NMGPhotos

I'm pretty good with math, lol! do you know of any comprehensive guides (perhaps maybe with visuals) that show how this works?

What is the 4mm focus in reference to, and also how is D-o-F calculated like this?

What are you basing this calculation on? Just curious. It was my understanding that the f-number has effect on DOF, but can focal length have effect as well? Completely understand and completely agree. Was just curious about the differences. That is interesting. Looking through the viewfinder, I was unable to see the grate. I don't know if it would have shown up on film as I didn't have any at the time.

I am still curious as to why my phone camera was unable to focus past the grate (even when focused manually). Not that I expect it to, just wondering about possible reasons.

Looking at specs it appears to be 27mm (full-frame equivalent). This does still seem a bit strange, as a shallow depth of field should let me focus past the grate? I would assume it's perhaps the size of the lens in relation to the size of the holes. Apologies! Attached is a picture I took with my phone camera. As mentioned, my SLR lens could easily focus past it and to the bus behind it.

I understand that. Just for your information though, I did try using a manual focusing app and even focused as far as the app would let me and the grate was still was clearly visible. Again, not particularly surprising, just wanted to add that. According to spec sheets, the lens on my phone is a fixed ~f/1.7 (which is surprising, as that should lead to a very shallow depth of field?). Could the size of the lens also play a factor? If it's (at least partially) solid, why would it disappear instead of obstructing the view? At what point does a grate become an obstruction you can't focus past? Thanks for this info! That does make sense. That does sound like a plausible explanation. That is also very interesting. They are small-ish holes. I still just find it fascinating that it's able to disappear like that.

I recently got a film SLR and was playing around with it at the bus stop earlier today. The bus stops shelters where I'm at have, on one side, a coarse grate-like design with circular holes. There is a lot of material between the holes. However, the lens I had was able to focus past it and onto the objects behind it very easily to the point where, at least through the viewfinder, you wouldn't be able to tell it was even there. Granted, it was late at night and perhaps objects beyond it being lit more helped, but I am curious as to the physics of this. My phone camera was not able to focus past it (although I didn't expect it to be able to).

I may take a look! I've actually gotten two more cameras in the meantime, lol!

Sounds interesting. And yeah, I don't expect much. But thanks for the help 🙂

Ok, no now I see what you're saying @AJG. It is likely the lever mechanism. But I am not sure why it is different on the Quantaray. Is an adapter needed? Or is it just a crappy lens? EDIT: Perhaps it is bent. If it is, that's impressive because it's pretty solid. EDIT 2: Use some pliers to bend it back upwards. Seems to have fixed it? No idea how it got bent in the first place.

The "bent" one is the only one in which the view through the viewfinder is dramatically changed when adjusting the aperture. The others show little to no change. I thought I noticed some change on one, but on repeat tests, I saw no change. I also put "bent" in quotation marks because it seems to be how it was designed. The material does not appear weaker at the curve (which would be more likely if it was actually bent from its proper position). As for the levers, I can move them on the lenses themselves, but when they are attached and I press the shutter, I see no movement on the aperture. Additionally, to be specific, it's the Quantaray lens that does not work.

Also, I was wrong about the other lenses not changing apparent brightness when the aperture is adjusted. It just seemed more dramatic on that one lens for some reason. EDIT: No, I was right. It's basically no change on the others.

Attached are photos of the difference lens (front, rear, and latch). @tony_parsons1

Yeah, I assumed as much, but a battery doesn't hurt! As for the lever, it does indeed move freely, but the lever mechanism itself is shaped slightly differently than the others. That may be the difference here. Photos incoming!

Will do soon! I went out to buy a battery for the camera's light meter. I'm also wondering if that may be the reason it doesn't work. Another interesting thing: for the lens that doesn't work, adjusting the aperture actually causes the view through the viewfinder to dim or brighten. The apparent brightness doesn't change with the other lenses.