Thank you all for your help on this. I may need a bit more help from you to explain some terms. I am just beginning and do not fully understand all the technical terms (focal length, focus distance, etc). I will get there but just need a little bit more help :-)
Here is what I understood:
- The reflection was caused by the position of the strobe.
- The vignette is seen because I did not have enough zoom in to get a tiny detail of the large nudibranch or the nudibranch was too large to have it in full using the CMC
I understand this and I am very grateful for the explanations you sent, thank you.
Here is where I need more help from you:
- What does the minimum focus distance mean vs. the use of the zoom? It is 10mm without CMC and 59 mm with CMC. Does it mean I can get the same level of details with the CMC being a bit further away from the subject, at 59mm? Does this distance imply using the zoom or not? I just tried and I can be closer that 59 mm with the CMC with a zoom in.
- 19mm frame width using CMC: does it mean that any subject larger than 19mm will not fit entirely in the frame? Is this distance using the zoom or not? Without the CMC, it can get to 30mm which I also do not get since I can easily fit a shark in the frame. I assume this is therefore implying using the maximum zoom in?
Here are the details of the pictures I posted above:
- xeno crab: focal length = 9.89 mm
- shrimp: focal length = 9.89 mm
- nudibranch: = 7.59 mm
Apologies for my ignorance and all my questions! I am very keen to understand all this as this is the only way I will understand how to best use my equipment.
Once again, many many thanks for your patience and time!
Your lens is zoomed out. The G16 range is 6.1-30.5 you are at the wide end close to the vignetting point. Closer to the black vignette the lens has another glass area not clear it is likely this is your reflection.
Because you are not zoomed out the camera working distance is around 1cm so to go further away you need to zoom fully.
Frame width 19mm means anything bigger will not fit the frame
In short I do not know who advised you to get the CMC for the majority of subjects you will achieve less than the traditional macro frame width of 35mm with a single Inon UCL-165 so unless you live in pygmy seahorse land the CMC will be too much for you and a weaker lens could have been sufficient.
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