Is the ultimate astro lens coming? Another RF 14-21mm f/1.4L USM mention [CR2]

Sep 9, 2020
4
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Is it really that important if the camera fixes it before you even look at the file?

Of course! It's not magic - the camera pulls up the exposure in those parts of the frame to remove the vignetting which increases noise. The RF 15-35 2.8 has 4.6EV uncorrected and 2V corrected. So if you shoot 3200ISO, the corners are now like they were shot at 3200->6400->12800->19200 ISO and you still have 2EVs of vignetting to deal with.

And remember vignetting doesn't just affect corners. at 15mm on the RF lens, you lose a stop by the time you get to the APC corners. Here's a comparison to the Sigma at f2:


Chris
 

cayenne

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There's a huge world of difference between an 11-24 and a 14-21 - so much so that I would argue that it covers the difference in speeds between the two lenses which is why I think they'll be the same price.

Of course, the more people post here saying "I'm sure this lens will be $4k or more", the more chance that Canon will take notice and think "yes, maybe we can sell it for that much!"

So, to counter that, I think it'll come out at $349 :)

Let's also add that it needs to come with a 2-for-1 coupon too, to even hope to be remotely successful at launch!!
;)
 
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twoheadedboy

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Of course! It's not magic - the camera pulls up the exposure in those parts of the frame to remove the vignetting which increases noise. The RF 15-35 2.8 has 4.6EV uncorrected and 2V corrected. So if you shoot 3200ISO, the corners are now like they were shot at 3200->6400->12800->19200 ISO and you still have 2EVs of vignetting to deal with.

And remember vignetting doesn't just affect corners. at 15mm on the RF lens, you lose a stop by the time you get to the APC corners. Here's a comparison to the Sigma at f2:


Chris

I get the technical side. I'm saying does it have an actual impact, at image sizes that actually get used? Corner resolution is already lower than in the center, I get that astro demands a consistent exposure corner-to-corner, I'm just not convinced that "vignetting + fix" is going to be noticeably different from "less vignetting" on a different lens beyond pixel-peeping.
 
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Sep 9, 2020
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I get the technical side. I'm saying does it have an actual impact, at image sizes that actually get used? Corner resolution is already lower than in the center, I get that astro demands a consistent exposure corner-to-corner, I'm just not convinced that "vignetting + fix" is going to be noticeably different from "less vignetting" on a different lens beyond pixel-peeping.

On an 8x10 maybe not. Depends on the difference. 3 stops is a lot. Maybe you could crop the worse away. I remember on my Rokinson 14 2.8 the 4-5 stops of vignetting vs my Nikon 14-24 was very noticeable.

In my astro shooting experience - and perhaps others will disagree - the biggest negative factor on my image quality is high iso noise. A one stop difference is huge (just think of the difference of 2.8 vs 4). I have some shots printed 16x20 and they only work because I stacked 15+ frames. It would be great to get another stop or so of speed. Makes post so much bette.

And with Aurora you can't stack or track so there it's even more critical.

It is also very noticeable if your noise profile is way worse anyway from the center.

Anyway, doesn't matter. Canon will make the lens like they make it. I'm just saying if they are going to make a monster like this, just make it a monster. I'd rather have it 10% bigger and 200g more and have 2-3 stops vignetting in the Sigma 14 1.8.

Chris
 

amorse

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On an 8x10 maybe not. Depends on the difference. 3 stops is a lot. Maybe you could crop the worse away. I remember on my Rokinson 14 2.8 the 4-5 stops of vignetting vs my Nikon 14-24 was very noticeable.

In my astro shooting experience - and perhaps others will disagree - the biggest negative factor on my image quality is high iso noise. A one stop difference is huge (just think of the difference of 2.8 vs 4). I have some shots printed 16x20 and they only work because I stacked 15+ frames. It would be great to get another stop or so of speed. Makes post so much bette.
....
I'm still using the old Rokinon 14mm f/2.8 for night sky - I'm just getting tired of stacking so many frames and having to manually align images in photoshop for it to stack acceptably. That moustache distortion adds so much time to the stacking process for me.

I'm pretty hesitant to use it for night sky without stacking, unless I'm taking photos of aurora or panorama stitching, so this rumour has some potential in my eyes. I was hoping to replace my 16-35 f/4 with something faster and replace the Rokinon with something faster (or at least with easier to correct distortion) as well, so I'm kind of hoping that the expected trade offs from this lens don't negate it's fit for my use - price and weight being the most obvious ones.
 
