Video/carbon images of croquet strokes

Images on this page Copyright © Jenny Williams. For links and references, the URL of this page is: http://www.hep.man.ac.uk/~jenny/kiwi/sport/croquet/video/video.html. Please also note that all croquet-related material on this site is private work and does not seek to represent the Department of Physics and Astronomy of the University of Manchester, or the University itself.

This page: Miscellaneous croquet strokes, pass rolls with minimal meshing of ball milling
page2: Pass rolls with maximal meshing of ball milling, full rolls with flat (horizontal) mallet
page3: Hammer strokes

These pages contain images (jpg) of croquet strokes. In most cases, the strokes were played with carbon paper and normal paper on the face of the mallet. Where this was done the carbon paper images are presented before the video frames.

Video: The images were captured on a Samsung camcorder with a shutter speed of 1/1000 sec. Faster settings were possible, but these yeilded no further information and served only to reduce the available light. The frame rate is 25 frames/second - this is standard, and is the fastest frame rate available in high street camera/computer/video shops. Higher frame rates are possible with specialist research equipment, and an application has been made to hire such equipment.

The images represent sequential frames - separated by 1/25 second (0.04 sec). Where there are several strokes repeated, subsequent strokes may lack first-contact frames, but in these cases, that contact looks just like the one before.

Small white stickers were added to the balls to make any rotational motion clear.

The poor photo quality is due to the (unavoidable) transfer process.

General conclusions:

Pass rolls are interesting
Flat (horizontal mallet) full rolls are illegal
currently available technology is unable to support the concept of a "3rd umpire" in croquet - the main action (double taps, etc) happens in less than 1/25 second - meaning that specialist research or television equipment would be required - even UKP1000 camcorders are not up to this task!

Acknowledgements Camcorder loaned by Ian Duerdoth, Striker is Dave Maugham, surface is carpet (it's winter here!), balls are Barlow G. Mallet face is 2inches by 2inches (manufacturer).

I will update this site as time permits, and as feedback requests. If anyone undertakes any measurements using this data, I'd be interested in (re)viewing the results. Any suggestions/comments welcome.

Note that the tables on these pages are set to a fixed width and have 4 columns.

page2, page3

Stroke: half-3/4 roll
The photograph to the right shows equipment used to carry out the croquet stroke experiments shown in these pages. The camcorder wasn't digital, so the strokes were saved to VCR.
Comments:

Stroke: 3/4 to full roll Comments: In all the roll strokes the striker's ball was rolling as soon as it left the mallet face, but the croqueted ball skidded for some distance. (In stop shots, both balls skidded for some distance.)

Stroke: Pass roll.
Studies were carried out to see the effect of milling on pass rolls.
The photo to the right shows the milling pattern of the contact point of balls in the green/blue ball strokes.
Comments: Note:

backwards spin on croqueted ball
elevation of striker's ball
grip on mallet

Stroke: Pass roll Comments: Note elevation on striker's ball

Stroke: Pass roll Comments: Fault. Double hit. Second contact shown in second frame. "Played badly"

Stroke: Pass roll Comments: Fault - second contact (shown in second frame). "Played badly"

Stroke: Half roll Comments: Very clean stroke, striker's ball jumps significantly in stroke.
This series of frames also show rather clearly that the contact time for the striker's ball is much longer than that for the mallet-SB-CB

Stroke:Pass roll.
The following 5 strokes (yellow/black) were played with the two balls placed so that they were in contact with the "G"'s on the balls touching. This is commonly used by players to minimise "pull" in peels. It has the effect of minimising the amount of friction between the two balls by minimising the amount of meshing of the milling of the balls. The part of the balls placed in contact is shown in the figure next to the carbon paper image to the right.
Comments: There is some evidence at the bottom of this image of a second contact between the bottom bevel of the mallet and the black ball just to the right of the main contact point.

Stroke: Pass roll Comments: Striker's ball jumps, croqueted ball does not. This is to be compared with the pink/brown strokes with different milling patterns of the balls in contact.

Stroke: Pass roll Comments: Clean

Stroke: Pass roll Comments: Clean. Striker's ball jumped, and no second contact is observable. Note interesting pattern of sliding of striker's ball across mallet face. (Some sliding is to be expected in all full and pass rolls as the friction between ball and ground is less than the friction between mallet and ball - hence the ball rolls along the ground from the initial contact time, but slides relative to the mallet face.)

Stroke: Pass roll Comments: Poor stroke on edge of mallet face. Slight tearing of the material on the mallet face is evident on the second frame.

page2, page3

Feedback

Last updated: 16 Feb 01

Stroke: half-3/4 roll The photograph to the right shows equipment used to carry out the croquet stroke experiments shown in these pages. The camcorder wasn't digital, so the strokes were saved to VCR.	Comments:

Stroke: 3/4 to full roll	Comments: In all the roll strokes the striker's ball was rolling as soon as it left the mallet face, but the croqueted ball skidded for some distance. (In stop shots, both balls skidded for some distance.)

Stroke: Pass roll. Studies were carried out to see the effect of milling on pass rolls. The photo to the right shows the milling pattern of the contact point of balls in the green/blue ball strokes.	Comments: Note: backwards spin on croqueted ball elevation of striker's ball grip on mallet

Stroke: Pass roll	Comments: Note elevation on striker's ball

Stroke: Pass roll	Comments: Fault. Double hit. Second contact shown in second frame. "Played badly"

Stroke: Pass roll	Comments: Fault - second contact (shown in second frame). "Played badly"

Stroke: Half roll	Comments: Very clean stroke, striker's ball jumps significantly in stroke. This series of frames also show rather clearly that the contact time for the striker's ball is much longer than that for the mallet-SB-CB


Stroke:Pass roll. The following 5 strokes (yellow/black) were played with the two balls placed so that they were in contact with the "G"'s on the balls touching. This is commonly used by players to minimise "pull" in peels. It has the effect of minimising the amount of friction between the two balls by minimising the amount of meshing of the milling of the balls. The part of the balls placed in contact is shown in the figure next to the carbon paper image to the right.	Comments: There is some evidence at the bottom of this image of a second contact between the bottom bevel of the mallet and the black ball just to the right of the main contact point.

Stroke: Pass roll	Comments: Striker's ball jumps, croqueted ball does not. This is to be compared with the pink/brown strokes with different milling patterns of the balls in contact.

Stroke: Pass roll	Comments: Clean

Stroke: Pass roll	Comments: Clean. Striker's ball jumped, and no second contact is observable. Note interesting pattern of sliding of striker's ball across mallet face. (Some sliding is to be expected in all full and pass rolls as the friction between ball and ground is less than the friction between mallet and ball - hence the ball rolls along the ground from the initial contact time, but slides relative to the mallet face.)

Stroke: Pass roll	Comments: Poor stroke on edge of mallet face. Slight tearing of the material on the mallet face is evident on the second frame.

Video/carbon images of croquet strokes

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