Thursday, 26 March 2015

depth of field of macro lenses.

This is a comparison of the depth of field of macro lenses. I am doing this so I can choose the most appropriate lens for focus stacking or macro photography.

Canon 1-5x MP-E 65mm f/2.8


Magnification       Depth of field

x1                                0.8mm
x2                                0.3mm
x3.5                             0.1mm
x5                                0.07mm

Data from http://pikespeakphoto.com/tests/canonlens_mp-e.html.


Olympus Zuiko x0.5 50mm f3.5 with 12mm extension tube


Aperture                    Depth of field       
                                (Meaured roughly,
                              by photographing a ruler)

f3.5                                   about 5mm
f5.6                                   about 10mm
f8                                      about 20mm
f11                                    about 25mm
f16                                    about 35mm
f22                                    about 70mm





Wednesday, 25 March 2015

Focus stacked rose bud

Today I have been trying again with my focus stacking system. This time experimenting with a larger subject, and a black background.

The focus stacked image below is a small rose bud that is in the process of opening. It was taken at x1 magnification. It's come out quite well.


Below is one of the slices from which the image was compiled. 



This is a close up of the image. I like the detail on the leaves very much. I think that keeping the subject completely still is going to be a challenge, with soft material like this. 



One of the challenges as keeping the light levels stable as my subjects are lit with natural light through a window. Helicon focus reports on the fluctuations of light levels, and for the coin that I used for scale today the light levels fluctuated by 22%. No fluctuating light level was reported for the rosebud image above. It's clear from the image below that movement has been a problem with the rosebud. No similar problems are seen with this more easily anchored subject. 



Next plans:

I think the next thing will be to work out the exact depth of field of my macro lenses and figure out the minimum number of slices needed to cover a given specimen. Perhaps if I can get the minimum number of really good slices then I can eliminate the ghosting. 

Out of interest, here is the rosebud image with the black background turned completely black in photoshop. I suppose that could be good or bad depending on the application of the image. 






Tuesday, 24 March 2015

A Fern Crozier of Extreme Smallness

This page follows on from Focus Stacking Coins of the Realm.

The aim of my focus stacking project is to take photos of tiny, tiny ferns, and today I am making my first attempt. So here it is, a fern crozier of extreme smallness.

This focus stacked photo was taken using the smooth.py script described on my previous blog page.

The crozier is the new unfolding leaf of a sporophyte fern plant. This leaf shown below is only the third leaf ever to be produced by this plant. I think it's turned out pretty well. The next thing will be to get the background and lighting right so that the detail is more clearly visible.

The big green splodgy thing on the bottom left of the photo is the gametophyte fern.



Below are a couple of the individual photos from which the focus stacked image above was compiled (using Helicon Focus). As you can see, depth of field is a bit of an issue at this level of magnification (5x). The image was taking with a Canon 5d MkII and a Canon M-EP 5x macro lens.



Here are some photos of the setup that I used to take the photos:

















This is a photo of the plant, back in it's pot, looking very small indeed.


Focus Stacking Coins of the Realm.

This page leads on from Testing the Focus Stacking System.

Today I've been doing a bit more testing of my focus stacking system, photographing a 5p coin.

The purpose of this was to test the effect of taking shots at larger and smaller increments by controlling the scanner differently.

The script scanprogramme.txt gives larger increments (about 0.08mm I think). The script smooth.py gives smaller increments (about 0.02mm-ish, probably).

According to the documenation of my camera lens, the depth of field at the maximum 5x magnificaion is about 0.1mm, so the bigger increments should really be enough.

Here are some results:

With larger increments the individual shots look like this:



and the focus stacked image looks like this:



With smaller increments the individual shots look like this:





and the focus stacked image looks like this:





I find it hard to say whether there is any improvement from using the tiny increments over the larger ones.


This is the setup that I used (The train set in the background is the important part, obviously):







The next page in this series is A Fern Crozier of Extreme Smallness.

Monday, 23 March 2015

Testing the Focus Stacking system

This post follows on from Focus Stacking - Connecting the wires.

