topic Re: 35mm for 70d!! in EF & RF Lenses

35mm for 70d!!

jaisomnmick1 — Mon, 02 Mar 2020 14:56:55 GMT

hi this is both a question and asking for recommendations. i have a 70D with a 50mm 1.4. i heard that the 70D is an APSC camera which means if i buy the wrong lens, the view could be narrower than intended.

do i have to specially look out for APSC lenses when i'm buying? if so, are there any letters or indicators that let me know that?

or better yet, can someone recommend me some great lenses i can look into?

i'm pretty new to cameras as a whole, so i apologize if this question is eye roll inducing.

Re: 35mm for 70d!!

ebiggs1 — Mon, 02 Mar 2020 15:07:55 GMT

Lenses are lenses and focal length is FL. Your 70D will use either "EF" or "EF-S" lenses. What is different is the angle of view. It is this AOV that you need to be aware of. On a FF DSLR the 50mm lens is considered normal. On a 70D it is more like the 35mm. Neither is actually normal as a factor of the approximate AOV of the human eye.

Re: 35mm for 70d!!

ebiggs1 — Mon, 02 Mar 2020 15:18:18 GMT

"...can someone recommend me some great lenses ..."

IMHO, either one of these two lenses is not only "great lenses" but mandatory if you want the best from your 70D. The EF-S 17-55mm f/2.8 IS USM Lens or the Sigma 18-35mm f/1.8 DC HSM Art Lens for Canon. One of those is where you need to start. Each has an advantage over the other but either is very good and a great choice. The Canon is slightly longer at the tele side and the Siggy is slightly faster at wide open. Which is more important to you?

You have probably noticed the 50mil you have is somewhat limited to its usefulness. IIWY, I would not look at any more prime lenses, that is non-zoom lenses. Zoom lenses are far more friendly and give up little, if any, in IQ.

Next you need to look at one of the 70-200mm zooms for tele work. There is an f4 version and a faster f2.8 model. For UWA (ultra wide angle) I like the EF-S 10-22mm f/3.5-4.5 USM Lens.

Re: 35mm for 70d!!

rs-eos — Mon, 02 Mar 2020 18:56:06 GMT

I believe the vast majoriy of lenses (or all?) denote the focal length in reference to the 35mm film/sensor size (aka full frame). So your 50mm lens on a full frame camera would have an approximate diagonal Field Of View (FOV) of around 46º.

You're correct in that when used on a camera with a smaller sensor, that the FOV will be narrower. By a factor of the crop value. Canon's APS-C cameras have a crop factor of 1.6. Thus, the FOV will be about 35º. To get a similar FOV on your camera, you'd use a 28mm lens. 50 mm divided by crop factor of 1.6 yields 31.25 mm. A prime 28mm is probably the closest you'll get to that 31mm figure.

Not to complicate things, but the crop factor affects other things as well. Here is one of the best explanations I've seen on the subject: Focusing on Depth of Field and Lens Equivalents

Regarding purchasing of lenses... There are lenses specifically made that only work with the smaller (crop) sensor Canon cameras. Canon calls these EF-S lenses. There are advantages in that they are typically less expensive, smaller and lighter than EF lenses. However, if you ever move to a full-frame Camera (e.g. EOS 6D, 5D, 1D), EF-S lenses won't work. So you may want to consider protecting your investment as needed.

Also, many of Canon's EF lenses are part of their L-series line. These often include weather-sealing, higher image quality, build-qualtity, etc. They are quite expensive, but well worth it, IMO.

Finally, unless you specifically need to have images that mimic a 50mm FOV on your camera, consider either a set of primes or a zoom or two to cover a range. The three most common ranges are wide angle, standard and telephoto.

Your 50mm is bordering on the telephoto side when used on an APS-C camera. As mentioned above a standard focal length for your camera is around 30mm. Wide angle I think would be around 20mm or less. Telephoto would be around 60mm or more.

Re: 35mm for 70d!!

rs-eos — Mon, 02 Mar 2020 19:00:56 GMT

Regarding primes vs. zooms... that is up to the original poster to make the determination based on what their vision is.

I personally use primes since my vision is often to capture as shallow DOF as possible and have the best possible low-light performance.

Both types of lenses have their advantages and disadvantages.

Re: 35mm for 70d!!

kvbarkley — Mon, 02 Mar 2020 21:41:31 GMT

"I believe the vast majoriy of lenses (or all?) denote the focal length in reference to the 35mm film/sensor size (aka full frame)"

Wrong. The focal length is a physical measurement of the lens and has nothing to do with image format - a 35 mm lens for a full frame is still 35 mm for a crop frame. They might note the full frame equivalent, but that should be clearly marked. For example, my EF-S 60 mm macro would still be a 60mm lens if you could attach it to a Full Frame Camera.

