Some calibrated-diffuser insect shots

[GardenersHelper]

A discussion at another site led me to think more carefully about my diffusers, and specifically about whether they are producing a problematic colour cast. It turns out that they are, and it varies a lot between diffuser setups. It also turns out to be fairly straightforward to deal with, with (for my images at least, and to my eye) clear benefits in terms of image quality. I have written this up in this post in my Journey thread. These images are taken from the session in our garden I used to test a new approach which takes into account the colour cast produced by the diffusers I am currently using for medium sized invertebrates.

The images were captured hand-held with a small (1/2.3") sensor Panasonic FZ200 bridge camera with a Venus Optics KX800 manual twin flash, using autofocus and an aperture equivalent to f/45 on full frame. The last image used a Raynox 250 close-up lens. The others used a Raynox 150. These images are taken from this album at Flickr.

#1

1624 02 2020_03_14 P1040213_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#2

1624 07 2020_03_14 P1040240_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#3

1624 17 2020_03_14 P1040294_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#4 This one was not in good focus and has one of the wings clipped by the edge of the frame, but I thought it was unusual enough to keep anyway. I have used Topaz Sharpen AI with the "Stabilize" setting to try to reduce the impact of the lack of good focus.

1624 15 2020_03_14 P1040291_PLab3 SP9-Edit LR 1300h AIS-S by gardenersassistant, on Flickr

#5

1624 27 2020_03_14 P1040377_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#6

1624 28 2020_03_14 P1040381_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#7

1624 29 2020_03_14 P1040386_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

#8

1624 30 2020_03_14 P1040427_PLab3 SP9-Edit LR 1300h by gardenersassistant, on Flickr

 

[Cobra]

Another cracking set Nick

 

[Dave-Cornwall]

great images.

 

[DrHook]

Hi Nick,

Can I ask a question? On your Flickr page the EXIFs for most of these photos say you have used an aperture of f/8. How does that relate to you saying it is the equivalent of f/45 on full-frame? My apologies if this is a stupid question, I just can't quite work it out myself

Thanks, Roddy

 

[Deleted member 34016]

Nice set Nick

 

[GardenersHelper]

Hi Nick,

Can I ask a question? On your Flickr page the EXIFs for most of these photos say you have used an aperture of f/8. How does that relate to you saying it is the equivalent of f/45 on full-frame? My apologies if this is a stupid question, I just can't quite work it out myself

Thanks, Roddy

It has to do with the difference in sensor size between the camera I used (1/2.3" sensor, which is 6.17x4.55mm) and a full frame camera (36x24mm).

I can show you how to calculate equivalent f-numbers between these two sensor sizes, but I don't know enough about the underlying maths/physics/optics to explain why this is the case. It does however fit well with various practical experiments I have done (see below).

The 1/2.3" sensor has a crop factor of around 5.64. That is the ratio between the diagonal of a full frame sensor and the diagonal of a 1/2.3" sensor.

The equivalent f-number is the f-number times the crop factor. So in this case f/8 on 1/2.3" is equivalent to around f/( 8 * 5.64) on full frame = around f/45 on full frame.

Two equivalent f-numbers give the same depth of field and the same loss of detail from diffraction blurring, and so will give similar looking results.

Two setups used at equivalent f-numbers may not produce exactly the same results because of other differences between the lenses and sensors in the two setups. However, when using such small apertures as I use the blurring effects of diffraction are so strong that they tend to dominate the image quality and in my experience can produce results that are pretty much, or in fact completely, indistinguishable between an image captured with high quality camera/macro lens and an image captured with a point and shoot with a close-up lens. If you are interested I have examples I can show as between APS-C, micro four thirds and 1/2.3". These are unfortunately mainly not like for like, but I do have a handful of like for like real world, out in the field, comparisons between APS-C and 1/2.3".

Since I don't get better image quality from high quality kit (because I go for minimum aperture to maximise depth of field, and therefore get maximum diffraction blurring), my choice of kit comes down to what kit I prefer to work with, and for me that is close-up lenses on telezoom lenses, primarily because that gives me usable autofocus for all the scene sizes I photograph. A large zoom range is good for use with close-up lenses, and the best zoom range I can get (in a not too heavy package) is a small sensor bridge camera. I use a small sensor bridge camera that gives me particularly good control over placement of a small autofocus point, which enables me to be rather accurate about where the centre of focus falls and hence the how the depth of field falls across the subject. I can also synchronise flash with very fast shutter speeds, which can also be advantageous.

This is all to do with insects, spiders and other invertebrates by the way. I use a larger sensor camera with a macro lens for flowers, for which I don't use the tiny apertures that I use for invertebrates.

This can all seem rather counter-intuitive and I sometimes run into a degree of disbelief and argumentation (more of the latter at dpreview than here). It certainly puzzled and surprised me after I had purchased expensive kit so as to improve my macros and it didn't work. That was six years ago, and since then I have done a lot of experiments and some reading and discussion with people who understand this stuff much better than I do to try to understand what is going on. That has been one of the underlying themes in my Journey thread where I have written up various of my experiments, discoveries, blind alleys and failures.

 

[GardenersHelper]

Nice set Nick

Thanks Les.