Lens Sharpness, Focal Length, and Aperture
Derek Smith • 6 May 2024
 
 In my experience it doesn’t matter what the size of sensor a camera has, most lenses will have a corner-to-corner optimum sharpness in the range of f/4 – f/8 aperture, often called “the sweet spot”. Camera lens design will often give a sharp performance in the centre at the widest aperture, for example at f/1.4, with the lens aperture resolving to sharper corner to corner sharpness as it is stopped down, then the performance deteriorates again becoming softer as the lens is stopped down further owing to diffraction at apertures above f/16, personally I wouldn’t push a lens on an APS-C camera much past f/11. 
 
 Why does this matter? For landscape photography ideally a photographer would want foreground to background sharpness, and simply always choosing to select an aperture of f/10, or f/16 arbitrarily may not give the correct front to back sharpness required. This foreground to background sharpness is defined in cameras as Depth of Field (DoF).
 
 Depth of Field is a factor of sensor size, closeness to the subject, and the focal length of the lens used, this attached image of a worm cast on a sandy beach illustrates perfectly the effect of DoF, shot at f/5.6 on an APS-C sensor, the band of sharpness runs through the focus point on the worm cast.
 
 For macro photography a photographer often needs to be close to the subject, which reduces the DoF, requiring a photographer to focus stack the images. Many photographers opt for a small crop sensor of micro four thirds format from Olympus, or Panasonic, to maximise the DoF in this genre of photography.
 
 Many of you know that I enjoy portrait, and fashion photography, DoF is critical as the focus should be on the eyes. A few years back, I succumbed to social media advice that I needed a full frame camera for portraiture, especially with an 85mm f/1.8 lens shooting wide open. Unfortunately, the DoF was razor thin, the lens a Sony FE 85mm f/1.8, and Sony A7 ii was heavy as a combination, and the large lens provided little room for my fingers on the handgrip, the Sony cameras were sold within a few months. On my last model photo shoot, with Ivy in Skegness, I used a new TT Artisans 56mm f/1.8 on my Fuji APS-C camera, shooting wide open the eyes were in focus but the ears, and nose were soft, stopping down to f/4 gave better focus on the face, but still retained a smooth out of focus background – bokeh.
 
 I use an app called PhotoPills on my mobile phone, the app provides a tremendous amount of data relevant to photography including a DoF lookup, here are the results from my past, and current cameras, and lenses.
 
 Camera                    Sensor           Lens                                              Aperture                  DoF
 
 Fuji                            26Mp             Sigma 30mm                             f/1.4                          0.36m
 
 Fuji                            26Mp             Fuji 16-80mm                            f/4 @80mm           0.14m
 
 Fuji                            26Mp             TT Art 56mm                              f/1.4                          0.13m
 
 Sony A7 ii                24Mp             Sony FE 85mm                          f/1.8                         0.08m
 
 Olympus EM5        20Mp            Sigma 30mm                              f/1.4                         0.28m
 
 Knowledge is power!! I know that any DoF greater than 0.20m for portraits will provide good definition on the face, without any softening of facial features. The Sigma 30mm f/1.4 lens allows for portraits to be shot wide open. My TT Artisans 56mm f/1.8 lens is probably best stopped down to f/4, also the benefit of stopping this lens down is that the lens will provide improved sharpness at this aperture.
 
 Mark Denny has posted a YouTube video on this topic which some of you may find useful. 
 
  
 In this video Mark discusses his mistakes in selecting aperture in landscape photography, he also touches on finding the “sweet spot” of a lens.
 
 My photo of Jayne, “English Rose”, was taken with the Sigma 30mm f/1.4, shot wide open at f/1.4, the foreground petals are out of focus but importantly the eyes, and facial features are in sharp detail. This portrait of Fleur, taken in natural light with the Olympus EM5, and the Sigma 30mm lens, was shot at f/2 again preserving fine detail.
 
 For landscape photography the image here is of the rocks in a bay at Flamborough, I can see on the set of images taken at this time that I’ve fallen into the trap outlined by Mark Denney of shooting at a fixed aperture, luckily in this case the selected aperture of f/8 worked on this image, with the Fuji 16-80mm zoom lens at 16mm, the foreground rocks are in sharp detail, and the background cliff still retains a lot of detail. 
 
