Technique question

I can't recall the name of the effect, but I was wondering what settings would be needed to get the spiral cloud/mist effect off of propellers when they are spooling up on the ground.

you mean where you see a disk rather than each individual blade ?
its just a slow shutter speed.
anything from about 1/60th to 1/200th should do it
at take off you can raise your shutter speed even higher - 1/320 etc

of course i may be wrong in which case i hope someone else corrects me - then we will both learn something
or i may be describing the wrong effect

If the aircraft is in profile, not much will help. You're usually going to have to get below 1/250 for a good prop blur. Do a search for "Threads started by" Marauder61 for some inspiration. Or look at his gallery which has the exif data: Marauder61

Airshow guys - prop freeze?
https://photography-on-the.net …/showthread.php​?p=2175804
Airshow guys - prop freeze?

Posted by adamsti: General rule of thumb for props, 1/250 and slower for flying aircraft. 1/200 and 1/160 give very nice blur. For aircraft taxing 1/125 and slower. 1/60 is very good here. Obviously here you need a steady hand, but it can be done with practice.

Posted by peacock: " I always try to shoot the prop plane @ less than 1/125..."
https://photography-on-the.net/forum/showthre​ad.php?t=209768

Some good info here, but he doesn't get shutter speed right either.
Air Show Photography

I haven't been able to find an example image, as I can't figure out what terms to search... what the effect looks like, is straight on the front of the props, as the plane is spooling up on the ground, early morning humidity/cool air + turning props creates an effect of a spiral cloud (think a tornado going down a drain) I don't believe the effect is visible with the naked eye, but once shot with a little longer of a shutter speed it appears.

I saw a photo of it once and a pilot/photog talked about it said it was one of those cliche'd but must have photos of aircraft.

hope my descriptions help what I am looking for...

Thanks!

It depends how close you are. A 1/200 exposure would probably freeze a helicopter propeller from a distance but it would be blurry up close. Apparent speed changes depending on your viewing distance (which is why an airplane going 600 miles an hour looks very slow when it's cruising over your head at 32,000 feet, but a car going 40 miles an hour seems very fast when you're on the sidewalk next to it). It's not an illusion either. It just has to do with change in distance divided by the arc of your line of sight that it traverses. If you have, say, a 50 degree angle of view through a telephoto lens, those 50 degrees delimit a much shorter distance 10 feet from you than they do a mile from you, so even an object moving at the same speed over the same distance will require different shutter speeds to appear frozen.

Anyway, the point is that it will be easier to achieve the effect you're looking for with a closer subject.

Also be aware that if you expose for too long the propeller will just disappear. I'd say a 1/30 or 1/60 exposure is a good place to start.

I understand the effects of speed vs distance vs angle, etc for prop blur vs total prop disappearance or static-ness... the effect I am asking about is an actual vapor trail cloud created by the propeller, nothing to do with the propeller itself...

It is more about atmospheric conditions existing at time of exposure once you have the cam setup you think will work.

Ok, I'm guessing that you'd see that on a high humidity morning? Why not PM Marauder61 & ask him?

Hmm, maybe in very cold conditions because you'll get more condensation.

I finally was able to find an example diagram of the effect:

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And thanks to the responses, I'll send a PM and see what I can learn.