Saturday, 16 November 2013

Forsythia Stem Gall

Growing in the corner of next doors front garden is an old forsythia bush. It had got to the stage where some of it was almost blocking the grass verge which is the nearest we have to a public footpath so I asked permission to chop it back somewhat.

While I was disposing of the branches I noticed many of the smaller twigs were covered with nodules. A search found that these are Forsythia Stem Galls, probably caused by the bacterium Pseudomonas savastanoi.

2013-11-16 10.12.01x

It seems a long while since I tried a serious macro using stacked photos so I got out the Heath Robinson effort I built a few years ago. This consists of a stripped down PC DVD player and an Arduino Nano. The Arduino drives the small stepper motor in the DVD player which moves the item being photographed a tiny distance further away from the camera at each pulse. At the same time it tells the camera to take a photo once any vibration has settled down.

 2013-11-16 12.51.46

The Canon 350D was fitted with a 70-200mm zoom lens with a Raynox DCR-250 macro lens added. As well as natural light an LED ring flash was used on continuous light. Each photo has a very small depth of field:


72 photos were taken, each with the gall a tiny fraction further away from the lens so each had a different part in focus. Finally I used CombineZP which stacks together the in focus bits from each photo. The idea is to end up with one photo with all the subject in focus:


This is the best result I have ever had using CombineZP so am well chuffed, worth waiting over 20 minutes of processing time to get the finished photo.


  1. Now that is very impressive. I keep meaning to have another focus stacking do. This is really inspiring. we are in for a few days bad weather so I'll have another go.
    I have always started at the front and worked to the back but I can't see it can make any difference.
    I'll go and get the camera lead out and tether it to the lap top.

  2. Adrian. I seem to remember reading that CombineZP works either way. It just so happened that that was the way the DVD mechanism was set up. Come to think of it, CZP used the shots in reverse order, maybe just the way XP presented them.
    I think this subject was more suited as there were lots of areas of tiny detail the software could work with.

    1. I don't use a stepping motor. I use a macro slide. I did buy a stepper from Maplin but it wasn't up to driving the camera and lens. Using Focus stacker it used to tell me I'd' twiddled too far between shots. I'll have another go with CZP. I didn't get on with it at all three years ago. I got nasty neutral grey bits popping into the image.
      I'll have another go but yours will take some beating. I have been saving a dead jumping spider I found but it as fallen apart. I knew I should have used it straight away.

    2. Time for a tube of super glue Adrian ;)

  3. Replies
    1. It worked better than I expected Keith.

  4. Very impressive, John! The detail is astounding.

    1. Thank you Wilma. I sure does show the detail.

  5. Wow ~ that is another amazing roundtuit with grand results. You could probably whip one of these things up ~ I think SuperSquirrel(TM) would enjoy it (and if not, may find somewhere else to live, once his dizziness subsided) Twirl-a-Squirrel link or this one.

  6. Thank you for the links Glo. There are times I feel like buying something like that.


Thank you for visiting. Hope you enjoyed the pictures. Any comment, or correction to any information or identification I get wrong, is most welcome. John

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