I Have What May Be A Stupid Question. EF, RF, EF-S, RF-S

[Far-Out-Dude]

I have what some may find to be a stupid question, but what exactly is aWispy Clouds. S lens? (EF-S, RF-S) What is different about them and in what circumstance would I want one over a EF or RF lens? Thank you very much for your time.

[AtticusLake · Accepted solution]

Canon use the "-S" suffix to indicate a lens or camera which is designed for a so-called "crop" sensor, also called APS-C, roughly equivalent to Super 35.  As opposed to "full-frame", which has a larger sensor.

So a "-S" camera will have a sensor about 23mm × 15mm.  A "-S" lens will create an image big enough to cover that sensor, so it will work fine.  A full-frame lens -- i.e. no "-S" -- will create a larger image, which will also be fine.

A full-frame camera -- i.e. no "-S" -- will have a sensor about 36mm × 24mm -- quite a bit larger.  A full-frame lens will cover this no problem, but a "-S" lens will not.  The camera will handle a "-S" lens by reading out only a part of the sensor ("crop mode"), which will give you a drastically reduced resolution.  Your pictures will be OK, but with nowhere near the resolution you paid for.

The benefit of a "-S" lens on a "-S" camera is that it will, in general, be smaller, lighter, and cheaper than a full-frame lens; the drawback is that if you later upgrade your camera to full-frame, then the "-S" lenses won't work well.

A "-S" camera, or a full-frame camera in crop mode, will also have a narrower field of view; so your lenses will all be a bit more telephoto.  Multiply the focal length by around 1.5 to get the "equivalent full-frame focal length".   So a 100mm lens on a "-S" camera is still a 100mm lens, but will give you the field of view that a 150mm lens would give you on a full-frame camera.

If you want to know more about lens mounts, I wrote an article which tries to explain this stuff: https://moonblink.info/MudLake/gear/lenses

Hope this helps.

[p4pictures]

When Canon introduced the first EF-S lenses with the EOS 300D / Digital Rebel they used S to signify short back focus design. This is because the EF-S design allowed the rear elements of the lens to be located deeper in to the mirror box of DSLR cameras. These cameras with smaller APS-C size sensors also had a smaller mirror so there was not the need for so much clearance behind the rear of the lens when the mirror raised to take a photo. Using short back focus design allowed the lenses to be smaller and lighter to make, wile also keeping the price reasonable. 

With mirrorless cameras there is no mirror to contend with and lenses mount much closer to the sensor anyway thanks to the shorter flange distance. The RF-S designation is used to continue the notion of "S" lenses being designed for mirrorless cameras with an APS-C size sensor. 

[Far-Out-Dude]

Thank you both very much. I see no reason to look at a RF-S for my new R5 Mark ii then. Thank you both for keeping me from wasting money. May if I chose to buy more lenses for my M50 look at one though. I still want a 32mm for that camera but have not found one that is new as they discontinued them. I think I was looking at a 24mm EF-S for that camera at one time but after seeing the results of the 22mm Prime I have no interest in that as I was very disappointed in that lens for that camera. I still want that 32mm though for it.

@AtticusLake I will check that out later, thank you.

[AtticusLake]

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@Far-Out-Dude wrote:

Thank you both very much. I see no reason to look at a RF-S for my new R5 Mark ii then. Thank you both for keeping me from wasting money. May if I chose to buy more lenses for my M50 look at one though.

RF-S and RF lenses will not work on an M-series camera.  EF-S and EF-M lenses will (EF-S will need an adapter).  But the M series is a bit dead, really, nor worth making a big investment in at this point.

The article I posted the link to explains the compatibility issues for M series.

[ebiggs1]

Remember in Photoshop less is more. Back off on the sliders.

[Far-Out-Dude]

Would you like to offer more detail? This is the original in Jpeg form. The was not much done with it other than bring out the sky a tad and adding shadows to add depth.

[ebiggs1]

Better judgement and my gut feeling tells me it may be better to refrain from further critique because it is all in what you want in your photos and not what me or anyone else.If you like it as is, then I do too.

[Far-Out-Dude]

That's alright. The funny thing is I went and looked at the sliders and they were barely moved. Oh and it was in Lr I can't see stuff well in Photoshop so I don't use it much.

[ebiggs1]

OK, I will step in to it one bit further. Canon cameras at least some or most of them have a Picture Style setting.. My recommendation is to set it to "Standard".  Again it's not for me to to say if you get what please you that's all that is important.

"I can't see stuff well in Photoshop so I don't use it much."

Hmm surprising because PS and LR have the exact same settings possible. Your best friend in PS is Curves or Levels. Curves is a bit more capable then Levels. Keep shooting.