Graham L Furlonger

Interesting debate John, I have always been led to believe that barrel focusing caused more image distortion but I have no substantial proof.

So, I have been at it again! Ferdinandea Cuprea, Stereo Microscope 20x Magnification. 36 Individual images merged in focus stacking software. (Affinity Photo) i was curious to see how finicky AF was to sequential order, from my own experiments it doesn't seem to matter. Without boring you all, here is a synopsis of getting the cleanest images with AF. you must lock down equipment so no unwanted vibration or movement between frames. ensure the camera (I use both Nikon FX D600 and Canon 50D DSLR ) is set to manual exposure. I perform manual white balance but auto white balance seems to be ok. I always shoot RAW and process in 16bit TIFF as lossless. I then convert to low res JPG for posting on social media etc. ensure a good border when starting around your specimen to allow for any vignetting or post process errors. This is where using a larger pixel content than required gives the ability to crop leaving a good sized image. ensure that no natural light effects the exposure, I took a set of images once starting by sitting and then got bored so decided to stand up. The standing up images were one stop over exposed due to the light I was shielding by sitting down! Ensure that you know your kit well, I always start with the stage highest IE. Focusing on the furthest part of the image and focus through the image lowering the stage away from the optics. This ensures no accidents with your specimen kissing your objectives! You can rescue some imperfections with post processing but it is very difficult to improve focus sharpness, don't be tempted to over sharpen using unsharp mask etc as this will destroy your tonal range and look artificial. I have tried lots of focus stacking software, even those for astronomy but I am finding Affinity Photo is coping well for my needs. I leave all my Microscopes (3) permanently set up. Why? Because I know from experience I am more likely to produce work if the setup and completion time is quick and hassle free. I personally do not use computer tethered software only because when MAC OS went to Catalina the Canon software I was using with my 50D stopped working, I wrote to Canon and received a reply saying they would look into this but alas still no result. I am currently transferring images to my Imac by Memory card and then transferring all the RAW images to hard drive prior to processing as the read time is much faster than directly from Mem card. Enjoy this hobby, its been a lifesaver during this time of lockdown in the UK. regards Graham.

Hello Forum, I am posting this because I searched on "Microscopy" "Entomology" and "Focus Stacking" and saw few if any results, I may be in a minority?...... Having spent many years perfecting Microscopy with Entomology and recently converting from a well know rival, I was impressed with the power of Focus stacking within Photo. These two images were taken with modest equipment and a Canon 50d digital SLR dating from 2008 and a Brunel MX1 Stereo Microscope with 1x Objective, 10x Oculars, Giving resolution power of 10x, plus magnification of the camera. Whilst I have DSLR's with much higher pixel resolution, it is often not required and extends processing time, the 15 mp sensor These two images comprise multiple shots (35 & 24) focus stacked within Affinity Photo. I won't bore you with the technical details, but if you want them you can message (I am happy to share) Affinity has saved me exporting my images to a third party software which has enhanced speed of operation and ease of use, one thing to note is that the Affinity software is not too picky on the order of focus slices presented, which is a major benefit to other rivals. Of course this technique could be useful to many area's of photography including, jewellery for record purposes, medical, veterinarian, instruction manuals and service documents where close up work results in very narrow depth of field. Enjoy your photography and enjoy using Photo. Regards Graham.