Lunch atop a (Springfield) skyscraper

Lunch atop a (Springfield) skyscraper
by andy-m                

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20h
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
But I didn't actually sit down to do the calculations, so I might be wrong. My wave optics classes were a long time ago, I guess I should sit down, brush up on optics and derive the exact result ;-) But not until later today.
20h
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
@Michael Regarding diffraction: the frequency of light won't be changed by the optics of course. The wavelength will be different inside glass and air. What ultimately matters is the difference in optical path length from various points of the aperture plane to the same point of the projection plane. This led me to the conclusion that it is indeed the apparent size of the aperture (from the perspective of the projection plane, as seen through the TC) that matters.
20h
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
@Michael I don't see the point of your last comment, does it contradict with anything I said? I am merely trying to help the OP understand the issues involved so he can come to the answer himself without having to "just believe". Let's not make this about who is right, I am not arguing with you, I am chasing the right answer ;-)
21h
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
@Michael Now it is true that the same opening will correspond to a different "f-number" in the two cases. But that has no significance, does it? It's the physical opening that is the relevant quantity to compare: that's what has to be the same between the two to cases to have the same amount of light and the same depth of field, and that's what has the same maximum value between the two cases. (The maximum f-number will be smaller for the teleconverter case.)
21h
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
@Michael Thanks for the comments. Regarding noise levels: the point I was making is that for the same opening of the aperture blades the same amount of light (photons) will be "recorded" in both cases if the teleconverter has perfect transmission. Since it doesn't, in fact the FF gets less light in the end, and will have more noise. Regarding diffraction: it happens at the aperture blades (the smallest opening the light passes through). The magnification happens at a later stage along the optical path. Again, there will not be a difference given the same opening of the aperture blades.
1d
comment Does a full frame with a teleconverter perform better than an APS-C without a teleconverter?
You say "in general when the best cameras are coupled with the best lenses the best teleconverters will usually give better image quality of static subjects shot from a tripod mounted camera than shooting without a TC and then cropping away.". But if you think about what a teleconverter actually does, all arguments point in the opposite direction. Please see my answer. If I made a mistake in my reasoning, what is it? Otherwise this is all just anecdotal.
Jan
26
comment Is there a website which will help me crowdsource the decision between similar images?
@igor Realistically, it is very unlikely that this proposal will go through (at least in its current form). It is not a good fit for the StackExchange format... That shouldn't stop you from trying, but you might at least want to think through the example questions and not make then A-or-B choices. What would be the purpose of voting on such a site? Which answer gets accepted? Why is this better as a Q/A site than as a discussion forum? It sounds like you are looking for something that has an interface for A/B choices instead.
Jan
26
comment Is there a website which will help me crowdsource the decision between similar images?
@igor Which photo gets stars on flickr has little to do with which one is better ... But flickr has several critique groups where you can ask for human feedback. flickr.com/search/groups/?q=critique
Jan
25
comment How does software exposure compensation work in RAW files?
To put it simply: a sensor pixel counts photons. The RAW file stores these counts for each pixel. When you tune the exposure with say, Lightroom, it just multiplies these counts by a factor. If a pixel collected 100 photons, you can multiply that by 2 to "make it look like" 200.
Jan
21
comment Does the detail in an image affect how large the image file is?
@supercat Here's an experiment showing the effect of noise on JPEG size (quality priority). Size is in bytes, written under each image. Of course the results should significantly depend on the encoder itself as lossy encoders have many choices to make about what details can be thrown away without humans noticing ... dropbox.com/s/gla3lmbe1d831od/lena.png?dl=0
Dec
29
comment Is autofocus important for ultra wide angle lenses?
@PhilipKendall OK, done.
Dec
28
comment Do Raw camera images store colors logarithmically, with black near 0 and white at infinity?
The simple way to think of it is that the sensor counts photons, and the RAW file stores these counts (or rather a number proportional to them) directly.
Dec
16
comment How does the GoPro achieve such high dynamic range?
It's field of view is wide enough to always include plenty of sky which is not so bright as to be blown out. Portions of the sky close to the sun will still be blown out (how big that portion is depends on haze, clouds, etc.)
Feb
26
comment How to match colors on photographs stitched together?
@WilliamKF "M" setting is not sufficient. Also use identical white balance settings when converting the raw files.
Feb
26
comment How to match colors on photographs stitched together?
Just google for "stitch panorama in photoshop" and you'll find everything you need. CS6 does have this feature. Key things are Edit -> Auto Align and Edit -> Auto Blend. Auto-Blend does sort of what you're asking for. Actually it will cut the layers along a line chosen to minimize the differences between them, it will usually look seamless. I haven't used this with your method though (moving camera position), only with rotating the camera while its position is fixed.
Feb
26
comment What should I look for in a wide angle lens?
I think yes: many more wide angle photos will have the sun in them than photos taken with narrower lenses.
Feb
26
comment How to match colors on photographs stitched together?
Are you using Photoshop's automated stitcher? It should take care of this automatically. Or is it producing bad results in other ways?
Feb
25
comment What should I look for in a wide angle lens?
What about flare resistance?
Feb
18
comment Nikon D60: Autofocus of two AF-S lenses not working anymore after using another lens
So you can see the focus ring on your 18-55 rotating, but the camera never achieves proper focus? It sounds like the camera cannot detect when the image is in focus anymore. What happens when you turn on the rangefinder (page 116 in the manual) and set the lens to manual focus? Does it ever indicate correct focus as you are focusing manually? If not, there may be a problem with the AF system.
Feb
13
comment Why is the Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR twice as costly as Nikon 55-300mm f/4.5-5.6G ED VR AF-S DX?
The 70-300 focuses much, much faster than the 55-300. The 70-300 feels almost instantaneous at large focus distances. With the 55-300 one can watch the focus slowly change in the viewfinder.