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My RF 28mm f2.8 STM Arrived Today!

snegron7
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p.2 #1 · p.2 #1 · My RF 28mm f2.8 STM Arrived Today!

johnctharp wrote:
Seconded!

Why is there a thread about people having it and not one single cat picture?

Sorry, laziness on my part!😀 I haven't had a chance to download them yet. Hopefully I'll have some time over the weekend!

Jul 12, 2023 at 05:32 PM

Gochugogi
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p.2 #2 · p.2 #2 · My RF 28mm f2.8 STM Arrived Today!

snegron7 wrote:
I share your concerns about the use of plastic elements. Many years ago I purchased a Nikon 35mm f2.0 Series E. It was super clear and sharp for around 5 years or so, then the plastic elements started to fade; had a "frosty" appearance.

Hopefully this won't happen with my RF 28 as plastics technology has improved over the years.

A high percentage of Canon lenses have been using plastic elements—especially plastic-molded (PMo) aspherical elements—for decades now.

Jul 12, 2023 at 06:16 PM

snegron7
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p.2 #3 · p.2 #3 · My RF 28mm f2.8 STM Arrived Today!

Gochugogi wrote:
A high percentage of Canon lenses have been using plastic elements—especially plastic-molded (PMo) aspherical elements—for decades now.

I hope that at least the front element is glass as plastic scratches way easier than glass.

Jul 12, 2023 at 07:00 PM

Gochugogi
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p.2 #4 · p.2 #4 · My RF 28mm f2.8 STM Arrived Today!

snegron7 wrote:
I hope that at least the front element is glass as plastic scratches way easier than glass.

It's usually an inner element that would be otherwise too expensive to bring and polish from glass. You might enjoy watching the teardown of the RF 28 2.8 STM. He shows off each of the plastic elements: https://www.canonrumors.com/canon-rf-28mm-f-2-8-stm-pancake-teardown/

Jul 12, 2023 at 08:04 PM

rscheffler
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p.2 #5 · p.2 #5 · My RF 28mm f2.8 STM Arrived Today!

AmbientMike wrote:
Any idea on the uncorrected distortion percentage of the lens? Vignetting?

As linked earlier, please see the TDP's RF 28 STM review. Distortion info can be found here. He also has vignetting info here and even flare performance/resistance, which looks to be very decent.

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Pixelpuffin wrote:
Really stupid question
But won’t the plastic lenses turn orange over time? I have some old reading glasses that had plastic lenses, they have a distinct orange tint.

Tbh
I had pined so much for a RF pancake, I’m now left a little deflated. The front element is way too tiny to clean effectively, add the plastic elements and then the fairly steep price. By comparison the RF 50 is half the price, all glass, and bright too. I honestly thought it would very similar to the RF just a fraction slimmer.
In the UK the new 28 is around £350 ish, can’t help...Show more →

I'm guessing Canon uses half-decent optical grade plastics.

One strategy would be to buy several copies and keep one in dark storage until the 'daily driver' wears out. Or buy another one before they're discontinued and out of stock, so you have a fresh copy for X more years.

The difference between this 28 and the RF 50/1.8 is that the 28 is actually sharp and usable across the frame from wide open. The 50 has all sorts of aberrations that take until at least f/4-5.6 to clear up and get most of the frame sharp. IMO the 50 performs optically to its low price point. In this respect, IMO the 28 outperforms its price point. I have easily spent a lot more on rangefinder 28mm lenses that may not be much sharper. Though of course not originally intended for adapting to the Canon R system, until now this was about the only option if I wanted a small, high performance 28 on Canon R (assuming good compatibility with the Canon sensor stack). This RF pretty much negates that need or desire.

Jul 12, 2023 at 11:25 PM

rscheffler
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p.2 #6 · p.2 #6 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
The Canon Japan RF 28 page has the block diagram:

A larger view of that block diagram from Gordon Laing's video better shows the rear protective glass 'element' to shield the more delicate plastic rear element.

This is one thing that bothers me a little more with RF lenses - rear elements very close to the rear of the lens, whereas with EF they were often more recessed. While shooting events, etc., I never keep caps on lenses and have had to more frequently clean the rear of RF lenses from inadvertent finger smudges, or whatever they came in contact with at the bottom of a pouch, etc.

