Friday, 7 October 2011

Macro Flash Diffusion

[note that a follow up post on macro flash diffusion, posted on 24th June 2015, is available here]

Many photographers rely upon flash when shooting high magnification macro and so the effective diffusion of that flash becomes crucial to the resultant image quality. I've done a lot of experimenting in recent years with different forms of diffusion and am now fairly happy with the light quality that I'm getting.

Below I will outline how I diffuse an MT-24EX flashgun and a Canon Speedlite (e.g. the 580 EXII) for use with a Canon MP-E 65mm macro lens or other short focal length macro lens, such as the Canon 60mm macro. Diffusing flash for higher focal length macro lenses is much more difficult because it is harder to get the flash close to the subject. As a result I don't use flash with anything other than short focal length lenses.

Diffusing the MT-24 EX twin flash:

The key to successful diffusion is to make the diffuser as large as possible and to position it as close as possible to the subject. Here is my current diffusion set-up:

PLEASE CLICK ON ALL IMAGES TO VIEW LARGER VERSIONS:



The 2 domes both started life as the front piece of a Lambency type diffuser, as shown below:



these diffusers are cheap and readily available from Ebay (search for lambency diffuser). The front piece, which curves inwards in the original diffuser, pops out and I then just cut off the rim around the edge. I then faced the issue of how to mount the 2 domes in front of the 2 flash heads. The solution was to hotglue strips of velcro to the domes, at the top and the bottom of each, and then to attach self-adhesive velcro to the top and bottom of each flash head. The following images show this more clearly.




the advantage of velcro is that it is then possible to adjust each dome to move it closer, or further away, from each flash head as required. In the image directly above I have simply unhooked the 2 upper pieces of velcro to allow the domes to fall forward to show them off more clearly,

The final step in the mounting process was to drill a small hole in the inner edge of each dome and to feed through a thin white cable tie. This then holds the 2 domes together and makes the whole set-up more stable. Also, holding together the 2 domes reduces the extent to which the diffuser produces 2 distinct reflections.

While using the 2 domes alone provides reasonable diffusion, it was still possible to see hotspots from the 2 flash heads on reflective surfaces. I therefore covered each flash head with regular kitchen roll and also lined each dome with kitchen roll. This extra diffusion removed all hot spots resulting in nice even light.

I currently raise one flash head on a Hama hotshoe, as shown below, with the aim of allowing one flash head to provide light directly from above. If I'm honest, it doesn't make a huge amount of difference.



Here are a few example images. The first 2 are highly reflective insects and hence provide a good test of diffusion. In my opinion the light looks evenly spread and reasonably natural looking.

A Garden Chafer Beetle:



A Flower Beetle:



On a less reflective insect, the light could almost pass as natural light. The hoverfly image below was taken using flash alone, with no ambient light (i.e. the camera settings were such that if the flash didn't fire the image would have been pure black):

A Syrphus species hoverfly:





Diffusing a regular flashgun such as a Canon Speedlite 580 EX II:

I found a very effective way to diffuser a regular flashgun was again to use a Lambency diffuser. The first thing I did was to line the outside of each diffuser with silver kitchen foil to prevent light loss and to hold this down with black insulation tape. This also makes the diffuser look smarter. The image below shows the diffuser with the front dome removed.



I then replace the front dome and cover the front with kitchen towel, held down around the edges with black tape as shown below.



The diffuser is then finished. However, it is very important not to position the flashgun on the camera's hotshoe (as shown in the picture on the diffuser box above) as it will be too far from the subject. Instead, it is necessary to use a side bracket, ideally with a ball head, which will allow the flashgun to be angled over the subject. One option is the Hakuba LH1 bracket (again, look on Ebay) although it is a little flimsy and so not ideal for heavier flashguns. The image below shows a 580EX II Speedlite on a Hakuba LH1 bracket with an earlier prototype diffuser, but gives some idea of how the diffuser should be positioned.