 Louth Photographic Society

At our meeting last night one of our members, Harry Kerman gave a talk on one of his favourite genres, flower photography.                                                    Harry's talk was accompanied by a slick, professional standard power point presentation, he also had his camera a Canon R6 II, a Sigma 105mm macro lens, a Lens Baby 56mm manual focus lens, and the standard 24-70mm zoom. Harry demonstrated his use of the equipment, which included backgrounds, a plamp to hold flowers in place, and a light box.                                                              After the break Harry presented some of his images, projected onto the screen, not all the images were "perfect" he wanted to show some of his mistakes so that we could learn from them, he also welcomed feedback from members, all of the flower images he showed were stunning, and you can see some of them on this post.                                                              It was an inspiring evening, providing many techniques, and creative ideas for members to emulate. Harry's passion for flower photography shone through during the whole talk, his clear narration, power point presentation, demonstrations, and images completed a very successful night.                                                              Thank you Harry for a fascinating evening, and to Richard Hildred for the refreshments during the break.
 

Good morning, All                                                    Last week at the club we held a retro night, with four members showing pre year 2000 transparencies. It turned out to be a really interesting evening, I didn't know Richard Hildred had started out at an early age photographing trains, it turned out himself and member Chris Birchmore were travelling on the Flying Scotsman in 1967 at the same time. There is a full report on the evening on our blog.                                                              This week, Wednesday 29th October, Harry Kerman, one of our members will be showing some of his projected images, and talking about his interest in flower photography.                                                              Don't forget Harry is now taking entries for our PDIOTY (Projected Digital Image Of The Year) competition. (closing date 12th November)                                                              Regards Graham
 

Last night was a nostalgic trip down memory lane, with four of our members presenting a slide show taken before year 2000.                                                    Now we all remember sitting in a darkened living room showing your latest holiday slides to friends, and neighbours, that click and whir as the slides changed, the stuck slide, the one that was upside down, or back to front, and uncle Jim dozing on the settee!                                                              It wasn't quite like that for last night's presentation, Richard Hildred began the evening with some amazing images of railways from British Rail days, we might ride one of the preserved heritage lines, and see the gleaming clean steam engines pulling a line of carriages, Richard's images  returned us to the reality of steam powered passenger and freight operations, with the dirt, the grit, and grime of daily steam running, this image captures the essence of steam hauled mixed goods traffic, Richard's slide was in colour, but renders better here in monochrome.                                                              Next up was Tony Gaskins, many of his slides featured his first trip to the Maasai Mara game reserve, and the Ngorongoro Crater, Tony also showed slides from his trip to Canada, his slides and narration made for a great presentation. This image of a mother elephant, and calf was taken in the Ngorongoro Crater.                                                              After the break, Chris Birchmore presented many images from the Lincolnshire area, some of the disused, and crumbling buildings in the images made interesting subjects for photography, I have used this image of Bolingbroke castle, and from this viewpoint the church is clearly visible in this image, compared with today where only the church tower is visible.                                                              Graham Harrison was our last presenter, last but not least, the variety of images shown was remarkable, several from Wales, and quite a few that had been entered into club competitions previously, and were of high quality, as this image of a Flamingo shows.                                                              It was a fascinating, and interesting evening, thanks to each of our presenters, and to Dave Mann for the refreshments.
 

Good Afternoon, All,                                                    Last week at the club we held  our monthly print competition, with the categories of "Mono" and "Open",  judged by Diane Seddon. It was a very good evening with Diane critiquing our prints with helpful comments on how we could improve our images as well as praise. The results are on our website but well done to David Whitehouse for best print in the mono and Dave Turner for best print in the open.                                                              This week, Wednesday 22nd October, we go back in time to before the millennium with transparency slides to be shown by Tony Gaskins, Chris Birchmore, Richard Hildred and myself.                                                              You can start sending Harry your entries for the PDI of the year, all the rules etc are on our website, but the important thing is you can enter any PDI's as long as they have never been in a PDI of the year before. There are six subjects and an overall max of six PDI's, no more than three per subject.                                                              Regards Graham
 