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tron

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I'm still using the old Rokinon 14mm f/2.8 for night sky - I'm just getting tired of stacking so many frames and having to manually align images in photoshop for it to stack acceptably. That moustache distortion adds so much time to the stacking process for me.

I'm pretty hesitant to use it for night sky without stacking, unless I'm taking photos of aurora or panorama stitching, so this rumour has some potential in my eyes. I was hoping to replace my 16-35 f/4 with something faster and replace the Rokinon with something faster (or at least with easier to correct distortion) as well, so I'm kind of hoping that the expected trade offs from this lens don't negate it's fit for my use - price and weight being the most obvious ones.
The difference in price will be a 10x or 15x one. Why not try to save 1.3 stops by using the Sigma 14mm 1.8?
See its review at:

 
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cayenne

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I'm still using the old Rokinon 14mm f/2.8 for night sky - I'm just getting tired of stacking so many frames and having to manually align images in photoshop for it to stack acceptably. That moustache distortion adds so much time to the stacking process for me.

I'm pretty hesitant to use it for night sky without stacking, unless I'm taking photos of aurora or panorama stitching, so this rumour has some potential in my eyes. I was hoping to replace my 16-35 f/4 with something faster and replace the Rokinon with something faster (or at least with easier to correct distortion) as well, so I'm kind of hoping that the expected trade offs from this lens don't negate it's fit for my use - price and weight being the most obvious ones.

You might try out a more dedicated piece of stacking software, like Helicon Focus.<P>
It seems to work VERY well for me doing focus stacking.....they have a 30 day free trial, so might be worth your while to audition it.

HTH,

cayenne
 
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amorse

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You might try out a more dedicated piece of stacking software, like Helicon Focus.<P>
It seems to work VERY well for me doing focus stacking.....they have a 30 day free trial, so might be worth your while to audition it.

HTH,

cayenne
Thanks for the suggestion - I'll give it a go! This lens always struggles with stacking but does fine in stitching panos. Hopefully this works as an intermediate solution - the ~20 minutes of manual tweaking per frame for the stack gets pretty discouraging when the number of frames gets over 8!
 

amorse

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The difference in price will be a 10x or 15x one. Why not try to save 1.3 stops by using the Sigma 14mm 1.8?
See its review at:

The Sigma is a really good alternative, honestly. I've been thinking about that lens since it launched but never pulled the trigger because I've also wanted to reduce the number of lenses I'm carrying when camping. I find that I'm doing landscape astrophotography mostly while camping, and replacing the Rokinon with the Sigma would drastically improve image quality, but also take up more bag space and increase my carry weight - it would work perfectly well, but it is a trade off.

Typically I've been bringing the Rokinon 14 and a Canon 16-35 f/4 (plus a 24-70 and 70-200), but if I can replace those wide lenses with one wide/fast zoom then I can potentially increase image quality and reduce the number of lenses. On the other hand, the price will definitely be an issue and the weight will likely be more than I'm already carrying, so this won't likely be a perfect fit either. Until this rumour though, I was expecting to just go for the RF15-35 and see if it stacks more efficiently, but considering that I can't really travel much at the moment, I'm not in a huge rush to solve the problem and can wait for some final details to decide what is the best fit.

Thanks for the suggestion!
 
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infared

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The Sigma is a really good alternative, honestly. I've been thinking about that lens since it launched but never pulled the trigger because I've also wanted to reduce the number of lenses I'm carrying when camping. I find that I'm doing landscape astrophotography mostly while camping, and replacing the Rokinon with the Sigma would drastically improve image quality, but also take up more bag space and increase my carry weight - it would work perfectly well, but it is a trade off.

Typically I've been bringing the Rokinon 14 and a Canon 16-35 f/4 (plus a 24-70 and 70-200), but if I can replace those wide lenses with one wide/fast zoom then I can potentially increase image quality and reduce the number of lenses. On the other hand, the price will definitely be an issue and the weight will likely be more than I'm already carrying, so this won't likely be a perfect fit either. Until this rumour though, I was expecting to just go for the RF15-35 and see if it stacks more efficiently, but considering that I can't really travel much at the moment, I'm not in a huge rush to solve the problem and can wait for some final details to decide what is the best fit.