Just to be clear, a 50mm lens on a crop frame camera provides a FOV similar to an 80 mm lens on Full Frame, i.e., a lens on a crop frame camera will change the FOV towards telephoto compared to the same focal length on a Full Frame camera.

Re: 35mm for 70d!!

rs-eos — Tue, 03 Mar 2020 01:48:00 GMT

Correct. I didn't mean to imply that the actual focal length would change. What I should have written is that you'll often see literature outline the 35mm equivalents.

Re: 35mm for 70d!!

kvbarkley — Tue, 03 Mar 2020 14:16:15 GMT

I think it is time to forget about "35 mm equivalents" that ship sailed 20 years ago when digital eclipsed film. Now you could argue that we should talk about "22 mm equivalents" since smaller frames have a much larger share of the market!

Re: 35mm for 70d!!

ebiggs1 — Tue, 03 Mar 2020 14:37:40 GMT

"I ... use primes since my vision is often to capture as shallow DOF as possible..."

Not to pile on about an unclear post, but no matter whether the lens is a zomm or a prime the DOF is exactly the same at similar FL and aperture. If you have a 17-55mm zoom set at 50mm and the 50mm prime both at f4, the DOF will be essentially the same. A big reason I recommend the EF-S 17-55mm f/2.8 IS USM Lens is the wide constant aperture. Again duplicating the charismatics of the prime. Only at the f2 or f1.8, etc, from a prime would you see a shallower DOF at a given FL.

Re: 35mm for 70d!!

wq9nsc — Tue, 03 Mar 2020 15:23:41 GMT

I agree Ernie about primes and I assume rs-eos is referring to those cases where the primes do have a wider maximum aperture than readily available zoom lens, particularly as you move into the telephoto range. I use prime telephoto lens often for sports because an extra stop really helps sometimes on dark fields even with the ISO performance of current bodies. More importantly for sports, the better primes acquire focus a little faster than a similar focal length zoom and the extra stop allows the camera body/lens combo to focus even faster (relative to a zoom) when light conditions grow worse. But this performance comes at a big cost in terms of dollars and versatility and modern better zoom glass is so good that for most shooting situations it is the best choice.

Shooting a lot of high school sports with the typical poorly lit venues makes me an outlier in terms of which characteristics of lens performance are most important.

Yesterday I calibrated 5 different lens (400 F2.8, 300 F2.8, 200 F2, 70-200 F2.8, and 24-70 F2.8) to my three different 1DX series bodies so that I can safely switch a lens between them on the fly if needed. I am planning to use some soccer team practice sessions to try some different shooting setups and today I am going to try shooting scrimmage with a three camera setup using 400 and 200 primes along with a 70-200 zoom to see how I like coverage from a fairly static position near the goal area. But this setup means in addition to my game setup 1DX series bodies I will need to throw the 5DS R with a 24-70 2.8 on it into the bag to get bench and group shots when needed so by season start I will probably just go with a 400 F2.8, 70-200 F2.8, and 24-70 F2.8 three camera setup that will do it all. Most of the JV games early in the season occur after sundown so the F2 200 provides some advantage there which is why I want to try it during practice sessions that run after sundown.

My plans for getting a lot of photography testing in during pre-season practice were somewhat diminished yesterday when I got drafted as an assistant coach but that will probably be the most enjoyable unpaid job I have ever done 🙂 It is a fun time to work with the team because the last of the kids I coached when they were little are now starting their freshman year so I get a few more years to work with them.

As a side benefit, the heavy primes keep me in shape (at least that is what I tell myself) 🙂 Photo is from getting ready to start the calibration process yesterday. It took about an hour total and none of the lens required more than a minor offset with most being dead on without adjustment.

Rodger

Re: 35mm for 70d!!

rs-eos — Tue, 03 Mar 2020 18:39:21 GMT

Roger,

Correct regarding my DOF (and low-light) comment. It was indeed tied to the larger maximum aperature values of the primes.

BTW, that's a serious collection you have there 🙂

Re: 35mm for 70d!!

ebiggs1 — Wed, 04 Mar 2020 16:15:44 GMT

"...referring to those cases where the primes do have a wider maximum aperture than readily available zoom lens,..."

I can't argue that point but zooms are gettign even better. And, they are getting faster. The Sigma 18-35mm f/1.8 DC HSM Art Lens and Sigma 24-35mm F2 DG HSM Art Lens. From Canon the RF 28–70mm F2 L USM. A few years ago anything under f4 in a high quality, high IQ zoom was thought not possible. The good news zooms will get even better and faster.

Zooms are not easy to make. They have lots of issues to overcome way more than a simple prime. Sometimes it comes down to how much customer are willing to pay. But manufacturing is better and more efficient so more difficult designs can be created.

