What is Lens Coma?
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- เผยแพร่เมื่อ 4 ต.ค. 2024
- Lens coma results from an imperfection in the way that a lens renders light around the periphery. Lenses like the Petzval, which is the poster child of poorly corrected lenses, typify this
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Making your way through basic film/camera/lens questions is a brilliant way to build a strong following, and actually help people with your concise but thorough explanations; like building an online encyclopedia. Keep up the great work David!
Thank you!
subscribed yesterday, fantastic channel for learning ; thanks
Thank you!
Helios 44 and loads of triplets. For example the Ricohflex triplet TLRs has some wonderful circular coma.
Good examples. I completely forgot about the Helios.
So that's what that means! My Helios 44m-7 Lens has these cool lens coma effects on wide open at f/2. Allows for some really cool effects.
I hadn’t even heard of it before, fascinating. I know it is an unacceptable fault, but I really liked the image of your dog. Another great video, TH-cam would be quite boring without without you.
Thank you. She was a really photogenic dog.
It's what happens when you can't decide which lens to buy.
There's so many good choices!
Hey, you guys are in SLC, right? I'm moving from SF to Denver in November and we're thinking of making the move a road trip. If we decide to take the northern route, would you be interested in doing a collaboration? The move is a long way of and our plans won't be solid until closer, but I thought I'd see if you had any interest.
Absolutely! Only, we also just moved. :) We're in St George now (Southern Utah, not far from Zion). I will be in SLC in November for a conference for a week though. If the timing lines up, I'd go out of my way to make a collab happen. Either way, it'd be fun to make one happen eventually.
Oh dang, that might even be better. My Plan A trip had us spending a few nights in St. George at a B&B there called Seven Wives. Where we stay in Utah depends on where we stop in California first. If we decide to spend our last nights in CA at Lake Tahoe, then we're driving through SLC. If we stay in Benton instead, then we're driving through St. George. I'll let you know in September or October when we have the dates and route pinned down.
Seven Wives?! Bwhaha.
Ok let us know!
Thanks sir
Thank you!
ok but what's the difference between coma aberrationa nd spherical aberration? aren't they both due to the same flaw in the shape of the lens?
In a nutshell, they're similar results of similar flaws but coma occurs off-axis and spherical aberration occurs on-axis.
Would the 19mm telw vue panoptic $250 usd go good with my f/5 orion spaceprobe 130st
No idea. I'm unfamiliar with both that telescope and the eyepiece.
good to know. I know the Yashica Mat-124G has this when shooting wide open and the Olympus 35RD has this aswell, but in a different way. The coma from the 35RD is perpendicular to the one from the Mat-124G which I find interesting. The Mat-124G one is like you drew in the comparison with the sharp corner pointing towards the edge of the frame and the one from the 35RD is more like the Petzval one that was seen in the image, but by far not as extreme. They are both fixed lens cameras and the front element is quite curved in both cases. Any explanation to why there is different types of coma or why it goes into the corner and in the other case perpenticular to the diagonal from corner to corner?
So the coma shape will derive from the lens' design when coma occurs. Coma occurs when light is improperly focused, and the closer to the edges of an image you get, the less well focused the image will be (this is true of all lens, which is why lens tests look at center and edge sharpness on images.) When a good lens projects light at the edge of a frame, then the dots are generally circular but softer. When a less-than-perfect lens does that, the dots take on a different shape (some look like comets, or pizza slices, half-circles, etc.) It's just the way that the glass is put together.
Me a physics student watching this video without realising it's a photography channel😂
Wait until next year when I get into depth of field cones and hinge lines on 4x5 camera lenses when movements are applied. 😀
I still don't know what coma is. your explanation was much too technical for my limited understanding. I would benfit from you taking the picture and actually showing it by point to it. I don't know what "a loss of a point source of light" means...
I have a series on this channel called Round Glass Review. Those videos have a section that analyzes lens blurry area for things like coma, spherical aberration, etc. Some of those might be really helpful in seeing different issue that different lenses have. Not all have coma and some have other problems, too.
shave, lose some weight, deepen your voice and bang: Chris Pratt
I'm going more for his Parks and Rec Sesaon 1 look.