ADP Photography | Macro Lenses: Getting it all in focus

Macro Lenses: Getting it all in focus

May 13, 2018  •  Leave a Comment

Macro lenses are great to work with; true macros that produce the image in full on the censor and have a fixed aperture can give wonderful shots.  I use the Sigma 105mm Macro f/2.8, my experience of it has been great, the lens can be wonderfully sharp...but of course only when used correctly.

Dreamy smooth bokeh isolates the subject and always looks good so f/2.8 is the go to setting, right?

Well, no, not always. 

Focal length and distance to the subject also affect the depth of field (DOF) and so, being a 105mm lens (+ a crop sensor) and getting up close to fill the frame, results in a DOF of just 0.19cm (with a distance to subject of 50cm).  That’s not easy to keep in focus hand held, regardless of shutter speed. (Stats according to Aimens DOF Calculator App).  You can try the rocking back with a fast shutter speed and high speed shot mode, close to the spray and pray technique I guess, but could work. 

Solutions then...

Specialist Macro lenses – normal macro lenses should show the image at full size, but there are also lenses around that offer even great magnification, one I’ve heard of is the Lomo 3.7x, also an 8x. These are called microscopic lenses I believe.

Increase the aperture – on some lenses you can probably safely go down to f/16 before diffraction starts to soften the image, and if you are filling the frame, ultra smooth bokeh shouldn’t be a factor, but even if you have some background, you can probably get to f/8 or f/11 (depending on your distance to subject) before the background becomes a problem.

Move further back – too far though and you won’t fill the frame.

Focus stack – this may be the only option if you want to maintain a creamy smooth bokeh and/or keep the frame filled with the subject.  Thanks to modern software, it’s relatively easy.

 

Photoshop has an auto mode.  Edit>Align Layers first, then Edit>Auto Blend Layers>Stack Images and some whizzo algorithm does it’s thing to work out what is/isn’t in focus and automatically applies layer masks and gives you a final image.

Recently though, PS didn’t quite hit the spot...some areas of the flower were left blurred as it choose the wrong layers/areas to masks, only slight, but noticeable around the centre of the flower.  I could’ve adjusted the masks manually.  Who am I kidding? No I couldn’t! I don’t possess that kind of PS skill!  Working out what’s showing and what’s masking what over 7 or 8 layers is beyond the scope of my brain power.

Enter specialised software. 

I hadn’t used a bespoke stacking program before so performed a web search to see what was recommended.  It came up with a couple that I tried, the first, the interface was a little bit weird, I needed as low a learning curve as possible.  Stacking is not something I do a lot, so I could well do without spending hours learning how to use a program.  The one I used to obtain the result below, stacked from 9 images, was Helicon Focus 6.  I performed this while using the trial program, and, no sponsorship involved, I have to say that I will have to buy this software.  It seems to have done the job very well. 

 

What do you use for macro work?  Do you have any go-to settings to ensure good DOF?  Share your thoughts with a comment!

Best wishes

The Frustrated Photog.


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