Up Work, I am an Electronics Design Engineer and do a Lot of Surface Mount Component Soldering, these components are like specs of dust, and I hand solder these using tweezers and occasionally a magnifying glass, and the optician did say I have a slight weakness in my Right Eye and Prescribed some glasses for Close Up Work Use and Computer Work.

So if I were to Adjust the diopter focus, how would I go about doing it, It has forecast bad weather tomorrow so ideally I do not wish to go out and get soaked, so how can I adjust it in the House, can I use a Brightly Lit Object?

I just had a quick look at it, and the diopter focus is set to it's most Negative Position, and seems to in effect have a zooming in effect, also what lens should I use to Adjust it with?

I just did a load more experiments testing out the Entire Range of the Macro Lens 1:4, 1:3, 1:2, 1:15, 1:12 & 1:1, from F2.8 to F32 still using the Matches and not a single image taken is Front to Back Sharp with Manual Focusing.

So I did try using the Auto focusing Side still set at F32 using Aperture Priority and the image still did not have any Front to Back Sharpness.

One point in Question, that was raised was the Shutter Speed

The Strawberry Flower was shot at 1/100 Sec at F13 Using Aperture Priority Mode



The Fly above was shot at 1/30 Sec at F16 Using Aperture Priority Mode

The "Crib Board" Experiment ran from 1/160 Sec at F2.8 to 0.6 Sec at F32.

Could this be where I am also going wrong, is my Shutter Speed set way too Loooow?

This would in Effect give me some motion blur, as I am unable to "Lock the Mirror up" only for cleaning or serving, I could be getting some slight movement as the mirror bounces up, I am using a remote release so pressing the shutter isn't an issue.

OK what's a suitable series of Test I can try tomorrow.

I imagine First is to Try and sort out the diopter focusing.

Then try DaiTheDragon suggestions.

Anything Else?

Ps Thanks Everyone for the help so far, it really is very much appreciated.

[WestLothian]

Your work means that you don't spend much of your day focussed at infinity then!

Ideally that is the feeling of looking into the distance that you should have when viewfinding.

Use any lens to set it - ideally a 50mm f/1.4 LOL (brightest in viewfinder)

Find a calendar or set some other printed sheet on a wall.

Stand about 10 feet away and hold the camera at the same height as the calendar.

Use the autofocus of the camera then adjust the diopter to be really sharply focused with your eye as relaxed as possible and looking into the distance.

[HowlinWolf]

A much easier way to set your viewfinder diopter to your eyesight is to remove the lens and point the camera at something bright i.e. the sky (not the sun!), and adjust the control until the focusing brackets are sharp. It's the focusing screen that your eye needs to focus on. Job done.

HW