Here's another tidbit from that video - lenses with PMo (plastic) elements, including the RF 50/1.8!

Other interesting info:

Jul 13, 2023 at 12:06 AM

Jman13
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p.2 #7 · p.2 #7 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
This is one thing that bothers me a little more with RF lenses - rear elements very close to the rear of the lens, whereas with EF they were often more recessed. While shooting events, etc., I never keep caps on lenses

Note to self: don't buy used lenses from rscheffler.

Jul 13, 2023 at 06:36 AM

Robin Smith
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p.2 #8 · p.2 #8 · My RF 28mm f2.8 STM Arrived Today!

He probably has them on the rear, just not the front...

Jul 13, 2023 at 10:44 AM

rscheffler
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p.2 #9 · p.2 #9 · My RF 28mm f2.8 STM Arrived Today!

When covering events, during which I tend to frequently change lenses, I use no lens caps at all. For my mirrorless transition, I decided on the 28-70/2 in part so I don't need to change lenses as frequently but can still get the fast prime look, if desired. Just depends on what I want to use on the second body, like 70-200 or an 85 or 135 prime. Has simplified things a lot. Still hoping Canon makes a 70-135/2 companion for the 28-70.

Jman13 wrote:
Note to self: don't buy used lenses from rscheffler.

I usually sell to KEH, rather than dealing with picky buyers expecting perfection. If you buy from them, stay with EX and higher grade Canon lenses.

Jul 13, 2023 at 10:47 AM

AmbientMike
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p.2 #10 · p.2 #10 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
As linked earlier, please see the TDP's RF 28 STM review. Distortion info can be found here. He also has vignetting info here and even flare performance/resistance, which looks to be very decent.

---------------------------------------------

I'm guessing Canon uses half-decent optical grade plastics.

But for the price point and complexity of the aspherical shapes involved, seems to be a reasonable tradeoff given the decent performance. 10-15 years? This is not a 'collectable' lens, or at least not intended as such, and IMO it is semi-disposable at this price point, assuming comparable better performing lenses are released in the future. It's likely most...Show more →

I already looked at that, but that page on TDP doesn't really work on my phone, and I can't tell if I'm looking at the 28 rf or not. Interested in the actual numbners, anyway and didn't see them anywhere on TDP yesterday

Are the plastic elements seriously going to degrade? My 28/3.5 OM is listed at 6.7oz or something, metal and glass, basically obsolete 20+ years ago on film, though it got popular again on digital. I don't know if it has lost anything over the past ~40 years or however long it's been around.

Hard to get excited about a $300 28/2.8. 16/2.8 I can see how it might have issues and require computational imaging. A $300 28/2.8 isn't that cheap and just needs to be good.

Jul 13, 2023 at 11:03 AM

AmbientMike
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p.2 #11 · p.2 #11 · My RF 28mm f2.8 STM Arrived Today!

Jman13 wrote:
Note to self: don't buy used lenses from rscheffler.

In all seriousness, though, rear caps are a good idea, since damage to a rear element is far more likely to cause image quality problems than a scratched front element, which rarely does.

The close rear elements are one of the key things that allow lens designers to take advantage of the short flange distance of mirrorless cameras, making lenses better optically and more compact.

I've always heard dust etc on rear elements is a bigger deal, people said that years ago,
but I don't know if that's actually the case or something people say. Funny just thinking about it in the last couple days. I'd be interested in the rationale and reasons if anyone knows .

I avoided the K1000 on film because you had to put the lens cap on, no meter switch. I knew I'd lose them. Pretty good about keeping rear one on though.

Jul 13, 2023 at 11:12 AM

tsdevine
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p.2 #12 · p.2 #12 · My RF 28mm f2.8 STM Arrived Today!

I've seen dust on the rear element of a lens producing what sort of looked like dust on the sensor. It was very vexing until I switched lenses and realized it wasn't the sensor that needed cleaning. I looked at the rear element of the original lens and saw the nice big speck of dust. After blowing that off, problem solved.

