ulf Posted February 18, 2021 Share Posted February 18, 2021 Last Update: 03 April 2021 agb/label/spacing Finalized: Work in progress. Canon 40mm f/2.8 EF STM Manufacturer: Canon Lens Label: CANON LENS EF 40mm 1:2.8 STM Currently manufactured: No Lens type: Auto focus, Prime, Wide Angle, Pancake lens Design: 6 elements in 4 groups Focal length: 40mm Aperture range: f/2.8 – f/22, electronic control only, 7 blades circular aperture Magnification range: to 0.18x at 0.3m. Sensor format/coverage: up to 24 mm x 36 mm Mount: Canon EF Flange Focus distance: EF-standard, 44.00mm Front filter: 52 mm x 0.75 mm Introduction year: between 2012 S/N of test object: 3261100252 Lens review (VIS), on the web: https://www.kenrockw...0mm-stm.htm#rex Lens info on the web: https://global.canon...duct/ef419.html Image of test object: Transmittance Summary Definitions of the parameters below Range: The Canon EF 40/2.8 STM lens transmits 1-84% in an increasing slope from 347nm to 400nm. TVISmax (%) = 94% T400nm (%) = 84% T365nm (%) = 40% λUV HMvis(nm) = 368nm λUV HM400(nm) = 366nm λUV Zero(nm) = 347nm These three values indicate that the lens is only working for some upper UV-A photography. Spectral Transmission Graphs UV-NIR, Canon EF 40/2.8 STM The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source. UV, Canon EF 40/2.8 STM UV-Log, Canon EF 40/2.8 STM Numerical Spectra Data available: Yes General comments about the UV-reach: tba Filters and how to use them on this lens: NOTE: The filter threads are plastic. So you must be very careful when mounting filters. A large filter stack may stress the filter threads. The front filter thread is 52mm standard filter thread. It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera. An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear surface, that provides a good reference plane for orienting the filter normal to the optic axis. The rear lens element is not recessed and thus needs a filter mounted in a filter ring to place the filter's glass surface at a safe distance from the rear lens element. Handling and focussing: Must be assisted electronically by the camera. Only possible on Canon cameras or with suitable active lens adapters. Autofocus in UV might work with enough light present. TBD Flare and sun-stars: TBD Sharpness: High according to net reviews. For UV ? Lens distortion: TBD Chromatic Aberration in UV: TBD Image samples: Link to comment
JMC Posted February 18, 2021 Share Posted February 18, 2021 Ulf, in the section "Filters and how to use them on this lens:The front filter thread is 49mm standard filter thread." it says 49mm filter, but the filter size is 52mm (you had it right further up). Also the link to the Ken Rockwell review goes to Pentax forums for the Novoflex 35mm. The other also goes to something about the Novoflex 35mm. Link to comment
Andrea B. Posted May 3, 2021 Share Posted May 3, 2021 Editor's Note: I added a warning about the plastic filter threads. Proposed simplification of Filters and how to use them on this lens. Front filter:The front filter is a (52 mm) standard filter.OR: The (Zobax 35/3.5) has no front filter threads.Rear filter:The rear lens element is recessed enough to permit a putty-mounted rear filter on the lens end assuming there is enough space inside the camera chamber.OR: The rear lens element is not recessed enough to permit a putty-mounted rear filter.If a mount adapter or extension tube is being used, then a rear filter can be added directly or internally using step-rings glued in place.Comments please?? Link to comment
ulf Posted May 4, 2021 Author Share Posted May 4, 2021 Editor's Note: I added a warning about the plastic filter threads. Proposed simplification of Filters and how to use them on this lens. Front filter:The front filter is a (52 mm) standard filter.OR: The (Zobax 35/3.5) has no front filter threads.Rear filter:The rear lens element is recessed enough to permit a putty-mounted rear filter on the lens end assuming there is enough space inside the camera chamber.OR: The rear lens element is not recessed enough to permit a putty-mounted rear filter.If a mount adapter or extension tube is being used, then a rear filter can be added directly or internally using step-rings glued in place.Comments please?? That is OK In general some wide lenses will have problems with dichroic filters and very wide lenses will demand very big front-filters to avoid vignetting, especially with filter stacks.In some cases you might use a split-stack, placing one filter on the rear side and one at the front. I those cases I would place the BG-filter at the rear, to be able to switch the front filter without exposing the sensor for dust.Should there be more OR alternatives including these additions? Link to comment