Here is an example of a very reflective Seven Spot Ladybird photographed using the Lambency-based diffuser:



Please comment below if you have found the above useful, if you would like more information or if you have any other thoughts or queries.


24 comments:

  1. Very interesting read Matt. Thanks for sharing. Any future entries planned that would deal with flash/camera settings for macro work?

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  2. thanks for the comment John. My standard settings for flash lit macro shots are 1/160 sec, ISO 100 and an aperture of between f5.6 and f13, depending on the degree of magnification (the higher the degree of magnification with the MP-E 65, the greater the diffraction softening and hence at 5x magnification, for instance, I tend to shoot at f5.6). If I'm using a regular macro lens with flash (such as the Canon 60mm macro) I tend to use f13. I set my flash to ETTL with flash exposure compensation typically of -1/3 or -2/3. For a pale subject, which the camera would tend to under expose, I may not need any negative compensation or may even need some positive compensation. Conversely, for a dark subject I may need more than -2/3 compensation.

    I hope that helps.

    best wishes
    Matt

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  3. Thanks for taking time to reply Matt. Yes, it answers a lot of my questions.

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  4. Hi Cole

    Came across this in your flickr profile.

    Gonna try a setup like yours as I am not 100% happy with my lighting, still getting harse highlights.

    Out of interest what makes you choose 1/160 for your shutter? Most people use 1/200. Does it make a difference in the lighting quality ?

    Regards and thanks for the info.

    Great photos btw.

    John

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  5. Hi John,

    Thanks for your comment. The shutter of 1/160 is just chosen out of habit. My images are fully lit by flash so the shutter speed is not doing anything and it's the duration of the flash that determines the exposure.

    Good luck with your new flash set-up.

    best wishes
    Matt

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  6. If the shots are hand-held, does a higher shutter speed help re. reducing image being out of focus due to any slight movement which is of course magnified in macro?

    Thanks,

    Geoff

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  7. Hi Geoff,

    A high shutter speed would help if the image is not flash lit or only partially flash lit. But if the image is lit entirely by flash (as most of my high magnification images are) then the shutter speed doesn't matter as the flash itself acts as a very fast shutter speed. In such cases, it is the duration of the flash that determines the amount of light entering the lens aperture. However, you have to ensure that no natural light is entering the image (i.e. if you switch the flash off the image should be completely black) otherwise you can get blurring due to camera movement.

    best wishes
    Matt

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  8. hi matt,thanks for the info on the lambency diffuser,now made one last nite,all seems good so far,will try it out better at the weekend tho,must say its a bit heavy though,popeye arms this summer me thinks

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  9. Thanks Matt, I have looked at all your macro photography tips and find them really helpful. Am an absolute beginner having only concentrated on bird photography until now but have bought a Sigma 150mm and aCanon speedlite. Now I just need the wind to drop a little, the rain to stop to have a go. It is brilliant having a site such as yours where you freely give so much help. Thanks. (I hope to manage one on UKNP eventually)
    Kim

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  10. you're welcome Kim and thanks for your comments. I'm glad you find the blog helpful. Do drop me a line if you have any specific queries (not that I'm claiming to be an expert!). You're right about the wind and rain, it's not good for macro photography!

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  11. Hi thanks very helpful, I've imitated the flash diffusion setup for the MT24Ex & MPE combo although I didn't fill the domes with anything. Still getting highlights so gonna go the full hog. Funny at first I thought no I'll just use stofens, then I thought Id change them for puffers and now I gone with the above as used also by Rob Ault, Abovelifesize and many others! Thanks for your info!! Muzby1801 (flickr)

    http://www.flickr.com/photos/muzby1801/

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  12. Woohoo, a proper flash bracket!!! I've been looking for ages. I just about gave up after my poor attempt at a home made bracket failed miserably. I've been using the 430EX hand held, triggered by the 7D, and when it works it's great, but trying to keep the 7D steady in one hand is near impossible!

