Correct about 2 blades vs 3 blades. Yes it works as shown with video. One blade vs two is equal in this case. Use to check old tachs but pointless with electronic ones.

Here is an easy one. The iPhone always shoots at the same aperture but varies shutter speed with precision. Compare with same target at same time and maybe evaluate the exposures.

I haven't tried this in many years but be aware that fluorescent tubes flicker at 60 hz. As for the other speeds, if that one is OK you can measure the density changes from there to other speeds. How? with a light meter and a white target on your monitor or some similar concept. There are light meter apps for smart phones. You camera has a light meter. You may even have or be able to borrow a real light meter.

If you are near a general aviation airport and can find a cooperative pilot, one whose panel is "glass" rather than old style, then have him/her run the prop at 1800 rpm. "You do the math". The prop should appear to stop at a multiple of your shutter interval.

Second update:

The big and expensive option from Siri is attractive but I decided to try a minimalist approach. The suggestion of a large rubber foot gave me the idea that something that would give me a little bit of resistance to movement of the monopod might help. I did some internet searching and eventually found something with a larger bottom surface than the monopod and with a hole into which my monopod's existing "foot" or hoove would fit. I had to order two to get them to accept the order and because Amazon didn't carry it I had to pay for shipping. Here is what I ordered. I will probably post another update at some point. BTW, the Perry video was helpful.

The foot you see here was the only one I could find that would fit and still offer some bottom diameter. I would have liked a bigger bottom surface but so far have not found that.

When jumping in and out of the car, carrying the monopod, etc., this will be easier and lighter than the $75 Sirui product. Of course, a really good tabletop tripod as a bonus might still be the way to go.

Those who say it makes no sense to them to add feet to a monopod will not be persuaded. I am OK with that.

However, the freedom of motion with a monopod that has a friction-adjustable ball joint at the bottom and then three feet beats a tripod's. That should be obvious.

Just to be clear, I'm not talking about the slimmer dimensions or the lower weight. I'm talking about being able to aid the camera while still having some support and some steadying forces.

I already have the carbon fiber monopod so the economics favor the attachment. But thanks for the suggestion.

Thank you to all who tried to help. Here is an update.

1. My monopod, it turns out, does not have a common bolt thread on the point. Rather, it has, from Sirui, a proprietary kit that includes an adapter and a sturdy looking tripod that can double as a tabletop tripod. One of you showed pictures of the same thing but on a different model. So I if I want to add a 3 footed adapter I have to spend about twice as much money. The large, flat, circular foot looked interesting, too, but it would not work on my gear. That's a shame.

2. All who point out that a monopod with feet is not a tripod and should not be used that way are correct. Obvious, but true. I have a tripod - two or three, actually - but carrying them around and getting them in and out of the car and then quickly setting up is not what I want right now.

3. When shooting birds, even in good sunshine, I use F8 for DOF and, besides, that is all my reflex lens offers. For the obvious reasons, I use at least 1/000 shutter speed. That means that I'm at ISO 200 already. I am thus already in the corner of the envelope. I'm simply not as steady as I was when young. I use trees, railing, car windows, etc. when available. But the monopod could offer another method. Another stop of shutter speed would help but can introduce noise in the image. I've experimented with this and found that sharpness is reduced from 1/000 to 1/2000 for that reason.

4. My 500 mm reflex lens offers AF and is very sharp. But it doesn't have any image stabilization of its own. My camera, a Sony 𝜶6500 has in-body stabilization but that's much less effective than when the lens also has it. When I rented a Tamron 150-500 the net effect was greater stability. But I haven't made up my mind to spend $1400 quite yet.

4. When shooting with a monopod some axes of motion (such as vertical) are stopped or steadied but some aren't. For example, yaw (left-right motion) is not affected. With a foot such as a little tripod device and a friction-set ball, more of the possible motions are either eliminated or slowed. Pitch is another that can be better. Some of you agree and some of you don't. I lean toward increased resistance to camera motion. The physics and geometry are easy. Real life is sometimes more complicated. At an equivalent of 750 mm, even the tiniest motions are detrimental to sharpness.