A print competition was held last night with the categories of; "Monochrome" and "Open".                                                    Diane Seddon from Cleethorpes Camera Club was the judge for the evening, Diane is very skilled, and thorough in her judging, providing useful insight, and critique of the prints. Many of her comments centered around the best cropping of an image to optimise the subject within the frame, and giving the subject "room to breathe" in the framing.                                                              Congratulations to David Whitehouse placed first in the "Monochrome" category, with his superb rendering of a face sculpture, and Dave Turner placed first in the "Open" category with his stunning print of the sunrise over Whitby Harbour.                                                              Thanks to Diane Seddon for a great evening, and as she remarked at the end of the competition all the prints were of an extremely high standard. The Competition Page has been updated with the highest placed images, but currently the score sheets for the competition are unavailable.
 

Good Morning All                                                    Last week Dave Bennett came to the club again, it has been a while since we have seen his photography but well worth the wait. Dave's photographs were excellent and his story telling along with AV's made it a very good night.                                                              This week, Wednesday 15th October, we are holding a print competition, with the categories of "Mono" and "Open", our judge for the evening will be Diane Seddon AFIAP CPAGB BPE3* she is well qualified to judge our prints.                                                              The following week we are going to try a retro night again, with Transparencies taken prior to the year 2000, please let me know if you want to take part and have a time slot allotted, time will depend on the numbers wanting to take part.                                                              Regards Graham
 

Last night Dave Bennett came to the club to show us AV's and narrate other sets of photographs on a theme. Dave started with photos along the Humber and then carried on the evening with AV's on nature, flowers and transport as well as talks and photographs showing us Grimsby docks including detailed photographs of fish smoking and engineering. Dave's photography is of a very high standard with strong colours, lot's of use of depth of field and they tell a story. A great night, thank you Dave.
 

Good Morning All                                                    Last week at the club we held a local PDI competition with a category of "5 Minutes From Your Home", we had some very good entries in each category with myself, and Dave Turner judging on the night. All the results are on our website, but well done to Derek for his mobile phone picture of a remembrance seat in Horncastle and Harry for his hellebores in the "Open" category.                                                              This week, Wednesday 8th October, Dave Bennett is coming to the club to show us what he has been taking lately, Dave does quite a bit of AV so as usual it will be a very good night.                                                              A reminder, send your print titles for the next print competition to Dave Turner by midnight Wednesday and bring your prints in this Wednesday night as well please.                                                              If you have any more N&EMPF Exhibition PDI entries send them to me by midnight tomorrow (Monday) please.                                                              Regards Graham
 

Our PDI "Local" competition was held last night, with the categories of "5 Minutes From Your Home", and "Open".                                                    Dave Turner, one of our members began the evening with judging the "Open" category, always a difficult category in my opinion because of the variety of subjects entered into the competition. Dave had previewed the images on his home computer, and had notes on each of the images, he provided excellent feedback on each image.                                                              After the break, Graham Harrison began judging the "5 Minutes From Your Home" category, this was a very unusual subject category which stretched the creative ingenuity of members, and it was particularly interesting to see what members had submitted. Graham judged the entries very fairly, and provided very good critique of the images.                                                              The standard of images submitted was high, which makes judging a competition such as this difficult, and as always is subjective, but a big thank you to both judges, it was an interesting evening.                                                              The first placed images, from each category are shown on this post, "At the Going Down of the Sun" by Derek Smith, "5 minutes from your home", and "Hellebores" by Harry Kerman in the "Open" category.                                                              The website Competition Page has been updated with the top three placed images, and the scoresheets.
 

Good Morning All                                                    Last week at the club member Tony Gaskins gave us an excellent presentation of his recent trip to Kenya on safari. Tony showed us the animals and birds he had encountered on his trip. It was an evening of excellent wildlife photography as well as a very informative talk, thank you Tony. There is also a report on our website blog.                                                              This week, Wednesday 1st October, we are holding a local PDI competition, with the subject categories of "5 Minutes From Your Home" and "Open", Dave Turner has kindly offered to judge the Open with myself the subject, and you have until midnight tonight to enter.                                                              Dave Turner is also asking members to send him the titles of their prints for the next print competition, the categories for this are "Mono" and "Open".                                                              Regards Graham
 




