Canon: To which side of an lens mount adapter is an extension tube connected?

In practice, apart from the potentially "strange" appearance, it is unlikely that there will be a significant difference between placing an extension tube between the body and the adapter or between the adapter and the lens. However, there are some potential differences:

  • The way the light is reflected and scattered inside the adapter and the tube would be different. One configuration can produce glare, while the other does not. Some adapters have this problem on their own. To fix it, cover the inside of the tube or adapter near the sensor with adhesive tape.

  • Having a smaller tube near the camera (or a larger tube near the lens) can affect the usability of the camera + assembly + lens.

  • Adapters often fit in with some play. It usually does not affect the use of the camera and the lens. However, add multiple adapters and tubes, and the assembly can become unbearably loose. A smaller tube connected near the camera body would exert more force on it (more leverage and a smaller size) than a widening adapter or a larger tube further.

  • One may be more convenient or easier to use when exchanging lenses. Suppose you have an EF lens that you want to use for macro and one that you want to use normally. To change the lenses with an EF tube, you can leave the tube connected to the lens, but with an EF-M tube, you would have to take out the tube Y Exchange lenses

  • The lenses you can wear with each would be different.

  • Prices may be different.

I have several adapters and extension tubes (which can be connected to both sides of the adapter). Most of the time, I would prefer to attach the tube to the lens because it is easier to change the lenses that way. But if I could do it again, I would skip the extension tubes.

If you are open to using manual focus lenses, consider using a fast-priming helical adapter. (Old 50 / 1.8 lenses are quite economical). The helical adapter will allow you to use the lens normally, as well as extend it to work in the foreground, without having to waste time connecting and disconnecting additional tubes.

Networks: I have a smart home with many Wi-Fi devices connected. Is there a limit to the amount I can have?

So I have approximately 30 devices that can only connect to 2.4ghz bands and about 20 devices that can connect to 2.4ghz or 5.2ghz.
Given that most of the first (only 2.4) are light switches, plugs and bulbs, most of the time they are inactive (I guess).
However, I have constant connectivity problems with this router since I started configuring smart devices.
I am working with a Nighthawk AC1900 smart WiFi router. Any suggestions?
Would a mesh network work better? (Like Google WiFi) I'm just asking because I'm not sure if each device increases the total "bands" I can work with.

9.0 foot: is it possible to use a Bluetooth headset while using a microphone connected to the headphone jack?

I will attend an event as a representative of a semi-professional podcast.

I am going to interview several people, but it is a long and busy event with no area for formal interviews, so I will use my phone (Samsung Galaxy Note 9) with an external microphone to save space.

In a discussion with the podcast host, it was suggested that we try to establish a "live broadcast" so you can give your opinion during the interview.
"Live streaming" is not a big problem since I am able to stream content from my phone.

My main concern is to hear about the crowd, usually a Bluetooth headset would solve this.
However, I am not sure if an external microphone connected to the headphone jack port would override the headset as a microphone.

Does anyone have any experience using a Bluetooth headset and a Jack microphone simultaneously?
If no one has tried this before, is it theoretically possible?

In a subset of $ mathbb {R} ^ 2 $ that is not simply connected, is there a simple loop that does not contract at one point?

Earlier I asked In what topological spaces the existence of a non-contractable loop to a point implies that there is also a simple non-contractable loop?

Given the wide scope of this question, I propose this special case as an independent question:

In a subset of $ mathbb {R} ^ 2 $ that is not simply connected, is there a simple loop that does not contract to a point?

Power: Macbook Pro (mid 2015) will not turn on even without the battery connected, the Magsafe light is amber

My Macbook Pro (mid 2015) does not turn on.

I recently replaced the keyboard and after reassembling everything and turning it on, the battery condition said "replace now", I didn't have this problem before replacing the keyboard.

It stayed that way for about a week and I could only turn on my Macbook with the Magsafe connected, there was no power coming from the battery. However, I don't think it was a battery problem, since my Macbook will restart after about 5 minutes, even with the battery disconnected. So it seems like a software problem or something.

Now I can't even turn on my Macbook. The battery is disconnected and I am trying to power the Magsafe, which should work, but it does not work. I have tried an SMC restart countless times without success. At first, the Magsafe light was changing color, indicating that an SMC reset has been recognized, but now even the light will not change color when I attempt an SMC reset.