Yes, for me it would be a given. But thanks for saying it. I would only use it like a foot-less monopod but hoping to get additional resistance to motion when using long lens (500mm) for birds.

I have a SIRUI P-326 monopod and I'm quite happy with it. However, I'm thinking about adding a 3-feet attachment to the bottom end. Amazon has several at reasonable prices.

Does anyone have actual experience with:
A. adding feet to existing monopod?
B. a particular brand or model that was either notably good or notably bad?
C. experience with a monopod that has feet, even if it came with them, to suggest that this is a good or bad idea?
D. any "gotchas" to consider that are not immediately obvious?

No, I don't want to use a tripod.

Thanks in advance.

When I drive 6+ hours a day for four days in a row I want to know my speed accurately. There are speed traps, for example. It isn't about saving two minutes.

When I fly my airplane I want accurate airspeed and groundspeed and fuel consumption. Maybe you can guess why. If you don't care about it, that's fine. But other folks may have valid points of view, too.

A reasonably accurate way to check exposure, in my experience is to start with a gray card if you have one or with a piece of white paper for which you know the reflectance (see the package it came in). If you use a gray card, determine in advance if it's 18% or 12% reflectance (or whatever)

Then, on a clear day in the mid-latitudes at mid-day, carefully take some test photos of the target. I know not everyone is in the mid-latitudes but life isn't perfect.

Why those test conditions? Because the EV should be close to 14.7 (Sunny 16 "rule").

Now view the image file in any of many available viewers or editors that can show a histogram. But, in my experience, the raw image histogram shows a lower exposure (left of center) as compared to the JPG. Be aware that there is no applicable standard for raw, only for JPG.

If you used a white target you need to compensate for the difference in reflectance (example: 92% vs 18%).

This is not really perfect and you have to take care to take your test exposure without angles that distort the reading. Since most cameras show "live" exposure, you can wiggle the target to know in advance how you are doing.

This is "old school" stuff but it's still correct.

With those test conditions you can compare your camera's or meter's readings to what you know they should be and you can also check the results on your computer.

I had two Hondas which both read about 4 or 5 mph high at highway speeds. My GMC Acadia and my Wrangler both read correctly. How do I know? Well I used to use a stopwatch on the highway where there were mile posts but now I just use my iPhone for which there are various apps.

Why bother? Because I want to be able to go as fast as is legal and not worry about a ticket. Duh!

This may apply, hope it does. I rented that lens in the version for my Sony 𝜶6500 which is an APS-C camera. I can't image how the hood would be a factor since it goes on the front of the lens. That lens is really, really good. It compares very well against lenses costing much more.

If the mount fits your camera then the only difference from full frame will be the coverage. In other words, the lens is able to cover a "full frame" sensor but on a crop frame camera it will only show you the smaller, center portion. The crop frame also means that your photo will appear to have been taken with a 225-750.

Your snark is duly noted. Of course nobody today could possibly benefit, right?

I have tried Spiratone 300, Sigma 500 and Minolta 500 AF. Recently I bought a Nikon 500. I wanted to see if it was better than the Minolta. It wasn’t. And the Minolta AF on my Sony a6500 using modified LA-EA4 is now perfect.

The mirror lens has all the well known drawbacks but I like it. Short and very light.

I rented a Tamron 150-500 and like it a lot. But the Minolta reflex is just as sharp. My test target is fine (noseeum) screen at >200’. The mirror lens has less DOF than a normal lens at same F8. The mirror lens also needs +1/3~1/2 stop compensation. This isn’t because of the translucent mirror in the adapter because the mirror is removed in the modification.

In good light for birds I use 1/1000 and auto ISO.

I would REALLY like to have my old micro-prism focus screen in my Sony 𝜶6500. Even at its best setting, focus peaking is just not very precise. I had that micro-prism on my Nikon FM2. I had swapped out the split image for it and was then quite happy.