I am looking to make a project that involves filming night scenes with many streetlights in the frame and I would like to minimize the flash, ghosts and halos ("solar stars" are expected unless you have found a way to eliminate them too). )
I just received a copy of the aspherical IF Tamron AF 20-40 mm F2.7-3.5 SP for my Sony a7 (using the Sony A / E adapter that is not AF) on eBay. I'm seeing what I find a surprising degree of softness at the long end of the lens. This is especially surprising to me, since the revisions (see the link) praise the clarity of this lens. However, I have not used a wide-angle lens before, much less this specific lens, so I'm not sure if this degree of smoothness is to be expected or indicates a problem with the lens. (It was listed as "excellent" condition without optical problems on eBay).
All of these shots are untrimmed, manually focused, approximately 25 feet (~ 7.5 meters) away from the fence, and hand held because I was too lazy to set up my tripod for three shots. In each case, the sharpest focus was timid of infinity. (The lens does not have focus marks between 10 feet / 3 m and infinity). I took these shots in Raw, I loaded them in On1 Photo Raw and exported them as 90% of JPEG files without any editing. Photo Raw does not seem to have a profile for this lens, so it does not seem to have applied any correction. (At least, I do not see any difference in activating and deactivating the lens correction panel.)
First, for reference, here is a photo at 20 mm, 1/200 sec, f / 10, ISO 160. With a 50% zoom I can see some small differences in the sharpness between the center and the edges, but that does not worries. I consider that this photo has a good sharpness for a lens of the mid 90's.
Then 40 mm, 1/200 sec, f / 10, ISO 125. The center has a good sharpness, but everything else is extremely smooth, even in the small preview version. The right side is especially bad. This is the problem that I am trying to understand.
Finally, only in the case that f / 10 can be considered "open" in this lens, or if there is something about the depth of field with wide lenses that I do not know, I tried the smallest aperture in this lens. 40mm, 1/200 sec, f / 32, ISO 1250. I think I can still see more sharpness decrease towards the edges, compared to the 20mm shot, but it's somewhere between tolerable and good.
If you look at the front of your kit's zoom lens, you will see a mark with a number and a symbol ⌀. This is the diameter of the filter thread: to which front-end adapter lenses such as the ones you bought come together.
I think that in the 18-55 mm lens that comes with that camera, the value will be ⌀52. That will not work with the adapter lenses you bought. (I think some other Nikon 18-55mm lenses had a 55mm filter thread diameter, which may have resulted in confusing labeling of the things you bought).
You can buy what is called "52-55mm step up ring". The link goes to a generic one that I can not answer but should show you the general idea and the price ($ 7).
However, keep in mind that this type of front-mount adapter lenses are basically toys. They will introduce significant optical faults in the images taken. The telephoto adapter can actually be worst I just use the 55mm lens and cut it to simulate the zoom. Of course, you can not do that at the wide end, so the wide adapter can open up new possibilities, but it can not really replace a real wide-angle lens.
See Can bolt-on wide-angle adapters / converters produce decent quality results? for more on this.
The BBC article in the United Kingdom on meteorite hunting in Antarctica, great tour, shows this ultra-wide angle picture looking directly at the ground but capturing large amounts of blue sky at the edges, and I can not understand how it can be do this. I can not distinguish the angular FOV, but it is beyond 180 degrees.
What kind of lenses, optics or other equipment are used to do this? How do you do this?
Most of the space rocks in collections were collected in Antarctica. KATHERINE JOY / UNIVERSITY OF MANCHESTER
It is difficult to get rectilinear and wider than 12 mm in the full frame, but it is also difficult to use. It is not usual to need more than this exceptionally wide angle in this context. The biggest problem with wider lenses is that they are more likely to suffer a flash (just trying to avoid the Sun or a bright light source in the shot may be impossible) and are (as a general rule) more prone to distortions.
If you need a larger image, consider joining panoramas in the software. There is a very good free software, like Hugin, that will do this and usually you only need superimposed images to do it. Stitching means that you can use images taken with a lens less prone to distortion and combine them to obtain a more detailed final image that is less affected by the optical distortion.
Unless you have a lens with a circle of images that does not completely cover the sensor (for example, a lens designed for 8 mm film cameras), the focal length (the number "x mm") determines the angle of view that get with a certain sensor size.