If my Macbook does not even turn on when I try to turn it on using only the magsafe and with the battery connected, what could be the problem? Macbooks are supposed to turn on automatically when Magsafe is connected if the battery is disconnected, so I am completely lost.

Haar measurement of the zero set of a non-constant analytical function in a connected Lie group

Leave $ G $ be a Lie group connected and equipped with its unique real analytical structure, $ f: G to mathbb {R} $ a real analytic function not constant in $ G $. It is the closed set $ Z_f = f ^ 1 (0) $ Haar always measures zero?

This article by John E. Coury seems relevant. I have a feeling that there should be a simple test to answer yes to this question, and I would be surprised if this were not true.

Privacy: Ubuntu remembers all connected drives and each DVD inserted, and PCmanFM shows it in the folder panel

I am using PCManFM 1.2.5 as a file manager in Ubuntu 18.04.2. When I go to my media folder, there I find a list of the names of each external drive that I connected and each disc that I inserted into my DVD drive and even for my WLAN they paste a separate entry for each time I connected it to the computer. How can I make Ubuntu empty this list daily or forget devices as soon as they disconnect?

Both CO2 and temperatures have risen worldwide, so why do people still insist that one is not connected with the other?

I will always remember my first apprenticeship in Research 101. It says:

As the baseball season progresses, people eat more ice cream. Therefore, ice cream is correlated with baseball.

While you could technically make that connection between the great American pastime and cold treats, there is something else at stake. That other thing is summer, which both baseball and ice cream have in common.

The so-called "warming" has been correlated with the emergence of urbanization since the Renaissance. Could urbanization cause warming? Consider these quotes:

"As population centers grow, they affect increasingly larger areas, which will generally experience a corresponding increase in average temperature."
–Ole Humlum, Professor of Physical Geography, U from Oslo


"But is it possible that the particular increase in temperature observed in the last 100 years is the result of carbon dioxide produced by human activities? Scientific evidence clearly indicates that this is not the case."

–Sallie Baliunas, Astrophysics, Harvard-Smithsonian Center for Astrophysics

It is often a trite date, but it is still useful when understood: correlation is not necessarily causation.

If you take into account much stronger forces such as the sun, galactic rays, planetary forces, etc., then simple correlations can be confused very quickly. That is to say nothing of very inconsistent / doubtful temporary measures for more than 200 years.


ios: can I use mobile data when connected to another device via WiFi Direct?

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Is a simple graph connected, if each node has at least one adjacent border and $ | E | ge | V | -1 $?

Leave $ G = (V, E) $ Be a non-directed graph without automatic loops or parallel edges.

Is the following statement true?
Yes $ | V | = n, | E | ge n-1 $ and each node has at least one adjacent edge, then $ G $ Are you connected.

I have tried it for $ | E | = n-1 $:

by $ left | V right | = $ 1 The graphic is trivially connected.

Induction step:
Let the statement be displayed for all graphics $ G = left (V, E right) $ where $ left | V right | = n-1 $ Y $ | E | = n-2 $.

Leave more $ G = left (V, E right) $ with $ left | V right | = n $ Y $ | E | = n-1 $ be given

Now we are looking for an induced sub graph $ G | _ {V ^ prime} $ where $ V ^ prime subset V, left | V ^ prime right | = n-1 $so that $ G | _ {V ^ prime} $ have at least $ n-2 $ edges

(Any of these sub-graphics can have at most $ n-2 $ borders, since there will always be at least one edge that originally leads to the deleted node)

Suppose now that each subgraph $ G | _ {V ^ prime} $ has less than $ n-2 $ edges
Then, the node removed in any sub graphic would have at least $ 2 $ edges

Therefore, each node must have at least $ 2 $ edges, and therefore it should exist at least $ n $ edges on the chart.

Therefore, there is at least one sub graphic $ G | _ {V ^ prime} $ with $ n-2 $ edges, for which our induction assumption is fulfilled. And because there is an advantage of $ G | _ {V ^ prime} $ to the erased edge, we get that $ G $ Are you connected.

Therefore, the induction is completed.

However, if I try to generalize the previous test, the same style leads to an inequality that is only met if $ | E |> | V | $.

Therefore, if the previous test can be generalized, what would it look like? If not, what is an example where it fails?