Thanks for the suggestion!
Hmm....I mentioned above that a Sherpa would be additional...hmmm...are your rates reasonable? You sound like the right guy! ...This thing, if it’s real...will be a monster! LOL!
 
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tron

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The Sigma is a really good alternative, honestly. I've been thinking about that lens since it launched but never pulled the trigger because I've also wanted to reduce the number of lenses I'm carrying when camping. I find that I'm doing landscape astrophotography mostly while camping, and replacing the Rokinon with the Sigma would drastically improve image quality, but also take up more bag space and increase my carry weight - it would work perfectly well, but it is a trade off.

Typically I've been bringing the Rokinon 14 and a Canon 16-35 f/4 (plus a 24-70 and 70-200), but if I can replace those wide lenses with one wide/fast zoom then I can potentially increase image quality and reduce the number of lenses. On the other hand, the price will definitely be an issue and the weight will likely be more than I'm already carrying, so this won't likely be a perfect fit either. Until this rumour though, I was expecting to just go for the RF15-35 and see if it stacks more efficiently, but considering that I can't really travel much at the moment, I'm not in a huge rush to solve the problem and can wait for some final details to decide what is the best fit.

Thanks for the suggestion!
You almost read my mind. I was thinking of suggesting you the16-35 2.8 to consolidate 14 and 16-35 f/4 !!

I have many UWA lenses because I got them as soon as they became available and then didn't want to part with the other ones!

Zeiss 21mm 2.8 (it has a hard stop at infinity!)
Canon 14mm 2.8 L II (that was a bargain bought used in perfect condition using many lenses I didn't want as part exchange).
Canon 16-35 4L IS (finally a travel uwa zoom with excellent IQ. I part-exchanged the old non-is 24 2.8 for that)
Canon 16-35 2.8L III (Because I wanted 2.8!!!!!!!! But it has huge vignetting)
Canon 11-24 f/4 (I used it less than I thought. And t is very big!)
Sigma 14mm 1.8
Canon RF 15-35 2.8L IS (because it has IS and I want to use it at church and museum interiors)
It has the same vignetting as the 16-35 2.8L III
So many overlaps!

I have done astrophotography mainly with 14mm 2.8L II and last year with Sigma 14mm 1.8

I liked the results (I think I had a little flare when there was the moon (not full of course) in the sky even when it wasn't visible in the frame. But when I shot at the lights at home I didn't see any flare!)

A 14 2.8 is small and can be put almost everywhere in a bag. By the way both 14mm lenses I have have much less vignetting than the 16-35 and the 15-35 zooms.

P.S By the way I can't travel either. Also there is the issue with light pollution. And the astronomik filters do not work well with fast lenses (they mention less than f/3 for FF cameras which practically limits them to f/2.8 lenses!)
 
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lbeck

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Jul 30, 2019
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To be honest, I’m very sure I have never had a lens as sharp as the RF 50/85mm f/1.2L lenses.... at f1.2. RF is a real game changer. Stopping down may not be needed.

+1 for the 50 1.2

It’s razor sharp wide open, stop down a few and it’s simply ridiculous.
 

20Dave

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Jan 19, 2013
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Thanks for the suggestion - I'll give it a go! This lens always struggles with stacking but does fine in stitching panos. Hopefully this works as an intermediate solution - the ~20 minutes of manual tweaking per frame for the stack gets pretty discouraging when the number of frames gets over 8!

There are other astro image processing apps out there such as PixInsight, Astro Pixel Processor, and DeepSkyStacker (free) that are excellent for stacking and automatically align the images. It won't help for quickly changing phenomena like an Aurora, but for Milky Way panoramas and other star photos, they can be very powerful. Admittedly, I haven't used them for panoramas that include a (moving) horizon, but I use PixInsight quite a bit for astrophotography. Stacking hundreds of images is easy.
 
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David - Sydney

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Lot's of budding astronomers here...lol
Splitting hairs.....
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either observational (by analyzing the data) or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. Related but distinct subjects like physical cosmology, which studies the Universe as a whole

There are astronomers in the group but they are into deep field astronomy (Ha/filtered spectrum, telescope mounted, long exposure/ EQ mounts, cooled sensors). This lens would mostly suit astro-landscapers to include earthly foreground elements for context and relatable interest.

Then again, the first thing that everyone does with a big white is shoot the moon :)
 
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