    Thanks for a fantastic post.

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  13. you're welcome Matt. Handholding the flash doesn't sound very easy...!

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  14. Hello Matt
    I have been experimenting in the wonderful world of macro photography for about a year now but have done very little macro flash work because of a lack of knowledge on the subject. Your information is very helpful and encouraging.
    I have a Canon 50D, a Canon 580 EX 11 Speedlite and the Hakuba flash bracket. I bought a lumiquest mini soft box and was wondering if this is a suitatble set up for this type of work or if the soft box can be modified.
    Secondly I noticed that in your reply to Geoffs question about shutter speeds you mentioned that using flash their should be no natural light entering the image. How do you accomplish that in the field in day light.??
    Thank you for your time and advice in advance.
    Regards.
    Alan Ginn

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  15. Hi Alan,

    Thanks for your query. I've never actually use a Lumiquest mini soft box but it looks like it would do the job nicely. If you find it is still producing harsh highlights (it probably won't) then you could always add a layer of thick paper or kitchen towel to the front or inside of it. Regarding your second question, if your camera setting are right then they will not let sufficient light through the lens to naturally illuminate the image. So, in manual mode, try setting your camera to f10, 1/160, ISO 100 and take an image in normal light conditions. Without flash you will find your image is completely black. If you now use flash with these settings in means your image is entirely lit by the flash. I hope that helps.

    best wishes

    Matt

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  16. Hi Matt
    Thank you so much for your time and prompt reply. It is very much appreciated.Your work was brought to my attention by Muzby 1801 who is a recent contact of mine on Flickr and wrote to you on July the 1st above.
    I was wondering if I may visit your flickr site and if so what would the url be? If you are interested, my url on flickr is. http://www.flickr.com/photos/bigalginn/
    my screen name is zenman3. I have a varied set of macro images including insects, spiders, botany and still life but sadly only a couple using flash so far.I am very keen to learn all that I can about this medium of photography and share the results with like minded photographers like yourself.
    Once again thank you and you have an awesome portfolio of beautiful macro work.
    Kind Regards
    Alan.

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    Replies
    1. you're welcome Alan. My username on Flickr is Matt Cole1 and my photostream can be found at http://www.flickr.com/photos/25171701@N08/

      best wishes

      Matt

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  17. Hi Matt,

    Please could you explain why the colours in the Syrphus species hoverfly image above look natural ie. why isn't the background dark as you might expect when using flash as the only light source?

    Kind regards,

    Colleen

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  18. Hi Colleen,

    The background on that image isn't dark because I made sure there was there was a backdrop of some kind (I can't remember precisely what) close to the main subject. Background darkness is caused by flash drop-off when you effectively shoot into empty space. In the flower beetle image above the hoverfly image, I was careful to bend upwards the green leaf on which the beetle was sat so that it formed the background. Similarly in the final ladybird image I made sure my shooting angle was such that the yellow petals formed the backdrop.

    Going back to the hoverfly image, the reason the colours and lighting on the hoverfly itself look natural is because of the diffusion described in this post. This has prevented harsh shadows and highlights.

    best wishes

    Matt

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  19. That's very helpful Matt, thank you for your explanation.

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  20. Great site Matt.

    As a newcomer to macro photography ( I've just purchased a Canon 60mm) and I was considering buying a ring flash.
    Forgive me if this has been asked before but what are your views on them? Are they a good place to start for a novice?

    Many Thanks

    Ian Clarke

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  21. Hi Ian,

    Thanks for your comment. I'm not a fan of ringflashes I'm afraid. They are very difficult to diffuse and, since the bottom of the ring protrudes below the bottom of the lens, they make it very difficult to take an eye level image of an insect that is on, or close to, the ground. My preference would be for a single flashgun, diffused as suggested above.

    best wishes
    Matt

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