Testing EF Lenses On IP Camera

Probably worth noting that the Canon lens you used was their L-series glass, which is the top-of-the-line pro-grade stuff. You can get the EF70-210 F4 (non-L) for about a third the price.

Tamron and Sigma also make competing EF-mount 70-200 or 210, F/2.8 lenses, at about 1/2 to 2/3 the price of the Canon.

Interesting test!

Do you think that ppf or the distance is the real driver of the declining superiority of the EF lens vs the Computar?

Said another way, were you to use a sensor with the same physical size but twice the resolution and without changing focal lengths, would you expect the performance of the two systems to converge in the same way?

Or might the EF be much better at all three distances in that case, because enough pixels are available to render a lens with better MTF?

Great test! I would love to see a similar test using the Axis Q1659 20mp EF mount camera when it releases using high end Canon L lenses along with value options from Canon, Sigma, Tamron, ect.

It's great for IPVM to do such a test to clear "myth" of how good a lens is, like super expensive lens used for security camera. There is a common misunderstanding that more expensive and more "professional looking" lens are better, which is not true. but this article has not discussed about that technical detail, so let me share some of my understanding.

Different lens are designed for different image size, which means big EF lens is not necessarily better than small C/CS mount or M12 lens. For example, on 1/2.3 inch 4K sensor, it needs the lens to have > 300LP/mm (Line Pairs per mm on imager) in order to resolve the full resolution, but regular EF lens is designed to have > 100 LP/mm, so we can say most of EF lens may fail for a tiny but high resolution sensor.

However, on some 1/2 inch 1080p sensors, it only needs to have 130LP/mm to resolve all pixels, then high quality EF lens can do better than regular C/CS mount lens. the Canon EF Tele lens usually have very high MTF, and the LP/mm is also higher, which can be helpful to get higher resolution, higher contrast, and less image artifacts.

Conclusion is, only on bigger sensor (like 1/2), and low resolution (1080p and below), EF (Luxury White) lens can have noticeable better performance than regular C/CS mount lens (under 100$).

I would say this test was... eye opening.

Since the 70-200 Canon L lens is an autofocus lens, but this feature not used for surveillance test, a premium price goes along with the lens. Testing older fixed focal length SLR lenses from the 1960's for example may be a lower cost alternative. a Canon manual focus 85mm f/1.4, higher power, or other brands may be considered. I would suspect noticeable differences comparing the Canon f2.8 used in test to a manual focus f1.4 or f1.2.

OK, so I'm glad someone else bumped this thread so I didn't have to be the necro-bumper, but either way, I have a question.

Per the thread that I posted awhile back, I have obtained a Bosch NBN-80052-BA 5MP box camera, the same Fotodiox CS>EF mount adapter used in this test, and a Canon 55-250mm zoom lens (specifically THIS one) that I just happened to already have for testing. I've been testing it over the past few weeks, and I've run into some issues that I'm hoping someone can point me in the right direction on. I'm admittedly green on this stuff so I'm sure there's something simple or straightforward that I'm missing, but I'm about to lose my mind over whether this is my issue or something being imposed by the camera/adapter/lens.

To make a long story short, I can only get the camera to focus within a fairly narrow zoom range. Regardless of what settings I change on the camera or anything else, actually changing the focus in the camera settings itself, there are many areas of the zoom (probably 70-80% of the camera) that I can never get to focus. I am able to zoom the camera to roughly 100mm and get it to focus, and then I can zoom it up to about 180mm or so and get it to focus there. But, anywhere outside of those ranges, it simply doesn't work. It's like the camera doesn't possess the ability to "focus" outside of those ranges, and the focus ring on the lens doesn't nothing whatsoever.

Is there something I can change in the camera to help this work? Anybody have any idea what would be causing this, or how I can fix it? I have some suspicions, but I'd be curious what everyone else here thinks, because this level of detail on the "why" a lens will/won't work is above my level of expertise.

For the record, the most frustrating part by far is that part of the range that I CAN get it to work will deliver an absolutely beautiful image (>40 ppf) at over 1100 feet away, with a depth of field of over 2100 feet. If I can figure out how to get the thing to focus, I'd have an absolute winner on my hands...

Final answer?

Ethan Ace is a golden god.

Well, that's at least PART of the final answer.

The lens does indeed power down and make the trim ring nonfunctional. The lens only allows focus via the trim ring when the camera is powered.

However, this still doesn't full solve the issue of the camera failing to focus, sometimes grossly so. No amount of working that trim ring is going to make it focus I don't think, so it would just be for finer adjustments once the camera did the heavy lifting.

So, my next step is to follow your advice and work on getting a CS>C>EF adapter to see if extending the lens away from the camera body will improve my ability to focus any. I've got a few things i'm going to test as well just to see what happens, but if anyone else has any thoughts or ideas, please share them.