Andrea B. Posted May 7, 2021 Share Posted May 7, 2021 I'm pretty sure everyone knows (or certainly should know) that wide lenses are prone to vignetting when filtered. I agree we should add something about dichroic filters. Would please suggest the proper terminology for that suggestion? I've never been sure what the dichroic discoloration is called. Link to comment
ulf Posted May 7, 2021 Author Share Posted May 7, 2021 I'm pretty sure everyone knows (or certainly should know) that wide lenses are prone to vignetting when filtered.Absolutely, I just wanted to add an idea of a possible solution, not having both filters of a stack in the front thread. I agree we should add something about dichroic filters. Would please suggest the proper terminology for that suggestion? I've never been sure what the dichroic discoloration is called. A seed of the cause of the problem is something like this: The filtering effect of Dichroic filters depend on the angle the light is passing though the filter.Many dichroic filters including the Baader U are made for astronomy and designed for light passing at a normal angle, (close to 90°) to the Filter's surface. When the angle deviates from 90°, the cutting wavelengths shift.At some angle the this shift becomes too disturbing creating too much of a discolouration in the images corners. Wide angle lenses are most prone to this problem with their wide FOV, but lenses with a small rear lens element and short back-flange distance might also see this problem. Link to comment
Andrea B. Posted May 7, 2021 Share Posted May 7, 2021 Well, yes, I know what causes it, but I was not sure what it is called. "Dichroic discoloration" is the terminology it seems. Link to comment
Stefano Posted January 12, 2022 Share Posted January 12, 2022 According to Wikipedia, this lens has been discontinued in March 2021: https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Canon_EF_40mm_lens&ved=2ahUKEwi2oKTtyqv1AhVQhv0HHRCiCBEQFnoECD4QAQ&usg=AOvVaw3YuuSrGeu6b0ACPpXE8nY4 If Canon will make a new version, I hope that it will have the same or comparable UV reach. Metal filter threads would be a nice improvement too. Link to comment
Doug A Posted January 13, 2022 Share Posted January 13, 2022 @Stefano guessing Canon will not replace this lens. They have been discontinuing DSLR lenses and pivoting to their mirrorless platform. They might bring it out for the the new mount. Thanks, Doug A Link to comment
ulf Posted January 26, 2022 Author Share Posted January 26, 2022 Updated the Manufacturing status to the new status, No. (2022) Thanks Stefano for the reminder. Link to comment
Avalon Posted January 13 Share Posted January 13 This is fairly new lens, what makes it better at UV? Please test Sony E-mount lens too. Link to comment
ulf Posted January 13 Author Share Posted January 13 33 minutes ago, Avalon said: This is fairly new lens, what makes it better at UV? Please test Sony E-mount lens too. Thin lens elements made of glass types that happens to have reasonably low UV-blocking makes it better at UV. Not designed for that. It just happened to be so. This is one of the few modern lenses known to be reasonably good for UV. Sorry, but I have no use for Sony E-mount lenses for the moment. The lenses I have measured and published here are mostly known to be acceptable for UV. After buying my UV-Nikkor and several Canon-TS lenses I do not want to spend more money buying even more lenses. I already have too many lenses in my collection that I never will use. If you want to buy me an E-mount lens I can measure it. ;-) Link to comment
Stefano Posted January 13 Share Posted January 13 4 hours ago, ulf said: After buying my UV-Nikkor and several Canon-TS lenses I do not want to spend more money buying even more lenses. So you got one too. I hope you like it. Who knows, maybe I will buy one too, far into the future, if I ever will. I cannot afford one, and I honestly can't justify the price, just like I won't spend 10,000 € for a SWIR sensor, even if I could afford it. Even if this lens is really sharp, corrects chromatic aberration, and is built vith very tight tolerances, I don't know if the price is justified, or if it's high also because it's a niche item. For just a little more (8,000 €), you can buy a Nikon Z 58mm f/0.95 S Noct lens. It has 17 elements in 10 groups, including 3 aspherical elements, and it's sharp in the center and corners straight from f/0.95. Its sharpness is an incredibile achievement at that aperture. Stopping down is only needed to increase depth of field, and here it is said that past f/4 diffraction is already softening the image. The UV-Nikkor has only 6 elements in 6 groups, all spherical as far as I know. This said, it's still a really nice lens, and I really wish you enjoy it. This wasn't a critic, just a personal thought. Link to comment