The "antique Canon" lenses are probably adaptable full frame lenses. 12 mm (as it has its MFT zoom lens) is already a extremely low focal length for full frame: straight glasses at 12 mm and below for full frame are exotic and will have a low price even if they are purchased second hand. Full-frame lenses can save you a lot of money when it comes to extreme telephoto ranges (if you can live with manual focus, size and weight), but it will rarely help in the extreme wide-angle range.
Its 12 mm are equivalent to a 24 mm full frame lens. It is considered that 24 mm is the longest "ultra wide-angle" length in the entire frame, including a 24 mm lens. for a fullframe camera It's almost an exot
For MFT, in 2018, it seems that shorter rectilinear options are also expensive: see Laowa 7.5mm (equivalent to 15mm full frame) or Samyang 10mm (equivalent to 20mm full frame).
There are so-called "wide-angle converters", but neither do they try to be rectilinear or they are not good for that.
There are cheaper fish eye options (not rectilinear) at 6.5 mm and 7.5 mm available, but you should correct the distortion in the software, losing some resolution and image fidelity in the process.
What could be useful for your purposes is the Sigma 10-20mm zoom (or 8-16mm, but this also tends to be expensive …) (it should be adapted and it will be manual focus! The "four thirds" version) it will not fit into an MFT camera. Do not try to adapt the Canon version, unless you have a very expensive / exotic adapter, you will not have opening control; the adaptation of Sony A, Pentax or Nikon is your best choice here …), or The Olympus 9-18mm (native MFT, expensive).
The fisheye effects are excellent for art, they are not useful in architectural documentary photography …
By the way, some technical background: P & S cameras can easily incorporate quite brutal wide angles for three reasons. First, the rear element of the lens can be obscenely placed near the sensor, simplifying the design of the lens. Secondly, the sensor can be optimized to handle a lens closed to the sensor and cover it with a small exit pupil. Third, you can leave all kinds of lens errors in place and correct them in the software and on the camera, since there is no intrepid way to test the lens outside the camera, there is no risk that the reviewers say the opposite. Because it is an optical catastrophe. In that way, the wide-angle mode in a P & S can be a very optically veined fish eye.
By the way, even some zoom games for DSLM already use a large electronic correction (there is a firmware on the lens that tells the camera what to do).
I probably took more pictures on full frame cameras with an EF 24-105 mm f / 4 L IS than any other lens. But for what you want to do in low light, it is not the best option. In f / 4, it's a bit too slow.
I would suggest a main lens of 24 mm, 28 mm or 35 mm. While cousins of 24mm f / 1.4 can be expensive because they are a challenge to design and produce well, there are more than a few affordable lenses of 24mm f / 2.8, 28mm f / 1.8 or 35mm f / 2 in the market. Compared with its previous culture body, 24 mm would give the same field of vision (FoV) with the 5D Mark III as 15 mm in its Rebel T2i / 550D. 28 mm in FF translates to 18 mm in the 550D, and 35 mm in FF is the same FoV as 22 mm in a 1.6X culture body.
Another great option would be the EF 16-35mm f / 2.8 L III, but it is even more expensive than the EF 24-70mm f / 2.8 L II. The previous versions of the 16-35 / 2.8 L are not optically as good as the "III", or the more economical EF 16-35mm f / 4 L IS (if you can do without the maximum aperture of f / 2.8). For larger landscapes with an FF camera, which includes cityscapes at night, the 16-35 / 4 L is a large lens. But I think you will not find it fast enough for group pictures in low light.
If your budget does not allow the EF 24-70 mm f / 2.8 L II and is fully concentrated in a zoom lens, my advice would be to go with the less expensive Tamron SP 24-70 mm f / 2.8 Di VC. It is sharper than the original EF of 24-70 mm f / 2.8 L (which I still use because it gives me what I need for a 24-70 / 2.8), but not as sharp as the new "II" introduced in 2012. The Tamron also offers something that Canon does not offer: Vibration Compensation, which is Tamron's term for & # 39; Image Stabilization & # 39 ;. I have several friends who have the previous version of Tamron, and are very happy with it. Tamron just released an update & # 39; G2 & # 39; (& # 39; Generation Two & # 39;) a few months ago that added the ability to update the firmware and calibrate the AF using the USB port & # 39; TAP-In & # 39; of Tamron. it is currently selling for a little more than it was before it was replaced, but it is still several hundred dollars cheaper than the Canon EF 24-70mm f / 2.8 L II.