AmbientMike wrote:
I've always heard dust etc on rear elements is a bigger deal, people said that years ago,
but I don't know if that's actually the case or something people say. Funny just thinking about it in the last couple days. I'd be interested in the rationale and reasons if anyone knows .

I avoided the K1000 on film because you had to put the lens cap on, no meter switch. I knew I'd lose them. Pretty good about keeping rear one on though.

Jul 13, 2023 at 11:18 AM

marsguy
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p.2 #13 · p.2 #13 · My RF 28mm f2.8 STM Arrived Today!

Man, I'm religious about putting my lens caps back on. I would rather not get a shot, or stitch/crop, than change a lens in a dusty or misty area. Then again, I'm not a professional, and some situations demand a lens change and you don't have tons of time to fiddle with caps, especially the awful RF caps that just don't seem to want to go on. I wouldn't want to shoot a paid engagement with lenses that have dust and fingerprints on them, though, so...

I would assume dirt/dust on a rear element to be worse than on the front element, as it would be obstructing a much larger part of the image than if it were on the front, assuming physical size of the particulate stays the same. I'm sure it's more complex than that though.

Jul 13, 2023 at 11:19 AM

rscheffler
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p.2 #14 · p.2 #14 · My RF 28mm f2.8 STM Arrived Today!

Yes, the terrible RF rear cap is another reason I skip re-capping after lens swaps because of the single correct mounting alignment, whereas with the EF rear cap it didn't matter. It just wastes too much time. But sure, if I'm out on a hike and it's wet or dirty and there's time, I'll maybe put the rear cap on.

I don't think TDP posts actual distortion percentage/numbers, at least I didn't see it for this lens. Vignetting is quite strong at about 2.5 stops in the extreme corners and down to 1.3 stops by f/5.6-8.

AmbientMike wrote:
Hard to get excited about a $300 28/2.8. 16/2.8 I can see how it might have issues and require computational imaging. A $300 28/2.8 isn't that cheap and just needs to be good.

Wow, tough crowd!

The RF 28 is half the length of a conventional 28/2.8 with just as good, if not better optical performance (sharpness). While its distortion is worse than the EF 28s, it's mild compared to the other 'consumer' RF wide angles. I guess it also depends on your feelings about 28mm. I like 28 and this lens really caught my attention in part because it's sharp and Canon put some effort and innovation into making it more compact while not totally falling back on software corrections.

Dust on the rear element becomes more noticeable in images the closer the rear element is to the sensor because at this point the light is mostly traveling in the same direction and the dust more completely blocks light from that portion of the image. With a more recessed rear element, light can 'wrap around' the 'shadow' caused by the dust spot and more effectively hide it. This is also more so the case when shooting wide open because the larger width of the pupil through which the light passes allows for more light traveling at slightly different angles. With a very small aperture, the light is more directional, more collimated. I've shot Leica M for around a decade and this was something I noticed pretty quickly, for example with the Zeiss ZM 21/2.8 on the M9 years ago. The rear element protrudes a bit from the lens mount and with my habit of working capless, it would pick up bits of dust in the bag that would then show up in images.

Jul 13, 2023 at 02:54 PM

AmbientMike
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p.2 #15 · p.2 #15 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
Yes, the terrible RF rear cap is another reason I skip re-capping after lens swaps because of the single correct mounting alignment, whereas with the EF rear cap it didn't matter. It just wastes too much time. But sure, if I'm out on a hike and it's wet or dirty and there's time, I'll maybe put the rear cap on.

...Show more →

You have me beat, I've mostly left the rear cap off the kit lens.

That one sounds a bit pricey! The front caps don't usually last long though, and it does help if you have less to fiddle/mess with like caps etc.

Light compact 28mm lenses aren't really new though. I guess I got used to paying $50

The old ones didn't usually have too much distortion AFAIK so I hope they didn't make one requiring extensive computational imaging.

28mm is useful I've been using it a lot ( roughly aps equivalent.) 2.5 stops is bad but if it can be stopped down 1.3 probably not too bad.

Jul 14, 2023 at 10:18 PM

rscheffler
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p.2 #16 · p.2 #16 · My RF 28mm f2.8 STM Arrived Today!