Stefano Posted January 13 Share Posted January 13 As for the Canon 40 mm pancake, I have one and it's a nice little lens. It has enough UV transmission to produce false yellows and lavenders, although not as saturated as those from a Soligor 35 mm f/3.5 lens, and it also works well in IR. I wish there were more currently manufactured lenses like it. Link to comment
moondigger Posted January 16 Share Posted January 16 Ulf, you mention owning some Canon TS lenses. Are these usable for UV imaging? I own a couple myself, which I have used quite a bit for landscapes (in the visible spectrum). But I haven't seen any indication elsewhere that they might be good for UV imaging. Link to comment
lukaszgryglicki Posted January 17 Share Posted January 17 I have Canon TS-E 17/4 - I use it on Fuji GFX - I cannot tell anything about UV transmittance because it is not possible to put filters on its huge front element. Link to comment
ulf Posted January 17 Author Share Posted January 17 Do a search for "tilt" in the forum search function. Select "This Forum" You will find that there are a few topics about TS-lenses and UV. When posting further about that, please create a new topic or continue in one of those better suited topics. It is very easy to do. Then the discussion and valuable findings will be much easier to find later. This topic is about the Canon 40mm f/2.8 EF STM that have no relation at all to TS Lenses. Link to comment
Avalon Posted September 1 Share Posted September 1 Can anybody share samples of these lens made photos in UV spectrum? This is probably only newer UV capable lens with autofocus. Can aperture be controlled if there is no connection to camera? Would be interesting to see more modern UV capable lens since they use advanced design such as low dispersion and aspheric lens elements. Link to comment
photoni Posted September 1 Share Posted September 1 11 hours ago, Avalon said: Can anybody share samples of these lens made photos in UV spectrum? This is probably only newer UV capable lens with autofocus. Can aperture be controlled if there is no connection to camera? Would be interesting to see more modern UV capable lens since they use advanced design such as low dispersion and aspheric lens elements. It does not have a manually controllable aperture. The aperture is controlled from the Canon camera body With other brands you need an adapter with electrical contacts. Link to comment
Avalon Posted September 2 Share Posted September 2 I see, it's a downside for those that don't Canon EF mount camera or at least Sony adapters. Link to comment
Stefano Posted September 5 Share Posted September 5 Here are some samples. .jpgs straight from the camera (I shoot in raw + jpg mode), simply resized. In-camera white balance from a PTFE sheet (I think for all of them). Full-spectrum Canon EOS M, ZWB2 (2 mm) + Chinese BG39 (or whatever that is, 2 mm). The lens is a bit soft at f/2.8, and improves when stopped down. It has some chromatic aberration, which is sometimes visible, but not too much. Trinità dei Monti, Rome. f/3.5, ISO 3200, 1/60 s. Fontana della Barcaccia, Rome. f/3.5, ISO 12800, 1/250 s. Colonnades in Saint Peter's Square, Vatican City, with visible retouchings. f/2.8, ISO 4000, 1/60 s. Amalfi. f/2.8, ISO 1600, 1/60 s. "Zebra crossing" in Pompeii. f/2.8, ISO 3200, 1/60 s. Rudbeckia-like flowers with nice nectar guides, somewhere in Veneto, f/2.8, ISO 12800, 1/125 s. f/2.8, ISO 12800, 1/125 s. f/2.8, ISO 12800, 1/125 s. Somewhere in Veneto. f/2.8, ISO 1600, 1/60 s. f/2.8, ISO 3200, 1/30 s. I like buttercups... Torre del Mangia, Siena. f/3.2, ISO 1600, 1/30 s. Piazza del Campo, Siena. f/3.2, ISO 1600, 1/30 s. Sunflower field in Tuscany, near Siena. f/2.8, ISO 3200, 1/30 s. f/2.8, ISO 6400, 1/60 s. f/2.8, ISO 6400, 1/60 s. The Two Towers of Bologna (Asinelli (left), Garisenda (right)). f/4, ISO 5000, 1/60 s. The sky is overexposed. View from the Sanctuary of the Madonna of San Luca, Bologna. f/2.8, ISO 800, 1/30s. Link to comment
Ming Posted September 8 Share Posted September 8 @Stefano These are wonderful images. It is interesting to see the purple tint on the water in Fontana della Barcaccia. Also, Piazza del Campo captures a convergence of lines, people, shadow, and trucks. Thank you for sharing them. Many forum members have this mighty little lens. It will be fun if everybody posts some UV pictures taken with it. Link to comment
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