Re: 35mm for 70d!!

RobertTheFat — Wed, 04 Mar 2020 17:33:12 GMT

@kvbarkley wrote:
I think it is time to forget about "35 mm equivalents" that ship sailed 20 years ago when digital eclipsed film. Now you could argue that we should talk about "22 mm equivalents" since smaller frames have a much larger share of the market!

I strongly agree in principle. If you're going to use a particular camera, you should think in terms of how a given lens behaves on that camera, not on a camera of some other type.

There is, however, one case I can think of where it is useful to think in terms of "equivalents". If you're you're going to do a shoot with two cameras, one a full-frame and the other an APS-C, being cognizant of equivalents helps you allocate your lenses so as to avoid inadvertent coverage gaps. I realized that when for a couple of years I had only one full-frame camera but was doing a lot of two-camera events.

Re: 35mm for 70d!!

kvbarkley — Wed, 04 Mar 2020 17:39:16 GMT

I don't know if I am disagreeing with myself or not, but the other place it is needed is when discussing zooms for small sensors. I have no idea how 4.5 - 18 mm relates to the real world, until you tell me that these are 25 - 100 mm 35mm equivalents. (Real numbers from my Olympus TG-5)

Re: 35mm for 70d!!

wq9nsc — Wed, 04 Mar 2020 18:10:57 GMT

It can be a pretty useful comparison metric both to have a relative feel for how a lens will behave on a different sensor "format" and also to adjust with reference to shutter speed for handheld photos.

My first quality digital was a 1D Mark II with its 1.3X "sports crop" and I mentally adjusted focal length to get a feel for it moving from 35MM film.

Rodger

Re: 35mm for 70d!!

rs-eos — Wed, 04 Mar 2020 18:12:23 GMT

Good points regarding use cases for equivalents. On my Vixia cam, the 3.67mm to 73.4mm marking on the lens is not directly useful 🙂

I sometimes take either stills or videos, then use my 3D software to infuse rendered assets. To get perpective correct, I set the 3D software's cameras to match exactly the physical camera/cam and lens settings. The software camera settings defaults to the 35mm standard (though you can change that). So it's just easier to enter in the 35mm equivalent values into the focal length field.

Side note/rant: On my Canon cam, unfortunately the sensor is marked as "1/2.3 inch" but that's ultimately meaningless since many manufacturers advertise that size yet can range from 7 to 8 mm. "1.0 inch" sensors are defintely not 25.4mm. They are much closer to 16mm. Sure hope the industry one day just marks stuff with the actual mm diagonal and not other designations that can vary. I think this also happens with medium format. Stating "MF" isn't enough since there are too many variations of the physical sensor size.

Re: 35mm for 70d!!

ebiggs1 — Wed, 04 Mar 2020 18:37:33 GMT

You see I really never did get into the whole crop factor thing until I got on some forums. It seems it abounds!

I guess it is because, for work, we used all different camera formats form 8mm to 35mm to 8x10 sheet film. There was no crop factor, or tele factor (?) then. That came about when the Rebels came out.

You just knew which lens to use one which camera.

Re: 35mm for 70d!!

Tronhard — Wed, 04 Mar 2020 19:35:25 GMT

I have said before, so forgive me if you read this agian, that we are not really served well by using focal lenght alone as a metric for identifying what a lens will deliver. A lens does not produce recorded image without a sensor: thus, the focal length of the lens - which is a valid optical metric for the LENS is further imacted by what the sensor captures. Combining these two is how we come to equivalence, an attempt to reconcile this issue, given that common nomencalture refers to this in terms of what the lens and a FF(35mm) sensor will produce.

For me Field of View goes some way to reconcile this. So aruably, in the documentation printed on the lens box and other literature, it could be easy to have both the Focal Lenght (which is certainly a valid identifying characteristic) and the Field of view. For EF-S lenses this will be just one value for a fixed FL lens, a range for a zoom. An EF lens would have to display a table showing what FoV the lens+sensor combination will offer for both AP-C and FF bodies, perhaps with a simple diagram to clairfy the intent.

I am the first to say that this is not critical for the majority of people who buy a lens after looking through a one on a camera in a shop or seeing one in action elsewhere. However it is more of an issue as in the OP, where one is seeking a specific FoV for a crop sensor body.

I certainly experienced that with a couple of people from a local photography group. A fairly new person seeking a lens was impressed by a particular L lens that took a bunch of images on show - the images showed the full gamut of the lens' FoV on a FF camera. Not being aware of the impact of a crop sensor they purchased the same lens for their APS-C body and when it was delivered they were convinced the lens was faulty as it did not deliver the same results. This elilcited a dispute between the vendor, Canon and the purchaser until someone enlightened the purchaser.

I stil refer back to the article from DPReview that tries to explain this issue

https://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care