That's true, many of the old manual focus SLR system 28mm lenses were the equivalent of 'kit' lenses to cover the wide end and pair with a 50/1.8 or 50/2 and a 135/2.8 or 135/3.5. A lot of those 28s were very small, but were also designed for ~45mm flange distances. To use them on mirrorless would add about 1" for the adapter tube. The RF 28 pancake could probably have been designed similarly, considering Nikon's recent Z mount 26/2.8 has a somewhat less ambitious, though still similar optical design, but may have had edge performance tradeoffs, such as even stronger vignetting and lower image quality due to the steep angle through which the light rays would pass through the sensor topping glass, which also can affect image quality (the lens would have to be designed to compensate for greater refraction by the sensor glass of light forming the periphery of the image area).

Just for kicks, here's a comparison of the RF 28/2.8 block diagram with that of the Nikon Z 26/2.8:

Canon:

Nikon (blue elements are aspherical):

MTF:

Canon:

Nikon:

Back to the PMo discussion, I was browsing Lens Rental's teardown of the EF 16-35/4L IS and noted they posted the block diagram from Canon's white paper about the lens, and in that block diagram it's indicated that the front two elements, both aspherical, are PMo...

I've had that lens since close to its release in 2014 and did not know that. It's been a very good lens.

EF 16-35/4L IS block diagram:

Jul 16, 2023 at 04:39 PM

Pixelpuffin
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p.2 #17 · p.2 #17 · My RF 28mm f2.8 STM Arrived Today!

I often leave the front cap off, actually I leave them at home
The front lens is usually protected by the hood or in rare cases I’ve fitted a uv filter

BUT, I wouldn’t dream of ever leaving the rear cap off, even a finger print would degrade the image, not to mention fluff or god forbid catching it on a zip or corner of something.

For the sake of 10 seconds I’ll always fit the rear caps.

Jul 17, 2023 at 01:47 AM

lighthound
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p.2 #18 · p.2 #18 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
While shooting events, etc., I never keep caps on lenses and have had to more frequently clean the rear of RF lenses from inadvertent finger smudges, or whatever they came in contact with at the bottom of a pouch, etc.

I just broke out in a cold sweat after reading that. I think I felt a little faint as well.

I baby the heck out of my lenses. As a hobbyist hack photographer I can't afford to replace lenses continuously or abuse them such that I take a financial hit when reselling due to poor condition. When I swap lenses or TC's, I make sure I have both lenses and body ready to make a swift and clean swap to minimize the time the rear elements and internal shutter area of the camera are exposed to any contaminants. Now that I think about it, I think I might even be holding my breath when I make the swap.

I guess I can understand how working pro's need to be a little more "carefree and fluent" when swapping out lenses but dayum. Still makes me cringe.

Jul 17, 2023 at 08:24 AM

mawz
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p.2 #19 · p.2 #19 · My RF 28mm f2.8 STM Arrived Today!

I'm pretty religious about rear caps (and the RF rear caps are actually pretty good, but not nearly as good as EF which are the best ones I've run across. FD rivals m42/LTM for the worst rear caps).

The reason is just to avoid having to clean rear lens elements in the field. I don't baby my gear, but I also don't want to be mucking with cleaning a lens when I'm perched at the side of a wetlands 5km from the truck.

Jul 17, 2023 at 08:36 AM

AmbientMike
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p.2 #20 · p.2 #20 · My RF 28mm f2.8 STM Arrived Today!

rscheffler wrote:
That's true, many of the old manual focus SLR system 28mm lenses were the equivalent of 'kit' lenses to cover the wide end and pair with a 50/1.8 or 50/2 and a 135/2.8 or 135/3.5. A lot of those 28s were very small, but were also designed for ~45mm flange distances. To use them on mirrorless would add about 1" for the adapter tube. The RF 28 pancake could probably have been designed similarly, considering Nikon's recent Z mount 26/2.8 has a somewhat less ambitious, though still similar optical design, but may have had edge performance tradeoffs, such as even...Show more →

I would say, in spite of ~45mm flange distance, they are still light, and have excellent performance.

In theory it should be easier on mirrorless given the shorter distance since you don't need the retrofocus design. Even less reason to need computational imaging

Jul 17, 2023 at 02:27 PM

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