I just tested my new focus stacking system and it was fairly successful. In the end I mounted the subject on the scanner and just triggered the camera manually using the shutter release button. The scanner ticks loudly every time the arm moves so it wasn't too hard to know when to release the shutter.

I used this python script to drive the scanner. The camera setup was a Canon 5d MkII with a Canon MP-E 5x macro lens. The camera was just resting on a box and working in auto mode. The battery was stuck to the arm of the scanner with a bit of blue tack to stop it wobbling.

Here are a few sample images:






This is the focus stacked image, compiled by Helicon Focus:


There's some strange fuzzy stuff going on at the top, but otherwise that seems to have been fairly successful. 

Good stuff. 



This post follows on from Focus Stacking - Connecting the wires.


The next page in the series is Focus Stacking Coins of the Realm.

Monday, 2 March 2015

Another bit of spring has arrived...



Another touch of spring has arrived in my garden today. The picture looks a bit unreal because I had to photoshop the shadows and highlights to make the flowers stand out from the soil. They look just as unreal in real life though. Such colours!

Sunday, 1 March 2015

Bud-watch 2015

I've just been out into the garden to see which of the plants are thinking about bursting their buds for the coming spring.

There seems to be several categories of plants there just now:

  • One set have decided it's time, and their buds are open, and growing quickly. 
  • One set have had buds ready to go for a long time, but they are not currently growing. They're just biding their time. 
  • One set have their buds still firmly closed
  • The strawberries and forget-me-nots are in a class of their own, since they never really went away for the winter anyway.
Here are some photos of what I've found. 


Plants that think spring has arrived. 


The wild plum, as usual, is the first to commit. It's buds were tightly closed last week, but it is now in full growth and will be flowering soon. 



These crocuses have definitely decided to get on with things.


Those are the only two that I could find that had definitely decided that spring had arrived. 


Plants that have been ready since autumn, but are still not convinced. 


Below are the plants that have pushed their buds through the ground, or have opened the buds on their stems, but which are waiting for warmer weather before they do anything with those buds. 

I always find these plants very interesting as they are not protecting their soft growth by keeping the buds completely closed or below the ground. They seem to like to get a little bit ahead, but not commit to serious growth until the weather is fairly warm. 

So here are the plants:

These buds have been through since late autumn, but will not do anything for ages yet. Their name escapes me just now. 


The sedum also pushed its buds through last autumn, but will not put in further growth above ground for quite a while. 


The rose is considering its position but will not be doing any serious growing any time soon. 


The honeysuckle has also opened its buds, but is now waiting. 


Finally the paeony has its large buds ready and waiting, but is not yet gung ho enough about the weather to actually start growing. 



Plants that still think it's winter


The most cautious plants are the set that are keeping their buds tightly shut for longest. For some reason this includes most, but not all, of the fruit trees. The wild plum is always slightly ahead and the others follow behind. Here they are the plants that commit last:


The apple tree will probably be the last to burst its buds. Once the apple buds are open then I always know that spring is definitely here. Apples never rush things. 


The pear tree is keeping its buds shut too. They will probably open slightly before the apple buds. 


The cherry tree is keeping its buds shut too for now. 



What do the earliest herbaceous perennials think?


What about the herbaceous perennials that keep their above ground growth over winter?

I always like to watch a particular set of herbaceous perennials that tend to commit to spring growth early. For me, their actions are a real sign of the timing of spring. 


This year, the forget-me-nots are still biding their time. They have last year's growth, but nothing new for this year. 


At this time of year the strawberries keep their leaves pulled down low to the soil almost as if they were trying to keep them warm by trapping a little bit of warm air underneath. That's what's happening now, and they have the deep read band around the edge of the leaves. I always assume that colour is something to do with frost proofing, but I'm not sure what it is exactly. I see the same pigment in the privet leaves in winter. 




Is it spring yet?


So there we are. It's mostly still winter in the garden here, but the wild plum has decided to get going, and that means that everything else is not far behind. As in every year, it will be very interesting to watch how the temperature changes as we go through March and April, and so see how soon the various plants commit to opening their buds and getting on with spring growth. 


This is continued on part 2.